Water Sensitive Design PhD study by giambattista zaccariotto

Universitaâ&#x20AC;&#x2122; IUAV di Venezia Dottorato in Urbanistica XXI ciclo

Integrated Urban Landscapes

Water Sensitive Design for the cittĂ diffusa of the Veneto Region

Ph.D. candidate: Giambattista Zaccariotto January 2010

Universita’ IUAV di Venezia Dottorato in Urbanistica XXI ciclo

Coordinator: Prof. Bernardo Secchi Tutors: Prof. Paola Vigano’ (IUAV) Prof. Sybrand P. Tjallingii (TUDelft)

Ph.D. candidate: Giambattista Zaccariotto

Introduction I. Spatial transformations and water issues, an analysis I.1 Frame I.1.1 Introduction I.1.2 Land and water 1. Geographical frame – 2. The wide hydrological cycle – 3. Climate frame I.2 Landscape processes I.2.1 Introduction I.2.2 Models and processes of transformation I.2.3 Conclusion I.3 Water processes I.3.1 Introduction I.3.2 Irrigation water and drainage water 1. Field system – 2. Stream system – 3. Plot system – 4. Road system – 5. Irrigation and drainage at the water board level – 6. Problems and challenges. I.3.3 Drinking water and waste water 1. Plot system. – 2. Drinking water and waste water at the water board level. – 3. Problems and challenges I.4 Conclusions

II. Water challenges and spatial design II.1 Landscape and water strategies II.1.1 Guiding model approach 1. Conceptual shift: guiding principles – 2. Guiding models II.2 Retrofitting scenarios II.2.1 Introduction II.2.2 Collective 1 1. Program – 2. Rhythm – 3. Orientation – 4. Situation – 5. Guiding model II.2.3 Individual II.2.4 Collective 2 1. Program – 2. Rhythm – 3. Orientation – 4. Situation – 5. Guiding model II.3 Conclusions

III. Guiding models appendix 1. Dwelling lot – 2. Industrial lot – 3. Agricultural field – 4. Forested buffer strip – 5. Road strip – 6. Highway corridor – 7. Stream corridor – 8. Quarry area

IV. References and sources for the maps

Introduction

In the decentralized urban landscape of Veneto Region, Northeast Italy, spatial process of change from a fine and decentralized grain to a coarse and centralized grain of land use spaces progressed at an unprecedented rate for the last decades. The process of change has had a positive side: it has brought economic prosperity to the region but it has been also accompanied by spatial problems such as loss of diversity, attractiveness and legibility. Less visible are increased water problems such as flooding, drought and pollution. These are related to an increase in large in-put out-put water flows and the loss of decentralized storage. The water and spatial conditions increase incidental damages and long-term uncertainty. How can the spatial form of an urban landscape contribute to more sustainable water flows and, in turn, how can more sustainable water flows contribute to the spatial quality of an urban landscape? For designers the challenge is to re-integrate decentralized storages by looking

Fig. 1 The urban landscape of Veneto Region: one of the most dispersed fine-grained urban landscapes in the European territory. 5

for opportunities in the local landscape. This leads to strengthening of the role of decentralized fine elements, such as ditches, hedgerows and plots to hold water. This is the carrying condition for promising spatial and functional combinations in making plans to support and develop a sustainable urban water landscape. Research-by-design in a case study in the Veneto region is the testing ground. Water system as carrying structure The European urban system is undergoing a process of transformation and restructuring. Urban landscapes of dispersion with different grains are emerging: the living space of the majority of mankind results from innumerable individual rational decisions. The plain of the Veneto Region in Northeast Italy is today, defined at the beginning of the Nineties a cittĂ diffusa (Indovina 1990, Secchi 1991), is today one of the most extensively inhabited and economically competitive urban landscapes in Europe. As part of the wider Padana Valley, its geographical limits are the Alps to the north and the Appennini and the Adriatic Sea to the south (fig. 1). From an aerial view it is possible to distinguish its spatial structure: a hybrid mosaic of fine and medium coarse grain resulting from different-sized patches and corridors stretched from the upper plain down to the lower plain. Varying in function, scale and use, the patches include ancient centres, modern centres and their periphery, villages, rural houses, villas; bell towers, water towers, small industrial buildings and the big advanced industrial platforms, treatment plants and pits. The corridors include the main rivers and the pervasive minor surface water networks of irrigation and drainage often accompanying the minor road network (Munarin and Tosi, 2001: 83). The visibility and rhythm of green structures enhance these networks. The patterns of the minor surface water networks exhibit capillarity and proximity to all land use programs. Diverging structures include systems of distribution for irrigation, hydropower and drinking water. Converging structures include systems of drainage and waste water collection. These structures permeate the underlying agricultural matrix, turning it into porous form (Forman, 1995: 279). Potable and waste water networks and the recent sub-irrigation systems remain invisible. The fine grain is the result of highly diverse small-middle spaces packed together and visible across different scales (fig. 2-3). Apart from rainwater and surface water, the unconfined groundwater of the upper plain and the confined groundwater of the middle plain are important water resources (Boscolo and Mion 2008). The management of these water resources has created basic conditions for land use throughout the history of human occupation in the plains (Bevilacqua, 1989) (fig. 4). Works of geographical scale include the roman centuriatio system, the acque alte (upper waters) network initiated by the Etruscans, the acque alte minori (upper minor waters) network of the Venetian Republic from the XIV century in the middle plain, the bonifica (reclamation) network of XIX and XX century in the low plain (Rusconi 1991: 101). The resulting water networks present a palimpsest, a basic pattern that is a carrying structure of the identity and quality of the dispersed, cultural landscape of the cittĂ diffusa (Secchi and ViganĂ˛ 2006). The Veneto Region has about 4,8 million inhabitants, spread over 580

Fig. 2 From a section of Treviso in the middle plain it is possible to distinguish a hybrid mosaic of fine and middle coarse grain which is the result of different sized patches and corridors stretching from the upper plain to the lower plain. The image of an isotropic urban landscape emerges. 7

municipalities. The average population of 75% of them ranges between 1000 and 10000 and covers the 64% of the regional area. The average population density varies from 245 to 508 inh/kmq. The agricultural matrix occupies 58% of the land; of this 20% has been urbanized in the last 40 years. Small and medium-sized firms and tourism are the driving forces of the economy (Statistical Report Veneto Region 2007). This is the decentralized urban landscape of the Veneto Plain. Here, unlike rapid sprawl developments in other parts of the world, there is a historic continuity of the diversity of spatial situations exhibiting the lifestyle variety of dispersed social groups and activities. Italian researchers (Indovina 1990, Secchi 1991) have conceptualized the urban landscape of the Veneto region as città diffusa and recently described it as isotropic, a decentralized pattern of equal spatial conditions in all directions (Secchi, Vigano’ 2006) 1. The Veneto studies contributes to the urban planning and research tradition which focus on decentralized urbanism: F.L. Wright in Broadacre City (1934-1935), N. B. Geddens in Futurama (1939-40), L. Hilberseimer’s with its New Regional Pattern (1945-49). As such, this decentralized approach questions the centralized practice, the main track of urbanism and planning, with its classical distinction between city and countryside and the planning objectives of densification (Waldheim 2005) and focuses on compact and dense patterns as a solution for environmental problems. Recent individual design-oriented studies have focused on different sections of the European territory2. They give legibility and intelligibility to the form of different decentralized urban landscapes and their quality, while contributing to the shift in perception and evaluation of them from being a threats to being a huge opportunity in opposition to its detractors. In the frame of these studies a common challenge emerged: the potential of urban landscapes of dispersion asks for a new design and planning culture. The Zwischenstadt and Territory of new modernity projects, particularly the environmental issues, are the main challenge, but in the first case, the grain of urbanization is related to the long history of heavy industrialization of the Ruhr region, while in the second case the ecological approach offers an encompassing strategy for interpretation and design in the fine-grain urban landscape, where agriculture, biodiversity and settlements have defined a new integrated mix. While the notion of archipelago emerges in the first case, in the second the sponge concept

“[..] The notion of isotropy refers to a body, a substance or a phenomenon that presents the same physical properties in all directions. Descriptions [..] often make use of geometrical terms and representations that can be categorized as isotropic, such as grid, nebulous, dispersion etc. As a scientific metaphor, isotropy hence regroups various generic forms, represented both in the physical facts and as ideal readings of the territory.” 1

Zwischenstadt (Sieverts T. 2003), New territories (Vigano’ P. editor 2004 ) , Territory of new modernity (Vigano’ P. editor 2001) , La ville Franchisée (Mangin D. 2004), Switzerland: an urban portrait (Diener R, Herzog J, Meili M, de Meuron P, et al., 2006) , The explosion of the city (Font A., Indovina A., Portas N., 2007). 2

Fig. 3 A section of Treviso territory in the middle plain. Source: Water and Asphalt (2006) 9

Fig. 4 The image exhibits the main water rationalizations in the eastern part of Veneto Region. Source: Water and Asphalt (2006). 11

reinforces the idea of a diffuse and porous territory. The project of isotropy, the design hypothesis, is to investigate also the ecological rationality of actions reinforcing the isotropic character of decentralized territories (fig.5). The need for studies of water systems design Presently, economic and culturally driven processes of change threaten the qualities of diversity in the cittĂ diffusa of Veneto. The pattern is embedded in the important modification from fine-grained to coarse-grained. As land use intensifies a process of spatial up scaling changes the landscape.. More and bigger buildings and paved surfaces, wider and homogeneous fields, go along with spatial problems like the reduction of fine-grained edge elements, such as ditches, related hedgerows and paths. Healthy, attractive, accessible and differentiated human habitat is reduced. Habitats, corridors and stepping stones for animals are also reduced. Opportunities for water storage are fading. And as water becomes invisible, it is dropping out of peopleâ&#x20AC;&#x2122;s sight and hearts. One of the basic ingredients of the diversity in the cittĂĄ diffusa is lost. The growth of paved surfaces changed the way water is discharged, increasing peak flows. As land use intensifies, modern water management centralizes the control of the drinking water supply and wastewater treatment, irrigation and drainage. This entails profligate water use. Excess water is tackled with large and rapid discharge and scarcity of water with more supply from the upstream parts of catchment basins. (fig. 6) The increased regulation of in-put out-put water flows combined with no retention draws heavily on the available resources (Mazzola 2003). Furthermore, problems are solved inside the system but often at the cost of neighbours, increasing water risks, such floods, draught and pollution in the upstream and downstream areas. Modern water management practice becomes part of the problem. Climate change (IPPC, 2007; Chiaudani, 2008:151) will make these risks more difficult to control, making it more urgent to find practical answers in different parts of the world. These issues are real,and they are urgent. If water and spatial problems are related, than the answers should have a meaning for both fields. This is the challenge for the designer. Against this background the following hypothesis will be the starting point of the present study. The hypothesis In general, the design answers to increased water risks and spatial up scaling, should be based on water storage, a key concept for coping with excess and shortage of water. This implies a closer relationship between the carrying capacity of climate and landscape and the practices of land use and water management. An area is a system that can regulate flows by input and output as well as by resistance and retention. It can hold, buffer and store water before draining it. It can also keep water longer and keep water clean. For example, it can store surplus water and use it to prevent shortage. Storing is the condition for recycling. From this perspective closing the cycle is a

Fig. 5 Orestad Regionen, Los Angeles, Randstad Holland and Veneto Central Area. Voids (black); built environment (white). Elaboration from Munarin & Tosi (2001). 13

strategy. Improving retention requires space and therefore also the cooperation of users of the space for managing the system (fig 7). In various parts of the world, urban projects on water storage have yielded an understanding of promising spatial and functional combinations. In water management there is also a debate between centralized and decentralized approaches (Schuetze et al. 2008). In diverse landscapes with a diversity of land use, this requires a more decentralized approach to water management. In the Veneto region, the question arises whether there can possibly be synergism between the need for decentralized spatial policy and design strategies to sustain and develop the qualities of the città diffusa and the need for decentralized water management. This leads to exploration of whether decentralized spatial conditions can be combined with decentralized water options. The objective of my work in the context of research and design projects in the Veneto region was, in general, to increase understanding of the role of fine water and spatial elements as carrying conditions in the process of formation of the urban landscape and to explore the potential for its ecological design and planning. The first research Landscapes of water (first report 2005 and Vigano’…Zaccariotto 2009) started from the reuse of one of the many gravel pits in the dry plain north of Venice as a storage space to prevent flooding and accumulate water for irrigation. It was the beginning of wider investigation of water-related topics, the research Water and Asphalt, the Project of Isotropy, for the metropolitan region of Venice. First presented in the X Architecture Biennale in 2006, it focused on the water networks together with road networks. Here the object was to reflect on the potential of the diffused infrastructures of water and asphalt to meet contemporary ecological and economical problems. In particular, the research started to consider the necessity of reinstating storage in decentralized small systems, such as ditches networks, scattered pits and building plots, looking for opportunities in the local landscape (fig.9). This led to development of the set of spatial models that my work investigates and illustrates the shift from an existing condition to a possible alternative. This is the main concern of this design-driven research, which further investigates this issue and toolkit. My work studies in detail the possibility of strengthening the role of decentralized spatial elements in the case-study landscape by looking for a promising combination among the area, flows and users at all levels. The process proceeds from the bottom up, to utilize the full potential of the local situation (the top-down approach has contributed to the water-spatial problems). The research may help point the way to restructuring spatial diversity while offering arguments in the discussion of the ecological potential of Veneto’s decentralized urban landscape as a carrying condition for a more sustainable interaction between society and with its physical environment.

Fig. 6 Top. Graph peak (conceptual). The growth of paved surfaces changed the way water is discharged, increasing peak flows which led to flooding risk downstream. The hydrograph shows the present situation in an area (continuous line), compared with the 1950s, assumed to be unpaved (dotted line). Bottom. Graph of supply and discharge (conceptual). Land use activities intensified, generating peak flows: in agricultural practice, the most water-demanding activity in Veneto, the volume of water supplied and discharged during the year increased, to cope with the requirements. In the diagram this is visible in the different fluctuation between the present (continuous line) and the 1950s (dotted line) during the different seasons of the year. Modern water management centralizes the control of the water irrigation supply and water discharge. The flows are usually driven by channels engineered for quicker input and output regulation, leading to scarcity upstream or excess water downstream. 15

Case study area The case study area is a small section (1.25 x1.25 km) of territory, located in the middlelow plain of the città diffusa between the rivers Piave and Livenza. It belongs to the municipality of Ponte di Piave, in the province of Treviso. The main criteria that have inspired the selection have been: 1. The area is situated in a water-stressed region. Water and spatial problems related to recent changes in space, society, the economy and climate manifest themselves. 2. Since the chosen area is situated in the low plain, findings from the study can be compared with those of another case study in the high plain, like Landscapes of water (2005 and 2009), which is based on the same hypothesis. 3. The underlying process of developing new municipal planning policy offers an opportunity for additional learning. The research and new planning approach focuses on environmental sustainability and synergism and cooperation among stakeholders making decisions affecting the urban landscape in an open process. This leads to the possibility of institutionalizing the guiding principles in new policy and regulations. Guiding models are appropriate communicative tools to create conditions for innovative projects. Outline of the research The first section, spatial transformations and water issues analysis, deals with the question: What are the ecological potentials of the Veneto region? The section is divided in three chapters: the frame, landscape processes and water processes. The frame starts with the question: what are the water resources and processes in Veneto region? This chapter frames the physical setting of Veneto’s citta’ diffusa. The geographical frame illustrates the basic interrelation between space and water flows across different scales of the region, i.e., the pattern of the surface water system and groundwater system in relation to the landform and soil systems and the processes of the wide hydrological cycle and climate. The carrying and limiting conditions of the human-dominated system in respect to water resources emerge. The Landscape and water processes chapter starts with the question: how has the role of water changed in the cittá diffusa in the last decades? This part investigates the processes of landscape and related water and spatial problems and opportunities. The description focuses on the interaction between flows and the case study area. It starts with the fine level and proceeds to the wider water board level. The conclusion frames the water paradoxes related to the processes of change in water use and water management. The second part, water challenges and spatial design, starts with the question: how can the role of water change in the cittá diffusa in the future? It is divided in two chapters: landscape and water strategies and retrofitting scenarios. This part explores possible future processes of water and landscape change in the frame of a more sustainable management approach of integration and decentralization.

Fig. 7 Ecological strategy. From in-out to resistance and retation regulations in an urban system. Elaboration from Tjallingii (1996). 17

Landscape and Water Strategies focuses on the role of designers and planners in the search for sustainable options for the future of the Veneto cittĂ diffusa. An analysis of the changing landscape is illustrated, and discussion of the underlying paradoxes leads to guiding principles that may enhance the process of exploring planning and design options. Thus, a set of principles has also emerged in many other planning situations and discussions about integrated and sustainable development: (a) the design of water systems should focus first on storage and recycling; (b) the basic variety of ecological conditions in the local landscape should guide the planning process; (c) specialization and synergism of activities are the basic principles for multifunctional regional planning; (d) planning and design processes should start from the bottom up. Together, these principles may guide the design process in the search for integrated solutions, promising combinations of the ecological potentials (flows-area-actors) of the Veneto cittĂĄ diffusa The gap between guiding principles and the real world is bridged by pilot projects that pioneer in the local situation and provide a practical basis for the essential learning process. Some innovative pilot projects in the Veneto region illustrate the feasibility of the guiding principles. This leads to a set of conceptual tools, a toolkit of guiding models, solutions in principle. Some more general conceptual tools for this approach have been developed in other parts of Europe. It will be investigated whether these guiding models work in Veneto, and how they can be adjusted and complemented to become an appropriate toolkit for concrete design projects. Retrofitting Scenarios explores practical questions related to working with guiding models in the case study areas, which offer a fine opportunity to test and further develop the design approach. Tools of the research A palette of research tools is used in the learning process, such as maps, conceptual and spatial models, interviews and workshops. Maps include GIS maps constructed for the Frame part as well as CAD maps for the Retrofitting Scenarios. GIS maps integrate data from various agencies. They are composed of empirical identities describing the features of water structures across different scales of the region. The condition of territorial complexity is tackled throughout the de-layering technique, resulting in the construction of a series of maps across different scales of representation: macro, meso, micro. The de-layering enables naming and describing the relevant water and land features, their structural and functional attributes and interrelations. The same principle is applied to the maps in Retrofitting Scenarios. The maps aim not only at describing but also unfolding potentials of the water system at all levels of scale to play a carrying role (Corner, 1999). Conceptual models. A model named ecodevice, is an important theoretical assumption throughout the research. The model, developed by Van Wirdum and Van Leeuven, does not indicate a formal spatial arrangement; rather, it describes the basic mechanisms of interaction between an area and flows: in-put, out-put and resistance-retention. The ecodevice model is assumed in the analytical and design process. It is effective for

Fig. 8 Inside the citta’ diffusa. Top. Ponte di Piave. Bottom. Codogne’. 19

understanding and describing water problems related to the in-put out-put feedbacks, and it also has heuristic value in developing tools for ecologically sound design, based on retention as a guiding principle (Tjallingii, 1996). Spatial models. The spatial arrangement and interaction of water structures and flows within defined spaces is described in schematic diagrams which aim to illustrate the interrelation among structures and water-flow dynamics. The set of models illustrated in Landscape and water processes are the result of analytical reduction of the features of variety of local spaces, analysed (in field and review of the literature) into basic permanent structure-water flow patterns. The models in this part are instrumental in illustrating the process of change of the local water landscape by comparing models of different periods. Furthermore, they reveal the basic local potentials of potential significance for exploring other models in the learning process of the research. These models, referred to as guiding models, link guiding principles for sustainable water flow management with specific spatial options in well-defined categories of local situations. In these terms the toolkit of guiding models, in the appendix, is a collection of hypotheses about the optimal organization of spatial structures and water flow processes (Tjallingii, 1996). The case study area offers the possibility of testing the guiding model as a hypothetical assumption in the relevant context. The guiding models are used as starting points in the design process. The challenge is to take advantage of potential synergism between the spatial structures, the water flows and the network of actors affected by the plan. The exploration of the â&#x20AC;&#x153;what ifâ&#x20AC;? in the case study area provides feedback, which leads to improvement and replacement of the model or the development of new guiding models. Retrofitting Scenarios illustrates the cycle of the learning process. In the context of the research, the case study area offers a fine opportunity for developing - context-oriented knowledge (Malbert, 1994). At different stages of the process, interviews and workshops were conduced to collect information and to asses results. Interviews with local users were conducted to collect information on the spatial and functional features of the water system in the past and present and the role it played in supporting diversity and the economy of the area they live in. Interviews are conducted with institutional actors, such as regional and local governmental bodies, involved in the decision-making process regarding water management or with those more closely involved, such as bodies managing irrigation and drainage and systems for drinking water and waste water . This led to collecting information on the status of important sectors of the institutional framework regarding centralized and decentralized options, problems, opportunities, perspectives in the framework of the specific spatial structure of the cittĂ diffusa and increasing water problems.

Fig. 9 Spatial models illustrate principles for reinstating storage in decentralized small systems, such as ditch networks, scattered pits and building plots, looking for opportunities in local landscapes across different sections of the plain, from the high plain to the low plain. The cumulative effect of their incremental application could be quite significant on the regional scale. Source: Water and Asphalt (2006). 21

Workshops. Participation in the design process by local actors such as technicians and operators of the bodies for water management in the area, as well as politicians and policy makers at the level of the municipality is a crucial factor. A good precondition at the local level has been a shared basic understanding of the problems and opportunities. A context of interaction and learning has fostered step-by-step adjustment of the design hypothesis to the cultural and physical potentials of the case study area. The work and research underlying this study was conducted under the direction of Prof. Paola Viganoâ&#x20AC;&#x2122; (Department of Urbanism IUAV University of Venice), Prof. Sybrand Tjallingii (Department of Environmental Design TU Delft). A shared reasoning and discussion regarding the potential role of water and its management in the specific urban landscape of the Veneto cittaâ&#x20AC;&#x2122; diffusa provided the opportunity to set up a common exploration with another colleague, Marco Ranzato, from the Department of Civil and Environmental Engineering at the University of Trento. Together we spent a period of the study at the Department of Environmental Design of TU Delft. In following a common research structure the authors focused on two distinct case studies. The conceptual models I elaborated in the framework of the study entitled Water and Asphalt: The Project of Isotropy, first presented at the X Architecture Biennale of 2006 in Venice, were used and further developed throughout the course and learning process of the present study. Some results of this research project have already been discussed in international conferences.

I. Spatial transformations and water issues, an analysis

I.1 Frame

Fig. 10 Veneto Region in the Padana Valley. The wider Padana plain is limited by the pre- Alp range to the north, the Appennini to the south and the Adriatic sea to the south-east. Surface water (red) + spring area (grey) + main cities (black crosses). Elaboration from Water and Asphalt (2009). 25

I.1.1 Introduction

Water runoff and glacial expansion and withdrawal were dominant agents in shaping the distinctive landform and the great hydrology of the region throughout the geological eras. This part frames the case study area in the wider geographical setting of the Veneto region. The subjects of the description are the landscape structures, the hydrological cycle and the climate conditions. The landscape structures are the basic elements carrying the territorial pattern. The water system (the hydrography of the drainage), landform and soil systems are named and described in relation to the case study area. The condition of complexity (e.g., the nested hierarchy of the elements) is tackled throughout the construction of a series of maps at different scales: macro, meso, micro. The de-layering makes it possible to name and describe the relevant elements, their structural and functional attributes and interrelations.

Fig. 11 Veneto Region: the case study area in Ponte di Piave (yellow) in the territory of the water board Consorzio di Bonifica Pedemontano Sinistra Piave (black). 27

I.1.2 Land and water

1. Geographical frame The following description frames the form-function relation between the surface water network – the hydrography of the drainage – and the landform in relation to the case study area.

Macro scale The Veneto region is a rough polygon around 210 km in length and a breadth of around 195 km. It includes a portion of the great mountain range systems of Europe – the Alps (15%) and the Prealp mountains and hills (30%) – a section of the extensive Padana plain1 (55%), isolated hills and the Adriatic coast (fig. 10). The case study area lies on the middle-eastern side of the Veneto region within the portion of territory managed by the water board, named Consorzio Pedemontano di Bonifica Sinistra Piave (71.700 ha). The water board domain stretches over the territory between the rivers Piave and Livenza and to the north frames a section of both the prealps range and the wider Padana plain (fig.11). Surface water network.The map shows the position of the area in relation to the wide surface water system and landform of the region (fig.12).The river network includes two main dendritic systems: the rivers originating from the Alps (Po, Adige, Brenta, Piave) and pre-alps and the rivers originating within a strip in the middle plain: the “spring area” (Tartaro Bacchiglione, Sile, Zero Meolo, Reghena..). Landform.The landform of the Veneto region exhibits a series of structures: the Alp mountains (15%), the prealp-hills (30%), the plain (55%), the isolated hills and the coast. The Veneto Alps include the eastern portion of the great mountain range systems of Europe. The alpino-dolomitica area stretches from the Austrian border to the wide Valbelluna

The wider Padana plain is limited by the pre- Alps range to the north, the Appennini to the south and the Adriatic Sea to the south-east. MURST 1997; Turri 2000. 1

livenza piave

Fig. 12 Veneto Region. Surface water network (red) + landform (grey). 29

Valley. It includes high (2000-3000 m), medium and low reliefs connected with the valleys of Piave River and its tributaries. The prealp-hills are the group of mountain range of medium and low elevation at the eastern wing of the Alps, stretching from the east side of the Adige Valley. The Veneto Prealps stretch from Baldo Mountain to the Cansiglio Plateau. They are delimited to the north by two wide valleys, oriented east- west: the Valbelluna Valley and the Valsugana. The main groups of reliefs are separated by valleys carved by rivers: Lessini between Adige and Bacchiglione, Asiago plateau between Brenta and Bacchiglione, Grappa and Colli del Prosecco between Brenta and Piave. Low isolated reliefs in the plain include the systems of Colli Berici, Colli Euganei to the west and the Montello to the east. The Veneto plain (10.000 km2) constitutes the eastern part of the wider Padana plain (46.000 km2), which borders the Alps to the north, the Appennini to the south and the Adriatic to the east. The Veneto plain is divided into a western and in eastern section, relative to the system composed by Lessini, Berici Mountains and Colli Euganei. In this area the sublayer of rock emerges, reducing to zero the alluvial layer. The two basins can be divided into three areas which follow one another from the prealp range: the high plain, the middle plain, the low plain, the plain of the coast and lagoons (Arpav 2005; Boscolo and Mion 2008). The high plain exhibits fans, the middle plain fine-scale ridges and depressions, the low plain dunes, lagoons and deltas. The high plain stretches east-west from the prealp range to the middle plain. The width varies from 5 to 15 km, stretching south. Fan-like forms suggest the runoff flow process of erosion deposition at its origin. Size and the lengthwidth ratio vary. The land gradient is more than 0,3 %. The middle plain stretches southeast close to the high plain, its width varying from 5 to 10 km, and it exhibits a system of ridges alternating with depressions. The ridges are elongated forms with a north-west to south-east orientation of the long axis. The height varies from 1-2 meters, the width from few hundred meters up to more than one km and the length from few to dozens of km long. The low plain stretches south-east. Close to the middle plain its width is about 20 km (Arpav 2008:24).The wavy structure ridge-depression is absent. The land gradient is about 0,1 %. Dunes, lagoons and deltas: Deltas of the Po, less outstretched, are the Piave, Brenta and Adige deltas (Arpav 2005). The water runoff and glacial expansion and withdrawal were dominant agents in shaping the distinctive landform of the region by means of a process of erosion and deposition. The depositions systems extend over the high and low plain (megafan) and were formed by the main rivers flowing from the alps Adige, Brenta, Piave, and by the minor rivers from the prealps and spring- rivers. In the Pliocene (one million years ago) the Padania was a vast gulf. The last glaciation (Quaternario) reached the climax expansion (Wurm) 30-40 thousand years ago, water was stored in the form of ice which lowered the sea level to 120 metres above the present situation. The plain was then wider. The withdrawal began 15-10

thousand years ago. Water bodies were fed mainly by the seasonal melting of the glaciers. Water flow discharge achieved the maximum range and went along with the increase of erosional- deposition process. The gradient of sediments was shifting from coarse, in the high plain close to relief or where river flows, had broken through existing channels, to fine as the flow proceeded toward the middle and low flood plain and the coast. During this period water networks were changing, abandoning preferential flow paths and forming new ones. The contraction of glacial mass, the sea level rise 6-7 thousand years ago, went along with the origin of the present water system (surface and groundwater basin) and landform (Arpav 2005; Saibene 1977). The high plain: fan-like deposits of gravel were produced by the rivers at the outlet of the valleys in different ages (Altissimo 1995). The middle plain: the shape of ridges and depressions is the result of water flow and its variability (quantity and rhythm) in flat terrain (low gradient) (Forman 1995) (fig 13). The ridge structures are: bars, extended in the long axis, resulting from continuous sand deposition in the active streambed, natural levees, as the result of sand-silt deposit, occurred with seasonal rhythm, and small fan, resulting from sand-silt deposit, occurred with wide rhythm of local overflowing. Depressions that extend between ridges are the result of silt-clay deposition. The low plain: deposits occurred in a wide, extended pattern because of the absence of ridge-depression structures. The flow was slow in relation to the land gradient of about than 0,1%. Sea level rise and the sedimentation process from rivers gave rise to the dunes, lagoons and deltas. The balance between river sedimentation and marine erosion resulted in less outstretched Piave, Brenta and Adige deltas in comparison with the Po delta. The surface water form, which depends mainly on landform (topography) and underlying bedrock, exhibits dentric forms (Arpav 2005, Naiman 2005)

Meso scale Surface water network. The case study area is located on the hydrological border between the middle plain (springs area) and the low plain (Fig.14-15). Within this portion of the plain the complete series of water corridors from lower to higher order form the Brian Catchment Basin, which measures about 44,483 ha (PGBTTR, 1991). This section is not drained by the two main rivers Piave and Livenza due to the embankment; the confined flow of the river results in higher and faster water flow above the surrounding land (PAI 2007) 2. The Piave, Brian and Livenza flow into the Adriatic Sea. The hydrological south border also defines a change of the main river corridors from a braided to a meandering structure, due to the low gradient of the plain slope. The case study area is crossed by the streams Bidoggiata and Grassaga, which originate in the spring area. Bidoggiata has its rise 4 km upstream from the point where it intersects the study area. It crosses through the area for 1 km and flows into the Bidoggia 2 km further downstream. The Grassaga has its rise 5 km upstream, from the point where it intersects the study area. It crosses the area for about 1 km and flows into the Brian 12 km further downstream. The streams Bidoggia and Grassaga are linkages of a vaster water network composed of water corridors flowing in a north-east south-west direction in a parallel pattern. The Piave and Livenza are the main corridors. In the portion of plain

PAI 2007.

Piave and Livenza are â&#x20AC;&#x153;caratterizzati da quote idrometriche dominanti rispetto ai terreni attraversati.â&#x20AC;?

bordered by the two main rivers are the Grassaga, Bidoggia, Piavon, Lia, Monticano. Grassaga, Bidoggia and Piavon are tributaries of the Brian. Lia flows into the Monticano. The Monticano is a tributary of the Livenza. Landform. At the water board level the Prealp-hills include the Colli del Prosecco system, which has two parts â&#x20AC;&#x201C; a north system of long parallel hogbacks with small valleys stretching east-west between the Vittorio Veneto and the Valdobbiadene and a south system of smooth ridges (100-200 m) with valleys stretching north-south between Pieve di Soligo and Conegliano (Arpav 2007). The plain elevations vary from about 125 meters in the high plain to 2 m above sea level in the low plain. The inclination also varies from an average gradient of 1%, in the high plain to 0, 2% in the low plain. The high plain exhibits deposition structures. Two large fan structures stretch out at the outlet of prealps, and they are both related with the Piave River: the Nervesa and Vittorio Veneto fans. Below the fans, the plain is crossed by a system of ridges, oriented north-west, south-east, that are related to former Piave water corridors. A ridge seems to be connected to the Grassaga. The case study area intersects a portion of the interdigitated systems of ridges and depressions oriented north-west, south-east. The average gradient of the plain is 0,1 %.

Fig. 13 Geomorphology map. Source: Mozzi 2005. 33

Fig. 14 Surface water network (red) + landform (grey). 34

Fig. 15 Surface water network (red) + landform (grey). 35

Micro scale Surface water network. At this level different types of water corridors intersect or are in the area. Two series of drainage patterns are recognizable according to the width: streams and ditches (Fig. 16) . Two diverging streams cross the area for about 1km: the stream Bidoggiata in the upper part and the stream Grassaga in the lower part. Both flow NE-SW, which is the natural water flow direction. A third water element is the Serafin ditch, 1 km long, which is a tributary of the Grassaga. Two corridors, each one consisting of two parallel deep drainage ditches, cross the streams, intersecting them in a north-east south-west direction, so they lie transversely to the natural water flow direction. The one on the east side of the frame goes along the single-line rail track Treviso-Portogruaro. The other in the middle is the drainage system of the road SR 53 Postumia. Other roadditches are visible. Patterns of fine parallel ditches stretch across a few areas. They are the first order of the field drainage system. The different corridors, of a single type, intersect to form a network. The stream network is dentric, and the ditch network is rectilinear. Landform. The case study area intersects a system of ridges, flat land and depressions (basins), which is reflected in the toponymy (Fossadelle) (Leoni 2008). Ridges are less than 1 m high, hardly visible in the land. The pattern of the high lines exhibits the topographical relation between landform and water corridors: the streambeds lie on the ridges and are held in place by natural or constructed levees.

Fig. 16 Surface water network (red) + landform (dotted lines 0,5 m). 37

The subject of the following description frames the form-function relation between the surface water system and soil system in relation to the case study area.

Macro scale Different types of deposits form the soil system of the plain of the Veneto region (fig.17). The plain can be divided into a west basin and an east basin, considering the system consisting of the Lessini Mountains, Berici Mountains and Colli Euganei. In this area the sublayer of rock emerges, reducing the alluvial layer to zero. In the two basins the subsoil layer of the Veneto plain can be divided into three areas which follow one another from the prealps range: the high plain, the middle plain, the low plain the plain of the coast and lagoons. In the high plain the alluvial fans deposits of different ages overlap. The deposits are composed of gravel (10-30 %) and other coarse sediments which are undifferentiated to a depth of a few hundred meters. In the west basin the Piave deposits are dominant relative to those from other rivers. In the middle plain the fans do not overlap but are separated by thick silt-clay soil of marine origin. This structure alternates gravel layers with silt-clay layers to a depth of at least 300-400 m (Altissimo et al.1995; Boscolo and Mion 2008).

Meso scale At the water board level the surface water network exhibits different gradients of density in the prealps and high plain between the Piave and Livenza, which is related to the different soil landscapes previously illustrated (fig.18-19). The patches of soil type crossing the area stretch NW-SE. In the prealps (Colli del Prosecco system) – in the part with long parallel hogbacks and small valleys which stretches E-W between the Vittorio Veneto and Valdobbiadene, and south part of smooth ridges (100-200 m) and valleys, which stretches N-S between Pieve di Soligo and Conegliano– the density is medium, indicating a medium level of surface water runoff, related to the impervious bedrock (terziario) and soil deposits of low impermeability. In the high plain the density of surface water network is low, on the fan of the Vittorio Veneto morainic amphitheatre and on the Piave fan between Monticano stream and Piave. This exhibits coarse, permeable gravel or sand soils, resulting in an area of high porosity (Arpav 2007:71). In the middle and low plain the surface water network exhibits higher density. This is where the resistance of the impermeable layer of fine materials drives up the groundwater, giving rise to “the springs strip”. Many water bodies originate in and get fed along this area.

Fig. 17 Surface water network + soils (lighter grey=gravel; darker grey=silt and clay). 39

Fig. 18 Surface water network (red) + soils (lighter grey=gravel; darker grey=silt and clay). 40

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fig 8_surface water network (red) + soilscape ( light grey = sand; gray = sand-silt; mediumdark grey = silt; dark grey = clay)

Fig. 19 Surface water network (red) + soil scape (light grey = sand; grey=sand-silt; mediumdark grey = silt, dark grey = clay). 41

The elongated patches crossing the area stretching north-east south west are nested in specific soil landscapes consisting of “ancient” fluvial depositions (Pleistocene 1.8000.000-10000 years ago). It forms a strip about 5km wide, stretching below the southern springs border, between the stream Piavon and river Piave. Patches alternate with different gradients of fine sediments (sand-silt, silt and clay) and landforms (ridges and depressions). Another soil landscape, consisting of “recent” fluvial depositions (from Holocene 10.000 years ago), borders the previous one. It consists of two parallel strips of coarse and fine sediments (gravel-sand-silt, silt), stretching along river Piave. A third one is composed of fine sediments (sand-silt, silt) and patches, stretching along the Livenza and its tributaries, and along the stream Piavon. The stream Bidoggiata flows on a ridge for most of its length. The Grassaga flows across areas with different topographical conditions. The relation between the water network, soils and topography is exhibited in the map. Along the main drainage vectors rivers and streams deposited coarse and mildly coarse sediments, forming ridges lying above the adjacent plain level. Fine sediments were deposited in the lower flooding areas and between ridges. From the shape of the patches emerge the former wandering courses3 of the Livenza and Piave network (Arpav 2005).

Micro scale Two main diverging soil patches cross the area, dividing it into two sections. Patch attributes include alluvial sediments, texture and landform (fig. 20). The material in the upper part of the area (light grey) is mildly coarse (sand-silt ). The material of the lower (light dark grey) one is fine (silt). The drainage for both is mediocre (Arpav 2005). A portion of a clay patch emerges in the in southern proximity of the area. Sand-silt patches coincide with ridges, and clay goes with depressions. The Bidoggiata and Grassaga flow is fed by “sources” like spring and seepage. Spring is the main distal source, located a few km upstream from the case study area. Seepage refers to the subsurface groundwater flow. Other sources are storm-water overflow and waste water in and outside the area.

“lungo le line preferenziali di deflusso si rilevano [..] i dossi fluviali, piu’ elevati rispetto alle aree circostanti e formati da sabbie e limi, nelle zone poste a quota inferiore prevalgono i deposti limo-argillosi” . Leoni 2008, p.15. 3

Fig. 20 Surface water network + soil scape (grey = sand-silt, medium grey = silt, dark grey = clay). 43

The subject of the following description frames the aquifer basin form-function-process. The soil structure and its permeability is a key topic for understanding surface water and groundwater relationships. The aquifer is an in-out system. Surface water and groundwater flows are linked forming a single hydrologic system.

Macro scale The groundwater basin occupies the underground porous system of the aquifer (fig. 21-22). The spatial configuration of the aquifer basin of the region is determined by the deposit structures. In the high plain overlapped gravel fans arranged in elongated patches are 5 to 20 km wide and undifferentiated in the material composition to a depth of a few hundred meters. In the middle plain, the fans of different ages do not overlap. Alluvial gravel layers alternate with silt-clay soil layers to a depth of at least 300-400 m. Infiltration processes are predominant in the high plain due to the permeable condition related to the uniform thick layer of gravel and coarse materials. This is the recharge zone of the entire regional system. Rainwater, rivers and irrigation systems feed and saturate the soil layer to form an unconfined groundwater body. This part is the main groundwater storage (Mazzola 2003: 19), one of the more important groundwater storages of Europe for capacity, potentiality and quality (Giupponi and Fassio 2007). In the high plain, the groundwater table (upper surface of the groundwater body) gradually reaches a maximum depth of 50 meters. A single, unconfined groundwater body from the high plain flows slowly, driven by gravity and low resistance (high permeability) offered by the gravel layer. In the middle plain the separated layers of impermeable materials previously illustrated goes along with a multiple groundwater system: a shallower unconfined groundwater body (falda freatica) and deeper confined groundwater bodies separated from each other (Altissimo et al. 1995). In the middle plain the resistance of the impermeable layer of fine materials drives up the flow, and where the groundwater table intersects the surface, it springs from the ground forming â&#x20AC;&#x153;the springs stripâ&#x20AC;?. Many water bodies originate and get fed along this line. This system of confined aquifers is the supply source of the individual and collective systems of potable and irrigation water. The system described makes it clear that the spatial continuity and porosity of the permeable layer of gravel stretching from the high plain to the middle plain is the condition for a single groundwater basin-a large flow system with two different and connected parts- the high plain and the middle plain.

Meso scale In the high plain the groundwater basin supply results from riversâ&#x20AC;&#x2122; surface water infiltration, mostly the Piave (30 m3/s) and Monticano, rainwater precipitation (25-35 % ) and irrigation (10%). The flow direction is north-west to south-east (Altissimo et al. 1995) (fig. 23-24). The case study area is located across the hydrological south border between the middle plain (spring area) and the low plain. Along this line the unconfined groundwater intersects the topographic surface. Many water bodies originate and get fed along this line. The Bidoggia and Grassaga originate in the spring area. At this scale a relevant fine system of paleochannels emerges. It highlights the pattern of the fluvioglaciali water flows. Within paleochannels the continuity of groundwater flow is higher (Siligardi 2007), and link channels flow with distal areas of the floodplain. Paleochannels connect the Bidoggiata with the Zocchella.

Micro scale In the case study area the unconfined groundwater table is located at a depth of 0 to 2 m. The drainage flow splits into opposite directions along the divide between the Bidoggiata and Grassaga catchment basins. In the area paleochannels stretch along the Bidoggiata and near the fosso Serafin (PAT 2009) (fig. 25).

Fig. 21 Hydrological model of Veneto plain. Source Altissimo-Dal Praâ&#x20AC;&#x2122; 2003. 46

Fig. 22 Groundwater isolines (red) + recharge area (dark grey). 47

Fig. 23 Groundwater isolines (red) + recharge area (dark grey). 48

Fig. 24 Groundwater isolines (red dotted lines) + permeability scape (lighter grey=good, gray-middle grey - dark grey=scarse + paleochannels (red). 49

2. The wide hydrological cycle Water can be stored in the atmosphere, lakes, rivers, streams, soils, snow fields and groundwater aquifers. Its circulation among these storage compartments is caused by processes, such as evapotranspiration, condensation, precipitation, infiltration, percolation, snowmelt and run off, which are the water cycle components. The text follows the path of water in the system. This section illustrates the location of the case study areas within the regional section and the interaction between the wide hydrological cycle and the extensive manmade water cycle and related infrastructures (fig. 26). In the mountain rainwater is held as an ice cap or feeds the water table and surface brooks. Part of the water is diverted in the reservoir and released downstream in the irrigation system in the high plain. In the high plain most of the precipitation infiltrates the ground and adds to the groundwater; only a small part of the surplus precipitation flows across the land to the surface water elements. Part of the groundwater (unconfined flow) quickly flows to the drainage system, but the remainder ends up in the deeper aquifers (confined flow) and slowly reaches the surface water elements or springs out on the ground level in the middle plain. From the confined aquifers fresh water is withdrawn and delivered into the drinking water pipe network, where it is transformed into waste water and carried into treatment plants, and through effluents it again gets into the surface water system. In the middle and low plain when the water level in streams is at a minimum, the flow is discharged by gravity into the receiving rivers. In case of heavy rainfall the water level rises, and discharge is accomplished artificially. Pumps raise the flow to a higher outlet point. In the low plain of reclaimed lands, the surface water level is high, and water discharge is performed artificially.

3. Climate frame In Ponte di Piave the annual average precipitation 1996 to 2007 was 950 mm (PAT 2009:16). The existing annual rhythm of precipitation, compared with the sum of evaporation and precipitation, shows that between May and September there is a deficit, which, is usually compensated by the total rainfall. In Veneto a critical rainfall depth of 130 mm after 24 hours is not uncommon. This occurs once every 10 years, and only once in 50 years might this depth reach 177 mm (PGBTTR 1991). Global warming will exacerbate weather conditions; not just extreme precipitation events are expected. Storms occurring in the past once in 100 years will probably occur more often in the future, but extreme draughts, causing water quality and quantity problems, are also expected to occur more often (IPPC 2007).

Fig. 25 Groundwater isolines and flow direction (red) + permeability scape (grey). 51

A recent study comparing the precipitation balance at the regional level in the periods 1956-1981and 1982-2004 demonstrates a trend towards dryer conditions which will also affect the case study area (Chiaudani 2008).The anticipated consequence is a deficit between precipitation and total evaporation in the coming years, which will push up the demand for water use. Climate-adaptive water management requires the development of systems that should allow for the seasonal storage of clean rainwater and flood control during extreme precipitation events in order to drive urban areas towards self-sufficiency. The frame described the landscape structures in the wider geographical setting of the Veneto region. The next part moves to the landscape pattern of a small portion of the territory.

Fig. 26 Natural and man made water cycle of Veneto Region. Interpretation from Tjallingii. 53

I.2 Landscape processes

Fig. 27 Aerial views of the case study area. 1952 (left), source RAF 1954, Circe Iuav. 2007 (right), source Telespazio 2007. 55

I.2.1 Introduction

In recent decades an incremental process of spatial change has progressed with unprecedented intensity and acceleration in the territory of the città diffusa – as in many other territories of Europe – driven by a specific process of economic and social growth (Coro’ 1998). A diachronic comparison of the land mosaic in 1952 and 2007 in the area of Ponte di Piave, making use of aerial photographs, illustrates the spatial processes of change, such as densification, up-scaling, separation and centralization (fig. 27). The major causes of land transformation are intensification of agriculture and urbanisation, which proceeded from 1980s with intense acceleration.

I.2.2 Models and processes of transformation 1952 The fine-grained landscape in 1952 is the result of different patterns of spatial components. Agricultural matrix. The large open space of the agricultural matrix is dominant. The fine grain-mosaic resulting from the integration of two patterns: a checkerboard composed of small-medium elongated rectangular fields alternates across the case study area, along with fine rectilinear corridors, north-south oriented. Other wider corridors are visible. The checkerboard patches are small plots of herbaceous crops. The narrow corridors are vine shrubs linked to trees (vite maritata). The integration of the two extends over the matrix. A hedgerow network is visible. The mosaic is the result of a specific mixed farming system named piantata (Sereni1961). The description of a local storyteller gives an account of the spatial features of the agricultural matrix “ ..Al colmo della Grasseghella c’erano gia’ agli inizi degli anni cinquanta le vigne industriali d’impianto razionale; pero’ ogni famiglia aveva una moltitudine di tipi d’uve, specie nei dintorni delle fattorie, in appositi appezzamenti, frammischiate insieme. C’era tanto pluralismo allora nelle colture come nei cibi. C’erano le siepi frondose e arcane..” (Mazzariol F. 1994). Settlements. Small buildings of similar size are scattered within the agricultural matrix and along roads. Each building clusters diverse farming activities and diverse crops in the same area. Roads Transportation corridors overlap each other. The straight and diverging corridors of the rail, the main road Postumia, and small wavy roads are visible. Fine dirt roads are also integrated in the matrix. Water elements.The diverging streams Bidoggiata and Grassaga cross the matrix. The

fine E-W corridor is the lower drainage order. The darker strip is visible along the streams. It exhibits a moisture different gradient than the adjacent matrix, which goes with the riparian corridor. One of the streams and the wavy road are approximately parallel.

2007 The grain of the landscape in 2007 is coarse. It is the result of a change in the spatial components patterns. Agricultural matrix The large open space of the agricultural matrix is perforated. The coarse grain mosaic results from a checkerboard pattern of wider elongated large and medium fields, alternating across the area. The fine rectilinear north-south oriented corridors are clear. The fields do not integrate mixed crops. Vine and herbaceous crops stand separate in specialized areas across the matrix. The fine network of hedgerows decreases to a few scattered corridors and small patches of wood, probably regenerated. Settlements. A new large elongated industrial area is set along the main transportation corridor. Added small and medium-sized houses expand previously built patches. The defined solids stand out against the background of the agricultural matrix, with a juxtaposition of residential and industrial functions. Roads. A wide road is added. Fine dirt roads are removed. Carriageways are wider. Processes Four main processes of transformation emerge from the comparison: Densification of building, such as the shift from a few to an increased number of structures. Upscaling of both fields and buildings is the shift from small size to bigger dimensions. Centralization: the dispersed pattern of buildings and fields shift towards spatial polarization. Separation: the integration of activities within the same area, such as living and producing, shifts to the separation of activities into specialized areas.

I.2.3 Conclusion The comparison shows highly contrasted mosaics. As a result of the four processes of spatial pattern transformation, the landscape mosaic changed from fine grain to middlecoarse grain. A comparison between the maps IGM 1891 and 1952 in general shows the persistence of the fundamental forms of patches and corridors. The shape of the landscape in the 19th century is very close to the situation in the 1950s. One observes the reduction of meadow space (Breda 2001:42), which probably coincides with the lower wet areas that are difficult to cultivate, and the channelling of the streams that was initiated before 1950. The persistence of the farming system named piantata reflects a long period of â&#x20AC;&#x153;indecisionâ&#x20AC;?

in the agricultural economy between two opposing forms of production: the self-sufficiency, which is typical of a pre-capitalistic or feudalistic phase, and production for the market, which is the form of mature capitalism. The “indecision phase” is the longestknown in Western countries, persisting from 1300-1400 to the 1960s (Farinelli 2003), in Ponte di Piave until the 1980s (interview Susanna). It was dominated by the mezzadria, a type of contract for management of the land. The owner of the land and local peasant families were used to making an agreement for cultivation. The land was divided into plots, one for each family. The dimension of the plot to cultivate was related to the capacity of the components to carry the seasonal agricultural practices in the area. The smaller the family, the smaller the land. The plot integrates both the piantata and the house into one system, which is provided by the owner. For example, in Ponte di Piave an area of 500 ha (owner Gallarati Scotti), near the case study, was inhabited and cultivated by about 500 people, with plots ranging from 1 to 20 ha (interview Gallarati Scotti). The harvest was divided in half in order to provide a food supply for both parties, the owner and the peasant family. The diversity of crops within each plot was driven by the logic of self-sufficiency in food and energy. The surplus was delivered to the local market. The fine, dense, pervasive edge structures related to the water corridors, such as hedgerows and paths, supported habitats, corridors and stepping stones for plant and animal species as well as a differentiated human habitat. Gatherings for recreation, fishing, swimming, picking up food and wood for energy were common activities of people living in the area. A fine description gives an account of the spatial features of the Bidoggia stream corridor in the early 1800s: “..tra mezzo il bosco vicino, dove mi piace meriggiar cosi’ spesso, fra quell’ombre fresche e gradite, sul margine erboso della Bidoja, che scorre bruna sotto i rami di folte roveri (Sanfermo 1806). The density of people and animals and the isotropic spatial arrangement of farms in the case study area reflect the socio-economic condition described. The small size of each rural house and the right distance reflect the dependence of farms and villages on local resources: cultivable soil and little flow of water and energy were involved in the food productionconsumption cycle at the plot level, which was hardly enough to support the family. The same situation is reflected on a higher level in the pattern of small-sized villages (Farinelli 2003). The indissoluble link between the multifunctional landscape, society and economy is confirmed by the interviews with the local inhabitants (Interviews Dal Pizzol; Gallarati Scotti). The radical transformation driven by urbanization and agricultural intensificatication relying upon new technologies of agricultural chemicals and mechanization led to the shrinkage of landscape elements, such as meadow patches and the fine, pervasive edge structures related to the water corridors, such as hedgerows and footpaths. The multifunctional fine grain landscape have been fading away.

Fig. 28 Cavini system in the territory of Treviso XVI c. The possessione di Zerman delle monache di San Parisio di Treviso. Source: ASTV, CRS, San Parisio, b. 22, â&#x20AC;&#x153; Pertegationi diverse del M.ro R. De Madri de San Parigi, 1526-1528, c.s.n. Courtesy of Gasparini. 59

I.3 Water processes

Fig. 29 Irrigation and drainage systems in the case study area 1952 (left) and 2007 (right). 61

I.3.1 Introduction The processes of spatial concentration and separation have had consequences for the water systems. The irrigation and drainage structures and flows are subjected to a series of operations and regulations, which developed as consequences, along with the spatial changes. A comparative analysis between 1952 and 2007 illustrates the processes (fig. 29).

I.3.2 Irrigation and drainage

1. Field system 1952 Drivers. The system supports intensive crop production and short cycle productionconsumption at the local scale. The cycle is driven by the self-sufficiency principle introduced with the mezzadria management system (Farinelli F. 2003:65). The per capita food supply was modest (Giardini L., 1991: 154) Landscape pattern . In 1952 the minor drainage system of the matrix exhibited a rectilinear network pattern, with different densities stretching across the area; the pattern is named the cavini system (fig. 29-32 left). Field structures and flows . The basic components of the drainage system at the level of the field are: the rectangular shape, convex section, surface drainage network1 (Oliva 1948) (fig. 31). The field or cultivation unity is rectangular. The vertical section exhibits a convex shape (baulatura) with a pitch from 1 to1,5 meters higher than the lateral borders. The width of the field, from 35 to 40 m, is defined by vine-tree rows. The depth of the field is limited by U-shaped troughs, grassy corridors free from cultivation (cavini or cavedagne),

There are many models developed to fit different terrain conditions. The models are divided into two main groups: hill arrangement (‘sistemazioni di collina’) and plain arrangement (‘sistemazioni di pianura’). The plain arrangement (‘sistemazioni di pianura’) include two types: extensive and intensive to which belong the ‘piantata’ and its Veneto variant called ‘cavino’. �� Oliva describe the different ecological conditions among European countries which explain the unique futures of the Italian ‘sistemazioni intensive’. Oliva A. 1948 : 29-30 1

Fig. 30 Field. Past situation and present situation. Source left picture Cenedese Ponte di Piave.. 63

Fig. 31 Field models 1952-2007. Structures and processes of change. Top. levelling and piping. Bottom. Filling and piping. 64

Fig. 32 Fields water system. Patterns 1952 (left), 2007 (right). 65

lower than the adjacent matrix. The distance between cavini depends on the gradient of the baulatura, which goes with the permeability of soil. The higher the permeability, the shorter the distance. Common distances run from 60 to 100 metres, the baulatura up to 3%2. The divide of the baulatura is transversal to vine-tree corridors. From the divide two slopes stretch to opposite sides of the cavini, 3-4 m wide, which lie at the two boundaries of the slopes. Cavini are linked to a second order of deeper collector ditches, named capofossi. Drainage. The primary role of the baulatura is to keep excess rainwater out of the field. The convex terrain has high storage capacity (Giardini L.1982). Surplus water flows into the cavini, the first order of the water network. Each cavino collects runoff water from many fields. The gradient of the cavini deliver water to capofossi, ditch corridors with flowing water and vegetation. From capofossi water is discharged into streams. Cavini combine water drainage and accessibility functions. They are dry for most of the year, which allows cart transit. In case of heavy rainstorms the troughs of the cavini function as a basin, “[...] the field looks like an island recognizable from the vegetated boundaries” (Oliva A. 1948: 111). Storing water temporarily in the system is one of the agronomic strategies for drainage: Drain the fields of surplus water flow in order to avoid stagnant water and,at the same time, foster water storage in the soil to guarantee the right height of groundwater3. Water also remains for a few days before draining out downstream.4 The water level is not equally distributed in the convex form of the land (Oliva 1948: 134).The conditions are reflected in the spatial crop arrangement . Erbaceus vegetation (cereals) in the higher part of the fields, shrubs (vines), tree5 vegetation in the lower part, hedgerows along the second order of ditches. Hedgerows absorb, hold and slowly release water toward the ditch. The interaction of cavini with the upper ranks of ditches results in a variety of networks, depending on the ecological conditions in the area. The section shows the diversity of networks with different orientations and density. Orientation goes with the land gradient, density with soil permeability. Irrigation. Precipitation is the main source. Flood irrigation was eventually practiced. Wells played a minor role. At the level of the field, drainage was the main issue. The convexity of the baulatura and the concavity of the cavino provided storage capacity close to the runoff

3 2

See Oliva A. 1948: 76,133; Bonciarelli F. -Bonciarelli U. 1993: 112

The �� main source of water was rain precipitation. In the low plain permeability of soil and high groundwater table conditions result, with heavy rainfall, in areas of stagnation and too much water in the porous soil . In case of drought a low water table goes with dry porous soil. both threatens cultivation. The control of water level in the terrain (franco di coltivazione) is the main driver to create carrying conditions for cropping. Giardini L., 1982 : 336.

See Oliva A. 1948: 37; The Kriegskarte 1798-1805 illustrates the network of ditches permanently filled with water (as indicated in the legend). This is also confirmed by the interviews with Maria Luisa Gallarati Scotti and Dal Pizzol Giovanni. 4

“..i piantamenti in cui la vite accoppiasi all’albero perché così coltivasi più elevata dal suolo, quindi meno offesa da nebbia, rugiada, brine… ”. Pichat C.B., Istituzioni scientifiche e tecniche, ossia corso teorico e pratico di agricoltura, Torino 1862, volume V, libro XXII, pag. 1245; in Finotto F. 2007. 5

source. The infiltration was a little fostered. The delivery of stormwater to the point of outlet of the field into the stream is long. The quantity of water discharged (peak) than is small in amount and frequency. The water level in the main ditches was high (interview Dal Pizzol). The condition was probably functional in coping with periods of both drought and surplus water. Water and the features of the network make the diversity of ecological conditions in the area visible. For example the different density of the network changes in the area in accordance with different permeable conditions. The flooding and stagnation of water in the cavini were regular events threatening crops and accessibility. The convex section was an obstacle after the introduction of machines6. At the level of the case study area, water surplus is buffered and kept in the extensive network. The whole system is a â&#x20AC;&#x2DC;megaspongeâ&#x20AC;&#x2122; that absorbs, holds and slowly disperses water toward the receving streams.

2007 Drivers. The system supports extensive crop production in the frame of a wider cycle of production-consumption at the continental scale driven by EU policy. Production is also supported by an increase in per capita food consumption (Giardini L., 1991: 154). The shift began after the 1950s. In Veneto agriculture manufacturing industry competes for water and land availability and accessibility (Coldiretti 1975: 74). In Ponte di Piave the good economic performance of vine production has driven intensification of agriculture at the expense of breeding. The extension of homogeneous conditions on the land and control of irrigation and drainage are considered crucial conditions for increasing productivity in accordance with modern agriculture techniques This accompanied the reduction of obstacles to machines maneuvering in the fields (Giardini L., 1991:152) and the use of chemical products. Landscape pattern In 2007 the continuity of the minor network was extensively cleared (perforation) by large impervious surfaces related to urbanization. The water system is composed of dispersed fragments of networks exhibiting various features and densities, such as larga ferrarese and the subsurface drainage networks (fig. 32 right). Field structures and flows The basic components of the drainage system, named larga ferrarese at the level of the field, are: the rectangular shape, the convex section, the drainage network.The width, from 30 to 50 m in accordance with the permeability of soil, is defined by a first order of parallel

See Oliva A. 1948: 37; interview with Maria Luisa Gallarati Scotti.

ditches (scoline). The depth, from 200 to 400 m, is limited by capezzagne and a second order of deeper collector ditches. The convex section is ortogonal to the scoline. The cavini are filled. (Giardini L., 1982: 340) The fields increase in depth. The basic components of the subsurface drainage system at the level of the field are: the flat section and the underground pipe network (fig. 31 right). The main component of the network is small perforated pipes buried just below the plow layer and open ditches. The order of pipes collects water that has infiltrated the soil and delivers it to an open ditch. Processes Processes of transformation emerge with the shift from the cavini system to the subsurface drainage system. The convex section of the terrain is flattened out (leveling or flattening). (Giardini L., 1982: 347) The scoline are filled and substituted by pipes (piping). While the network of open ditches decreases in density, the density of underground pipes increases (densification). The fields become wider and deeper (upscaling). Fine related elements, such as paths and hedgrow, decrease. Another change associated with agriculture is the filling and draining of lower fields, which used to play a role in the storage of runoff and floodwater. Drainage. The drainage systemâ&#x20AC;&#x2122;s performance increases (efficiency). Infiltration is not fostered; stormflow is collected and delivered faster downstream to the point of outlet to receiving larger streams, the discharge peak increases in magnitude and frequency. Two case studies in the low plain of Veneto, Tezze-Praâ&#x20AC;&#x2122; di Levadaâ&#x20AC;&#x2122;s case study (Dalpaos 1991:41) and Ponte di Piave (Bixio V., Bendoricchio G. Giardini L. 1994), have demonstrated the relation between water problems, such as increased flooding risk and pollution and the recent drainage networks. This leads to a lower average level of water in the main system of ditches during the year in the area, compared with the situation in the 1950s Irrigation. Precipitation is still the main source. The balance between precipitation and evaporation usually make it possible to cope with increased demand for irrigation. In case of dry periods, the stream is an additional source of water (Irrigazione di soccorso). A system of sluices along the streams is used during high water fluctuation in the stream section. The enclosure raises the level upstream. There are different systems of irrigation. For example, water from the stream is pumped into the order of open ditches and delivered in the scoline or pipe order (drenaggio attivato). Water is also pumped up and delivered to the field, making use of a temporary pipe network (sprinkler irrigation). Groundwater is an additional source.7

At the municipal level 102 farms use groundwater as a source for irrigation (Istat 2005). At the municipal level 62 farms use groundwater as a source for irrigation (Istat 2005); 102 individual wells are declared (Regione Veneto 1999). The Regione Veneto survey includes data on the average rate of groundwater abstraction for irrigation use. 7

Storage issue At the level of field drainage and irrigation, structures and flows changed incrementally. The succession from cavini to larga ferrararese to a subsurface drainage system goes hand in hand with a reduction of storage capacity and an increase of drainage efficiency. Water is not kept in the system; rather, it is delivered out quickly. Separation of structures into distinct spatial and functional elements also occurred. The multifunctional role of the ditches is lost. The increase of drainage efficiency resulted in increasing demand for irrigation. Water discharged downstream is replenished from upstream. At the level of the area, in the past, the dense cavini network provided a multifunctional storage system exhibiting continuity. In the present situation, the abundance of corridors is reduced. The fragmented system of ditches provides a lower storage capacity.

2. Stream system 1952 Drivers. Flood control, extension of agricultural areas. The spatial pattern, structures and flows In 1952 the external structure of the streams Bidoggiata and Grassaga exhibits portions with curvilinear as well as straight features (fig. 35 left). Along the curvilinear parts of the corridor, it is likely that the cross section of the structure is closer to a U-shaped pool. A low bank gradient goes with a wide flood buffer strip stretching along the stream corridor and riparian vegetation (fig. 34 left). The medow patches along the bank and scattered in the matrix, which are visible in the IGM map dated 1891, are probably related to lower wet areas difficult to cultivate (fig 36). The streams exhibit high flow in pools. Drainage. The streams drain surplus water from neighboring areas (sink function) at a low rate. Irrigation. The streams are not designed for irrigation purposes; precipitation is the main source.

2007 Drivers. Flood control, agricultural intensification. The spatial pattern, structures and flows In the 2007 the curvilinear ratio on the same portion is lower, resulting in shorter length and straight features (fig 35 right). A system of sluices is distributed along the corridor. The structure of the vertical section exhibits a wider trapezoidal shape, steep bank gradient and dykes. The distance between edges of the corridor is shorter. The river bed is deeper The stream exhibits a narrower riparian corridor (fig 34 right). Processes Together the straightening, widening, deepening and embanking of the former stream structure is called a channelling or straightening process of transformation (fig 34). The process intensified after the 1960s, managed by the water board. At the level of the two streamsâ&#x20AC;&#x2122; basin, a system of weirs regulates the inflow-outflow related to irrigation and drainage practices. The discharge downstream is regulated by pumps. Irrigation. Water need in the low plain is lower than in the high plain due to the high water table and the capacity of soil structures to store rainwater (Dâ&#x20AC;&#x2122;agostini and Franceschetti 1983: 25; PGBTTR 1991:315). The frequency of irrigation is about 2-3 times a year. The streams are the main source for the irrigation of the neighboring areas of the matrix

Fig. 33 Stream. Past situation and present situation. 71

Fig. 34 Stream models 1952-2007. Structures and processes of change. Channelling.. 72

Fig. 35 Streams system. Patterns 1952 (left), 2007 (right). 73

within a buffer corridor 300-400 m wide. Individual wells also provide groundwater for irrigation. It is assumed that farmers more distant from the streams’ sources are provided for individually. A system of weirs is used to control water level fluctuation. In case of drought the system of sluices along the streams is the appliance used to control fluctuation. When the weirs are closed, a backward effect distributes water upstream (PGBTTR 1991: 316). Water is pumped up from the stream and delivered to the field’s basins where water infiltrates through the order of scoline or subsoil pipes. At the level of the two streams’ basins, inflow is regulated by weirs in the inlet point along the Bidoggia upstream where both streams originate. Drainage.The streams drain the adjacent matrix (sink function). The Bidoggiata flows by gravity into the Bidoggia, and outflow is regulated by a weir. The Grassaga and Bidoggia are a rank of the Brian drainage basin. The effect of channeling is the concentration and acceleration of water movement downstream; water flows from the adjacent matrix upstream into the streams at a higher rate. This drains land and lowers the water table upstream. Today the stream exhibits lower flow level than in the past (interview Dal Pizzol). In case of excess water the sluice system is kept open to foster drainage. At the level of stream drainage and irrigation, structures and flows changed incrementally. In the case study area the succession of transformation goes along with incremental control of the stream structures and dynamics. Drainage and irrigation efficiency are enhaced; water storage capacity decreased, while water consumption increased. The emphasis on discharge and irrigation performance causes downstream flooding, drought upstream and soil erosion of stream channels due to rapid water flows (field survey).

Fig. 36 Surface water system, maps overlapping 1891(grey) -1952 (red). 75

3. Plot system 1952 The spatial pattern, structures and flows Small impervius areas are scattered in the case study area in a isotropic pattern (fig 29-39 left). Ditch corridors are adjacent to build plots (fig 38 left- 29 left). Rainwater surplus is removed from roofs and surfaces within build plots. Water is discharged at a low rate into ditches and streams. Ditch corridors, forming the minor drainage network, are stretched over the area and embed the plot system. The network drains both built and unbuilt (agricultural matrix) areas.

2007 Drivers.Extension of paved surfaces and landform change. The spatial pattern, structures and flows An extensive and continuous patch of impervious areas occupies most of the case study area (fig 39 right). Underground pipes forming the storm sewer are introduced (fig 38 right- 29 right). Rainwater surplus is removed quickly from roofs, impervious and unpaved surfaces within build plots and discharged via sewage pipes into the streams. Water is removed from the surface and delivered to a separate system. Fragments of the former ditch network drains both build and agricultural areas. Recent plots tend to have a higher ground level than previously; emblematic is the case of several condominiums and single houses that are elevated around 60-80 cm higher than street level. Recent plots also exhibit intensification of activities, with related densification of structures and extension of the paved surfaces. Processes The clearing and filling of open ditches adjacent to plots, the clearing of edge vegetation and the extense of effective impervious cover in the plots, go with a decrease of storage capacity and quicker discharge of water (fig 38).

Fig. 37 Plot. Past situation and present situation. Source left picture Cenedese Ponte di Piave. 77

Fig. 38 Plot models 1952-2007. Structures and processes of change. Top. Paving and piping. Centre. Raising and paving. Bottom. Paving 78

Fig. 39 Impervious cover. Patterns 1952 (left), 2007 (right). 79

4. Road system 1952 The spatial pattern, structures and flows A rectilinear and dense network is composed of open ditches going along both sides of the main and minor road corridors. Ditches collect runoff from the carriageways, which are not paved (fig. 42 left). Drivers. Increase of traffic rate, agricultural modern practices.

2007 The spatial pattern, structures and flows The density of the network has shrunk; only the main corridors persist (fig. 42 right). The ditch corridors adjacent to main roads are filled and replaced by storm-sewer underground pipes, which conduct surface water by gravity flow from roads to streams for example, along the road, like Postumia and the former road connecting Levada with Negrisia. Paved surfaces extend over wider carriageways. Most of the dirt roads are erased. Processes The addition of new paved roads and the extensive, effective and impervious cover of existing roads, the piping instead of open ditches and the clearing of edge vegetation have led to concentration of runoff in the pipes, the decrease of storage capacity and quicker water discharge. Furthermore, the elimination of paths has reduced accessibility to the landscape (fig. 41).

Fig. 40 Road. Past situation and present situation. 81

Fig. 41 Road models 1952-2007. Structures and processes of change. . Top. Adding roads. Centre. Paving roads . Bottom. Piping. 82

Fig. 42 Roadside ditch system. Patterns 1952 (left), 2007 (right). 83

Fig. 43 Low plain pits models 1952-2007. Structures and processes of change. Top. Digging pits in the high water table condition. Bottom. A mosaic of ponds emerges. 84

Fig. 44 High plain pits models 1952-2007. Structures and processes of change. Top. Digging pits in the low water table condition. Bottom. A mosaic of deep hollows emerges. 85

5. Irrigation and drainage structures at the water board level Pattern and flows At the water board level the area crossed by the two streams is located in the low plain within the Brian Basin, which stretches between the Piave and Livenza divides (fig. 4647). The Bidoggia and Grassaga, which cross the case study area, are the main carrying structures of the drainage-irrigation system of the Brian hydraulic basin. In the high plain permeable soil goes along with low density of the converging surface drainage water system (see fig. 18) . A diverting system of irrigation reacts to the permeable soil condition to supply this section of the plain. The system consists of small concrete canals arranged in tree-form structures, extending from inlet points. This system is superimposed on a former system composed of open ditches arranged in mesh-form structures. Below in the middle plain, numerous spring rivers join the mountain river network, enriching the surface water network. They form over the low plain, converging into a dense drainage system. In recent decades, the water board has linked some stream corridors in order to control the flow across the basins. As a result the networks were turned into a mesh shape. In the low plain pumps intensify the drainage. The high plain system of irrigation is connected with the low plain system of irrigation and drainage to form a complete hydraulic structure (fig 46-47). The superficial network in the high plain is fed almost exclusively from the outflow of the hydroelectric system. The water is diverted for use in the irrigation systems. With this irrigation flow a quantity exceeding what is required by the land in question is produced. Most of it filters through the aquifer and feeds the springs in the middle plain downstream in the spring belt. Part of the excess quantity feeds the superficial network of the Brian downstream through the flux of unutilised surplus of irrigation in the high plain (called discharges). The nodes of connection between the high plain and low plain network are located along the streams Negrisia and Lia, flowing respectively into the Piave and Monticano. Small channels divert water from the Lia into the Formosa Peressina, a tributary of the Bidoggia. Another channel diverts water from the Negrisia into the Grassaga, which is a tributary of the Grassaga. Irrigation and drainage system structures functioning here are driven by the low gradient of the plain, the high level of the groundwater table and the water level in the rivers. Irrigation is needed less frequently than in the high plain, and drainage is the main issue for the higher flooding risk related to impermeable soil conditions and a high water table.

Fig. 45 Piave hydroelectric system. Hydropower plants (red crosses), dams (red thick lines), surface water (grey lines), diversions (dotted lines). Source: Viganoâ&#x20AC;&#x2122;â&#x20AC;ŚZaccariotto (2009). 86

Fig. 46 Irrigation and drainage structures in the area of the water board. The extensive agricultural matrix (light grey). 88

Fig. 47 Detail. The streams crossing the area (red). The middle-coarse grained mosaic of agriculture (grey scale patches), the urbanized areas (white patches), the pumps (yellow crosses). 89

A weir regulates the inflow of water into Bidoggiata from the Bidoggia (inlet) upstream and another weir regulates the outflow in the point of discharge downstream to the Bidoggia again (outlet). In summer when irrigation is needed, the weir upstream is kept open, and the one downstream is closed to raise the water level. In winter they are kept open to increase drainage. Pumps regulate the outflow discharge of the Bidoggia and Grassaga downstream in case of heavy rainfall. Processes The channeling proceeds on the entire network of streams from the 1960s. In the 1990s an analysis attached to the planning document of the water board (PGBTTR 1991) shows that in a few decades the spatial transformations changed the flow speed and volume during heavy rainfall. The document emphasises the role played by the increasing number of impervious surfaces related to urbanization. Nevertheless, the study of Dâ&#x20AC;&#x2122;Alpaos demonstrated the role of transformation in agriculture as well in changing of the drainage pattern. The analysis leads to the design proposal of further channelizing streams and increasing the power of pumps (PGBTTR 1991). This means that emphasis is put on discharge rather than retention.

6. Problems and challenges Visible and multiple water problems threaten the water systems that are here ordered according to the scope involved, from the case study area up to the water board domain. Irrigation water system Field system. In the area open ditches and underground pipes function for both irrigation and drainage of the field system. Inflow is delivered from the streams Bidoggia and Grassaga, which are the main source of water supply. Streams system. Farmers pump water from the stream during dry periods to maintain a sufficiently high groundwater level in the fields. Individual wells also provide groundwater for irrigation. The consumption from the stream is managed by the water board. The high cost for pumping pushes most of the farmers to wait for rain until forced to use the stream water. They concentrate volume and rate of abstraction in a short period. The withdrawn outrun of the stream recharges, and the quantity of water required in the system is not enough to cope with irrigation demand. This led to dry conditions in neighborsing upstream areas. The level of water is lower than in the past . During the dry seasons, the quantity of water in the system hardly copes with the demand for irrigation (interview Artico). In the low plain, groundwater is also a source (Regione Veneto census 199495). Farmers are forced to make use of individual wells to cope with irrigation needs,

as emerged from a field survey conducted in this study and a study on the territory of Treviso (Dâ&#x20AC;&#x2122;agostini, Franceschetti 1983: 25). Some parts of the agricultural matrix are not connected to the collective system of streams; they lack structures and flow for coping with irrigation demand ( PGBTTR 1991: 316). The process contributes to the tendency to withdraw groundwater. In the high plain meeting the use demands in summer is possible only by releasing a vast amount of water from the mountain reservoirs of the hydroelectric system. Many reservoirs are meant for multiple-use, waterpower and irrigation, but there is open conflict between the uses in the mountains (waterpower) and in the plain (irrigation). To increase the production of electric energy in general, the need is to store as much water as possible, and this conflicts with the need of irrigation . The system lacks the reservoirs of Vaiont (150 M of m3) and Pontesei (9 M di m3), envisioned in the 60s to regulate the quantity and rhythm to also cope with the irrigation demand downstream in the plain (Fassio 2007). This limiting condition contributes to the withdrawal of groundwater. This has led to the idea of using pits in the high plain; the pilot project of Cava Merotto, which will be presented below, is situated within this framework.

Drainage water system Field system. The outflow of surplus rainwater from fields in the area is collected in the drainage ditches or drains and discharged into the receiving main ditch or streams downstream. The shift from open ditches to drains increased the magnitude and speed of storm flow discharge into the receiving streams in case of rain. Water-soluble nutrients, such as phosphorus and nitrogen, are also removed quicky from the field and delivered to streams. Eutrophication and dysfunction result from the accumulation of nutrients and toxic substances (interview Artico ). Road system. The runoff rainwater from road surfaces is discharged into the road system of open ditches or pipes. The shift from open ditches to pipes increased the magnitude and speed of storm flow discharge into the receiving ditch or stream. In case of heavy precipitation, both become overloaded, and flooding occurs in urban areas in the lower parts. Water pollutants are quickly removed and delivered directly into water, especially where verges and riparian vegetation are reduced or removed (e.g., the Postumia section ). Building plot system. The runoff rainwater from paved urban surfaces is collected in drainage inlets which lead to the storm sewer system which delivers water into an open surface system. In case of heavy rainfall sewers become overloaded. Inundation starting from the sewer and â&#x20AC;&#x2DC;water in the streetâ&#x20AC;&#x2122; occur. From the field survey one notes the different microtopography that has been modified in

the incremental constructive process. The more recent plots tend to have a higher ground level quota than previous ones. In general this tendency produces problems of local flooding for the nearby houses that have a lower ground level quota. For example, this process is visible along the road called Via di Mezzo, where one of the oldest abandoned houses in the street shows signs of a water barrier on the door. On the street level this common problem of local flooding becomes clearly visible. Visting during the day made it possible to observe the areas where the water gets stagnant. The question was also raised by an interviewed inhabitant of the zone as well as one of the employees of the water board during two different field trips. The situation is particularly difficult in the industrial area because of the extensive impervious surface, which leads to larger peak discharges, while it is difficult to find space for water storage to prevent flooding risk. Stream system. The surplus of rainwater outflow from the matrix system, road system, urban areas and sewage enters the Bidoggia and Grassaga upstream and within the area. They are the sink where excess water from different sources collects. The shift to channeling features shortened the length, increased the gradient, and decreased the room for water. Water flows with high magnitude and speed. A system of sluices and pumps regulate the point of discharge in the neighboring water board system downstream. In case of heavy precipitation, receiving streams are hardly able to accommodate the water quantity. Backwater effect and flooding risk occur frequently downstream, and the water level increases locally. The cleared bank vegetation, due to the channeling, reduced the self-purification capacity of the stream corridors. Contamination from different sources threaten water quality. The disappearing specie of flora and fauna in the closeby stream Negrisia (Zanetti 2008) is deemed a possible indicator for the Bidoggia and Grassaga. Spring flow feeding the streams decreased. The amount of water retained in the system is lower than in the past . Water level decreased. This makes it more difficult to cope with the demand for irrigation during the dry seasons. Spring and stream biotopes disappear (Zanetti 2008). Flooding. In Ponte di Piave and in the low plain generally there is public awareness that flooding risk is becoming more and more frequent. Two types of floods are distinguished in the literature: those locally generated by high-intensity rainfall and those generated in a larger river catchment and passing through the urban landscape, where they may inundate the flood plain (van de Ven 2009). In the first case, the threat comes from inside, it is actually more frequently driven up by high groundwater level (soil saturation) and the changed surface flow regime related to urbanization and agricultural transformations. In the second case, the threat came from outside as in the case of the extensive flooding in the low plain in 1966. A break in the dike involved the Ponte di Piave and brought heavy damage. The planning policy (PAI 2007) set limiting conditions to urbanization in certain areas.

The Ponte di Piave in recent local flood events (e.g. 1998, 2000, 2004, 2005 ) put the drainage system into crisis, bringing damage and hindrances. This demonstrates the systemâ&#x20AC;&#x2122;s difficulty absorbing water surplus and the contaminant load released from different sources. This intensifies the debate on causes and solutions, such as the scaling of pumps for extra discharge as an ongoing process or the setting of limiting conditions for protection from urbanization (PAI 2007). A general awareness that the room for storing excess water is less today than in the past is also part of the local public discussion (PAT 2009). The irrigation and drainage systems are strained in coping with the flows of supply and discharge. Water problems, such as flooding risk, draught and pollution, are burdens that threaten the territory of the cittĂ diffusa in the water board territory. The system itself is part of the problematic effects.

I.3.3 Drinking and waste

Fig. 48 Drinking and waste water systems in the case study area 1952 (left) and 2007 (right). 95

1. Plot system 1952 Landscape spatial pattern In the beginning of the 1950s, the drinking water supply system for buildings was composed of decentralized individual wells related to the buildings (fig. 51 left). The construction of a collective drinking water network took place in 1952 (PGBTTR 1991: 25). The depth of the wells was shallow (15 m), and the abstraction is from the freatic groundwater level. Deep artesian wells (200 m) are few and related to land-owner plots and big farms (not in the area) (interview Dal Pizzol, Gallarati Scotti). Plot drinking system structures and flows Each plot is equipped with a well (source function). Water abstracted from the groundwater is used locally for domestic supply and farm-related uses (interview Dal Pizzol) After use, water is transformed into waste water, collected and delivered to the minor matrix drainage network in the proximity (sink function) (fig. 50 left). In the 1950s the local main source is the unconfined aquifer a few meters below groundwater level (Interview Coral).

2007 Drivers. Increased demand related to population growth and changes in lifestyle, the sink of the local surface and groundwater system and decreased quality go with the depletion of local sources, the increase of industrial activities and the changes in modern agricultural. Landscape section spatial pattern In 2007 the water supply system related to buildings is composed of both the former decentralized well system and the added centralized drinking water network (fig. 51 right). Plot drinking system structures and flows Drinking. Each plot is connected to a pipe system (fig. 50 right). Water is abstracted a few km upstream in the spring area from wells, collected and delivered downstream in order to supply each final water user. Most of the houses (detached), a few industrial plots and a farm are also equipped with wells located on the individual plots8. Groundwater from individual wells is an integrated source, which supplies, respectively, domestic non-potable uses and production processes. For example, food and building components industries

At the level of the CS area 100% of the plots are connected (field survey and interviews). At �� the municipal level the system was introduced at the end of the 1960s and developed incrementally; the population is 6.500; the water consumption is 613.000 mc/y. 10 % of the population is not connected (Piano d’Ambito 2003 ). 277 individual wells for domestic uses, including drinking water, are declared (Regione Veneto 1999), but a higher number of wells is assumed possible (Mazzola 2003:7, interviews). The Regione Veneto survey (Regione Veneto 1999) includes data on the average rate of groundwater abstraction for domestic uses. 8

Fig. 49 Drinking water. Past situation and present situation. 97

Fig. 50 Drinking water model 1952-2007. Structures and processes. Piping. Groundwater (gw), surface water (sw), drinking water (dw). 98

Fig. 51 Drinking water system. Patterns 1952 (left), 2007 (right). 99

in the industrial area use artesian wells. More often than not the source is the artesian groundwater layers (Interview Coral). Processes The drinking water supply shifted from the individual system of abstraction from wells and surface water near the users in the 1950s to a centralized pipe system at the end of the 1960s (centralization) (fig. 50). The source was located in Ponte di Piave. A well was connected to a municipal scale network of distribution. At the beginning of the 1990s, the well was closed and the network was connected to the wells of Rai San Polo in the spring area, which is the source of a wider network of distribution (upscaling).

Plot waste system structures and flows After use water, transformed into waste water, is collected and delivered to the municipal treatment plant (fig 53-54 right). In the area, the industrial and housing plots are connected, while not all households are connected. Water is discharged locally into the minor matrix drainage network near the plots after individual pre-treatment at the plot level. The treatment plant dimension will be increased (Piano dâ&#x20AC;&#x2122;Ambito 2003) in order to also connect an adjacent municipality (upscaling).

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Fig. 52 Waste water. Present situation. 101

Fig. 53 Waste water model 1952-2007. Structures and processes. Piping. Surface water (sw), waste water (ww). 102

Fig. 54 Waste water system. Patterns 1952 (left), 2007 (right). 103

2. Drinking and waste system at the water board level

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Fig. 55 Drinking water system in the area of the water board. Network (red), nodes of abstraction (black), case study area (yellow). 104

Fig. 56 Detail. Network (red), nodes of abstraction (red dots), buildings (black) case study area (yellow), settlements (black). 105

Drinking water system The drinking water network in the case study area is part of a wider system. The case study area is located in the southern part of the network. The systems are managed (ente gestore) by the company Azienda Servizi Idrici Sinistra Piave S.r.l. Pattern and flows The aquifer is the main water resource for drinking water in the region. The approximately 4,8 million inhabitants overwhelmingly depend on groundwater, which is the source of nearly the entire collective drinking water system of the region. The continuity of the aquifer over the plain also makes the isotropic availability of water possible, which supports the dispersed system of settlements spread over it. Current situation. At the consorzio level the total length of the drinking water network is 2.376 km; in 1998 consumption was about 17 000 000 mc.The existing sources can provide 850 l/s. The forecast for consumption in 2015 indicates a need for 1242 l/s. (Piano d’Ambito 2003). (fig. 55). The northern network distributes water abstracted in the pre-alps (Vittorio Veneto) and in the high plain (Cordignano, Conegliano). The southern network delivers water abstracted in the spring area (S.Polo, Ormelle). A pipe link integrates the two networks into one system in order to provide a backup source to the southern part. At the municipal level (Ponte di Piave) the total length of the drinking water network is 49 km; the total water consumption from the system was about 530 000 mc in 2003 (Piano d’Ambito 2003) (fig. 56). Processes In 1977 a crisis occurring in the drinking water system led to a project for restructuring and expansion of the existing network. The total length of the network in 1977 was 400 km, and it was supplying 22 municipalities . The project reports the constraints of the system to be “obsolete” . The flow from the existing source is not sufficient to cope with the increased demand of water between 1950 and 1970 and the trend of growth. The driving forces reported are: lifestyle change, the need to extend the network to areas where the local surface and groundwater system was depleted in terms of quantity and quality, the increase of industrial activities and the change in agricultural production. Problems like leakages, which were around 15%, and the adaptive rigidity of the technology in use, were emphasized (Consorzio di Bonifica Sinistra Piave, 1978). Till the1980s the entire territory was fed only by northern sources. The recent policy and related plan, Piano d’ Ambito, introduce further integration and upscaling in the management of the two systems. The system, owned and managed by each municipality individually, is grouped into bigger domains of management control by the company.

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A map (Piano d’Ambito 2003 Potenziamento rete adduttrice) (fig 59) illustrates the future transformation process. New elements are introduced. The result is a shift toward a mesh structure. Connectivity. which goes with the efficiency of the system, improves. If any one section of the main water distribution fails or needs repair, a section can be isolated without disrupting all users on the network. Problems in the south system Polluted water (desetilatrazina and composto organoalogenati) detected in a confined groundwater table threatens the south sources of drinking water. Production of the contaminant was related to land uses in the up plain. Contamination infiltrated from the source in the unconfined groundwater zone and diffused into the confined groundwater zone. This proved the potential of pollution plume to stretch along the plain and resist the aquifer’s purification processes (Piano d’Ambito 2003, Interview Pesce). Depletion of groundwater threatens the south aquifer. The incremental growth of water consumption drives up the withdrawal rate, the increase of wells and extension of the network.

Waste water system The waste water network in the case study is part of a wider system. Pattern and flows At the level of the water board domain, the drinking water system measures 670 km (Piano d’Ambito 2003) (fig 57-58). The map illustrates a pattern of small and medium scattered networks and related treatment plants (sink nodes). Each network collects, delivers and treats the waste water at the level of each individual municipality. The treatment plants are small (most between 10.000 and 1.500 AE), the total capacity is about 200 000 AE (Piano d’Ambito ). The system process is no more than 40% of the total amount of AE (PTP 1988). Many treatment plants are not efficient. A map (AATO Interventi infrastrutturali di fognatura e depurazione: carte di sintesi Piano d’Ambito) (fig 60) illustrates the projects of transformation for the main component of the system. New pipe linkages “bridge” the scattered existing small and medium networks (e.g., S.Polo-Ormelle- Oderzo). Existing treatment plants related to the networks show different types of change: some expand (e.g., Ponte di Piave and Salgareda). Many are cancelled and replaced by bigger ones located in a different location (e.g., Oderzo, Motta). Processes. At the water board level the pattern shifts from a small system of scattered networks and related sink nodes (treatment plant) to a system of bigger networks and nodes (upscaling). Each network merges structures of several municipalities into a wider system of the collection, delivery and treatment of waste water (centralization).

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Fig. 57 Waste water system in the area of the water board. Network (red), nodes of treatment plants (black), case study area (yellow). 108

Fig. 58 Detail. Network (red), treatment plants (black cross), case study area (yellow), settlements (white). 109

3. Problems and challenges

Visible and multiple water problems, here ordered according to the different scales of observation, from the case study area up to the drinking water board domain, threaten the water systems. Drinking water system The drinking water system sources are in the pre-alps (Vittorio Veneto) in the high plain (Cordignano, Conegliano) and in the spring area (S.Polo, Ormelle). Water is abstracted, processed and delivered to the end users. The water tower reservoir is in the center of Ponte di Piave. At the municipality level 90% of users are connected to the collective system of drinking water ( Regione Veneto census 1994-95). Wells at the level of the plot are common devices to supply mainly non-potable water uses for domestic and production activities. The leakage rate of the drinking water network is high (30%) in Ponte di Piave . The leakage contributes to recharging of the water table, but the high quality water mixes with contaminated water at the ground level. The capacity of the reservoir is not sufficient to cope with peak consumption . Lack of pressure in the system. The distance and gradient from the source in the network goes with lack of pressure downstream, e.g., in the recent development of the industrial area and Levada (Piano d’Ambito 2003). Depletion of the groundwater table led to the abandonment of individual phreatic and artesian wells in Ponte di Piave (e.g., house in the industrial area et al. field survey). At the provincial and water board level, in recent decades, the withdrawl of groundwater increased to meet the growth of domestic industrial and agricultural uses. The trend of groundwater sink (3 m on average) in both the high and low plain occurring over the last 30 years demonstrates that the total groundwater withdrawn outruns the aquifer’s recharge volume and rate (Mazzola 2003:8; Piano d’Ambito 2003). This trend challenges the groundwater carrying capacity. Contaminants led to the abandonment of phreatic and artesian wells in Ponte di Piave visible during a field survey conducted during this study. The pre-alps sources and south sources are treatened by contaminants (Piano d’Ambito 2003). At the provincial and consorzio levels extensive parts of high plain groundwater are polluted (desetilatrazina and composto organoalogenati – Piano d’Ambito relazione commune Ponte di Piave ) The production of the contaminants was related to past industrial, and agricultural uses, especially in the 1970s ( Altissimo 1995; Mazzola 2003). This threatens the drinking water quality of collective and individual sources in the low plain. Contamination infiltrated from the source in the unconfined groundwater zone in the high plain and diffused into the confined groundwater zone in the low plain. This proved the potential for a pollution plume to stretch along the plain and resist the aquifer’s purification processes (Piano d’Ambito 2003; Interview Pesce; Mazzola 2003). The contaminants threaten Ponte di Piave sources and quality standards under regulations.

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This led to the search for and addition of new sources (Piano d’Ambito 2003). The costs for construction, operation and maintenance are high. The system was optimised in relation to the scattered distribution and low density of users, leading to high material and energy consumption, which challenges its feasibility. Waste water system The waste waster is collected into the sewer network and delivered to the treatment plant downstream situated by the Cre’ rivulet. Excess water .In case of heavy rainfall, groundwater rise and upward seepage occur in the pipe network. Excess water leads to the overloading of the pipe network. Dirt and smell rise from the sewer (e.g., Via della Vittoria). The leakage rate from the sewer is high. It threatens groundwater and surface water quality. Surplus rainwater flow is carried to the treatment plant. Untreated wastewater is discharged into open water via overflow structures into the effluent (Cre’ rivulet) a few times a year as confirmed by the (interview De Bianchi). Surplus waste water flow is carried to the treatment plant. Untreated wastewater is discharged in open water via overflow structures to the effluent. Some industrial activities, which, in case of peak of waste production, have to be provided for individually for reclamation tend to discharge illegally either into the sewers or the minor water network nearby (PAT Atlante 22; Piano d’Ambito 2003; press review). The receiving surface water element is hardly able to absorb the lower quality of water. Flora and fauna are distorted, and people complain of the smell. The municipality is fined due to effluent quality exceeding the statutory standard (PAT, press review). The costs for construction and maintenance of the network are high, given the scattered distribution and low density of users. The collective waste water system introduced is regularly being restructured and expanded to cope with the increased demand for discharge and to comply with quality standard regulations. These problems are common at the water board level (Piano d’Ambito 2003). The drinking and waste water systems are are pressed to cope with the flows of supply and discharge. Water problems, such as flooding risk, draught and pollution, are burdens threatening the section of the città diffusa analysed . The system itself is part of problematic effects.

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Fig. 59 The upscaling of the drinking water network. Source AATO Veneto Orientale, Piano dâ&#x20AC;&#x2122;Ambito 2003. Planned pipe network (red); existing network (black). 112

Fig. 60 The upscaling of the waste water network. Source AATO Veneto Orientale, Piano dâ&#x20AC;&#x2122;Ambito 2003. Planned treatment plants (red); existing treatment plants to be deactivated (white, magenta); unplanned area (red dots); existing network (black). 113

I.4 Conclusions

Paradoxes of change: water, space and actors The water paradoxes relate to the processes of change in water use and water management. Paradoxically, in general, solving some water problems has also created water problems. Improved irrigation and drinking water supply networks have led to increased water use that asked for bigger reservoirs and expanded piped networks, drawing more heavily on the available resources. The huge amount of water abstraction has led to sinking groundwater tables as a sign of depletion of surface water and aquifer resource depletion. Increased water use also implies that fluctuations become more problematic than they used to be. In both areas the irrigation system performs well, but is often unable to cope with the higher agricultural requirements. Water shortages frequently occur in summer periods as the available resources of surface water and groundwater cannot meet the demand. Dwellings and industries also make use of groundwater abstraction for nonpotable uses like garden, irrigation or car washing. More efficient drainage with larger and straightened channels leads to higher peak discharges downstream and, as a result, more risks for downstream floods. New business areas, as in the Ponte di Piave case increase the paved surface without sufficient space for buffering the resulting storm water run-off peaks. In general, storage for peaks and storage for dry periods are missing at the level of households, farms and villages. Drinking water and waste water systems changed from decentralized to centralized (fig 61). From individual shallow wells for water supply and onsite waste water disposals to deep collective wells and waste water collection and transport to municipal treatment plants. These plants only partly remove pollutants and thus improve the general situation but still pollute the surface water where they discharge their effluent. Heavy rainstorms sometime exceed the capacity of the treatment plants and in such cases there is an overflow of untreated wastewater. Increased use of fertilizers and pesticides leads to increased diffuse contamination that filtrates to surface waters and to groundwater. Centralized systems do not solve all problems and also create problems. Moreover, costs for construction and maintenance are high, especially in relation to the scattered distribution and low density of settlements in the Veneto area. Thus, there are good reasons to also explore more decentralized options for storage and recycling. The spatial paradoxes relate to the process of change in land and water use. Paradoxically, improving spatial conditions for production has also worsened spatial conditions, especially those related to the diversity of the cittĂ diffusa landscape. Drinking water supply and irrigation ask for distributive water networks, whereas wastewater collection and drainage require contributive networks. All those structures permeate the underlying agricultural matrix turning it into a porous form with patches and corridors (Forman 1995: 279). In the

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Veneto, this has generated different patterns in the higher plains with a gravel underground that facilitates drainage and in the lower plains with dominating clay soils. The intermediate spring zone has artesian wells and thus, its own characteristic pattern. The process of modernization in agriculture, however, tends to level these characteristic differentiations. Fields are enlarged and levelled, ditches filled and trees removed. As illustrated by densification of buildings and up-scaling of both fields and settlement plots go with a shift from a decentralized system of homogenously distributed farms and related fields towards a concentration and separation of the activities and cultivations in specialized areas (Zaccariotto & Ranzato 2009: 153). As a result the mosaic changed from a fine grain of land parcelling and farm units where the buildings hardly emerge from the agricultural matrix, to a coarse grain pattern with larger units of residential and industrial buildings. In 1950 the agricultural matrix of the fine grain was supported by the surface water system. In 2003 the minor surface network of irrigation and drainage supported a different matrix of a middle coarse grain. The shift from mixed agriculture to monoculture, the development of the manufacturing industry and the logistics and transport movements that go with these changes are the drivers of the spatial and water network transformations resulting in a different landscape (Bevilacqua 1991:30). The new landscape is less diverse for people to live and recreate. Reduced variety and less gradients also create reduced conditions for biodiversity. There are good reasons to further explore the options for sustainable differentiation, using the ecological and the functional potentialities of this situation. The actor paradoxes relate to the changing patterns of peoplesâ&#x20AC;&#x2122; activities in the cittĂ diffusa. Paradoxically, improving the conditions for economic activities sometimes threatens to reduce the quality of life in this landscape. On its way from a local economy to a world market economy, the Veneto has embarked upon a path of specialization. The fashion and shoes industries, the manufacturing of fine mechanics and also different agricultural and food industries in the Veneto have survived by specialization. Not the economy of scale of the bulk industry but the economy of niche markets for specialized products represents the economic strength of the region in the age of globalization. Yet, as demonstrated by the spatial development of the case study area, also in the Veneto there is a tension between up-scaling and diversity. Moreover, not visible on the aerial photographs are some developments related processes such as the growth of traffic and transport and the increasing pressure on water quality and resources. The challenge for planning and design in Veneto is to develop scenarios for mutual adjustment of the ecological and economic opportunities. Further expansion of monofunctional coarse grains in the area will eventually destroy the diversity that is the core quality of the region. Further growth of resources will also jeopardize the sustainable future of the cittĂ diffusa. And this asks for feed back mechanisms in the use of resources. The case of water is a good illustration. In the process of centralization, water supply and wastewater disposal is taken out of the hands of the individual users. For them it improves the situation. As a result, however, the cycle is no more visible and does no longer act as an incentive for water saving, reuse and recycling. Water is out of the eyes and out of the hearts. The consuming actors turn the tap. The actors at the municipal treatment plant have to take the existing pollution for granted. Their

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Fig. 61 Centralization of the water system. From left to right: natural hydrography, irrigation and drainage system, drinking water system; the permanency of the decentralized system of wells; waste water system. 117

task is purification. Inhabitant equivalents of pollution and water quality standards are the leading criteria. Direct feed-back is no longer in the hands of the actors. There are good reasons, therefore to further explore the options for multifunctional synergism in spatial planning and for feed-back mechanisms in environmental planning. The role of water may be a good starting point because water carries both important environmental processes and important spatial patterns.

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II. Water challenges and spatial design

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II.1 Landscape and water strategies

II.1.1 Guiding model approach 1. Guiding principles This part focuses on the role of designers and planners in the search for sustainable options for the future of the Veneto cittĂ diffusa. An analysis of the changing landscape illustrated and a discussion of the underlying paradoxes leads to some guiding principles that may guide the process of exploring planning and design options. First, three guiding principles emerge from the discussion of the paradoxes of water management, spatial development and the activities of actors. Likewise, a set of principles has also emerged in many other planning situations and in many discussions about integrated and sustainable development. Integration here means planning and design strategies that seek to work with the various water systems as a coherent whole and coordinate and integrate water management with activities in other fields. Sustainability means that in addition to improving environmental and living conditions in the existing urban landscape, water management should ensure that the functional, recreational and nature conservation value of water are available to future generations. The following principles are basic to this approach: 1. The design of water systems should focus first on storage and recycling. This implies a shift from a more traditional priority for input-output planning. The principle is a practical way to formulate the idea of closing the cycle. Storage is the basic answer to quantity issues, such as too much (e.g., risk of floods) and too little (e.g., risk of shortages). Recycling stands for the reduce â&#x20AC;&#x201C; reuse - recycle priority sequence advocated by UNEP and UNESCO (see, for example,Schuetze et al. 2008). The shift is illustrated by the scheme named ecodevice model, developed by Van Wirdum and Van Leeuveen (Van Leeuveen 1982) (fig. 62). The model represents an ecosystem, in which the life-support conditions are regulated by input (supply from a source ) and output (discharge to a sink) flow control. But an ecosystem also has the capacity to resist (the concave side, not-in) and retain (convex sided, not-out). An urban landscape is a system that traditionally regulates flows by input and output. For example, water scarcity is solved by increasing supply, and excess water is solved by

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Fig. 62 Ecodevice model. 121

increasing discharge. This solves the problem inside the system but often at the cost of the neighbours upstream (e.g., depletion) or downstream (e.g. flooding and pollution). However urban landscapes are ecosystems. They can also store surplus water and use this storage to prevent shortage. This draws attention to the convex side. Storage is a condition for recycling (Tjallingii 1996). 2. The basic variety of ecological conditions in the local landscape should guide the planning process. This is a shift from a more traditional function-guided planning approach. The principle is also known as part of the layer approach (see, for example, CEC 1999) with its focus on the underlying structures of the landscape (the soil and the water system), the infrastructure networks and the occupation pattern (building for living and working). 3. Specialization and synergism of activities are the basic principles for multifunctional regional planning. This implies a shift from approaches involving economy of scale and cost reduction. A principle such as this plays an important role in the current discussions about territorial cohesion. The special character of the diversity of the cittĂ diffusa urban landscape in the Veneto and the need to create visible incentives for environmental feed-back processes justify a fourth principle: 4. Planning and design processes should start bottom-up. This does not mean that individual solutions are always better than collective systems, and these will be always better than centrally organized solutions. The design process seeks optimal solutions fitting the local landscape and the local actors. But starting bottom-up means exploring the decentralized perspectives first and only moving up scale if there are very good reasons for it.

2. Guiding models Together the four principles may guide the design process in its search for integrated solutions that fit the planning situation of the cittĂ diffusa. The best way to bridge the gap between guiding principles and the real world is setting up pilot projects pioneering in the local situation and providing a practical basis for the essential learning process. In the Veneto area, there are a number of interesting pilot projects demonstrating the feasibility of the guiding principles (fig. 63). Some examples are the recent project of Cava Merotto in the high plain, between Piave and Livenza rivers, and the Vallevecchia project in the low plain, between the Livenza and Tagliamento rivers. In the Cava Merotto project in the Veneto Region, the water board Pedemontano Sinistra

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Fig. 63 Top. Pilot Project Cava Merotto, 2008. Project proposal and realization. Source: Landscape of Water (ViganĂ˛â&#x20AC;Ś Zaccariotto 2009). Bottom. Pilot Project Vallevecchia, plan and realization, 2000. Source: Veneto Agricoltura. 123

Piave and the IUAV University of Venice co-operate. The plan retrofits a former gravel stone quarry area. Water storage in the former quarries is the key concept. The system manages flow processes in two basins in different spatial and temporal combinations. From autumn to spring, one basin stores water from the nearby river Meschio to provide agriculture with irrigation water in summer. Another basin acts as storage for excess water from the rivers, buffering and thus preventing downstream floods. At the same time this water infiltrates and recharges groundwater, thus increasing underground storage. The exercise on Cava Merotto shows the interest in a design starting from water management and becoming a reflection on the contemporary notion of public spaces in a dispersed territory. In the Vallevecchia project the regional agency for agriculture (Veneto Agricoltura), supported by Veneto Region and the water board Pianura Veneta Orientale, has retrofitted a farm drainage system, situated in a reclaimed area, to retain rainwater surplus. The storage buffers and holds water from autumn to spring, avoiding downstream discharge. Within the system, water flows through a circuit of ditches to prevent upward saltwater seepage and to supply irrigation in dry periods while reducing energy costs for pumping. Both projects shaped physical spaces and flows in the spirit of the guiding principles. In this context promising combinations, guiding models, emerge. They may be combined with other experiences in other situations to develop a collection of more general guiding models, a toolkit for designers. Guiding models are concrete models of the optimal organization of space and processes in well-defined categories of situations. Designers do not need to reinvent the wheel in every project. There is a learning process that has generated promising combinations of spatial design with economic, social and ecological processes, financial planning and public and political support. This may result in a toolkit, and the designer may take the model that seems to fit to the planning situation as a starting point of the design process (Tjallingii 1996, 2009). It is worth noting that guiding models are tools for plan making, for the process of generating creative and innovative alternatives. To be realized these proposals have to pass a process of plan testing, including environmental assessment procedures. This process is essential for improving plans and turning then into realistic proposals. Plan making and plan testing need each other. In practice, spatial planning is often dominated by the standards, norms and criteria of plan testing, but without good plans all testing procedures are blind. This is why guiding models are important. They improve the quality of plan making. Two models are presented as an illustration of the toolkit of guiding models at different levels. They take their own area as a system that can regulate flows by input and output and also by resistance and retention.

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Fig. 64 Dwelling lot guiding model. Cleaning water (cw), drainage (dr), drinking water (dw), groundwater (gw), irrigation (ir), rainwater (rw), surface water (sw), waste water (ww). 125

Low scale: dwelling lot model In a conventional dwelling lot system (fig. 64 left) rainwater falling onto the lot is rapidly discharged; a considerable amount of groundwater and drinking water is let in, after use wastewater is driven out. The dwelling lot guiding model (fig. 64 right) is appropriate for small and large lots. Rainwater from the roof and paved surfaces buffer in one storage (peak storage) and is stored insofar as feasible (seasonal storage). Also wastewater treated in a purification system is retained in the storage. A pond, a ditch, a water butt or a tank are examples of storage devices. Only when the system is full, does it drain the water surplus downstream. This water can be used in and around the house, for example, for flushing the toilet, for cleaning water or watering the garden. The reuse and recycling of water reduce the external supply of drinking water and the extra discharge of storm water and wastewater. A set of guiding models for the low scale is illustrated in the guiding model appendix.

Middle scale: circulation model In a conventional middle scale settlement (fig 65 left) water flows is regulated with the same in-out mechanisms previously described. The guiding model, called circulation model (fig 65 right), is appropriate in low plain situations. Storage capacity in the ground is limited because the high groundwater and soil conditions do not easily allow infiltration. Retention of surface water is therefore the suitable way to store water; in addition or alternatively to preventive measures in the individual lots. The conceptual model illustrates how an area can retain water by allowing temporary rises in the surface water levels, before buffering water surplus into one storage (peak storage) and storing insofar as feasible in another one (seasonal storage). Also, wastewater treated in the reclamation system is retained in the storage. A pond, lake, or stream section are examples of seasonal storage. In the model a reclamation system for wastewater treatment, a peak storage system and a seasonal storage system are integrated as a whole device. Only when it is full does the system drain the water surplus downstream. The water flows around the system; in each cycle water passes through a bed of reeds or rushes and so can in principle begin each cycle again as clean water. The model is a version of the circulation model developed by S. Tjallingii as a result of the design process.

Conclusion The shift from removing to holding water makes the illustrated systems less dependent on inflow from the surroundings and less vulnerable. The retention of rainwater and wastewater treated in the systems own storage and the integration of the complete water management system into one chain contribute to making up for periodic water needs. The rhythm of supply and discharge (in-flow and out-flow) is replaced by a rhythm of

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Fig. 65 Circulation model. Drinking water (dw), surface water (sw), waste water (ww). 127

fluctuating water levels in water bodies in the area. The peak storage fills rapidly in case of heavy rainstorms, the seasonal storage fills slowly to reuse water as needed. Pollution of retained water can be avoided through preventive measures and separation at source. Water should flow from clean to polluted; different water qualities should not be mixed. Flows of different quality are separated at the source and differently clean (fig 66). The water cycle becomes visible, and water comes back under the control of the inhabitants. The last part explores the practical questions related to working with guiding models in the case study area.

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Fig. 66 Water recycling in low plain contexts. The diagram illustrates a combination of different flow qualities and water treatment processes in the comprehensive chain sequence. Each water flow requires a specific recycling process. Water runs in accordance with the â&#x20AC;&#x153; from clean to pollutedâ&#x20AC;? principle. For example, the recycling of waste water output from households is destined for irrigation reuse, requiring primary, secondary and tertiary treatment. 129

II.2 Retrofitting Scenarios

II.2.1 Introduction

Starting with flows suggested a portion of the Bidoggiata catchment basin to select as case study area (fig 67). In the context of the research, the case study areas offer a fine opportunity for developing context-oriented knowledge (Malbert, 1994). From analysis the research moved to a process of design. The two leading questions were: 1. How can a decentralized Veneto urban landscape contribute to sustainable water flows? 2. How can decentralized water flows contribute to this urban landscape? As an illustration two case studies are presented: a housing area in the small centre of Levada and a wider area including the previous one. The guiding models result mainly from a research-by-design learning process exploring the interrelation between flows and spaces. The following questions are explored: what if the areas are retrofitted as an integrated spatial device for water storage? What if the device of retention, reclamation and reuse (storage device) is alternatively organized at the collective and individual levels? The results of the design process are structured in categories reflecting the main conceptual steps: program, rhythm, orientation, situation. Program concerns the existing and future design of a desirable situation . Rhythm concerns the dynamic aspect of water. Situation regards the use of the quality of the existing landscape (Tiallingii 1996).

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2 1

Fig. 67 The Bidoggiata catchment basin and the case study areas. Housing area (1). Housing, industrial and agricultural areas (2). 131

II.2.2 Collective 1

The object of the scenario named Collective 1 is a portion of the Bidoggiata catchment basin, a housing area in the small centre of Levada (fig 68).

1. Program The main issue is the shift from removing to holding water. To treat the study area as an independent system, it should be disconnected from upstream and surrounding water courses. The retention of rainwater and wastewater treated in the systemâ&#x20AC;&#x2122;s own storage and the integration of the complete water management into one chain contribute to making up for periodic needs of garden irrigation. The area selected, a recent housing patch, is a portion of the small centre of Levada in the municipality of Ponte di Piave ; the form is a rough polygon of 150 x 295 m, oriented eastwest; the surface is about 3,7 ha, and about 60% is paved and 40% unpaved (fig 69). The area is framed by two corridors: in the eastern part, the road Postumia, which stretches NS on high banks with deep ditches, and to the north, the stream Bidoggiata, which flows NESW. A finer analysis of the micro-topography of the area revealed that the terrain was raised to compensate for the height differences between the road and the lower ground level of the former agricultural matrix. The topsoil is sandy-loamy, resulting in mediocre drainage. The water quality of the stream is good, a condition supporting ecological diversity. The existing urban water system in the area includes a series of flows and related management systems. The groundwater table is relatively high (-1,5 m is the average level). The groundwater flow intersects the E W direction (fig 70). Rainwater is removed quickly from roofs and impervious surfaces, such as roads, parking lots and gardens, and discharged via a piped network into the main collector under the road or via open ditch to the Bidoggiata (fig 71). A few plots remove and discharge surplus rainwater directly into a ditch, which borders the NE side of the area. Border ditches are the outlets for those plots. The Bidoggiata spring a few km upstream drains an elongated section of territory and discharges its flow downstream into the Bidoggia. The drinking water supply is abstracted upstream in the spring and pre-alps areas, and delivered to the plots via a piped network (fig. 72-73). A lesser amount of groundwater

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Fig. 68 The housing area in the small centre of Levada. Source Telespazio 2007. 133

is abstracted locally. Wells are the sources at the level of the individual villa plots; they are used to supply limited domestic uses, such as garden irrigation and car washing, assumed to be the main water consumption practices in the residential area. Wastewater (black and grey) from domestic use is quickly removed from plots and discharged via a pipe system to a municipal treatment plant located a few km downstream (fig.74-75). Relatively clean rainwater and wastewater is removed from the area (daily and seasonally). Instead, water of good quality (drinking quality) is withdrawn from aquifers for non-potable use. Relatively clean rainwater and wastewater is removed from the area (daily and seasonally). Instead, water of good quality (drinking quality) is withdrawn from aquifers for non-potable use. For the future water system this means that the high groundwater and soil conditions do not easily allow infiltration. Retention in surface water is therefore the suitable way to store water. The illustrated guiding model, called circulation model, seems to be appropriate for further investigation.

2. Rhythm The shift from removing to holding water makes the system less dependent on inflow from the surroundings and less vulnerable. The retention of rainwater and wastewater treated in the systems own storage and the integration of complete water management into one chain contribute to making up for periodic irrigation needs. The rhythm of supply and discharge (in-flow and out-flow) (fig 76). should be replaced by a rhythm of fluctuating water levels in water bodies in the area. The peak storage fills rapidly in case of heavy rainstorms, the seasonal is slowly filled to reuse water when needed. An analysis of the rain precipitation and evaporation rhythms demonstrates that, in principle, the surplus rainfall the rest of the year can meet the existing deficit between May and September (fig 76). A trend towards drier climate conditions, also affecting the Veneto region (Chiaudani 2008), will push the demand for water use. In the case study the seasonal rhythms of garden irrigation and garden drainage react to periods of shortage and surplus. An analysis of the rainfall frequency curve demonstrates that it is not uncommon in Veneto to take curve showing a critical rainfall depth of 130 mm after 24 hours return time 10 years. The peak storage basins buffer the storm water surplus of the whole area and are dimensioned to cope with extreme events within a 30-year return time (fig 77). The peak of water generated by the paved surface in the area in case of heavy rainfall drives the

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Fig. 69 Housing area. Top. Impervious surfaces (dark grey). Bottom. Relief and soil type. 135

Fig. 70 Housing area. Top. Groundwater direction. Bottom. Existing drainage system. 136

Fig. 71 The map exhibits the relation between the area and the drainage system at the level of the catchment area. 137

Fig. 72 Housing area. Existing drinking water system. 138

Fig. 73 The map exhibits relations existing between the area and the drinking water system on a wider scale. 139

Fig.74 Housing area. Existing waste water system. 140

update

Fig. 75 The map exhibits relations existing between the area and the waste water systems on a wider. 141

calculation of the peak storage volume required. A retention basin with a depth of 130 cm (fluctuation of 110 cm) which covers 3% of the total area or a retention basin with a depth of 50 cm (fluctuation of 30 cm), which covers 11% of the total area, meeting the volume required. The purification system, a forest buffer patch,1 purifies the wastewater of the area and is dimensioned for about 190 inhabitants. (fig 77).The area of the forest buffer patch needed to treat the wastewater is assumed to be 10% of the area. The forest buffer strip system’s own treated flow is enough to supply water for garden irrigation. In summer, the effluent of the phytoreclamation system is connected directly to the gardens. From autumn to spring, daily treated wastewater goes to the seasonal storage, which also stores as much as possible of the periodic runoff. Thus, the system can cope with peak irrigation demand The seasonal storage reservoir copes only with peak irrigation demand (fig 77). The quality of water needed for the irrigation supply for gardens in the area drives the initial calculation of the seasonal storage volume . A retention basin with a depth of 130 cm (fluctuation of 110 cm), which covers the 10% of the area, meets the volume requirement, which is later reduced during the design process since the forest buffer strip system’s own treated flow is enough to supply the water for garden irrigation. The depth of the pond should be sufficient to prevent it from falling dry in summer. An inlet is necessary in case of extreme drought, and in the case of extreme rainfall the system outlet discharges water downstream to the Bidoggiata.

3. Orientation Water should flow from clean to polluted, different qualities of water should not be mixed, flows of different quality are separated at the source and differently reclaimed. Relatively clean rainwater is mixed with polluted storm water runoff and discharged into the stream. In the collective scenario rainwater from roofs is retained in an individual rainwater butt. Grey water and black water are processed locally in a chain of treatment facilities including the woodlands. Storm water runoff from paved surfaces, flows into the existing storm drains and is purified in the collective wetland treatment system before being led into the seasonal storage.

The forest buffer patch as purification system It is based on an interpretation of the pilot project “Nicolas”, Veneto Agricoltura and the water board Dese Sile 1999. 1

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Fig. 76 Top. Rhythm of precipitations and evaporation during the year. Elaboration from Chiaudani 2008. Bottom. Rhythm of supply and discharge during the year. Elaboration from Chiaudani 2008. 143

4. Situation The variety of ecological conditions in the local landscape, either abiotic or biotic structures, can significantly contribute to the water flow strategy. The design should follow and use the existing soil and landform, groundwater conditions. The existing water management system should also play a role. A general guiding principle is that peak storage devices could be better accommodated on lower and less vulnerable depressions closest to the point of peak generation (specific); the seasonal storage (retention basin) can be located at the highest levels to which the water is slowly pumped up. The analysis of the existing conditions suggests the rational positioning of the three elements. (fig 78- 79). The existing lower public green area can be used as peak storage. The woodland purification system is located in the open fields bordering the area on the north side, using the existing field ditches. The purification system is connected with the existing wastewater network within the area. The seasonal storage is concentrated along the upper west side of the area, close to the outlet of rainwater surplus carried by the existing network (white water). A circulation system integrates the parts. Existing and new ditches merge to form a water course circuit, tuned to the different conditions of space and flows. The outlets of storm water and wastewater are connected to the local circulation system and disconnected from the main collectors delivering water flows far from the area. A wetland purifies water before it is discharged into the seasonal pond. The outlet of wastewater is also disconnected from the main pipe collector delivering wastewater for municipal treatment and connected to the forest buffer area after pre-treatment.

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Fig. 77 Top. The peak storage area options in relation with the different depths of the volume basin (right). The diagram for the calculation of volume based on the percentage of the areaâ&#x20AC;&#x2122;s impervious surfaces (left). Centre. The seasonal storage area (right) and the diagram of calculation of the basin volume based on the water needed for irrigation (left). Bottom. The water purification area (right) and the diagram of calculations based on the inhabitant equivalent number in the area (left). 145

Fig.78 Top. Peak storage. Centre. Purification system. Bottom. Seasonal storage. 146

Fig. 79 Collective scenario. 147

5. Guiding model The output of the learning process from the case study is an improvement of the circulation model adding the treated wastewater to the storage (fig 80). This strategy combines water storage and closing the cycle. A new spatial model illustrates the possible solution applicable in principle in type of spaces showing conditions similar to those of the case study, such as the ratio between the number of inhabitants and surface area of gardens. The purification systemâ&#x20AC;&#x2122;s own treated flow can be enough to supply water for garden irrigation. In summer, the effluent of the phytoreclamation system is connected directly to the gardens. From autumn to spring, daily treated wastewater goes to the seasonal storage, which also stores as much as possible of periodic runoff. Thus the seasonal storage can cope with peaks of irrigation or might be used to cover other non-potable water uses in the area. The direct connection between the purification system and the garden reduces the space needed for seasonal storage.

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Fig. 80 Guiding model collective result of the learning process. 149

II.3.3 Individual

The individual scenario (fig 81) is based on the same principles and tailors the guiding model to the variety of flows and space conditions on the different plots. To treat the study area as independent system, it should be disconnected from upstream and surrounding water courses. An integrated system of storm water storage, wastewater reclamation and seasonal storage is arranged within each parcel (see dwelling lot guiding model in the Guiding models appendix). In a few cases spatial conditions challenge the feasibility of individual options.

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Fig. 81 Individual scenario. 151

II.2.5 Collective 2

The scale of interest for the scenario named Collective 2, is just above the housing area of Levada. A broader section of the catchment basin is selected.

1. Program The main issue is the shift from removing to holding water. The complementary spatial condition stimulates seeking for combinations of promising water flows. The retention of rainwater and wastewater treated in the systems own storage and the integration of the complete water management system into one chain contribute to making up for periodic needs for agricultural irrigation. The area, a checkerboard of diverse land uses patches, is a rough polygon of about 600 x 900 m (fig 82-83), which to the north borders with a farm building plot and a related ancient villa, to the south with the road connecting Levada with the industrial area, to the east with the villa’s avenue and to the west with a railroad track and the adjacent road. The Postumia Road and the stream Bidoggiata cross the area, respectively, with N-S and E-W orientations. The surface is 54,7 ha, and about 50% is paved. The main land uses include the housing strip, the northern part of an industrial area and a portion of farmland. The housing strip, about 5 ha, includes the Levada area previously described and additional plots along the ancient road to Levada. The industrial area, is a polygon of about 20 ha, the result of an incremental process of urbanization from the 1980s; about 90% is paved. The plots include small and large industrial, commercial buildings hosting a variety of commercial and manufacturing functions, and pre-existing houses. The area borders on Postumia to the east, the railroad track to the west, the recent bypass road to the north and the ancient road to Levada to the south. The ground level of the industrial area rises higher than the ground level of the agricultural matrix, and it is lower than both the railway and the road on Postumia banks. It is the result of a levelling operation accompanying preparation of the site. The stream corridor runs through the industrial area. The corridor is a public green space ‘in between’, which is formally defined by the straight edges of the retaining walls on the two sides of the industrial platform. The farmland area, about 24 ha, partially surrounds the housing and the industrial patches. The arrangement of the fields is the result of recent agricultural intensification. It is a portion of a wider agricultural system, including the plot for the wine growers’ buildings with an ancient villa and related vineyard. The farm building plot is adjacent to the stream

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Fig. 82 Area 2. Source:.Telespazio 2007. 153

Zocchella. The existing urban water system in the area includes a series of flows and a related management system (fig.84). Rainwater is removed quickly from roofs and impervious and unpaved surfaces within individual and collective areas, such as plots, roads and parking lots, and discharged via sewage pipes. Subsurface drains collect rainwater quickly from fields into the open ditch crossing the area. Both the industrial platform and the farmland discharge water surplus into the Bidoggiata. The drinking water system supplies activities, while a lesser amount of groundwater is abstracted from individual wells related to at least one industry and the farm. Wastewater (black and grey) from domestic and industrial uses is quickly removed from plots and discharged via a pipe system into a municipal treatment plant downstream. In dry periods, in the farmland, the drainage system is also used for irrigation. Surface water from the Zocchella is pumped into the open ditch and carried to the fields via subsurface pipes. Relatively clean rainwater and wastewater is removed from the areas (daily and seasonally). Instead, water of good quality (drinking quality) is withdrawn from aquifers for potable and agricultural uses. In the agricultural area the lack of water in the surface water system in dry periods threatens crops. This leads to drawing heavily from the stream while the use of groundwater contributes to its depletion. Finding room for water storage is economically inconvenient due to the high cost of land. These constraints make the problem too difficult to solve within the agricultural area. In the adjacent industrial area, on the other hand, in case of heavy rainfall, the extensive effective impervious cover leads to increased amount and speed of rainwater surplus, which produce a larger peak discharge for receiving streams. This threatens the neighbours downstream due to the risk of flooding. Furthermore, climate change will produce water tendencies that will exacerbate the problems. These conditions underlie efforts to work up a strategy including the three systems. The complementary conditions stimulate the search for promising combinations in order to solve problems in each area within the frame of a collective strategy embracing the three main systems. For the future water system the circulation model previously illustrated is applied at the area level. The retention of rainwater and wastewater treated in the systems own storage and the comprehensive integration of water management into one chain contributes to making up for periodic needs for irrigation. The rhythm of supply and discharge (in-flow and out-flow) should be replaced by a rhythm of fluctuating water levels in water bodies in the area. The peak storage fills rapidly in case of heavy rainstorms, the seasonal storage is slowly filled to reuse water when needed.

154

Fig. 83 Area 2. Housing (1), industrial (3) and agricultural (2) areas. Source: Telespazio 2007. 155

2. Rhythm The peak storage buffers storm water surpluses of the industrial and road areas. It is dimensioned to cope with extreme events within a 30-year return time. The peak of water generated by the impervious surface in case of heavy rainfall in the industrial and road areas drives the calculation of the peak storage volume required. The retrofitted Bidoggiata stream accommodates the peak storage volume required for the industrial area. A stream bed which is the 3,5% of the area will meet volume with a fluctuation of about 50 cm. A sluice is introduced along the stream s a selector-regulator device to control the fluctuation quantity and rhythm. The purification system is a wetland which is dimensioned to treat wastewater from the industrial area and from the housing areas (400 AE). The area of the wetland patch needed to treat the wastewater of about 400 inhabitants is assumed to be 0,5% of the area. Three seasonal storages are calculated to cope with the irrigation demand of both gardens in the industrial area and crops in the agricultural area. The quantity of water needed to supply the irrigation of both gardens in the industrial area and crops in the agricultural area drives the seasonal storage volume required. Three retention basins with a depth of 110 cm (fluctuation of 100 cm), covering 5,5 % of the area, meet the volume.

3. Orientation To make the system independent of the quantity and quality of the upstream areas, there should be a bypass connecting the upstream area of Bidoggiata to the Zocchella, using the existing ditches on the west side of the railway. Water qualities should not be mixed. Flows of different quality are separated at the source and treated separately. Thus, prevention and control at the source emerges as a general principle. In the collective scenario rainwater from roofs is retained in an individual rainwater butt. Grey water and black water are processed locally in a chain of treatment facilities, including the wetland. Storm water runoff from paved surfaces flows into the existing storm drains and is purified in the collective wetland treatment system before being led to the seasonal storages. Buffer strips along field ditches perform the same function.

4. Situation The analysis of the existing conditions suggests the rational positioning of the three

156

Fig. 84 Area 2. Existing water system. 157

Fig. 85 Area 2. Top. Peak storage. Centre. Purification system. Bottom. Seasonal storage. 158

Fig. 86 Area 2. Collective 2 scenario. 159

160

Fig. 87 Collective 2 scenario. A stage in the process of learning. 161

elements (fig 85-86). A section of the stream Bidoggiata is retrofitted to function as peak storage. The banks are reshaped to get more room for water and diversity of riparian vegetation. The enlargement follows the former meandered shape. The purification system wetland stretches along the Bidoggiata’s banks in the public green space between the two industrial sections. The system makes partial use of the existing pipe network to deliver the flow to the purification system. Three seasonal storages. are inserted: the first stretches along the west side of the industrial area, between the recent bypass road and the railroad track; the second is located along the same road, retrofitting a neglected agricultural area on the north side, which is on the edge of the Zocchella water basin divide. Both sites are ‘waste grounds’, the result of the recent spatial arrangement of the new road. The third seasonal storage is combined with the peak storage, making use of the stream’s fluctuation potential. A circulation system integrates the parts. Two circuits of small ditches, arranged along the plots’ edges of the industrial area are connected with the seasonal storages. A few times a year heavy surplus rainstorm water fills the peak storages. The housing area keeps water in its own peak storage system. The existing subsurface drains in the field and storm water sewers in the industrial area collect and discharge storm water runoff into the stream peak-storage. The circular ditch surrounding the industrial area can store the runoff on the periphery of the lots. From autumn to spring the seasonal storages are slowly filled as much as possible with the periodic runoff ,while wastewater treated daily in the wetland also goes to the seasonal storages adjacent to the industrial area. The small ditches, arranged along the plots edges of the industrial area connect the stream’s peak-storage with the seasonal storages. From spring to autumn water from seasonal storages can flow by gravity to the farmland, its own existing water system connected to cope with irrigation demands. Limited non-potable uses in the industrial area can also be met making use of the system of small ditches.

4. Guiding model The output of the process of learning from the case study is an improvement of the circulation model adding the treated wastewater to the storage (fig.88). This strategy combines peak water storage and closing the cycle with seasonal storage for agricultural use. The shift from removing to holding water makes the system less dependent on inflow from surroundings and less vulnerable in attaining complementary benefits for the different activities in the area. In the industrial area the peak storage decreases the time and volume of rainwater surplus in the outlets downstream, thus decreasing flooding risk. The case study also demonstrates how a scenario system can be disconnected from upstream inflow. This is important for a step-by-step approach allowing for continued functioning of the upstream systems. The parallel system of streams in the plain between the Piave and Livenza makes the model appropriate for this category of situations. The upstream system can be easily connected through a bypass to a parallel stream.

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Fig. 88 Guiding model collective result of the process of learning. 163

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Fig. 89 Scenarios of the early stage in the process of learning: storm water storage options and patterns in the case study area. Top. Ditches network storage. Centre. Low-laying areas storage. Bottom. Stream corridors storage. 165

II.3 Conclusions

The contemporary decentralized urban landscape of Veneto città diffusa is challenged by densification, up scaling, concentration and functional separation of activities and related structures. From a water management perspective, these transformations go with the increase of water consumption, the concentration of water problems such as drought, floods and pollution. A decentralized water approach is needed to explore whether decentralized spatial conditions can be combined with decentralized water options. In the low plain a variety of existing situation exhibit basic conditions which are similar with the one described. The guiding models have a large range of applicability. Collective and individual retrofitting scenarios illustrate that the internalization of guiding principles assumed from sustainable water management lead to self-reliant and selfresponsible alternatives for a città diffusa situation. Rainwater and wastewater are renewable resources. By retaining, purifying and recycling within the system the dependence of the housing, industrial and agricultural areas on external inputs and outputs can be reduced. The latter could also prevent floods. In order to link explicit theoretical assumptions (guiding principles and guiding models) to a real context of flows and physical elements, the design process is guided by a chain of questioning and reasoning characterized by “what if” as a continuous conversation with the problems and opportunities of the situation. The aim is to seek win-win combinations for flows, space and actors. For example, the spatial variety of decentralized structures, existing ditches and depressions is adapted to convey, retain or process flows. Peaks related to paved surfaces in an area become opportunities because they provide an extra amount of water for another area where is needed. The storage in stream meandering slows down peak flows, reducing flooding risks downstream and creates conditions for keeping good habitats for plants and animals in dry periods. The exploration of synergism between activities and actors increases the water system multifunctionality. The collective woodland strip and wetland plants may combine wastewater purification with firewood and nutrient production respectively, matching agriculture and water services. The bottom-up approach, taking advantage of the details of the local landscape, generates design proposals that fit in with the città diffusa. These design proposals are open for assessment and debate. The results can be evaluated in terms of consistency, feasibility and compatibility with the spatial, social and economic context understanding what in the real context makes sense and what doesn’t. For example, a critical discussion of the collective and individual alternatives reveals the difficulties that will especially occur in the individual scenario. The

166

diversity of residents expressed in the design and the use of their gardens and the climate variation would make it desirable to look for combinations of collective and individual. The learning process might produce other proposals based on the same guiding models could criticize the models themselves, or generate new guiding models. Unlike a list of standards or maps with limiting conditions, guiding models may steer the research-by-design process that can generate innovative solutions that can provide answers to the present conflicts in the cittĂ diffusa resulting from spatial, actor and water paradoxes. The participation to the design process of local actors such as technicians and operators of the bodies for water management in the area, as well as politicians and policy makers at the level of the municipality was a crucial factor. A good preliminary condition, at the local level have been a shared basic understanding of the problems and the opportunities. A context of interaction and learning led to the possibility to adjust step by step the design hypothesis to the cultural and physical potentials of the case study area. As a result a norm included in the new municipal urban planning policy (PAT) has created the conditions for pilot projects in the area.

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III. Guiding models appendix

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1. Dwelling lot

169

The guiding model illustrates the retrofitting of a generic dwelling lot1. As a result the system shifts from dependency on centralized input-output water regulation to more reliance on local sources.

Existing conventional dwelling lot site (Fig. 90, 1a, 1b) The conventional dwelling lot uses water of good quality from upstream and discharges water of worse quality downstream. Structures and flows. Drinking water is let in by a centralized service (dw). Rainwater, collected by a storm water system (dr), is quickly removed from the lot (rw) and discharged into surface waters (sw). Grey water and black water are mixed and collected by a sewerage (ww) that discharges into a purification system far away from the lot. At the parcel level ground water (gw) is pumped up and used for watering and car washing (ir). Maintenance and institutional conditions. Connections to public services are in the private domain and therefore maintained by the owner. Maintenance operations of private surface water bodies are also the ownerâ&#x20AC;&#x2122;s duty.

Multifunctional dwelling lot site (Fig. 90, 2a, 2b) A dwelling lot retains, stores and recycles flows, making use of its own lot resistance and retention potential. Structures and flows. Rainwater (rw) from roofs is held, stored at the building level and directly reused for non-potable water services. Overflow from the roof-rainwater storage, runoff from paved surfaces and gardens (dr) flows through a purification system (like a buffer strip) before being buffered by a surface water body like a lot ditch that can either combine peak and seasonal storage or not (Fig. 90, 2b, storage) 2. Controlled groundwater (gw), abstracted onsite, serves potable uses and bathing (dw). Gray water, if not separately recycled3, is processed together with wastewater (ww) that is recycled by a lot-scale purification system consisting of primary, secondary and finishing treatments (Fig. 90, 2b, treatment) 4. The effluents are retained in the storage facility (Fig. 90, 2b, storage). The water stored is reused for water services like cleaning water (cw) and

Lots of different scales and coverage can be isolated or grouped within housing areas. Usually the lot presents premises, private open spaces of paved surfaces, a garden and, sometimes, a vegetable garden. 1

3 2

Dimensions of the peak storage are computed according to the DGR 1841/07, Regione Veneto.

Grey water is separated from black water only in the case of new construction. In the existing situations grey water remains combined with black water.

A good example for a wastewater purification system is a chain consisting of a sedimentation tank (primary treatment), gravel/sand filter (secondary treatment) and a constructed wetland (Thorsten et al. 2008, 141). 4

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Fig. 90 Dwelling lot guiding model. 171

watering (ir) 5. Groundwater makes the system capable of coping with extreme droughts. Water surplus is discharged into the surface water network by means of an outlet (sw). In the model purification system, peak and seasonal storage are integrated in a flow chain. Water is circulated (Fig. 90, 2a) or is otherwise oxygenated to maintain its quality. Maintenance and institutional conditions. The owner maintains the system, following some important instructions6. Treatment facilities are periodically monitored by experienced and skilled guidance representatives, working for the water services company. The quantity and quality of ground water are also monitored by a remote system run by the water company. In case of extreme pollution, the system is automatically blocked. Fees for excessive abstraction are charged. The private owner is responsible for the efficiency of the other parts â&#x20AC;&#x201C; a lot-ditch system, storage facilities, pumps, weirs and connections. Costs and benefits. The storage equipment moves the dwelling lot toward higher levels of self-reliance and self-responsibility (Tjallingii 1996). The extra costs for retrofitting the system can be flattened in the long run. Indeed, the storage of rainwater and treatment of wastewater lead to disconnection from the centralized water services for drinking and waste, and this results in lower fee payments. Besides, the biomass produced from storing and recycling facilities (like wetland and buffer strips) can contribute to supplying the dwelling heating system.

Examples - Best Management Practice for residential parcel. IN: MARSH, W., 2005. Landscape Planning: Environmental Applications. Hoboken: John Wiley & Sons Inc.: 252. - SCHUETZE. T. & S.P.TJALLINGII (ed.), 2008. Every Drop Counts, Environmentally Sound Technologies for urban and Domestic Water Use Efficiency. TUDelft/UNEP, Delft/Osaka: 146-148 - Quelques exemples de promotion des techniques alternatives. IN: CHOULI, E., 2006, La gestion des eaux pluviales urbaines en Europe: analyse des conditions de developpement des techniques alternatives, Ph.D. diss., Ecole Nationale des Ponts et Chaussees, Paris.

Cleaning water (cw) stands here for non-potable domestic water uses like washing clothes and flushing toilets. See Thorsten et al. 2008, 88. 5

For example, in the case of a constructed wetland serving as a tertiary purification facility, the reeds need to be harvested to remove the nutrients absorbed into leaves and stems (Thorsten et al. 2008, 141). The harvested reeds can be used as raw material for biogas production. This activity can be maintained by the municipality in accord with the water services company. The by-product (sludge) can be spread on farmland (Hansson and Fredriksson 2003). 6

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2. Industrial lot

173

The guiding models illustrate the retrofitting of a generic industrial lot7. As a result the system shifts to a resilient industrial lot.

Existing conventional industrial lot site (Fig. 91, 1a, 1b) The conventional industrial lot lets in water of good quality and discharges a considerable amount of polluted water downstream. Structures and flows. Drinking water (dw) that is let in from the centralized service is used for both potable and not potable uses, like flushing toilets and industrial processes. Often groundwater (gw) is abstracted at the level of the lot and used as an additional source to supply industrial processes (se)8. Rainwater from roofs (rw) and rainwater from paved surfaces (dr) is collected by storm drains, mixed and rapidly discharged into surface waters (sw). Grey water and black water are collected by sewerage (ww) and delivered to a purification system far away from the lot9. Maintenance and institutional conditions. Connections to public services, lot purification facilities and lot drainage facilities, like gutters and ditches, are private and therefore maintained by the owner.

Multifunctional resilient industrial lot site (Fig. 91, 2a, 2b) The resilient industrial lot gets higher levels of self-reliance and self-responsibility by storing and recycling water (Tjallingii 1996: 242). Structures and flows. Rainwater (rw) from roofs is held and stored at the premises level and directly reused for non-potable uses. Overflow from rainwater storage from roofs and runoff from paved surfaces (dr) flows through a first flush purification facility that traps storm water pollutants like metals and oil (Fig. 91, 2b, buffer strip). After treatment water flows into a surface water body having enough capacity to buffer peaks (Fig. 91, 2b, storage)10. The storage facilityâ&#x20AC;&#x2122;s composition might depend on whether retrofitted or new-lot ditches are used, and and whether they can or cannot combine peak storage and seasonal storage. Controlled groundwater (gw) is abstracted on-site to serve potable uses only (dw)11. Black waters, grey waters and the effluents of the industrial processes (ww) are locally retained and processed by a lot-scale purification system, composed

Lots of different scales and coverage can be either isolated or grouped to form industrial areas. Commonly in a lot the open spaces are, to a large extent, impervious and used for storing materials or parking. 7

9 10 11 8

The acronym â&#x20AC;&#x2DC;seâ&#x20AC;&#x2122; is used here for generic water services. Potable uses are excluded. Often highly polluted industrial effluents are locally treated. Dimensions of the peak storage are computed according to the DGR 1841/07, Regione Veneto.

In case of industrial processes making use of water of potable quality, groundwater is a suitable local source. However, its exploitation is not unlimited and is thus controlled by the water service company.

174

Fig. 91 Industrial lot guiding model. 175

of primary, secondary and finishing treatments (Fig. 91, 2b, treatment) 12. The outlets are stored in the storage facility (Fig. 91, 2b, storage). The water stored and recycled supports cleaning services like washing and flushing toilets and not potable industrial processes (se). When the requirements for an industrial process are larger than the amount of rain falling in the lot, water is let in from the surface water network (sw). In turn, water surplus from storage can be discharged into the surface water network by means of an out-let (sw). In the model purification system, peak and seasonal storage are integrated in a flow chain. Water is circulated (Fig. 91, 2a) or is otherwise oxygenated to maintain its quality. Maintenance and institutional conditions. The owner maintains the system, following some important instructions13. Treatment facilities are periodically monitored by experienced and skilled guidance representatives, working for the company providing water services. The quantity and quality of ground water are also monitored by a remote system run by the water company. In case of extreme pollution, the system is automatically blocked. fees are charged for abstraction excesses. The private owner is responsible for the efficiency of the other devices â&#x20AC;&#x201C; ditches, storage facilities, pumps, weirs and connections. Costs/benefits. The costs of retrofitting the system can be flattened in the long run. Indeed storage of both rainwater and treated wastewater leads to disconnection from the centralized water services for drinking and waste. This means a reduction of the ownerâ&#x20AC;&#x2122;s fee payments. The biomass produced from storing and recycling facilities (like wetlands and buffer strips) can be sold to the water board or the water service company. The high level of self-responsibility reached by the firm can be redistributed in the form of tax breaks.

Examples - Industrial site management. IN Marsh, W., 2005: Landscape Planning: Environmental Applications. Hoboken: John Wiley & Sons Inc.: 181-183.

A good example of a wastewater purification system is a chain consisting of a sedimentation tank (primary treatment), gravel/sand filter (secondary treatment) and a constructed wetland. In case of high levels of pollution, an individual or semi-collective mechanical wastewater treatment plant can be a suitable treatment alternative. 12

See the resilient dwelling lot guiding model. In addition, attention has must be paid to the maintenance of first flush facilities. 13

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3. Agricultural field

177

The guiding models illustrate the retrofitting of a generic agricultural field14. As a result the system shifts to resilient agricultural field.

Existing conventional agricultural site (Fig. 92, 1a, 1b) The conventional agricultural field withdraws a considerable amount of surface water from upstream, and sometimes from the ground (aquifer), and discharges polluted water downstream. Structures and flows. Rainwater surplus is quickly removed from the field by a drainage system of ditches and drains to a receiving stream (Fig. 92, 1a, stream). In summer surface water from stream is let in and distributed into the field for irrigation (ir)15. When surface water is insufficient, groundwater is locally pumped up and distributed (Fig. 92, 1b, groundwater and well). Maintenance and institutional conditions. Field ditches are in the private domain. The owner is responsible for their efficiency.

Multifunctional agricultural field (Fig. 92, 2a, 2b) The agricultural field reduces its dependence on its surroundings by storing, recycling and finally reusing rainwater. Structures and flows. Rainwater (dr) flows through a buffer strip before reaching field ditches (Fig. 92, 2b, buffer strip). Overland and subsoil flows are treated by the combined action of roots, soil and microorganisms contained in the soil. Nutrients stimulate the growth of trees and shrubs. Water is then retained in the ditches that have been retrofitted to have more room for water (Fig. 92, 2b, ditch). Storm water also fluctuates into the field ditches, and only the excess is released downstream. Ditches merge to form a water course circuit through which water is circulated and further processed by reeds (Fig. 92, 2a). The recycled and harvested water is reused for irrigation (Fig. 92, 2b, ir). When the seasonal storage has in sufficient capacity to make up for summer irrigation, pre-treated wastewater can be let in, and reused after recycling. Buffer strips and retrofitted ditches make the agricultural site more resilient, combining flow purification, peak and seasonal storage as a whole16.

Fields packed in the agricultural matrix might present a variety of arrangements and extensions.

There is a wide range of irrigation systems and arrangements. For example, water from the ditches is pumped and distributed by sprinklers or a drop irrigation system. For a comprehensive overview see Giardini 285-305. 15

The water stored tends to make the water table higher with possible loss of cultivation. In order to avoid such loss, the use of clay soil to cover the slopes of ditches can reduce their permeability. The shift to hydroponic cultivation is also an alternative. 16

178

Fig. 92 Agricultural field guiding model. 179

Maintenance and institutional conditions. The owner maintains and controls the system. The use of additional inlets, like treated wastewater, are overseen by the water company charging for water services. Costs/benefits. The costs for the additional land use to retain and process water locally can be flattened by benefits related to the multiple services that the system provides. The agricultural field stores and recycles water that can be used for irrigation, production of biomass and a source of carbon credits. The owner can also benefit from additional products from the buffer strip, like mushrooms, herbs and honey (Veneto Agricoltura&Consorzio di Bonifica Dese Sile 2002, 30).

Examples - Pilot project Vallevecchia, Veneto Agricoltura and Consorzio di Bonifica Pianura Veneta Orientale. Project: 2000. Realization: 2004-2005. - Ricerche Sperimentali sugli effetti del drenaggio controllato nella riduzione del rilascio inquinanti da sorgenti diffuse. IN: BENDORICCHIO, G., BIXIO, V., GIARDINI, L. 1994. Ricerche Sperimentali sugli effetti del drenaggio controllato nella riduzione del rilascio inquinanti da sorgenti diffuse. XXIV Convegno di idraulica e costruzioni idrauliche, Napoli, 20-22 Settembre 1994.

180

4. Forested buffer strip

181

The guiding model illustrates the retrofitting of a generic agricultural field. As a result the system shifts to forested buffer strip.

Existing conventional agricultural site (Fig. 93, 1a, 1b, 1c) The conventional agricultural field withdraws a considerable amount of water from upstream and sometimes from the ground (groundwater) and discharges polluted water downstream17. Structures and flows. Rainwater surplus is quickly removed from the field and discharged into receiving streams (Fig. 93, 1a, stream). In summer surface water is let in from the streams and distributed into the field for irrigation18. When surface water is insufficient, groundwater is locally withdrawn and distributed. Maintenance and institutional conditions. Field ditches are in the private domain. The owner is responsible for their efficiency.

Multifunctional forested buffer strip (Fig. 93, 2a, 2b, 2c) The retrofitted field, called a forested buffer strip, recycles water and contributes to preventing floods. Structures and flows. Polluted water from a stream (Fig. 93, 2a, 2b, stream) or a wastewater pre-treatment facility (Fig. 93, 2c, treatment) is delivered to a system of distributing ditches. Water slowly filtrates into collecting ditches. Trees are planted along ditches to form forested buffer strips19. Overland flow and subsoil flows are purified by the combined action of roots, soil and microorganisms contained into the soil (Fig. 93, 2b, red arrows)20. Collecting ditches deliver purified flows to either a storage facility (Fig. 93, 2a, 2c, seasonal) or a stream. The system lets in water of low quality and slowly releases water of better quality downstream. Nutrients stimulate the growth of trees. Small dykes encircling the field system can foster retention potential of excess water

From the agricultural fields a wide range of contaminants can reach the river either via groundwater or through drainage ditches, including artificial fertilizer residues, insecticides, herbicides, pesticides and farmyard waste, all of which are potentially very harmful. (source: http://www.naturegrid.org.uk/rivers/gt%20stour%20 case%20study-pages/plln-frm.html). 17

Distances between ditches can vary from 7 meters (one meter of plantation per each side plus 5 meters for a maintenance passage) to few dozens of meters. It depends on the imperviousness rate of the soil. Each buffer strip can have a width varying from a few to several meters. The species planted can be very different, but possibly native and in accordance with the species already in the area. 19

Nitrates are significantly removed in a quantity depending on soil permeability, the height of the water table and concentration of inlet pollutants (from the third year the total amount of nitrates can be reduced by 60 %. Source: Gumiero et al. 2008, 20). 20

182

Fig. 93 Forested buffer strip guiding model. 183

from either a stream or sewage system (Fig. 93, 2a, peak, 2c, overflow )21. The forested buffer strip buffers and recycles flows, making use of natural processes and conditions of the local terrain. The agricultural site abates water pollution, reduces either flooding risk downstream or the risk of sewage overflow. Water purification becomes integrated in the local landscape. Maintenance and institutional conditions. The agricultural site continues to be in the private domain. Maintenance operations are the owner’s duty. When the forested buffer strip works as a surface water purification facility, the water board oversees the maintenance operations. If the system functions as a finishing treatment for wastewater, the water service company controls the quantity and quality of both inflows and outflows. Costs/benefits. A portion of the agricultural matrix is retrofitted to provide a variety of functions benefitting farmers. The agro-forestry system purifies water; the owner can get part of the fee for the water purification service. The agricultural site produces biomass that can be sold. The agricultural site contributes to the reduction of CO2; it can mean getting subsidies or carbon credits to sell (see the European Union Emission Trading Scheme).

Examples - Sito sperimentale ‘Nicolas”, Mogliano Veneto, Treviso. IN: Gumiero, B., Boz, B., Cornelio, P., 2008. Il sito sperimentale “Nicolas”, Legnaro: Veneto Agricoltura.

Water of different quality is kept separate. This function is very importan t especially when the system purifies pre-treated wastewater. 21

184

5. Road strip

185

The guiding model shifts a generic minor road of different ranks and dimensions22 to a multifunctional road strip that recycles and stores water.

Existing conventional minor road (Fig. 94, 1a, 1b, 1c) In the conventional road rainwater is quickly driven out and discharged downstream. Structures and flows. Rainwater rapidly flows from the roadway either to a ditch (Fig. 94, 1c) to underground pipe (Fig. 94, 1b). and delivered downstream to the surface water network. Maintenance and institutional conditions. Depending on their rank different institutions provides for maintenance and control of ditches and pipes.

Multifunctional road strip (Fig. 94, 2a, 2b, 2c, 2d) In the multifunctional road strip interstices between roadway and plots (agricultural, industrial or dwelling plots) are retrofitted to play as a whole that locally buffers, recycles and stores water. Structures and flows. Rainwater runoff from asphalt flows through a strip of grass (verge) before reaching the drainage bodies (Fig. 94, 2b, 2c, 2d). Iron metals and oil washed in with the water are trapped. Water then either flows into a retrofitted ditch where reeds further recycles water (Fig. 94, 2d), or slowly penetrates though permeable layers that remove sediments and pollutants (infiltration trench) (Fig. 94, 2c). Where possible the strip expands and water has a longer way to reach the drain (Fig. 94, 2b). Water flows along the drainage system and is retained into linear storage facilities placed where space is available and water is demanded. Storm water can fluctuate into the road strip system which has an extra capacity to flatten peaks at source. Earth mounding, trees, grass, shrubs meet stop and extend one beyond one another supporting recycling and storing of water. Maintenance and institutional conditions. The road strip or singular segments are managed by locals and the users of the water stored. The water board oversees maintenance activities and distribution of the waters. Costs/benefits. The road strip retrofits waste lands like interstices and residual spaces overlapping a variety of programs. As linear, varied and dynamic infrastructure the road strip percolates the matrix supporting activities of the local landscape: besides

Roads selected are municipal, provincial, regional and even state roads. They cross and connect different environments and communities of the Veneto cittĂ diffusa. 22

186

Fig. 94 Road strip guiding model. 187

water storing and recycling, the retrofitted ’ecotone’ buffers noise and supports walking, orientation, biodiversity and biomass production.

Examples - Austin, Texas. IN: MARSH, W., 2005, Landscape Planning: Environmental Applications, John Wiley & Sons, 211. - Investigations into alternative treatment options for road runoff. IN: RYAN, B. 2004. Stormwater infrastructure. In: RAXWORTHY J. AND BLOOD, J., ed. The MESH book: landscape / infrastructure. Melbourne: RMIT Publishing.

188

6. Highway corridor

189

The guiding model regards a shift from a generic highway system to a multifunctional highway corridor that recycles and stores water.

Existing conventional highway (Fig. 95, 1a, 1b) In the conventional highway rainwater is buffered and, after pre-treatment, is discharged downstream23. Structures and flows. Rainwater is rapidly removed from the road and delivered to a rut (Fig. 95, 1b) alongside the asphalt-ribbon. After mechanical treatment (Fig. 95, 1b) water is delivered to a parallel surface water body (stream) where it is buffered (Fig. 95, 1a, black weirs as contractions). From there water is slowly released to the surface water network downstream. Excess flow (overflow) is flushed to the surface water network without any treatment. Maintenance and institutional conditions. The highway company provides for maintenance and control of the system.

Multifunctional highway corridor (Fig. 95, 2a, 2b) The highway corridor is a system consisting of a first flush detention device (verge), an infiltration trench (filter berm24) and a storage facility (storage) combining bioremediation (recycling), a detention pond (peak storage) and a retention basin (seasonal storage) into an integrated whole. Water is retained and stored after recycling. Structures and flows. Rainwater runoff from asphalt flows into the road ditch (rut), passing through a strip of grass (verge) that retains contaminants, such as oil. Water slowly filtrates through a sandy mound (filter berm). Afterward infiltration water is further processed (recycled), passing through the wetland of the storage facility (Fig. 95, 2b). Finally, the water is stored (seasonal storage). Storm water fluctuates in the storage facility (peak storage), where it is even recycled by wetland bioremediation. Only excess is slowly released to the surface water network. runoff and groundwater flowing into the storage from the surroundings is processed by shrubs and tree roots of a buffer strip (Fig. 95, 2b). The highway corridor intercepts, recycles and stores water that can be circulated and locally reused.

The conventional highway system represented Is based on recent highway projects in the Veneto Region, like the new bypass called Passante di Mestre. 23

Filter berms are elongated earth mounds constructed along the contour of a slope. They are usually constructed of soil containing different grades of sand and a filter fabric and are designed to function in the same fashion as soil infiltration trenches, which have been shown to be highly effective in contaminant removal (Marsh 2005, 211). 24

190

Fig. 95 Highway corridor guiding model. 191

Maintenance and institutional conditions. Maintenance and control of the system continues to be the duty of the highway company. In addition, grass should periodically be mowed, reeds harvested and polluted sediments in the verge and storage removed. Costs/benefits. The costs for the additional land required can be flatten by the benefits from the multiple services that the system provides. The highway stores and remediates water enough water that can be reused by the activities set along its corridor. The buffer strips and wetlands produce biomass (and carbon credits) that can be sold. The corridor reduces noise pollution and noise. As linear park, besides fast transport, the retrofitted highway can support a variety of full-free mobility such as walking and cycling.

Examples - Northeast-southwest highway, Slovenia. Bulc, T., Sajn Slak, A., 2003. Performance of constructed wetland for highway runoff treatment, Wat. Sci. Tech., 48(2), 315â&#x20AC;&#x201C;322. - A 70 motorway, Germany. Association of a motorway storm water tank and the treatment of runoff from roads. IN: IZEMBART, H. AND LE BOUDEC, B. 2003. Waterscapes. Barcelona: Editorial Gustavo Gili.

192

7. Stream corridor

193

The guiding model illustrates the retrofitting of a generic stream25. As a result it shifts to multifunctional resilient streams corridor.

Existing conventional stream (Fig. 96, 1a, 1b, 1c, 1d) The conventional stream collects flows of different qualities (and from different sources) from surroundings and delivers them rapidly downstream. Structures and flows. Run off from urbanized patches and roads, overland flows from agricultural sites treated and untreated wastewater effluents, overflow from sewerage, flows/waters from road ditches and field ditches, interflow and groundwater flows, all discharge quickly into the stream that rapidly delivers its flows to water bodies of higher ranks downstream. In summer huge amount of water derived from upstream sources or, sometimes, stored before along the stream, gets back to the private surface water network via streams and then used for irrigation26. Weirs allow control of fluctuation and exchanges. Maintenance and institutional conditions. Commonly streams are state property managed by the water board. Maintenance operations like removing of vegetation along the banks are turned towards keeping the stream own discharge capacity. The water board manages and controls weirs, gates and in general any structure installed along the streams needed to control water in the landscape.

Multifunctional stream corridor (Fig. 96, 2a, 2b, 2c, 2d) The multifunctional stream corridor slows down, retains and purifies its waters making better use of resistance and retention mechanisms along its course. Structures and flows. The widening the cross section of a stream (Fig. 96, 2b, riverine wetland) or the adding by-passes (Fig. 96, 2d, riverine wetland) both provide the stream corridor with extra room for water. Runoff from urbanized patches and roads, overland flows from agricultural sites and groundwater pass through the buffer strips set along the stream banks (Fig. 96, 2b, 2d, buffer strip). This lead to slow down overland flow and to trap the pollutants (Siligardi 2007, Gumiero et al. 2008). Stream water can also flow through the riverine wetlands (Fig. 96, 2b, 2d,)27. In the wetlands water is cleaned. Infiltration rate and groundwater recharge increase. In case of high water mark water surplus fills the expansions. Discharge delays. The enhancement of longitudinal and transversal ecological functionality enables the stream corridor to recycle water and

26 25

The guiding model is applicable to streams of different rank and dimensions.

In the water board many streams combine drainage and irrigation functions. During spring water is stored along the stream by the regulation of a system of sluices. 27

194

The shift considers even the removal of any concrete layers covering the stream beds.

Fig. 96 Top. Stream corridor guiding model. Riverine wetlands attached the stream course. Bottom. Stream corridor guiding model. Riverine wetlands detached the stream course. 195

released it slowly downstream28. Maintenance and institutional conditions. A path along the bank allows the water board to maintain the system (Fig. 96, 2b, 2d, left bank side). The operations like mowing of grass and harvesting of reeds should cause fewer disturbances as possible on habitats (Tjallingii 2000). Costs and benefits. The stream expansions possibly retrofit former meanders or paleochannels that are often state property (Fig. 96, 1a, 1c, red dotted line)29. Therefore costs for land expropriation can be significantly reduced. Moreover, in case of by-pass, expansions that are above phreatic groundwater can still be cultivated. The water board refunds farmers only when water expands. The stream corridor plays multiple functions that can further justify the costs for its restoration. For example the stream corridor considerably pulls down the total amount of pollutants coming from the in-flows. It reduces the risk of back effects downstream30 and polluters should pay a fee for this service. The stream corridor slows down and retains flows reducing risk of flooding both upstream and downstream31. As linear park the stream corridor supports recreational activity such as walking, cycling and canoeing. The stream corridor produces biomass (both from wetlands and buffer strips) that the water board can use for biogas production. Finally when playing as irrigation system the stream corridor has greater storage capacity with benefits for farmers.

Examples - Interventi di riqualificazione ambientale dei corsi d’acqua della terraferma veneziana, Regione Veneto & Consorzio di Bonifica Dese Sile. - Room for River, Holland. IN: MINISTRY OF TRANSPORT, PUBLIC WORKS AND WATER MANAGEMENT, 2006. Spatial Planning Key Decision ‘Room for the River’. The Netherlands.

In his book Indice di Funziuonalita’ Fluviale, Siligardi emphasis the role of the transversal dimension of the rivers (Siligardi 2007, 80). 28

At least one bank is re-shaped in a stepped profile that performs a more ecological gradient.

The retrofitted stream contributes to improve the quality of the water in the landscape. Indeed the purifying systems and processes typical of a stream environment are improved or reactivated (Siligardi 2007, 68, IFF 2007, Indice di Funziuonalita’ Fluviale, Linea Grafica Bertelli Editori, Trento). 30

In case of heavy rainfall the stream can accommodate more storm water from upstream and therefore water does not go back to the drainage system upstream. 31

196

8. Quarry area

197

The guiding model illustrates the retrofitting of a generic a quarry site32. As a result the system shifts to a resilient multifunctional quarry area.

Existing conventional quarry site (Fig. 97, 1a, 1b, 1c) The conventional quarries retain water. Superfluous waters are discharged downstream. Structures and flows. Rainwater falling into the site is retained by the quarries and, often, mixed with groundwater seepage. When water exceeds a certain level, surplus is discharged downstream in the surface water network. Maintenance and institutional conditions. Pits are private domain. Maintenance operations depends on their use and function33.

Multifunctional quarry area (Fig. 97, 2a, 2b, 2c) The retrofitted quarry site stores and recycles waters by making better use of its own ecological potentials. Structures and flows. Quarries are reshaped to perform as storage and water purification facility. On site rainwater and groundwater seepage are retained into the wetlands. Waters that enter from surroundings like overland flow and interflow are treated by the buffer strips encircling the site (Fig. 97, 2b, buffer strip). Flows of different quality like stream water or the effluents of a wastewater treatment34 are also let in (Fig. 97, 2b, stream; 2c, treatment). Excesses of water from streams or overflow from wastewater treatments can therefore be buffered into the wetlands that are connected in a whole chain. Water easy circulates and is processed and oxygenated. Waters harvested and recycled can fluctuate till a certain level and be reused for different purposes (Fig. 97, 2a, fw). For example, from the wetlands water can get back to the surface water network and be used for irrigation. The quarry area gets in waters of different qualities and serves the surroundings with water of better quality. Maintenance and institutional conditions. The quarry area is a private domain managed by the water board that monitors quantity and consistence of inflows and outflows. When the quarry area functions as finishing treatment of wastewater, the water service company controls quantity and quality of inlets and outlets. Periodically reeds have to be harvested.

Pits area can be composed of holes of various depth and extension often ranked in groups, the quarries selected are result of land digging to obtain minerals such as clay, sand and, sometimes, interposed gravel stone. 32

After the exploitation pits sites are differently retrofitted or turn into wastelands. Common uses are aquaculture, game fishing and hunting reserve. 33

Effluents from treatment plant or other primary and secondary treatment facilities can be further recycled by the quarry system. Attention is recommended in the case of groundwater seepage. 34

198

Fig. 97 Top. Quarry area guiding model. Bottom. Alternative patterns of water structures and flows. 199

Costs/benefits. The quarry area retrofits quarries (that are often wastelands) to play a number of functions. The quarry area recycles water and offers flood prevention and water supply. The quarry area produces biomass (reeds and wood) that can be reused as construction material or for energy production (biogas). The quarry area can integrate recreation activities like bird-watching and canoeing.

Examples - Cave di Noale restoration, Noale, Venezia. Consorzio di Bonifica Dese Sile. - Cave Cavalli restoration, Marcon, Venezia. Consorzio di Bonifica Dese Sile. - Cave di Salzano restoration, Salzano, Venezia. Consorzio di Bonifica Dese Sile. - Crailoo sand quarries, Zanderij Crailo, Vista Landscape and Urban Design (19982004).

200

201

IV. References

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Interviews Artico Vincenzo – Chief engineer at the water board: ‘Consorzio di Bonifica Sinistra Piave – service agency for irrigation and drainage water management. Interviewed on 06.11.2008. Coral Alberto – Geologist Ponte di Piave 2009 Interviewed on 29 09 2009. De Bianchi Luciano: town councilor for the environment at Ponte di Piave. Interviewed on 27 11 2008. Giovanni Dal Pizzol – independent farmer Ponte di Piave Interviewed on 30 08 2009. Gallarati Scotti Maria Luisa – agricultural entrepreneur Ponte di Piave. Interviewed on 30 09 2009. Pesce Carlo – Engineer of Water Works: ‘Servizi Idrici Sinistra Piave’ – service agency for drinking water supply and management of waste waters. Interviewed on 15 10 2008. Susanna Denis: President for the Provincial chapter of the Italian Confederation of agricultural workers. Interviewed on 01 09 2009.

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(left) IGM 1952, Cartografia Istituto Geografico Militare. RAF 1954, Royal Air Force. (right) CTRN 2003, Regione Veneto. Telespazio 2007.

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IGM 1891, IGM1952, Cartografia Istituto Geografico Militare. RAF 1954, Royal Air Force.

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(left) IGM 1952, Cartografia Istituto Geografico Militare. RAF 1954, Royal Air Force. (right) CTRN 2003, Regione Veneto. Telespazio 2007.

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(left) IGM 1952, Cartografia Istituto Geografico Militare. RAF 1954, Royal Air Force. (right) CTRN 2003, Regione Veneto. Telespazio 2007.

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(left) IGM 1952, Cartografia Istituto Geografico Militare. RAF 1954, Royal Air Force. (right) CTRN 2003, Regione Veneto. Data file, AATO Veneto Orientale.

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(left) IGM 1952, Cartografia Istituto Geografico Militare. RAF 1954, Royal Air Force. (right) CTRN 2003, Regione Veneto. Data file, AATO Veneto Orientale.

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CLC 2000, Joint Research Centre. Data file, AATO Veneto Orientale. Data file, Regione Veneto.

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CTRN 2003, Regione Veneto. Data file, AATO Veneto Orientale.

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CLC 2000, Joint Research Centre. Data file, AATO Veneto Orientale. Data file, Consorzio di Bonifica Pedemontano Sinistra Piave.

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CTRN 2003, Regione Veneto. Data file, AATO Veneto Orientale. Data file, Consorzio di Bonifica Pedemontano Sinistra Piave. Data file, Consorzio di Bonifica Pedemontano Sinistra Piave. Data file, Regione Veneto.

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CTRN 2003, Regione Veneto. Data file, Consorzio di Bonifica Pedemontano Sinistra Piave. Data file, Regione Veneto.

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CTRN 2003, Regione Veneto. Data file, AATO Veneto Orientale.

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CTRN 2003, Regione Veneto. Data file, AATO Veneto Orientale. Data file, Consorzio di Bonifica Pedemontano Sinistra Piave.

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