PERMEABLE CITY

Marco Gazzola

permeable city Water-sensitive urban design towards climate change

Graduate Degree Thesis professors B.Albrecht E.Antonini L.Schibuola Università Iuav di Venezia - Facoltà di Architettura Corso di Laurea Specialistica in Architettura per la Sostenibilità academic year 2008 - 2009

Contents

the problem

8

best practices

12

general model

23

pluviometric regimes

permeable city 01 - alps

30

33

p e r m e a b l e c i t y 0 2 - p o va l l e y

permeable city 03 - centre

permeable city 04 - south

45

57

69

introduction building a new water culture “I went to Spoleto and I visited the Aqueduct [...] The ten brick arches, which strech above the valley, carry calmly the weight of centuries and water, in Spoleto, keeps on gushing everywhere. It is the third work of the ancients thet I see, always of the same magnificent character. Their architecture is a second nature working for civil purposes ” Johann Wolfgang Goethe, Italian Journey, 1817

“Les choses ne sont pas difficiles à faire, ce qui est difficile, c’est de nous mettre en état de les faire” Constantin Brancusi

There is no other natural resource on which mankind makes such heavy and complex demands as it does on water.

Waterplanning, from supply to management and distribution of water resources, is one of the oldest driving forces in urban development.

To achieve these goals, every civilization has used the most advanced technologies at its disposal. Art, architecture and engineering were a unit and worked together.

For these reasons water has always been the centre of a fundamental part of mankind’s social relations. Its management reflected the way society itself worked, it was the basis of its stability and embodied the relationship between city and territory.

If you ask people about environmental problems in surveys, more of them are aware of traffic, noise and air pollution and the hole in the ozone layer, but water is almost never mentioned. We need to drink water every day and use it to keep clean, to promote a sense of wellbeing and for recreation. So why is it not watched with particular care in respect to possible environmental problems?

Obviously because of the fact that water is generally and constantly available, naturally and through technology. But anyone who looks at the world a little more closely knows that desert is spreading in the Sahel region, remembers people affected by droughts in Somalia and has heard about wars for the waters of the river Jordan. But why water should be a problem in Europe? In fact ours is only in part a problem of quantity. The principal issues to be dealt with are a shortage of water of outstanding quality and the pollution of the water bodies, which goes far beyond the point at which rivers can clean by themselves. In recent decades people have become accustomed to the fact that rivers are not suitable for bathing or springs for drinking.

Even tap water is distrusted. Groundwater pollution has accustomed people to the fact that large cities can draw only a tiny proportion of their water from their own territory. Poor groundwater quality means considerable expenses for treating and transporting water.

But why are people not conscious of the problem despite high costs,

possible damage and the risk of endangering health? The search for an answer to this question leads to the issue of the structure of the modern city.

Its development began with the cholera epidemics which haunted many European cities during the 19th century. The construction of sewerage systems and the piping of drinking water to individual houses and flats, the gradual spread of private toilets, the establishment of public bathing facilities did not just build up a general culture of hygiene, but fundamentally changed the relationship between the city and the citizens.

Many of the vital processes of urban life were put under state control and offered to citizens as a compulsory imposed service. This did not just apply to water supply and waste water disposal, but also to food supply in new abattoirs and covered markets, built and controlled by the police, waste disposal, health care, etc.

What does all this mean in terms of the way problems are perceived in towns?

Firstly, many aspects of everyday life were withdrawn from civil authority and handed over to state and municipal bureaucracies.

The transformation to the civilized modern town consisted in fact in making citizens less responsible of vital processes within the city.

Secondly, most of the technical and natural side of these processes became invisible to ordinary citizens. Significant elelements of urban life were no longer directly visible.

So the water problem extends between two poles: the material side, which presents itself as a threat to the quality of the resource, and a social side, which is characterized by the loss of awareness of the problem.

Herbert Dreiseitl, probably the most active of contemporary waterdesigners which has dealt for decades with those issues, says that the solution is building the ‘water culture’ of our time.

When he speaks of ‘water culture’ he refers to the meanings and senses that relate to water as a material, to water technology, to the

aesthetics of water and to the various social ways of dealing with water. For instance, a sustainable water culture would have different water available for different purposes and the same lot of water put to work in different ways in use cascades.

Of course this is not a simple path, and there are many questions to be answered. Can we afford ecology? Are ecology and urban life contradictions in terms? Do towndwellers want to address, or better, under what conditions can they address, ecological urban redevelopment? How can ecology become a guideline for future cities? What do ecological aesthetics mean in concrete terms?

The thesis wants to give an aswer to these questions, knowing that the domain of the issues is very large and that dealing with them would require an integrated approach of different disciplines. Its aim is to take at least a first step towards common awareness rainsing.

8 the problem

Water scarcity >= 68 highest scoring 62 - 67.9 higher middle scoring 56 - 61.9 middle scoring 48 - 55.9 lower middle scoring < 48 lower scoring data not available Points are given according to: resources (flow of rivers in and out the country); availability (percentage of the population with drinking water); capabilities (income, mortality, school attendance); use (daily domestic use); environment (water quality, pollution, regulations).

the problem state of water resources in italy Manâ&#x20AC;&#x2122;s bulding activities interrupted the so-called water cycle. At least in some parts of the world. But we must remember that neither person nor place is totally independent, all the elements which together constitute the planet are somehow connected in time and space. This is the origin of the responsibility principle, which is the basis of sustainability since its first formulations. Stormwater management CAN restore the water cycle in urban areas but, first of all, we have to know what we are talking about. Data about quantity and quality, peopleâ&#x20AC;&#x2122;s lifestyle, environmental threats and future trends give us suggestions on what to do and where to do it.

water all around the world water is (in theory) a renewable resource 3

1.4 billion Km water on the planet earth 3

35 billion Km freshwater

2,5% of the whole

68,9% ice - perennial snow 30% underground (almost the whole of all available water)

3

350.000 Km available freshwater 1% of all freshwater 0,025% of all the water on the Earth

groundwater is the most abundant and accessible, followed by natural water bodies

Due to the rapid increase of Earth population, the water availability per capita has decreased

0,3% rivers and lakes

1,5 billion people use it as main source of freshwater, Italyâ&#x20AC;&#x2122;s 97% of freshwater

3

1970

12.900 m /year

1990

9.000 m /year

2000

7.000 m /year

2025

5.000 m /year

3 3 3

3,5 bn people suffer from water scarcity

9 recharge

Relationship between human activities and water resources GHG emissions

climate

terrestrial part of the hydrological cycle (quantity and quality)

Groundwater exploitation

water table

river

well sea salted water

freshwater

population lifestyles, economic and technological development

water resources management

land use

recharge

Standard situation.

The drawing of freshwater out of proportion to the recharging time of the water table enhances the natural infiltration of salted water from the sea.

water table

food production river

water use

well sea

freshwater

salted water

Situation after massive drawings.

A dangerous process of salted water absorption begins. Freshwater properties change and ongoing desertification speeds-up.

water and the city

italian hydrologic balance

cities cover the 2% of earth but use the 75% of its resources

italy is one of the richest nations in water of the world.

The problem is not quantity but quality and management.

in the european union today

urban population 75%

2020

urban population 80% (in certain countries 90%)

3

155 billion m annual availability in theory 3

urbanized land > 25%

2.700 m per capita due to irregularities and ineffectiveness 3

the city after world war II

42 billion m actual annual availability

from 1950 to PRESENT DAY

764 m per capita

cities are grown of 78% their population of 33%

3

90% of existing Italian building stock

37% of the water flowing in pipes does not arrive to people

urban sprawl Itâ&#x20AC;&#x2122;s the low-density way large urban areas grow.

The growth is in the form of formless spots, with a tendency to discontinuity.

No signs of halting in this process. It is getting faster due to transports improvement.

lack of planning in the use of land resources uncontrolled increase in energy and resources consumption

The environmental problems of the planet have to be solved in the urban sphere.

Italy is the major daily water consumer of Europe: 280 l/pers day 15% of Italian population, from June to September, doesnâ&#x20AC;&#x2122;t meet its minimal water need (50 l/pers day)

agriculture

49%

Industry

21%

domestic needs

19%

Production of energy

11%

max Milan 359 l/pers day min Ascoli Piceno 104 l/pers day average 90% of the cities 100-250 l/pers day

in italy groundwater is about to finish and the 25 â&#x20AC;&#x201C; 30% of the land is threatened by erosion and increasing saltiness

10 the problem

Temperature anomaly [K]

Relationship between urbanization and runoff production

from +1 to +2 from +2 to +3 from +3 to +4 more than +4 The picture shows the registered anomalies in temperature across all Europe.

We see that almost the entire continent has been touched by such dangerous warming that is just supposed to increase in the next few years.

evapotranspiration 40%

runoff 10%

evapotranspiration 38%

runoff 20%

superficial infiltration 25%

superficial infiltration 21% deep infiltration 15%

vegetated soil

deep infiltration 21% 10-20% of urbanization

climate change

adaptation 01

it is an actual process whose trend is strengthening

water is the 93% (in weight) of the input for a city’s survival

European Union

Italy

+0,90°C

1901 - 2005

+0,40°C every 10 years 1979 - 2005

pluviometric regimes change The annual average stormwater volume has decreased and it is distributed in a shorter serie of days with tropical rainfalls.

2

(1 mm of rain = 1 litre/m )

2050 scenario The Mediterranean Sea will rise 20 cm 2

4.500 km of shores could face floodings average warming of 3°C (especially in the North) glaciers will diminish of 20 - 30% rainfall variation in quantity and intensity

+0,7°C

new supply strategies annual average

+1 /+2 °C in large uban areas North - 8% on an average rate of 1.000 mm/year Centre - 10% on an average rate of 750 mm/year South - 12% on an average rate of 600 mm/year

North Centre

25,4 % 5,4 %

sardinia 6,6% South

65%

+10% winter rainfall in the North - 30% summer rainfall in the South

In the urban sphere we can make a distinction between three kinds of water: freshwater - the most precious, to be used just for human needs stormwater wastewater - coming from urban waste, it is collected by the sewer system and channeled to treatment plants before being released in natural water bodies

new pROGRESSIVE fares In the UK they are about to adopt a fare system for water supply that can assure to everyone an affordable minimum supply whose price raises as far as its use is not fundamental, such as water for a pool.

runoff Stormwater begins to flow on the surface when the soil can get no more water due to major rainfalls.

In urban areas this happens because of the excess of impervious surfaces. collected water Stormwater that falls on buildings roof can be collected, stored and used for all those human activities that don’t require drinking water.

11

evapotranspiration 35% evapotranspiration 30%

runoff 55%

runoff 30% superficial infiltration 20%

infiltrazione superf. 10% deep infiltration 5%

deep infiltration 15%

30-50% of urbanization

75-100% of urbanization

adaptation 02 new building standards The city of Auckland (New Zealand) has limited the quantity of impervious surface in new projects according to the hydrogeological features of the site.

max 60% of impervious pavements

awareness raising, modifying lifestyles, reducing and rationalizing consumptions Use distribution of the national average of 280 litre/day per capita: Bath, shower

109 l 39%

Sources

Flushing toilets

56 l 20%

Washing clothes

33 l

12%

Dishwashing

28 l

10%

Washing cars, watering gardens

17 l

6%

Cooking

17 l

6%

Drinking

2,8 l

1%

www.iwmi.cgiar.org (International Water Management Institute)

Other

17 l

6%

www.legambiente.eu

E.R.Trevisiol, S.Parancola Lâ&#x20AC;&#x2122;acqua salvata, utilizzo integrato in una prospettiva biourbanistica Monfalcone Edicom, 1997 www.auklandcity.govt.nz

106 l (38%) could be collected water

www.greencrossitalia.org www.ipcc.ch (Intergovernmental Panel for Climate Change)

12 best practices

water infrastructures

permeability at the regional scale

the meaning of tradition best practices

AQUEDUCTS OF THE CITY OF ROME

YEREBATAN SARAYI

Rome (Italy) 4th c. B.C. – 3rd c. A.D. “[…] the past as a resource that can be potentially developed instead of considering it a passive form of celebration of one’s ancestors.”

L. Mumford, The Culture of Cities, 1938

“[…] municipal control of water, with multiple sources, gave communal life a decided advantage over rural life. It was an evolutionary development that permitted larger number of individuals and more of their culture to survive. The stories of how our forebears faced the challenge of living in larger groups in a fragile and unforgiving landscape are germane to our own time of severe resource constraints.”

D. Crouch, Water Management in Ancient Greek Cities, 1993

In the 19th century urban water supply and water management systems, which untill that moment had structured cities all around the world, underwent a hiding process. Industrial development and population growth had made them unhealthy and dangerous and new public health regulations were adopted. Rivers and streams were buried or were not accessible anymore, aqueducts and urban water reservoirs became a merely technical fact and no more an urban phenomenon, the city’s backbone, as they were before. Nowadays, dealing with stormwater management and looking for models of sustainable development (in order to produce contemporary ones), we want to restore that precious knowledge and to connect our proposal to the interrupted stream of tradition, aware that a city’s value lies mainly in the stratification of historical layers which constitute it.

typology network of aqueducts both underground and open-air with (sub)urban terminals for storage or distribution size network length 480 km daily discharge 429.940 m3 terminals within the city 247

Istanbul (Turkey) 4th c. A.D. typology underground urban cisterns for water storage size basilica cistern 138 x 65 x 7 m Filosseno’s cistern 64 x 56 x 15 m

supply strategy water was collected from rivers, lakes, springs

supply strategy filled by stormwater or by the aqueduct

service period from 4th c. B.C. to 5th c. A.D. (some parts are still working due to baroque restoration)

service period from 4th to 15th century A.D.

hydrological and climatic contest Rome’s aqueducts were designed to cope with the seasonal variation of water availabity in order to provide a constant stock of water

hydrological and climatic contest mediterranean climate, plenty of water in the sorrounding mountains but constant danger of siege and being cut off from natural water resources

13

the aqueduct of sulmona

the aqueduct of livorno

Central park reservoir

qanat

Sulmona (Italia), 1256 A.D.

Livorno (Italia), 1793 - 1858

New York (USA), 1856- 1862

typology urban aqueduct with ending fountain

typology superficial aqueduct with urban reservoirs

size 21 arches total length 100 m

size pipes length 18 km capacity of the principal reservoir 11.000 m3

typology artificial storage basin integrated in a project of urban landscape

origin Armenia, 8th c. B.C. diffusion Mediterranean area, Middle East

supply strategy underground water

supply strategy water is drawn from natural spring on the sorroundings hills and stored in three reservoirs on the way to the city centre

service period from 1265 untill today hydrological and climatic contest the city fulfilled its water needs by many wells, the aqueduct was built in order to provide water for mechanical production processes (mills, manufactures...)

service period 1816 â&#x20AC;&#x201C; 1912 (some parts are still operating) hydrological and climatic contest mediterranean climate, Spring rainfalls, no water shortage periods

size surface 43 hectares, capacity 4.000.000 m3 supply strategy the basin was the water reservoir at the end of the aqueduct fed by the river Croton

foggara

khottara

typology system of draining underground galleries connecting vertical wells which lead collected water to the city size legth could vary from a few hundreds of meters to 2-4 km

service period 1862 - 1993

supply strategy rare rainfalls and the condensation of air water due to night temperature variation

hydrological and climatic contest Manhattan has always had a few water resources of bad quality, due the early pollution, that led to the need of bringing water from ouside

hydrological and climatic contest this system was adopted in arid areas with rare rainfalls and strong night temperature variation

14 best practices

urban models permeability at the urban scale

angkor

(Cambodia) building period 900 - 1050 A.D. inhabitated until 15th century morphology the cityâ&#x20AC;&#x2122;s backbone was the channels and basins (baray) network integrated with the hydrological system of the river Mekong; the mandalic geometry transposed physically on earth and on society the order of Hindu universe

uros floating village

population 1million people lived in Angkor and in its suburbs role of water water made it possible to produce more food but it was used also for its symbolic value hydrological and climatic contest monsoon climate, seasonal plenty of water, rivers with variable flow with frequent floodings

tenochtitlan

lake Titicaca (Peru), present day morphology the village is based on the aggregation of floating islands, entirely built with an aquatic plant (totora, the basis of Uros technology), 30 m large and 1-2 m thick hosting from 2 to 10 families population 400 (the totality of Uros people is 2.000)

role of water this solution was chosen because it provided defence for the village but then the Uros started to identify themselves with the lake ecosystem, building on water identity and culture hydrological and climatic contest the lake is 3.800 m above mean sea level in an area rich in water but without any other resources useful to man

hababa partly integrated in the mosque; the urban fabric is regulated on water infrastructures

Mexico City (Mexico) founded in 1325, destroyed in 1521

population 200-250.000 inhabitants

Yemen present day

morphology built on two islands of lake Texcoco, the city was linked to the land by dyke-streets 9 km long which subdivided the city into quarters. In the very heart of the city, there was the square with the market and the temples. An aqueduct made it possible to maintain floating gardens too

role of water the network of streets and channels made it possible to reach the city both on foot and by canoe and provided defence and food

morphology on the top of the hills sorrounding the city there is a drainage network which leads stormwater to basins often protected by a fortress; on its way to the city, water passes through terraced fields and gardens and reaches another basin within the city centre

hydrological and climatic contest the site, 2.000 m amsl, had no available water

role of water water has a major urban role considering its being the main characteristic of the public space par excellence, the market; moreover, on the highlands its presence is highlit by a fortress while in the lower part there is a mosque doing it hydrological and climatic contest on the mountains of Yemen we there is a continental climate with cold Winter, severe differences of temperature between day and night and intense rainfalls

15

venice

(Italy) founded in the 5th century A.D. morphology the city is built on foundations of wooden piles; the pedestrian system of streets and bridges is independent from the canals, they meet only in interchange points population 200.000 in the golden age (60.000 today)

matera

Italy inhabited from 10.000 B.C. to 1750 A.D. (some parts are still inhabitated) population 30.000 inhabitants

amsterdam

role of water people settled in Rialto because at the very heart of the lagoon they felt safe, they found food, natural resources, a strategic position and the opportunity of water transport hydrological and climatic contest the lagoon is a very frail ecosystem which has always required strong maintenance to preserve conditions suitable for manâ&#x20AC;&#x2122;s life

morphology man inserted a city in a natural hydrologic regime in which stormwater flows rapidly from a plateau to the bottom of a canyon to feed seasonal streams; the city absorbed this natural process, interacted for centuries with it instead of stopping it, using it for human purposes by means of suitable architectural forms whose functioning regulated social and private life role of water the collection of water has always had practical aims but its management, mirrored in the urban fabric, has always given to it the role of social condenser and pivot of local culture

(The Netherlands), founded in the 12th c. morphology in the Netherlands the driving force of urban development was very often the hydrological management of the country and Amsterdam was born as a dyke on the river Amstel population 200.000 (referring to the historic city)

role of water canals were the main transport way within the city and between Amsterdam and other cities; the dyke was the most important public space for people and goods transportation hydrological and climatic contest the dyke was built to control seasonal floodings of the river in an area rich in wetlands but safe from the fury of the North Sea

dacca

(Bangladesh) redesigned in 1962-1974 morphology L.Kahn designed the Capitol adopting an artificial basin as backbone of the new urban fabric; the relationship between the buildings and the basin enbodies the logic of the complex population the members of the parliament and their families

role of water the basin separates the assembly from the rest of the city, giving at the same time the image of a building founded in water, whose symbolism is linked to rebirth and purification (Kahn paid much attention from the very beginning of the designing process to the importance of islamic religion in Bangladesh society) and whose presence is typical of Indian architecture

16 best practices

water typologies and morphologies permeability at the scale of the building

katsura imperial villa

jag niwas (lake palace)

marghera fort

pol - e khaju (khaju bridge)

Kyoto (Japan), 1620-24 and 1642-60

Udaipur (Rajastan, India), 1743 - 46

Venice (Italy), building period 1805 - 1881

Esfahan (Iran), 1650

commissioner, design, function Prince Hachijo Toshihito designed a country estate where he could embody the aristocratic lifestyle of the novel Genji Monogatari

commissioner, design, function Jagat Singh II wanted this building to be his golden hiding place not very far from the urban palace on the shore, carrying on with his ancestorsâ&#x20AC;&#x2122; oeuvre of designing Udaipur artificial lakes complex and the city itself

commissioner, design, function in 1797 Napoleon gives the Republic of Venice to the Austrians. Their naval base in the city is given a network of forts all around the mainland access to Venice; key element of this plan was Marghera Fort

commissioner, design, function shah Abbas II built this bridge to link different part of the city and to provide a dam on the river

morphology the Jag Niwas covers an entire island in such a way that it seems a fragment of the near palace floating away from the city; it is a complex of white marble buildings clustered around gardens, opening up towards the waterscape

morphology built in a wetland where land periodically disappears, made by canals sorrounding earthworks, the fort is placed at the key point of the main waterway which led from the city centre of Mestre, on the mainland, to the back of Venice itself

morphology the landscape architecture of the time wanted gardens to show seasons natural rhythms; artificial basins and hills were designed to emulate nature; the insertion of the pavilions within the landscape sets up all the possible relationships between water and buildings role of water water is the leading element of the composition; it is not just something to look at but a fundamental part of the project; some of the buildings are replicas of vernacular typologies as if the complex would represent an ideal microcosmos

role of water building on water, just in front of the city, on a site fabulous and unreachable for anyone, testifies the will of giving a demonstration of might

role of water the fort uses water for defence, just like many other buildings of this kind, but here it is part of an urban system between land and water

morphology 123 m long, it is built on 24 arches. On the upper level, a street passes through two rows of commercial buildings, on the lower one, there is a covered passageway close to the water. If the dam is locked, the water level decreases and the stepped structure of the piles emerges, giving to people an interesting public space where they can meet their river role of water the bridge embodies different ways of perceiving water in the city: an obstacle to get over (bridge), a resource to be managed (dam) and an opportunity to create quality public spaces

17

ponte vecchio (old bridge)

punjab High Court and assembly

Florence (Italy), 1345

Chandigarh (Punjab, India), 1956 - 1961

commissioner, design, function it replaced an older bridge destroyed by floodings, in 1442 city authorities forced the butchers to move on the bridge for health reasons

commissioner, design, function pres. Nehru asked Le Corbusier to design the new capital of Punjab; LC paid particular attention to the Capitol

morphology first bridge in Europe built on segmental arches; buildings were first built filling old porticoes, then the butchers expanded them on posts above the river; in 1506 Vasari designed the aerial passage on the upper level, linking the Mediciâ&#x20AC;&#x2122;s urban Palazzo Vecchio with the suburban estate of Palazzo Pitti, on the other side of the river Arno

morphology buildings are at opposite sides of the Capitol; at the feet of the main facades there are rectangular basins crossed by the main access ways

role of water the bridge represents a spontaneous urban growth phenomenon over a structure which is being modified in such a way that it is the continuation, across the water, of the urban fabric

role of water the basins are important elements of the composition: they express a founding character, they bind the Assembly and the High Court buildings to the podium they are on and, by mean of water reflection, the link them to the visual reference of Himalaya; they are the monumental starting point of the city water system

18 best practices

urban devices permeability at local scale

fountainhouse - springhouse

roman domus (the faun’s house) venetian artificial well

the bottino aqueduct fountains

Corinth, Athens (Greece), 6th - 5th c. B.C.

Pompeii (Italy), 2nd c. B.C.

Venice (Italy), 9th - 17th c.

Siena (Italy), 13th c.

typology fountainhouses were covered rectangular basins part reservoir and part fountain in urban area; springhouses governed natural springs by means of horizontal cavities (i.e. Peirene in Corynth) or vertical wells (i.e. Klepsydra in Athens) that had to be periodically deepened

typology the Roman domus internal distribution pivoted on a central peristylium (open air court limited by columns) with pitched roofs that led stormwater to a central basin called impluvium

typology underground filtering and storage cistern for collected stormwater in dense urban areas

typology rectangular basin covered by monumental structures in urban and suburban areas

size av. capacity 230 m3 av. daily availability per capita 6,8 l

supply strategy ‘bottino’ refers to the old aqueduct of Siena based on an Etruscan technique of vaulted galleries built at the edge of the watertable; it collected groundwater and led it to the fountain

size Peirene galleries in Corynth were 3.000 m deep supply strategy fountainhouses were mainly fed by aqueducts; springhouses used natural underground streams urban value of the device it is clearly stated by Euripides who talks about Peirene fountain as ‘the centre of Corynthian life’ (especially for women); placed in the agorà or at the city gate to be admired by strangers, they were often spectacular buildings

supply strategy the impluvium led to underground tanks (and to an overflow pipe connected to the public sewer); users could draw stored water from a well urban value of the device the large diffusion of this system modified the morphology of the urban fabric; it was mainly a juxtaposition of independent and introverted units of a sort of patio houses hydrological and climatic contest due to sulphuric infiltrations from the volcano into groundwater, this was the most diffused water supply strategy in Pompeii

supply strategy storwater is led from pitched roofs and pavements to holes in the open spaces and to an underground cistern, it is filtered by the sand inside and percolates through brick walls in the vertical well where it can be drawn urban value of the device land scarcity gave open spaces multiple needs to fulfill: water management was the first and it shaped the morphology of the tradional campo (square). The system was a sort of artificial watertable which granted life and self defence

urban value of the device the main part of the fountains were built during the Golden Age of Siena (13th-14th c.) in order to provide water for the growing population; the ideal of the ‘buon governo’ (good government) and of the balance between urban and natural was represented also by an equal distribution of water throughout the city; very often the fountain identified the quarter itself and outside the urban walls it demonstrated to strangers the grandeur of Siena

19

urban island mills

stepped wells

urban bath house

seawall

Padua (Italy), untill first years of the 20th c.

Delhi (India), 14th c.

Berlin (Germany), 1817 - 1933

typology the mills were directly built in the middle of the Piovego canal and connected one to the other by paths suspended on water

typology open air storage many meters down in the earth to be reached by complex staircases

typology wooden squared structures with perimetral covered paths, built on piles not very far from the shore of the river

Footdee village - Aberdeen (Scotland) 19th - 20th c.

supply strategy water was used as source of mechanical energy to move the machinery inside the buildings, the reason of building them in the middle of the canal was to make the most of its flow speed urban value of the device this preindustrial settlement was a specialized part of the city; its morphology was clearly linked to its functions and to the presence of water; it maintained the continuity of the urban fabric between the two shores of the canal hydrological and climatic contest this typology was coherent to Paduaâ&#x20AC;&#x2122;s behaviour and relationship with water

size 20 m deep supply strategy these wells generally collect groundwater, the stepped morphology is suitable to water level fluctuation urban value of the device this system was born to grant access to water to as many people as possible in the same time; this peculiar fruition in Indian particular climate made these wells become the focal point of the cityâ&#x20AC;&#x2122;s social life and the action of going down in the earth to meet water enriched this common action of a special value

typology linear barrier placed at the back of row houses to face the storms of the North Sea

size about 40 x 20 m

size 120 m long, 4-5 m above mean sea level

urban value of the device quite common in European cities between 19th and 20th c., its value consists in the opportunity it offer to the citizens to get in touch with the river. This valuable relationship, lost since World War II, it is being restored today, especially in Germany, and people is becoming more and more interested in it

urban value of the device when this infrastructure, that encircles and protects the coastal side of the village, passes at the back of the houses becomes part of them, a sort of continuation of their pitched roof, a shelter, but nevertheless it maintains the pedestrian path on its top; not far from there it widens and provides access to the sea

hydrological and climatic contest maybe one of those urban rivers that today flow between two high embankments, far away from peopleâ&#x20AC;&#x2122;s sight

hydrological and climatic contest the system fulfill peculiar needs: defence against the fury of the North Sea and the dangerous erosion of the waves

20 best practices

systems and techniques

qanat minimal maintenance required - natural self organization

matera flexibility - adaptivity - modularity

siena decentralization

symbolic meaning

uros village collective design and management

dacca contribution to the definition of collective identity

venice social cohesion increase

roman aqueduct representation of community membership

interaction with peopleâ&#x20AC;&#x2122;s life

qanat social self organization

central park reservoir great possibility of fruition - multipurpose design

pompeii access - equity

relationship with natural resources

qanat close relationship with the territory (functioning by means of natural dynamics

aqueduct of livorno awareness raising and environmental responsibility promotion

hababa keeping resourcing exploitation at the local scale

insertion in the urban fabric

central park reservoir locating water infrastructures in strategic places

matera strong integration in the urban fabric

venice connective tissue role capability of working as driving force of urban growth

21 It is fundamental to use the smallest amount of energy possible, it doesnâ&#x20AC;&#x2122;t matter which system we choose.

For this reason we should use natural dynamics, to reduce management costs too. Assuming that it is very difficult to lay out clear future scenarios, the system shall be as dynamic and flexible as possible.

All the previous issues require the adoption of systems whose elements are spread through the territory: the goal is maximum decentralization.

The infrastructures that lasted the longest were those able to embody the values of the society which used them.

The idea of water management often corresponded to the idea of urban social living itself. As long as the values were shared by people and deeply rooted in society the infrastructure worked well and this fact often depended on the possibility of fruition of the infrastructure.

Water is the element which grants the survival of every living being and so it is clear how important its management will always be for the city.

The basic principle of it should be equity in distribution and availability. Citizens themselves should be entrusted of water management, leaving to central authorities a control as feeble as possible.

Moreover, the infrastructures that lasted the longest were the ones able to fulfill multiple needs.

Water is a renewable resource only in part.

The relationship between water management and the resources of the territory in which it is done is fundamental. The infrastructures that lasted the longest were those capable to keep under the reasonable limits of the area they worked for the extent of resources exploitation.

This fact made the city act far-sightedly in managing its territory resources.

These principles should be pert of peopleâ&#x20AC;&#x2122;s common knowledge: many water infrastructure had also didactic purposes.

Water management is basicly a service, a practical need of the city.

Nevertheless, without indulging useless monumentality, the choice of placing water infrastructures in strategic places of the city has always been successful, because there it was easier for functions and users to mix.

Sometimes it worked so well that the infrastructure itself became prototype of the city and a model for urban development. History shows that this can happen even better if the infrastructure undergoes a process of fragmentation through urban fabric.

why have water infrastructures of the past been so long-lasting and successful ?

21 general model

22

towards permeable city general model “...the future task of urbanisation: the re-establishment, in a more complex unity, with the full use of the resources of modern science and techniques, of the ecological balance that originally prevailed between city and country in the primitive stages of urbanisation.”

Lewis Mumford, from an article of 1956

“Water problems must be solved specifically and within the immediate vicinity for every town, every district, every neighbourhood. [...] The city of the future will have to be a city of neighbourhoods in which lifestyle and development are determined on a small scale .”

Herbert Dreiseitl, Waterscapes, 2001

Permeable City works on four levels. Every level corresponds to a major issue dealing with water management in the urban existing environment. The fundamental aim of the system is to reduce urban water need through the adoption of water-sensitive policies and designing strategies, taking into account that water resources (groundwater above all) are dramatically extinguishing.

The strategy consists in the insertion, within the existing urban fabric, of a network of ‘urban devices’ made of ‘nots’ and ‘streams’.

‘Nots’ are important points of collection, storage and re-distribution of water (sometimes of infiltration as well), ‘streams’ could be ditches, swales, channels, trenches or simply gutters that lead water to the ‘nots’. The leading design principle is visibility. The moment has come to rebuild the relationship between towndwellers and water. The first thing to do is to regain water visibility in the urban fabric by means of a new infrastructural network, mainly open and possibly able to provide new urban spaces where water can be directly experienced again by people. Meeting urban water needs would be easier dealing with neighbourhood units instead of the

whole of a city. The era of large infrastructural networks is at the end. Considering the dimensions of contemporary cities and today’s energy problems, they are not affordable anymore. The city of the future has to be based on neighbourhood units where changes in lifestyle could really be effective on water shortage. The small dimensions of the neighbourhood unit could enable citizens to regain part of the control on water management and raise their awareness about water management issues within their city. To achieve these goals the design must be site-specific: there are many different kinds of soil with different permeability ratios, chemical and physical properties, many different kinds of orography and every inhabited area has had a peculiar urbanization process. All this must be dealt with to produce a good and effective project for the city of tomorrow.

Building in the existing city means that finding free space could be very difficult. So, wasting soil is not allowed. The infrastructures we build must be as multipourpose as they can, providing different kinds of urban experiences and landscapes, according to different weather conditions. Acting as a social condensers they can revitalize the city.

24 general model

project goals

project agenda Adopting an integrated approach in designing the urban water system

human resources

fighting pollution and wastes at their origin by the modification of lifestyles

raising environmental awareness and responsibility

taking advantage of the self-organizing skills of natural and social structures

restoring the relationship between society and natural environment

adopting new building standards

increasing social cohesion

adopting new progressive water fares

enhancing citizensâ&#x20AC;&#x2122; participation to urban design and management building a common identity

Neighbourhood unit as urban model designing the different surfaces of the neighbourhood unit in order to make people live again the open spaces (the main model is the Dutch woonerf)

physical resources (re)activating underestimated urban spaces enhancing urban water management reducing urban ecological footprint reconnecting physical and natural morphology adopting dynamic management systems to cope with climate change producing local solutions within global strategies

designing the different surfaces of the neighbourhood unit in order to make them the first stage of the urban water management and to make this process visible and plain to everyone making the area as recognizable as possible in order to enable people to identify themselves in the inspirating values of the project to make it last longer

adopting infiltration and open air drainage systems for urban runoff reducing the adoption of sewage systems that make stormwater discharge unnaturally fast minimazing the impermeability of urban surfaces restoring impervious surfaces permeability adopting retention system to delay stormwater discharge

natural resources

integration of water infrastructures in the urban fabric

conserving the biosphere

insertion of a new connective network made by low impact projects at different scales

conserving and restoring hydrological systems

creating a hybrid between new insertions and multipurpose public spaces to enhance awareness raising, participation and social relations

increasing of biodiversity closing the water cycle within the territory which is concerned by it enhancing groundwater recharge and conservation protecting water resources

use natural processes promoting an olistic vision of urban water systems and finding new supply strategies save the green areas along the rivers to protect infiltration and retention areas runoff cleansing by means of soil infiltration and open air flowing enhancing urban microclimate by water evaporation

25 project layers

infiltration The major design strategy consists in cracking the impervious layer that, due to urbanization, covers earth surface. The aim is to open passages for stormwater to infiltrate into soil deeper layers.

temporary retention The surfaces of the neighbourhood units work like a subtile network of drainage paths.

In the network there are â&#x20AC;&#x2DC;notsâ&#x20AC;&#x2122;, devices for temporary retention before infiltration.

collection and storaGE The system is composed by two different levels: collection on the roofs of buildings and storage in underground cisterns built under the open spaces.

surface drainage Runoff collected by the system is drained to infiltration areas or basins or to the urban water treatment plant. In any case it undergoes a partial infiltration due to its flowing in the vegetated canals.

26 general model

infiltration

urban devices

site specific design - preliminary studies

soil porosity

infiltration barriers

vegetated surfaces

artificial porous surfaces

On steep bare slopes they can slow down surface runoff and make it undergo infiltration into the soil. With proper planting land erosion can be stopped and water table recharged.

This is the easiest way to obtain infiltration surfaces. It could be an entire raingarden or a narrow stripe along the side of a street. Vegetated surfaces infiltration power depends from the soil lcomposition.

Every pavement, except those carrying very heavy traffic, could be built varying the aggregates size of its layers in order to obtain different degrees of permeability and allow stormwater infiltration.

urbanization

hydrological balance â&#x2C6;&#x2020;Stock = R - Et - Ro

soil permeability

R = rainfall Et = evapotranspiration Ro = runoff

contemporary city orography water table

permeable city natural drainage systems (NDS) Low Impact Development philosophy adopts an approach to stormwater management as close to nature as possible. Stormwater must remain within the site it concerns. NDS are small scale, decentralized and distributed to restore pre-development hydrology of sites.

27

temporary retention

urban devices

deep watersquare

surface watersquare

floating cisterns

The watersquare is an actual basin inserted in the design of a square or being the square itself which, during rainfalls, is flooded by runoff in order not to cause overcome the carrying capacity of the sewer system.

When the watersquare is dry and it is not operating its action of runoff retention, it can be lived as any other public urban space. The ponding time can be controlled and be object of the design.

To be anchored to river banks in urban areas so that, during major rainfalls, they can collect either runoff or the overflow of public sewers in order to protect the river.

Their top is an interesting public space.

multipurpose infrastructures Being multipurpose is the fundamental condition for the project to have success and the most important issue in its conception.

According to weather conditions the infrastructure presents a varying configuration which changes the urban landscape providing at the same time different ways of living the public space.

Moreover, it draws the attention of people to water cycle by let them experience it.

Artificial drainage systems (aDS)

floating cisterns

superficial watersquare (retention)

superficial watersquare (retention and storage)

deep watersquare (retention and storage)

28 general model

collection and storage

urban devices

private storage tanks

common cisterns

Collection roofs

They are obviously not a high value architectural solution but when the urban fabric becomes less dense, bigger water infrastructures become less affordable. It is anyway a step towards self-sufficiency.

Big undergound common cisterns can be placed just under watersquares in order to optimize the building effort. They are convenient when the neighbourhood unit is quite dense. Water is collected from roofs.

The main feature of Permeable City. Normal roofs (it doesn’t matter wheter flat or pitched) can be adapted for water collection with proper sealing and covering materials.

Directly connected to common storage.

neighbourhood unit scale

CITY scale

soil permeability design

CONNECTIVE FABRIC

The unit’s dimensions make it the perfect fundamental unit of urban water management by means of a proper soil design and proper paving materials.

The urban design, common to the water management (neighbourhood) units which form the city, is structured as an infrastructural network of devices of varying dimensions and specific surface treatments.

residentiaL USE OF THE STREET

different transportation pattern

The re-design of soil paving lets the street gain new quality, new safety for people of all ages and a new condition suitable for different social activities to which vehicular traffic is subordinate.

The interventions at the scale of the neighbourhood unit create a new transportation pattern: residential areas become limited traffic zones which stimulate the use of alternative transportation systems.

contemporary city is paved without distinction

permeable city: buildings with water-collecting roofs

different surface treatments for residential and traffic streets

network of infrastructures for water management

NEW MODEL OF DESIGN AND MANAGEMENT

collective identity and new lifestyles

The unit’s dimensions encourage the citizens’ participation to the design/management of the water cycle, increase the citizens’ interest in issues closer to their daily life and limit the uncertainties of designing with water.

The first step towards more sustainable lifestyles is at a home level within the neighbourhood units. The participation to the design/management of them will make people identify themselves with them.

shared designing principles

modification of lifestyles

self-sufficiency, abandon of large centralized technological networks

closing local water cycle

29

surface drainage

urban devices

open drainage network

Subtile drainage network

An open air network of canals, streams, dirches...to be built in urban areas to collect runoff in order to lead it towards infiltration areas and, in the meanwhile, to partially cleans it during its flowing through plants.

An open air network composed of paths just a few centimeters deep and gently sloping pavements to lead runoff towards infiltration areas nearby, maybe within the same neighbourhood unit.

site specific design - preliminary studies

infiltration possible ?

yes

storm water management system totally intelligible for everyone

water quantity

closing local water cycle

soil permeability?

possibility of having a relationship with water

demand of area?

developing plan

infiltration allowed ? quality and quantity of infiltration water

structure plan

water protection area?

master plan

water from surfaces with heavy traffic?

task

site development

adjacent building affected?

yes

area available? storm water management system

no

partially visible closing local water cycle near to drained areas

no

yes open drainage (ditches) possible ?

water cleansing and improvement of microclimate conditions

storm water management system

demand of area?

artificial inflexible network incable of dealing with peak discharges

area available? topographical conditions?

no

mixing with wastewater and decreasing of effectiveness of cleansing plant no possibility of having a relationship with water

30 pluviometric regimes

Climatic chart

Annual average rainfall [mm]

tundra mediterranean coastal mediterranean mediterranean mild oceanic humid subtropical humid continental cold continental

defining boundaries pluviometric regimes The next step is to test the general model in different urban environments.

Italy provides a variety of urban landscapes perfect for the testing. First of all we shall subdivide the physical reality of the country. The aim of this is to make easier the designing process by giving limits to a domain by far too large and in the same time to find out â&#x20AC;&#x2DC;extremeâ&#x20AC;&#x2122; examples of urban areas affected by the problems, related to water management, previously stated. Italy has been divided into four macroregions, homogeneous for what concerns the main issues dealing with stormwater management.

The main source of data is a study of the Centro Nazionale di Ricerca (CNR), published in 2006 on the International Journal of Climatology, called Temperature and precipitation variability in Italy in the last two centuries from homogenised instrumental time series.

In this way the output will be four projects, as accurate and complete as possible for what concerns their natural and physical context, which can act as prototypes of a new concept of water management in urban areas.

Soil desertification

350 - 630 630 - 920 920 - 1200 1200 - 1500 1500 - 1800 1800 - 2100 2100 - 2375 2375 - 2650 2650 - 2950

very low low medium high very high

alpine regime

po valley regime

central regime

southern regime

Annual average temperature [°C] - 12 / - 9 -8 /-6 -5 /-2 -1 / 1 2 / 5 6 / 8 9 / 12 13 / 15 16 / 19

Satellite image of the country dating back to March 2003, with superimposed boundaries of the four macroregion.

Some of their geographical features and orographical peculiarities clearly emerge from this view.

31 Distribution of rainfalls through the year

alpine regime

po valley regime

central regime

southern regime

where The regions of the Alpine area along the Northern borders of Italy

where From Turin to Trieste, in the Po Valley through all Northern Italy

where Apennines area, central regions both on the Adriatic Sea and on the Tyrrhenian Sea and the Northern Sardinia

where Southern part of Sardinia, Sicily and the extreme Southern regions of continental Italy

when Major rainfalls in summertime

when Two peaks in Summer and Autumn and a marked minimum in Winter during which water shortage is not rare

when Mainly in Autumn and Spring; Autumn peak is bigger than the Spring one; nearly water shortage in Summer

when Rainfalls are concentrated in Winter (from December to March), long period of intense Summer water shortage

how much 100 - 120 days/year 1200 - 2950 mm/year

how much 60 - 100 days/year 630 - 920 mm/year

how much

how much

annual average temperature - 5 / +8 °C

annual average temperature 9 - 15 °C

annual average temperature 6 - 15 °C

annual average temperature 13 - 19 °C

orography Mountain landscape asks for a very specific stormwater management. The strong variation in slope, the presence of just a few open plain spaces to infiltrate water in and the fact that the most important river basins of Northern Italy have their roots here are the main issues of this macroregion that must be dealt with.

orography The landscape along the river Po (the longest and largest Italian river) is plain and agricultural. The river is very polluted due to the industrial cities that lie on its banks. The Po Valley is also Italy’s principal groundwater stock but, due to the urban overdraw and the decreasing river flow, there is just a little water remaining which is mixing with the salted water of the Adriatic Sea nearby.

orography This macroregion’s backbone is the mountain range of the Apennines. The major cities have grown at its feet in a hill landscape. The growth of the urban areas has stressed the frailty of the soil, so often lacking of maintenance.

Leaving urban runoff out of control has proved to be very dangerous.

orography The cities have grown mainly in the plain stripes along the coast so that the principal urban water body to be dealt with is the sea. The critical point of this relationship is often to be found in the interface between these two entities, the urban waterfront.

Nearly the entire macroregion suffers from soil desertification and water shortage.

needs If the large adoption of flat roofs simplifies stormwater collection, the peculiar orography makes it quite difficult to build a distribution network for collected water. Devices to slowing down the flow of urban runoff over the bare surface of hills shall be required.

needs Rainwater collection is the priority, we need large amount of water to storage for summetime, we need every colection surface possible (in this case, it may be necessary to increase urban surfaces impermeability).

needs Management of large quantity of rainwater that has to undergo infiltration to feed river basins.

Needs A medium collection is needed because of the good distribution of rainfall.

Further polluted urban runoff overflows in the rivers must be avoided. Water retention will be very important.

60 - 120 days/year 630- 1500 mm/year

60 - 100 days/year (somewhere less than 60) 350 - 920 mm/year

32 PC01 - alps

33

permeable city 01 alps

preliminary studies intervention strategy concept project

34 PC01 - Alps

preliminary studies pluviometric regime and climate

orography and pedology

where The regions of the Alpine area along the Northern borders of Italy

Soil Metamorphic rocks are the most diffused in the Alps. They are the result of high pressure and temperature transformation of other rocks. They have low permeability and low water conductivity, infiltration is difficult.

when Major rainfalls in summertime how much 100 - 120 days/year 1200 - 2950 mm/year annual average temperature - 5 / +8 °C

Riverbed During the last glaciation alpine glaciers produced the peculiar section of alpine valleys eroding their sides while they grew.

Detritals layered on the bottom of the ancient oceans when the glaciers retired, forming the soil of the riverbed at the bottom of today’s valleys. It has quite good permeability and water conductivity, infiltration is quite easy.

urbanization streets, orthogonal, very large with large unused (unpaved) spaces along them.

green areas, large, both public and private. courtyard houses, they form the city built after WW2, they are natural neighbourhood units.

The courtyards are low quality unused semi-public spaces. river, a torrential river, easily accessible, natural element to protect and riqualify. riverbed, gently sloping towards the river, a messy system of sport fields, vegetables gardens and orchards. They testify the city’s will to use this space.

aerial photo of the chosen piece of urban fabric

0

100 m

metamorphic rocks glacier’s head detrital riverbed

35 infiltration 90%

intervention strategy pluviometric regime and climate rainfall is considerable all over the year The summer peak can be a problem for the public sewer system

90% surface drainage

storage cisterns can be quite small due to rainfall frequency stormwater disposal is by far more important than its collection Drainage and infiltration devices will be required to help public sewer system

collection and storage 50%

temporary 70% retention

urban devices infiltration

urbanization the riverbed is characterised by the messy presence of different structures and activities

the new system will have to be able to host different kinds of activities while contributing to stormwater management

it is the edge between urban and river ecosystems. its role has to be planned and its spaces smartly used

the design of open spaces and streets will produce an open drainage network while the requalification of the courtyards will allow the insertion of common underground cisterns

within the urban fabric, the open spaces suffer from an indeterminacy of functions reflected in the absence of design, pavimentation, maintenance

orography and pedology there are two kinds of soil: the one the city is built on (low permeability) and the one near the river (good permeability) orography helps runoff to flow towards the river

the devices will contribute to the restoration of peopleâ&#x20AC;&#x2122;s relationship with water by means of contact with it

the two soils will have to work together on stormwater infiltration The soil of the city will require drainage to infiltration areas on the riverbed soil

infiltrations barriers

vegetated surfaces

artificial porous surfaces

surface drainage

open drainage network

subtile drainage network

collection and storage

private storage tanks

common cisterns

collection roofs

surface watersquare

floating cisterns

temporary retention

runoff discharge or overflow in the river will be stopped by site-specific infiltration systems deep watersquare

36 PC01 - Alps

concept disposal open drainage

vegetated infiltration area

temporary retention area

watershed

surface design for draining water

In this area it is really demanding but fortunately there is plenty of space for management devices to be inserted.

Main streets have open drainage vegetated canals leading water to the main one, along the large boulevard at the edge of the city centre. From there, water flows to the infiltration basins in the riverbed. In case of heavy rainfall, the runoff drained from the city flows from the first level of basins to the second one and eventually to the third. It is an infiltration system which involves both the city at the top and the large riverbed at the bottom. Within the urban fabric, infiltration is put into practice by means of vegetated surfaces both public and private and urban soil permeability design.

neighbourhood unit

collection single building roof designed to work as catchment surface neighbourhood unit

common storage (underground cistern)

pipes back and forth from the storage

The urban fabric is mostly formed by courtyard houses which are neighbourhood units on their own. The roofs of the buildings are the stormwater catchment surface while the courtyards host underground common storage cisterns which can be relatively small.

Where the urban fabric is too fragmented (i.e. in the residential areas mostly formed by one-family houses), collection and storage of stormwater are individual merely technical devices (i.e. tanks) Due to the large possibility of putting into practice open drainage and infiltration, temporary retention facilities are not required.

37 project

secondary drainage canals next to the pavements, trees rows and parking surfaces requalification of existing public green areas and their infiltration-oriented redesign re-configuration of the urban edge by means of the insertion of the main drainage canal integrated to traffic course, bycicle tracks, pedestrian walks and green stripes planted with trees new underground common garage next to common storage cisterns both with coverings which can be used by people in different ways

aerial photo of the chosen piece of urban fabric with project insertion

0

100 m

new layout for the riverbed with earthworks and vegetated infiltration basins

38 PC01 - Alps

plan of the chosen piece of urban fabric project insertion scale 1: 5000 urban section of project samples scale 1:4000

zooms scale 1: 1000 courtyard houses boulevard with main drainage canal

39

40 PC01 - Alps

41 Permeable City 01 - Alps photo of 1:50 model transversal section of a secondary ditch leadind to the main canal along the boulevard (cross-sectioned) and to the upper level of infiltration basin in the riverbed

42 PC01 - Alps

Technological details

a

b1

b2

a

1 2 3 4 5 6 7 8 9

20 cm stone kerb 15 cm lean concrete foundation 2,5 cm asphalt 8 cm aggregate bitumen-stabilized binder 8 cm aggregate levelling course 40 cm gravel base course pebbles draining layer 6 mm diam. fixing steel bars 2 mm diam. metallic netting 60x80 mm meshing 10 10 mm tridimensional geosynthetic 11 local shrubs

b1 12 13 14 15 16 17 18 19 20 b2 21 22 23 24 25

10 cm sitting stone slab seat structure, 12 cm reinforced concrete 20 cm reinforced concrete foundation 12 cm lean concrete open-jointed paving 30x30x8 cm stone slabs 3 cm sand bedding 40 cm gravel draining base course separation geotextile HDPE waterproofing membrane 30x30x8 cm stone slabs 6 cm sand and cement bedding gravel base course 12 cm precast concrete retaining wall 15 cm lean concrete foundation

43 a

b1

1 2 3 4 5 6

12 13 14 15

7 8 9 10 11

16 17 18 19 20

b2

21 22 23

24

25

44 p c 0 2 - p o va l l e y

45

permeable city 02 po valley

preliminary studies intervention strategy concept project

46 P C 0 2 - PO va l l e y

preliminary studies pluviometric regime and climate

orography and pedology

where From Turin to Trieste, in the Po Valley through all Northern Italy

The Po Valley is Western Europeâ&#x20AC;&#x2122;s largest alluvial plain (30.000 Km2).

The soil is made by gravel, sand, silt and clay, layered by the river flow.

The landscape changes quite frequently along the river Po. In the northern part we find detrital deposit and sediments due to the action of the secondary rivers originated by alpine glaciers. In the South we find low lands where man had often to drain large areas of the plain to settle in them, building embankments, dikes and canals. Near the Adriatic Sea there is the typical delta landscape where freshwater meets salted water by means of a network of canals.

when Two peaks in Summer and Autumn and a marked minimum in Winter during which water shortage is not rare how much 60 - 100 days/year 630 - 920 mm/year annual average temperature 9 - 15 °C urbanization green areas, unused and lacking in quality, in spite of their scarcity

parking areas, large, one-task, impervious, increasing heat island effect river, polluted, easily accessible from the city but abandoned all the same, it receive the overflow of the public sewer system in case of heavy rainfall. Many cities of the Po Valley grew on the banks of large, accessible rivers which are nowadays a stranger and forgotten element within the urban fabric. streets, straight, sometimes planted, large enough to be re-configurated aerial photo of the chosen piece of urban fabric

0

100 m

alluvial plain terraces delta coastal plain river lagoon dunes sea

47 infiltration 70%

intervention strategy

40% surface drainage

pluviometric regime and climate collection needs are medium due to rainfall intensity rainfall variations make it necessary to temporarily retain runoff discharge to public sewer system to avoid dangerous peak charges

storage cisterns can be quite small due to rainfall frequency collection and storage 70%

Drainage and infiltration devices will be required to stop sewer overflow going into the river roofing re-configuration is the basis of the collection system

temporary 80% retention

urban devices infiltration

urbanization deterioration of the relationship between city and urban water bodies (river) open spaces and streets present configuration do not support public sewer system public sewer system is the only kind of stormwater management adopted open spaces are one-task

temporary retention is fundamental to protect the river and to grant the correct working of present water management facilities

infiltrations barriers

vegetated surfaces

artificial porous surfaces

surface drainage

the river must be accessible to citizens the lacking of open space within the city encourages multi-task infrastructures to be built open spaces pavings must interact, in different ways, with the drainage network

open drainage network

subtile drainage network

collection and storage

orography and pedology soil has low permeability presence of so-called â&#x20AC;&#x2DC;negative orographyâ&#x20AC;&#x2122;, soil surface is under the level of the water table, tendency to ponding, direct contact with regional groundwater stock

soil peculiarities make it necessary to use infiltration surfaces as large as possible

private storage tanks

common cisterns

collection roofs

surface watersquare

floating cisterns

temporary retention

surface drainage is fundamental but space scarcity make it necessary to replace it by means of a subtiled rainage network

deep watersquare

48 P C 0 2 - PO va l l e y

concept disposal open drainage

vegetated infiltration area

temporary retention area

watershed

surface design for draining water

neighbourhood unit

The quantity of water to be dealt with can be large and give some problems.

Stormwater disposal is mostly carried out by an underground drainage network.

Temporary retention is put into practice in the upper part of the watersquares and in cisterns floating on the river connected to the network.

Open spaces in-between the buildings and residential lanes within neighbourhood units can be properly paved to encourage runoff to flow to the watersquares.

Larger streets can be equipped with Natural Drainage Systems to increase on-site infiltration. It seems impossible to supply the city with an open drainage network. It will be necessary to use an underground network dedicated to stormwater leading water to treatment plant or infiltration areas.

collection single building roof designed to work as catchment surface neighbourhood unit

common storage (underground cistern)

pipes back and forth from the storage

The Po Valley pluviometric regime would require medium-sized storage cisterns.

Unfortunately the high density of the uban fabric does not provide spaces to host stormwater management infrstructures and so a deep watersquare seems to be the best device to adopt.

Stormwater collection is put into practice by means of the roofs network whose drainpipes lead water to the cisterns just under the watersquares where possible treatments take place before the use.

The extent of the neighbourhood unit and the consequent dimensions of the watersquare depend strongly on the configuration of the urban fabric.

49 project

floating tanks for temporary retention of runoff infiltration areas

design of neighbourhood units surfaces equipment of the roofs to allow stormwater catchment watersquare with public facilities and retention/ storage devices linear infiltration by means of vegetated stripes along the streets large enough to allow it aerial photo of the chosen piece of urban fabric with project insertion

0

100 m

50 P C 0 2 - PO va l l e y

plan with project insertion and urban section scale 1: 4000

51

zooms scale 1: 1000 waterquares and floating tanks

52 P C 0 2 - PO va l l e y

Permeable City 02 - Po Valley photo of 1:50 model cross section of the watersquare lower level, visibility of the cistern from the pavement

53

54 P C 0 2 - PO va l l e y

Technological details

a

b

c

a

1 2 3 4 5 6 7 8 9

2,5 cm asphalt 8 cm aggregate bitumen-stabilized binder 8 cm aggregate levelling course 40 cm gravel base course separation geotextile 130x130 cm coarse aggregate spreading volume 35 cm diam. perforated plastic pipe 20 cm stone kerb 15 cm lean concrete foundation

b

10 11 12 13 14 15

15 cm porous concrete 15 cm draining base course 40 cm diam. draining pipe metallic grille overflow 12 cm lean concrete

c

16 17 18 19 20 21 22 23

3 cm stone paving 2 cm mortar bedding 20 cm aggregate levelling course foundation drain 4+12+12 mm safety double glazing HDPE waterproofing membrane 40 cm reinforced concrete retaining wall metallic grille

55 a

b

1 2 3 4 5 6 7

8 9

c

10 11

12 13 14 15

16 17 18 19

20 21 22 23

56 pc03 - centre

57

permeable city 03 centre

preliminary studies intervention strategy concept project

58 Pc 0 3 - c e n t r e

preliminary studies pluviometric regime and climate

orography and pedology

where Apennines area both on the Adriatic Sea and on the Tyrrhenian Sea, Northern Sardinia

Volcanic soil Tuff is by far the most diffused kind of rock in central Italy.

Tuffaceous soil is very permeable but also very sensible to erosion.

when Autumn and Spring; Autumn peak is bigger than the Spring one; possible water shortage in Summer how much 60 - 120 days/year 630- 1500 mm/year annual average temperature 6 - 15 °C

soil erosion Population growth (some of the largest Italian cities like Rome and Naples are here) caused intense exploitation of volcanic ecosystems and an increase in soil erosion due to stormwater runoff. Soil erosion is influenced by rainfall frequency and intensity, vegetation structure, lenght and slope of hills. Subdividing the sloping in shorter portions and encouraging infiltration can slow down water and erosion itself.

urbanization slopings, many of them, large, unused due to their steep slope

streets, curvilinear and varying in slope, not very large open spaces, not very big due to the need of making the most out of the ‘hard’ soil

flat roof, almost every building has one, it make it easier to put into practice stormwater collection

green areas, they are present but they are useless spaces with merely ornamental functions aerial photo of the chosen piece of urban fabric

0

100 m

evolution of a river drainage basin

59 infiltration 90%

intervention strategy pluviometric regime and climate rainfall ditribution throughout the year is quite homogeneous There is just one peak that can cause problems to the public sewer system

50% surface drainage

storage cisterns will be mediumsized due to rainfall frequency stormwater disposal will be as important as collection the only peak doesnâ&#x20AC;&#x2122;t differ too much from the average rate so that infiltration devices of proper dimensions will be sufficient to help the public sewer system

collection and storage 70%

temporary 50% retention

urban devices infiltration

urbanization soil has been exploited in every possible way: building on slopings which allowed it and terracing the steepest ones

the relationship between city and soil must change from mere exploitation to collaboration

unbuilt sites are unused and prey of erosion

unused and abandoned areas must have an active role within the city

the high density of the urban fabric allows to make the most out of common cisterns

it seems hard to find spaces large enough for cisterns installation (cisterns must be quite deep)

besides traditional stormwater management systems it will be necessary to adopt specific soil stabilization techniques

the configuration of the urban fabric make it a bit difficult to define neighbourhood units

orography and pedology highly permeable soil (easier infiltration) but at risk of erosion maintenance needed very changeable orography which allows a certain estimation of runoff dynamics

peculiar orography fixes limits to the dimensions of the devices and asks for site-specific solutions runoff management devices must work also to protect the physical integrity of the soil

infiltrations barriers

vegetated surfaces

artificial porous surfaces

surface drainage

open drainage network

subtile drainage network

collection and storage

private storage tanks

common cisterns

collection roofs

surface watersquare

floating cisterns

temporary retention

the subtile drainage network design will collaborate with natural orography deep watersquare

60 Pc 0 3 - c e n t r e

concept disposal open drainage

vegetated infiltration area

temporary retention area

watershed

surface design for draining water

neighbourhood unit

Soil composition would be perfect for stormwater infiltration but soil orography definitely not. There are no plain areas. It will be necessary to install transversal barriers along the hillsides, earthworks and â&#x20AC;&#x2DC;infiltration barsâ&#x20AC;&#x2122; in unbuilt slopings. In this way fast surface runoff, main cause of soil erosion, should be slowed down or stopped and stormwater infiltration encouraged.

To protect the physical integrity of the soil, trees should be planted. This issue provides the occasion to produce a water-sensitive urban landscape design.

We will have to pay attention to the distance between buildings and infiltration devices which can cause damages to the foundations.

Street section and pavements design is the basis of every kind of intervention.

collection single building roof designed to work as catchment surface neighbourhood unit

common storage (underground cistern)

pipes back and forth from the storage

Urban cisterns sizing depends on many factors: orogaphy limits, presence of voids in the urban fabric, neighbourhood units definition...

Anyway the great majority of buildings has flat roof which can easily become a proper catchment surface and the proximity of buildings make it possible to limit the extent of the network.

Watersquares do not provide temporary retention of runoff both not to subtract space to storage and because it seems no necessary.

61 project

transversal practicable dams

green plain infiltration areas

subtile drainage put into practice by neighbourhood units surfaces design roofings arrangement for stormwater collection earthworks soil arrangement with infiltration bars

watersquares with public facilities

aerial photo of the chosen piece of urban fabric with project insertion

0

100 m

62 Pc 0 3 - c e n t r e

plan with project insertion and sections of project samples scale 1: 4000

63 zooms scale 1: 1000 transversal practicable dams watersquare with public facilities

64 Pc 0 3 - c e n t r e

Permeable City 03 - Centre photo of 1:50 model cross section of the practicable dam top level, connection to the street

65

66 Pc 0 3 - c e n t r e

Technological details

b a

c

a

1 filling compacted terrain arranged during the placing of geosynthetics 2 HDPE geogrille 3 welded mesh disposable formwork 4 70 cm draining coarse aggregate volume

b

5 6 7 8 9 10 11 12 13

2 cm stone cladding 1,5 cm mortar 10 cm precast concrete cantilever steel bearing element 15 cm reinforced concrete retaining wall HDPE waterproofing membrane 20 cm reinforced concrete foundation 12 cm lean concrete HDPE tridimensional cell with terrain filling 50x50x2,5 cm meshing 14 30 cm gravel and sand vegetative base course 15 separation geotextile 16 draining layer

c

17 18 19 20 21 22 23 24 25 26 27 28 29 30

3 cm stone cladding 2 cm mortar 40 cm reinforced concrete retaining wall HDPE waterproofing membrane 10 cm diam. overflow 20 cm vegetative terrain separation geotextile 30 cm draining layer 10 cm diam. perforated plastic pipe foundation drain 50 cm reinforced concrete foundation 12 cm lean concrete HDPE waterproofing membrane 10 cm diam. perforated plastic pipe

67

b 13 14 15 16

c

17 18 19 20 21

22 23 24 25 26

27 28 29 30

a 1 2 3 4

5 6 7 8 9 10 11 12

68 pc04 - south

69

permeable city 04 south

preliminary studies intervention strategy concept project

70 pc04 - south

preliminary studies

pluviometric regime and climate

orography and pedology

where Southern part of Sardinia, Sicily and the extreme Southern regions of continental Italy

calcareous soil Coastal soils where the major cities of this area have grown are mainly composed of limestone, a sedimentary rock formed by the layered shells of dead microorganisms. There are no surface water bodies due to limestone high permeability.

when Rainfalls are concentrated in Winter (from December to March), long period of intense Summer water shortage how much 60 - 100 days/year (somewhere < 60) 350 - 920 mm/year annual average temperature 13 - 19 째C

groundwater salinization Drawing groundwater without any concern about recharge time has modified the balance between freshwater and salted water in the coastal areas. Salted water infiltrates to the inland speeding up desertification. areas suffering from soil salinization or overexploitation of water resources

urbanization beach, unused and almost abandoned even if very large streets, very large, with hypertrophic secondary spaces, messy and indefinite but homogeneously hard-paved so to enhance urban heat island effect open spaces, they are the remainings of the private spaces, fragmented but quite abundant to be re-configurated with drainage and infiltration features flat roof, almost every building has one, it make it easier to put into practice stormwater collection urban fabric, subdivided in almost regular blocks, it makes the definition of neighbourhood units easier

aerial photo of the chosen piece of urban fabric

0

100 m

71 infiltration 80%

intervention strategy pluviometric regime and climate rainfall ditribution requires big cisterns There is just one peak that can cause problems to the public sewer system

30% surface drainage

catchment surface must be as large as possible to feed very big cisterns assuming that public sewer system size wonâ&#x20AC;&#x2122;t be based on the only peak per year, medium temporary retention areas will be required

collection and storage 90%

temporary 60% retention

urban devices infiltration

urbanization absence of any relationship between city and seaside in spite of groundwater salinization and soil desertification there are no infiltration devices open spaces are homogeneously paved with asphalt which makes it impossible to use them in some other way the only stormwater management is by means of the public sewer system

orography and pedology highly permeable soil (easier infiltration) mainly plain orography to be dealt with in open surfaces design

restoring the cityâ&#x20AC;&#x2122;s specificity by reconstructing its relationship with the seaside space is lacking within the urban fabric, therefore stormwater management infrastructures must be as multi-task as possible The different surfaces of the open spaces must interact with the new system by means of different design features which make them active part of the urban landscape

soilâ&#x20AC;&#x2122;s composition grants good results for what concerns infiltration even with small areas (i.e. vegetated stripes along the streets)

infiltrations barriers

vegetated surfaces

artificial porous surfaces

surface drainage

open drainage network

subtile drainage network

collection and storage

private storage tanks

common cisterns

collection roofs

surface watersquare

floating cisterns

temporary retention

considering the high permeability of the soil it is better to put into practice on-site infiltration by means of porous pavements instead of draining water somewhere else to infiltrate deep watersquare

72 pc04 - south

concept disposal open drainage

vegetated infiltration area

temporary retention area

watershed

surface design for draining water

It is of outstanding importance that not collectable water undergoes on site infiltration because of the chronic problems of water shortage, of groundwater salinization and soil desertification.

Soilâ&#x20AC;&#x2122;s permeability is very good but there is no space for infiltration areas. Considering the plain orography of the area and the width of the streets it seems feasible to adopt a linear infiltration system for runoff generated on the streets.

Runoff generated on the impervious surfaces of the neighbourhood units can be temporarily retained in the upper level of the watersquares and then it can be led to the public sewer system and to cleansing plants.

neighbourhood unit

collection single building roof designed to work as catchment surface neighbourhood unit

common storage (underground cistern)

pipes back and forth from the storage

Considering contemporay and future water scarcity, large storage volumes will be required, a sort of artificial water table, in order to collect an amount of stormwater as large as possible during the rare storms.

The great majority of the big cities of this area are located on the coast. Their seaside, especially in the peripheral areas, is often abandoned. It seems useful to equip the waterfront of the cities with a system of watersquares. The seafront would become a multi-task axis which can be used and lived by people in many ways. Its surfaces, properly designed, would be the catchment areas of real urban cisterns located in the underground. This could be the first step towards an urban network of collected water.

73 project

â&#x20AC;&#x2DC;artificial water tableâ&#x20AC;&#x2122; common collection and storage design of the permeability of the surfaces within the neighbourhood units roofings arrangement for stormwater collection linear infiltration

watersquares with public facilities

aerial photo of the chosen piece of urban fabric with project insertion

0

100 m

74 pc04 - south

plan with project insertion and cross sections of the new waterfront scale 1: 4000

75 zooms scale 1: 1000 equipped waterfront sample cross sections

76 pc04 - south

Permeable City 04 - South photo of 1:50 model cross section of the equipped waterfront solution of the difference in level between the street (left) and the beach (right)

77

78 pc04 - south

Technological details

a

b

c

a

1 2 3 4 5 6 7 8 9 10 11 12 13

2,5 cm asphalt 8 cm aggregate bitumen-stabilized binder 8 cm aggregate levelling course 40 cm gravel base cours 20 cm stone kerb 15 cm lean concrete foundation metallic grille 40 cm diam. draining pipe overflow 12 cm lean concrete 40 cm vegetative terrain draining layer 20 cm diam. perforated plastic drainpipe

b

14 15 16 17 18 19 20 21 22 23

3 cm stone cladding seat structure, 8 cm precast concrete slab 12 cm cast concrete edging 12 cm lighting 30 cm reinforced impervious concrete retaining wall metal sheeting drain gully 3 cm stone paving 6 cm sand and cement bedding 30 cm reinforced concrete cistern covering HDPE waterproofing membrane

c

24 25 26 27 28

impermeabilized formwork joint 15 cm synthetic resin impermeabilizing joint 30 cm impermeable concrete slab with welded mesh 40 cm reinforced concrete foundation 12 cm lean concrete

79 a

b 14 15 5

16

6

17 18

1

7

2

8

11

3 4

9 10

12 13 19

20 21 22 23

24

25 26

27 28

c

Bibliography Wat e r C u l t u r e

Jain Kulbhushan, Udaipur – the city and its elements, Novrangpura, Ahmedabad 1977

H. Dreiseitl, D. Grau, New Waterscapes - Planning, Building and Designing with Water, Birkhauser, Basel, 2005

Cyril Mango, Architettura Bizantina, Electa, Milano 1974

H. Van Engen, D. Kampe, S. Tjallingii, Hydropolis - The role of water in urban planning Proceedings of the international Unesco - Ihp workshop, Backhuys Publisher, Leiden, 1995

Dario Matteoni, Pasquale Poccianti e l’acquedotto di Livorno, Laterza, Bari 1992 Naomi Okawa, Edo architecture: Katsura and Nikko, Weatherhill/Heibonsha, New York, Tokyo 1975 Pierantonio Pace, Gli acquedotti di Roma, Art Studio S.Eligio, Roma 1983

Wat e r t e c h n o l o g y Bruce K. Ferguson, Porous Pavements, Taylor & Francis, Boca Raton, 2005 Bruce K. Ferguson, Stormwater inflitration, Lewis Publishers, Boca Raton, 1994 E.R.Trevisiol, S.Parancola, L’acqua salvata – utilizzo integrato in una prospettiva biourbanistica, Monfalcone Edicom, 1997

Antimo Rocereto, I segni della memoria – Architetture dell’acqua, Clean Edizioni, Napoli 1996 R.Rosenzweig, E.Blackmar, The park and the people - a history of Central Park, Cornell University Press, Ithaca 1992 V. Serino, Siena e l’acqua – storia e immagini della città e delle sue fonti, Nuova Immagine Editrice, Siena 1998 L. F. Troyano, Terra sull’acqua – Atlante storico universale dei ponti, Flaccovio, Palermo 2006

best practices

John B. Ward-Perkins, Architettura Romana, Electa, Milano 1978

Marilia Albanese, Splendeurs de l’art Khmer, Editions Gründ, 2002 Giuseppe Anzani, Luoghi d’acqua – appunti per un’archetipologia dello spazio, Electa Napoli, 1999 Thomas Ashby, The Aqueducts of Ancient Rome, Clarendon Press, Oxford 1935 Edmund N. Bacon, D’Athènes à Brasila, Edita, Losanna 1967 L.Benevolo, B.Albrecht, Le origini dell’architettura, Laterza, Bari 2002

We b s i t e s

Kevin Bone, Waterworks – the architecture and engineering of the New York City water supply, The Monacelli Press, New York 2006 Ennio Concina, La città bizantina, Laterza, Bari 2003

www.auklandcity.govt.nz (Auckland city official website) www.carloratti.com (MIT researcher and architect)

Massimo Costantini, L’acqua di Venezia – l’approvvigionamento idrico della Serenissima, Arsenale Editrice, Venezia 1984

www.eea.europa.eu (European Environment Agency)

Dora P. Crouch, Water Management in Ancient Greek Cities, Oxford University Press, NY – Oxford 1993

www.ipcc.ch (Intergovernmental Panel for Climate Change)

N.I.Faruqui, Water Management in Islam, UN University Press, Tokyo 2000 R.Foffano, D.Lugato, Da Marghera a Forte Marghera, Multigraf Stampa, Venezia 1988

www.greencrossitalia.org (Green Cross Italian section) www.iwmi.cgiar.org (International Water Management Institute) www.legambiente.eu (Italian ONG for the protection of the environment) www.lid-stormwater.net (Low Impact Development technologies)

F. Fusaro, Il parlamento e la nuova capitale a Dacca di Louis I. Kahn, Officina Edizioni, Roma 1985

www.minambiente.it (Italian Minister for the Environment)

S.Held, C.Jacques, Angkor: Visions de palais divins, Hermé, Parigi 1997

www.spree2011.de (project for the revitalization of river Spree in Berlin)

F.Hooimeijer, H.Meyer, A.Nienhuis, Atlas of Dutch Water Cities, Sun, Amsterdam 2005 Michael Hough, Cities and natural process, Routledge, Londra 1995

www.protezionecivile.it

(Italian public rescue force)

www.trinkwasser.ch (Swiss water supply) www.watercare.co.nz (Auckland city water supply) www.waterconserve.org (world portal for the protection of water resources)

Marco Gazzola marcogazzola.ve@gmail.com