The Green Heart of Groningen by Maryam Rastegar Pouyani

The Green Heart of Groningen Regeneration of Groningen’s Peat Landscape With a Focus on Water Management and Agriculture School of Architecture Urban Planning Construction Engineering Politecnico di Milano Author: Maryam Rastegar Pouyani Student M.Sc. Landscape Architecture - Landscape Heritage Supervisor: Antonio Emilio Alvise Longo Professor Landscape Architecture Academic Year: 2020 - 2022 Defence: 04/05/2023

ABSTRACT The traditional land use that has established and evolved for roughly a thousand years on Dutch peat soil, is not simply a way of exploiting the land, but a way of living and a cultural identity. The peat culture, or the lifestyle of the farmer, as the intangible heritage is deeply invested in this tradition as is the physical manifestation and tangible heriatge of polder landscapes. It is challenging to replace an unsustainable practice with a sustainable one when the former is ingrained with cultural tradition and physically established over vast stretches of land in a country. This thesis questions whether a new relationship between man and his cultural landscape can be defined that is not only sustainable, but above sustainable: reganarative. A relationship that respects and pays tribute to the thousand-year-old tangible heritage of polder landscape and utilizes it to remediate and bring back what is lost; which is the peat soil. It investigates whether this new relationship can be manifested in a design strategy, in which history and soil have the main influence in shaping it. Another important influencing factor is the scarcity and preciousness of land in the Netherlands, that imposes limitations but also provides interesting opportunities for innovation and creativity.

Table of contents Introduction Context Problem statement Research questions Methodology Literature study Historic maps GIS mapping Site visits Sketching Photogrphs

The basics What is peat? Terrestrialization process Importance and management Ecosystem services Main threats Restoration

A sea of land

02 03 04 04 05 05 05 05 05 05 05 06 07 07 08 08 08 08

The polder-boezem system Draining the land The boezem system The polder landscape

10 11 11 12

A new productive landscape

A regenerative approach Paludiculture Ecosystem services

14 15 15

About the site Site location The landscape palimpsest Polder structure of the site

16 17 18 20

The design Design goals and challenges The goals General challenges Context specific challenges Design concepts Salinity shield Productive defence layers Understanding the landscape Defining project perimeters Large-scale programming The landscape masterplan Design features Nutrient removal Hydrology Water storage examples Landscape sections The adjustable dams Widening of the ditches Water nutritional profiles The double ditch system Natural succession A detailed frame of the landscape The landscape perception

21 22 22 22 22 23 23 23 24 27 29 30 31 31 35 36 38 38 38 38 39 40 41 42

Conclusion

References

INTRODUCTION The Netherlands was once home to vast areas of peatlands. Initially, these wetlands were considered dangerous and mysterious places to be avoided, but perceptions changed as people began to explore, exploit, and settle on them. For thousands of years, peatlands have been an integral part of the Dutch cultural landscape (Van Beek, 2019). However, the relationship between humans and peat has changed significantly over time. Today, Dutch peatlands are considered highly valuable, unique, and fragile landscapes facing increasing challenges for survival. This chapter briefly discusses the importance and relevance of peatlands and peat ecosystems. It also elaborates on the objective of this thesis and the methodology used.

Image 1. Image of a peat meadow landscape

CONTEXT Peatlands provide important ecosystem services, such as regulating water flows, providing fresh water, food, and essential resources for livelihoods, and are home to many plant and animal species, making them a critical source of life (IUCN UK Peatland Programme, n.d.). Despite covering only 3% of the global land surface, peatlands are the world’s largest carbon stock, storing more than twice the amount of carbon found in forests worldwide (About Peatlands | IUCN UK Peatland Programme, n.d.). This carbon storage capacity gives peatlands a vital role in mitigating and adapting to climate change.

Peatlands are classified into around 20 wetland categories in the Ramsar Conservation Classification System and host many specialized species, making them biodiversity hotspots. Peatlands are diverse and vary from paludified boreal forests and tropical peat swamps to spring mires and upland blanket bogs (Bonn et al., 2016).

heritage (Historic England, 2022). However, humans have turned these long-term carbon sinks into carbon sources in many places for an extended period. Only in recent years has the importance of peat been recognized, and considerable efforts have been made to restore and protect peatlands.

Moreover, peatlands serve as significant archaeological and paleo-environmental archives that hold records of past vegetation, climate, landscapes, and artefacts from previous human societies. As such, peatlands are living historic landscapes and part of our biocultural

Image 2. Cutting the turf; for centuries people made a living extracting peat from the soggy soil

Image 3. The extracted peat laid out to dry, the so-called “turf ” for burning as fuel

Image 4. Peat has been extracted fo centuries as an effort to reclaim the land for agriculture and settlements, and for burning as fuel

Image 5. Workers extracting the peat

PROBLEM STATEMENT

RESEARCH QUESTIONS

Peatlands have been an important part of Dutch cultural landscape for thousands of years. Peat was excavated as fuel for burning, and the peat soil was drained for agriculture. As a result, about 90% of the original raised bogs have disappeared due to exploitation for farming and peat extraction, and the remaining peatlands are threatened by climate change, agriculture, pollution, and urban expansion. The population of the Netherlands is highly concentrated in cities, which adds pressure to the rest of the landscape in terms of production and changing land use.

The traditional land use that has established and evolved for roughly a thousand years on Dutch peat soil, is not simply a way of exploiting the land, but a way of living and a cultural identity. The peat culture, or the lifestyle of the farmer, as the intangible heritage is deeply invested in this tradition as is the physical manifestation and tangible heriatge of polder landscapes.

Agriculture and dairy production are a significant part of the country’s economy, and the fertile peat soil is subject to intensive agricultural practices that continue to harm the peat. These practices have led to major environmental problems such as land subsidence, increased flood risk, release of CO2 in the atmosphere, and groundwater salinity. Tackling these issues is challenging, particularly in the context of a fast-changing climate. However, envisioning a gradual shift towards sustainable utilization of the immense carbon storage capacity of peat seems inevitable to preserve and restore peat as a cultural heritage landscape for future generations (Van Beek, 2019).

It is challenging to replace an unsustainable practice with a sustainable one when the former is ingrained with cultural tradition and physically established over vast stretches of land in a country. This thesis questions whether a new relationship between man and

his cultural landscape can be defined that is not only sustainable, but above sustainable: reganarative. A relationship that respects and pays tribute to the thousand-year-old tangible heritage of polder landscape and utilizes it to remediate and bring back what is lost; the peat. In this thesis, I investigate whether this new relationship can be manifested in a design strategy, in which history and soil have the main influence in shaping it. Another influencing factor is the scarcity and preciousness of land in the Netherlands, that imposes limitations but also provides interesting opportunities for innovation and creativity.

Image 6. The Borremose Man, one of several bog bodies found in and arround Borremose

Image 7. The perfectly preserved corpse of the Tollund Man from 4th century B.C. 04

METHODOLOGY

Literature Study

GIS Mapping

The first knowledge on peat soil and peat formation is obtained from previous academic courses, and the course materials are used in the first step of formulating the research questions. Afterwards, a focused literature study is conducted on the history of peat soil and land reclamations in the Netherlands, the environmental issues caused by peat oxidation in general and in the province of Groningen specifically, the current agricultural activities that are practiced on peat in Groningen, and what type of alternative agricultural practices on peat soil already exist. Several books are studied on the technical knowledge of the landscape such as polder landscape types, their history and formation, and the dike structures and typologies. Along with papers and books, some websites are also used as resources. A study on landscape design projects that deal with peatlands, agriculture on peat and peat restoration is also carried out. All the bibliography used in this thesis can be found in the resources section.

GIS analysis is conducted on the local scale to better understand the landscape typologies and soil types, agriculture lands and crops classification, urban sites and urban sprawl, main water bodies and nature reserves, land subsidence and flood risk, groundwater flow, and water defences. The acquired data is analysed and used to create maps that show the relationship between these factors and where the challenges and opportunities lie in the region.

Historic Maps An integral step in the process of formulating the research questions and also developing the design concept was the thorough study of the historic maps of the Netherlands and Groningen province. The oldest of these maps belong to the 18th century and clearly depict the polder structures, settlements and roads. A clear understanding of the landscape configurations was obtained through this analysis.

Site Visits A first-hand experience of the site was obtained through site visits. Spending some time in the area, sketching and photographing helped to deeper understand the area, its weaknesses and potentials. These sketches and photographs were frequently reviewed and analysed in the design process.

Sketching Various sketches were made in each step of this design journey. First were the analysis sketches that facilitated a deeper understanding of the landscape and its transformations. Some of these sketches helped with creation of the design concept. After that, several sketches of design ideas stacked on top of each other helped with developing the full-scale design, from landscape scale to the detailed scale.

Photographs Throughout this thesis, many photographs are presented to

convey and compliment the ideas information, ideas, and sentiment. As this project is interwoven with history, old photographs are chosen to deliver this historic influence. Aerial images are used as well because they clearly depict and introduce the landscape and the state of its existence.

THE BASICS The basis of every landscape is its soil. In a peat landscape such as the peat landscape of Groningen, peat is the foundation of the landscape and all the lives that it has sustained for generations. Therefore, it is essential to first understand the peat, to then understand how the landscape is formed - by nature and by man. This chapter focuses on the basic knowledge of peat, its formation, importance, and factors that threaten it.

Image 8. Sphagnum moss, a peat making plant

WHAT IS PEAT? Peat soil is composed of partially decomposed organic matter, primarily dead plants, under waterlogged conditions. Oxygen and nutrient deficiency, high acidity, and constant waterlogged conditions are necessary for the formation of peat (Bonn et al., 2016). The term “peatland” encompasses both the peat soil and the wetland habitats growing on the surface. Peatlands play a crucial role in mitigating flooding and drought, reducing the risk of fire, ensuring clean drinking water, and supporting astonishing biodiversity. In its natural state, peat serves as a major carbon sink due to the absence of a closed nutrient cycle under permanent waterlogged conditions. The remnants of dead plants and semi-decomposed organic matter aggregate as peat forms, locking away the carbon absorbed from the atmosphere by these plants (Bonn et al., 2016). Consequently, peatlands exhibit a unique capacity for longterm carbon sequestration. However, human activities such as extracting, burning, and draining peat transform it into a substantial carbon emitter, releasing the stored carbon into the atmosphere (Bonn et al., 2016). Drained peatlands, in fact, contribute to 5% of global anthropogenic greenhouse gas emissions. There is a growing global awareness towards the importance of peatlands and wetlands, leading to a trend in protecting and restoring these valuable ecosystems.

Terrestrialisation Process There are two types of peat: Fen peat and Moss peat (peat bog) that grow under different environmental

conditions. Fen peat feeds from surface water and groundwater that is relatively rich in nutrients (eutrophic), whereas peat Bog feeds from rainwater that is nutrient poor and highly acidic (oligotrophic). Peat forms through a form of succession called terrestrialization, which means the infilling of water by plants. In the terrestrialization process, the system goes from a relatively nutrient-rich environment with low pH to a nutrient-poor environment with a higher pH, which hosts specialized species. Fen peat develops in the early stages (reed, sedge, woody peat) and is replaced by moss peat in the final phase of this succession once the influence of rainwater dominates over surface and groundwater. Therefore, peat bogs are richer in carbon than fen peat (van Guldener et al., 2017). Peat bogs can regulate their own hydrology and are called ecosystem engineers. They act like sponges and can retain water from cell level to plant level and all the way to the ecosystem level. The amount of retained water can be up to 30 to 40 times their own weight (Limpens, 2022). North Sea Tidal Area Enclosed Estuaries Inland Water Bodies Sand Dunes Sandy Soils River Landscape Peatland Sea Clay Hills Figure 2. Landscape types in the Netherlands 07

Figure 1. The five stages of terrestrialization

IMPORTANCE AND MANAGEMENT

Ecosystem Services

follows:

Peatlands are a source of life for many plants, animals, and people. They offer important ecosystem services such as: - regulating water flows - mitigation of flood and drought - reducing the risk of fire - providing freshwater and food - hosting an astonishing biodiversity

1. Constant drainage of the peat, mostly due to agriculture

Peatlands also provide many cultural services. They can be used for aesthetic and recreational purposes, tourism, educational opportunities, training and research (Kimmel & Mander, 2010).

Main Threats There are many factors that harm the peat and impede its recovery and growth. Among these factors, three have the strongest impact and are as

2. Nutrient overloading due to release of nutrients as a result of peat oxidation itself, inlet of river water, fertilization for agriculture, atmospheric nitrogen deposition. 3. Becoming too isolated as the consequence of urban growth and expanding farms

Restoration

restoration of the hydrology. It can be seen how the hydrology of the system is essential and intricately interwoven with the health and quality of the ecosystem. After restoration of the hydrology, the next step is to remove the excess nutrients in the system. This step can be particularly challenging in the given agricultural context with regular use of fertilizers on grasslands. The final step is to (re)connect the restored bog to the existing peat bog landscape (Limpens, 2022).

The graph on the right shows the relationship between the peat bogs’ state of degradation, biodiversity, and the effort and steps required for restoration (Limpens, 2022). According to this graph, the first step in the restoration process is

Figure 3. The state of degradation of a bog is directly linked to the time and effort needed for restoration. Dependning on the degradation state, various actions need to be done 08

A SEA OF LAND Today, Dutch peatlands are regarded as highly valuable, unique and fragile landscapes that face increasing challenges for survival. These polder landscapes of the Netherlands are characterised by vast, open stretches of grasslands and sustained economically through dairy farming. This spatially unique constructed landscape is an important aspect of the Dutch national identity. This chapter discusses the importance, history, and structure of the polder boezem system.

Image 9. The old Ducth windmills that used to pump the water from the polders into the Boezem system. Some of them are still in use today.

THE POLDER-BOEZEM SYSTEM The Dutch have developed an intricate system of draining the land and manually controlling the groundwater level over the centuries. In this system, the land is divided into “Polders.” A polder is an enclosed land with controlled water levels, in which the ratio between wet and dry can be decided by man (Bobbink, 2017). This land parcel is enclosed using dikes or other water defenses, and through the utilization of a range of water works such as pumping stations and weirs, the water level inside is set independently from the rest of the land.

Image 10. Vast grasslands for meat and dairy production are symbolic of the polder landscape

In the Netherlands, there are a total of 3891 polders. If not drained, most of them would fill up entirely with water, as they lie below Amsterdam Ordnance Datum (Normaal Amsterdam Peil, NAP), the reference level which corresponds approximately to the mean sea level. The traditional polders are the result of systemic reclamations that started from the 12th century onwards. People began draining the swamps (peat) into nearby rivers to create arable land for farming. As a result, the drained peat started to oxidize, and soil levels subsided first up to river water levels and then lower (Bobbink, 2017). In this regard, a polder landscape describes a landscape in which the natural force of gravity no longer drains the land, and humans intervene to do so. These polder landscapes of the Netherlands are characterized by vast, open stretches of grasslands on peat soil and are sustained economically through dairy farming. This spatially unique constructed landscape is an important aspect of the Dutch national identity.

Image 11. Aerial image showing part of a polder structure and the so-called “Ribbon Villages” the villages and settlements built on dikes along a polder - typical of the reclamation landscapes

Image 12. A historic aerial image of the Vriezenveen ribbon village and reclamation landscape 10

DRAINING THE LAND

The boezem system Farmers had to adapt to the inevitable subsidence and figure out how to keep sea and river water away. As a result, they invented a drainage system that transported the water through hundreds of drainage windmills - and later pumping stations - to rivers and then the sea (Bobbink, 2017). The boezem system is an intermediate step in the process of discharging water from a polder to outside of the system (main rivers or the sea). A network of watercourses isolated from the adjacent polder(s) by means of dikes and embankments

creates the boezem. This system is also separated from the primary water bodies through sluices and pumping stations. The boezem has the capacity to store and transport water. It is worth mentioning that the boezem not only discharges the excess water from polders to larger water bodies, but in drier times, it can release the water back into the polders (Bobbink, 2017). This feature becomes increasingly important in recent times. It serves as a tool to deal with droughts that happen more frequently and severely during drier seasons, as well as pushing back the seepage of brackish

water and sometimes flushing out the polder water to prevent salinization. The prominent feature of the polder-boezem system is that water has to be transported to a higher level and discharged outside the system by the boezem.

Figure 4. Diagram of the Noordoost Polder with technical and landscape architectonic water elements invoved in draining the polder (Bobbink, 2017) 11

THE POLDER LANDSCAPE With the advancement of technology and use of steam- and electric-powered pumping stations, larger areas of land could be drained. Therefore, younger polders are much larger, and usually the polder and its waterworks are designed together and are less improvised. As seen in the map on the right, the darker polders are the younger ones that cover larger surfaces, and are also deeper than the older ones. This increase in scale and depth is due to the increased capacity of modern pumping stations.

Natural landscape

Cultural phase 13th century

Cultural phase 17th century

Cultural phase 18th century

Cultural phase 19th century

Figure 5. The polder map of the Netherlands, showing the respective depth of the polders. Darker polders are deeper (Bobbink, 2017)

Figure 6. The transformation process of the Dutch landscape in five phases (Bobbink, 2017) 12

A NEW PRODUCTIVE LANDSCAPE Much of agricultural practices of today have been developed since the Mesopotamian era, where relatively dry soils are common. Cereals and grains such as wheat that are cultivated in this type of agriculture require dry soils. In places like the Netherlands, this means draining away the native swamps and bogs. This chapter focuses on the concept of regeneration in design approaches. It investigates an alternative agricultural practice that is more suitable for wet or rewetted peatlands called paludiculture.

Image 13. Peat polder grasslands in northern Netherlands for meat and dairy production

A REGENERATIVE APPROACH The main objective of this thesis, is to regenerate the peat landscape of Groningen. To understand what regeneration means, it is important to understand first what is meant by restoration. From an ecological design point of view, restoration does not mean restoring a system to its original condition. It means “restoring a subsystem (for example a wetland, a riparian, or a beach-dune ecosystem) so that it has the self-organising capability to evolve” (Reed, 2010). Accordingly, regeneration means “considering all dimensions of life and restoring them in parallel”. It means to obesrve how life wants to work, and work in that way (Reed, 2010).

The figure below shows how the green, sustainble, restorative and regenerative design approaches are related and where each of them stands in relation to living systems and energy, from an ecological design view. According to this graph, conventional and green designs are not involved with creation of living systems, rather they are concerned about efficiency. These two design approaches come usually at a greater cost and require more energy. A sustainable approach has neither a positive, nor a negative impact on life. On the other hand, restorative and regenerative designs strive to create living systems and therefore require less energy, and less initial

Figure 7. Trajectory of ecological design (Reed, 2010)

and operating costs, as living systems evolve on thier own (Reed, 2010). Therefore, to repair the harm that generations have created on peatlands, a sustainable apporaoch is not enough. First, a restorative design approach is needed to restore this unique landscape and its ecosystem. As the basis of every landscape is its soil, the peat soil should be restored. Then, in order to mitigate the impacts of climate change and cope with a growing population and their many needs, it is not sufficient to restore a certain state and stay there, but to utilize the many possibilities within this living system to meet the upcoming challenges. This is what a regenerative approach seeks to do (Reed, 2010).

PALUDICULTURE: A REGENERATIVE AGRICULTURE Paludiculture derives from the latin word “palus” meaning “swamp” or “marsh”, and is the productive use of wet or rewetted peatlands that preserves the peat body (A definition of paludiculture in the CAP, 2021). In traditional drainage-based agricutlure, the water table is lowered to the level of crop roots. This traditional practice is unsustainable because drainage is followed by soil degradation and subsidence, water pollution, loss of biodiversity and eventually, loss of the productive land. These issues can be avoided by increasing the water table. In this regard, paludiculture practices cultivation of flood tolerant species that not only preserve and restore peatlands, but also create an alternative revenue for farmers. It is interesting to note that paludiculture is not an entirely new concept, as it

also includes traditional activities such as reed mowing or collecting litter for bedding ( Joosten et al., 2016). As mentioned before, in paludiculture a closed nutrient cycle does not exist, meaning that the above-ground biomass is used, while the below-ground biomass (major part of the net primary production) remains for peat formation (Bonn et al., 2016).

Ecosystem Services Paludiculture enables a spaceefficient, multifunctional use of peatlands as this land type is becoming more scarce. It provides supporting services by preserving and restoring peatlands and therefore effectively takes part in climate mitigation. Paludiculture enables peatlands to provide provisoning

services, along with maintaining important regulating and cultural services ( Joosten et al., 2016). Some of the most important ecosystem services are as follows: - Reduction of GHG emissions - Water regulation - Promoting biodiversity - Preventing peatland fires - Opportunities for agriturism - Diverse revenue sources: food, fodder, fuel, raw material, medicine Among these services, water regulation is one of the key aspects of paludiculture. By creating a paludiculture buffer around an existing bog, the external hydrology can be restored, which is the first step in peat restoration process.

Image 14. Mechanical harvesting of reeds, a type of crop used in paludiculture

Image 15. A farmer harvesting the reeds, a type of crop used in paludiculture 15

ABOUT THE SITE This chapter discusses the site location, soil composition in the province of Groningen, land use and polder structure changes in the project area through time, and the state of current existing polders in the landscape. The research on historic maps on this chapter shows that polder structures are not fixed and solid structures through time, but they are subject to change an adaptation to respond to the needs of people through time.

Image 16. An old photo showing the peat meadow landscape. Image is from the Groningen City Archive.

SITE LOCATION The project site is situated in the peat landscape of Groningen province, in the area that stretches between the cities of Groningen and Delfzijl. This area is one of the last remnants of the peat landscape that used to cover much of the central and southern part of Groningen.

This zone is lowest in the landscape, with the deepest parts being as low as 3 meters below the sea level. Most of this remnant peat soil is designated as nature parks and reserves today. As shown in the map below, the soil composition of the province

Clay Sand Peat

Figure 8. Groningen’s location and soil composition 17

consists of northern clay deposits from the North Sea, sandy soil in the south and peat in the middle. Studying the historic maps of the region shows how its polder structures and agriculture have evolved through time.

1870

1850

1827

THE LANDSCAPE PALIMPSEST

1:250,000

N 18

1:250,000

2 0 1 5 - Nature Resrve formation 1976

1 8 7 3 - Creation of Eems Canal

POLDER STRUCUTRE OF THE SITE As polders form the main structures of this project, study of the polder structures, structure shifts, and the reasons behind these shifts is a central part of this research. The historic maps and archival documents show a gradual merge of the old, smaller polders to form bigger polders in recent times. This transformations are understandable in the shadow of technological advancements and industrialized agriculture, and show how the polders are subject to change and adaptation to the needs of people throughout time.

Image 17. Groningen’s polder map in 1872

Delfzijl

Groningen

Figure 9. Current polder structures in the area where the project site is located 20

THE DESIGN This chapter discusses the design process and steps, based on the research and knowledge acquired in the previous chapters. First the design goal is emphasized and the main challenges are underlined, followed by two main design concepts that address these challenges to achieve design’s goal. Next, a thorough landscape analysis is carried out to define the exact perimeters of the project boundaries. The design concepts are then translated into a large-scale spatial program for the landscape, fulfilling the third step of peat restoration, that is “connection”. Based on this program, a detailed and comprehensive landscape masterplan is designed that implements the second and first stages of peat restoration (nutrient removal and hydrology) simultaneously. In this landscape design, peat formation and economic productivity go hand in hand, while addressing the pressing issues of land subsidence and groundwater salinization in the province.

Image 18. A visualization of the “Cranberry Lakes” in the project masterplan

DESIGN GOALS AND CHALLENGES

The Goals

General Challenges

The design goal is to establish a new landscape system that first stops the cycle of peat loss and ultimately, regenerates the peat in a sustainable fashion - environmentally and economically.

The first challenge is land subsidence, a direct consequence of peat oxidation, that is caused by the constant drainage of grasslands and use of nutrients. The second challenge is the fragmentation

of peatlands, as more of them convert into farms or settlements, accelerating the rate of peat loss. These challenges are even more urgent in the context of Groningen, a land that is already below sea level and dominated by agriculture as the rest of the Netherlands.

Context-specific Challenges As a result of land subsidence and constant drainage, the freshwater threshold that defies saline seepage from the North Sea is becoming less and receding more towards inland. Conventional agriculture requires freshwater, and the increasing salinity is devastating to the products.

Figure 10. Subsidence as a result of peat oxidation, due to drainage and soil nutrient overload

Peatlands are natural buffers of freshwater, and keep the saline groundwater away. Therefore they have a crucial role in protecting the farmlands in the area. Figure 11. Fragmentation of the peat landscape contributes to increased peat oxidation and loss

Delfzijl

A Groningen

Hoogezand N

Figure 12. Saline seepage from the North Sea

Figure 13. Section A-A reveals how the freshwater contained in the preserved peat acts as a buffer to push the saline seepage away from the south 22

DESIGN CONCEPTS

Salinity Shield

Figure 14. This concept diagram shows how connecting and reinforcing the peatland fragments in the landscape creates a defensive shield against salinity (right illustration is design situation)

Productive Defence Layers North Sea

North Sea

Saline intrusion zone

Saline intrusion zone Water storages (water buffer) Paludiculture

Nature park

Nature protected zone

South Farms

Figure 15. This concept diagram shows how the productive defence layers protect southern farms from saline seepage (right illustration is design situation) 23

UNDERSTANDING THE LANDSCAPE Next step of the process is to carry out a landscape analysis to understand better how peat influences the elements and patterns of the landscape. This analysis helps to identify areas that are more prone to the effects of peat oxidation, areas that need to be protected, the

relationship between these landscape layers, and their implications on the design. The layers addressed are soil and settlements, height map, roads infrastructure, natural network, water network, and agriculture.

Delfzijl

Clay Peat Sand

Groningen

Settlements Water Bodies

Figure 16. Soil and settlements map. As shown in the map, settlements are avoided on peaty areas

Delfzijl

+8.0 m

Groningen

-3.0m Figure 17. Height map. Where peat is drained and oxidated, the land has subsided deeper 24

Delfzijl

Railroad Highway Regional Roads

Groningen

Local Roads Peat

Figure 18. Roads infrastructure map. Like the settlements, peat soil is not suitable for heavy road infrastructure

Delfzijl

Nature Network of the Netherlands Natura 2000 Area

Groningen

Settlements Water Bodies

Figure 19. Natural network map. Most of the nature areas belong to the peatlands

N 25

Delfzijl

Boezem

Groningen

Lakes Canals & Ditches

Figure 20. The water network map. This map shows the the main water bodies and drainage system

Delfzijl

Grassland

Groningen

Arable Land Water Bodies

Figure 21. The agricultural map. As shown in the map, most of the peat soil is used to grow grasslands for meat and dairy production

N 26

DEFINING PROJECT PERIMETERS As explained in previous chapters, polders constitute the main spatial structures for the design proposal. Therefore, to understand the exact perimeters of the project, the selected polders must be able to address the main issues and challenges of the

design. These challenges, as stated before, refer to preservation of peat, putting land subsidence to a halt, connecting and reinforcing peatland fragments to defy saline intrusion, while maintaining economic productivity of the landscape.

The current polder structure is put on top of relevant landscape layers to identify suitable regions for design implementation. Polders (whole or parts) that correspond to all layers or the layers which directly link to design aims, form the project boundaries.

Delfzijl

Groningen

Figure 22. Polder structure + peat soil. Highlighted polders indicate all the polders that contain peat

Delfzijl

Groningen

Figure 23. Polder structure + deepest areas. Highlighted polders indicate where addressing the issue of subsidence is more urgent 27

Delfzijl

Groningen

Figure 24. Polder structure + nature network. Highlighted polders indicate where peatland fragments need to be connected and reinforced

Delfzijl

Groningen

Figure 25. Polder structure + grassland agriculture. Highlighted polders indicate where grassland agriculture can be replaced with an alternative production that does not harm the peat

N 28

Delfzijl

Groningen

N Figure 26. The exact perimeters of the design project, based on current polder structures

Large-scale Programming Once the project perimeters are established, design concepts can be translated into a spatial program for the landscape. This large-scale spatial program ensures the effectiveness of the design in the broader landscape context, unifies the landscape structure, and provides guidelines for the detailed design of the landscape masterplan. The diagram on the right shows the productive buffer layers of water storage zone, paludiculture, and the new nature park, and how these layers connect to the peatlands south of Groningen, to reinforce the peat and form a salinity shield.

Restoration Stage 3: Connection

Productive Defense layers

Salinity Shield

Figure 27. The large-scale spatial program of the landscape that implements the design concepts 29

THE LANDSCAPE MASTERPLAN

LEGEND Paludiculture Type A: Cattails Family Paludiculture Type A: Cranberries Paludiculture Type B: Reeds, Sedges, Other Perennials Paludiculture Type C: Willow, Alder, Birch Trees New Nature Zone Protected Nature Area Water Bodies Water Storages

A detailed frame

Figure 28. The design masterplan. The different paludiculture types, water storages with varying nutritional profiles, the new nature zone, the wandering trails, and the existing nature park can be seen 30

1:90,000

DESIGN FEATURES

Nutrient Removal Nutrient removal is the second step in the process of peat restoration. In this project, nutrient removal, building up the peat soil, and economic productivity go hand in hand in the form of paludiculture. A set of paludiculture crops are cultivated sequentially. This new paludiculture system is allowed to follow its natural course from a nutrient rich to a nutrient poor environment, instead of fast methodes such as complete top soil removal that is harmful to the system. Depending on the depth of the polders, different types of paludiculture can be cultivated. The different paludiculture types provide a diverse palette of crops that replace the monoculture grassland. This diversification promotes the biodiversity and brings in flows of revenue from a variety of markets:

Figure 29. Some polders are deeper than others. An average depth is estimated for each polder

- building and construction (timber, insulation) - energy (biomass) - agriculture (haymaking) - medicine - horticulture (growing media) - research and education - agritourism and ecotourism

Nature Zone

Height not relevant for paludiculture

Deepest Areas

-2.50m to -2.20m, Paludiculture Type A

Middle Areas

-2.20m to -1.70m, Paludiculture Type B

Highest Areas

-1.70m to -1.00m, Paludiculture Type C

Figure 30. Depending on the average depth of the polders, different paludiculture types with varying rates of peat accumulation is associated with each polder 31

Figure 31. Stage 0, Current Situation

Present

2030

2040

2050

2060

2070

2080

pH Nutrients

Figure 32. Stage 1, Paludiculture Type A

Present

2030

2040

2050

2060

Establishment of the New Nature Zone

INITIATE Deepest areas

pH Nutrients

Raising groundwater level for Paludiculture Type A Cattails take out excessive nutrients from the soil Highest rate of peat accumulation

2070 2080

Figure 33. Stage 2, Paludiculture Type A

Present

2030

2040

2050

2060

2070

2080

Establishment of the New Nature Zone

CONTINUE Highest areas

pH Nutrients

Raising groundwater level for Paludiculture Type A Cattails take out excessive nutrients from the soil Highest rate of peat accumulation

Figure 34. Stage 3, Paludiculture Types A+B

2080

2030

2040

2050

2060

Establishment of the New Nature Zone

CONTINUE Middle areas

Present

pH Nutrients

Raising groundwater level for Paludiculture Type B Reeds stabilize a relatively nutrient-poor soil Moderate rate of peat accumulation

2070

Figure 35. Stage 4, Paludiculture Types A+B

Present

2030

2040

2050

2060

2070

2080

2070

2080

Establishment of the New Nature Zone

CONTINUE Highest areas

pH Nutrients

Raising groundwater level for Paludiculture Type B Reeds stabilize a relatively nutrient-poor soil Moderate rate of peat accumulation

Figure 36. Stage 5, Paludiculture Types A+B+C

Present

2030

2040

2050

2060

Establishment of the New Nature Zone

CONTINUE Highest areas

pH Nutrients

Raising groundwater level for Paludiculture Type C Willow, alder, and birch establish on nutrient-poor soil Slow rate of peat accumulation

Hydrology Restoring the hydrology is the first step in the process of peat restoration. The new hydrology system is isolated from the rest of the landscape and is an inherently different system that: - is supplied by several water storages, - with varying nutritional profiles

Nutrients pH

These water storages compose the first defence layer against saline intrusion, and support all the other layers. The water storages are established at the same time with paludiculture types to irrigate the crops with the required water source. In this regards, first the surface water storages and water networks are built to support the growing of cattails, then groundwater storages and water networks are built to support reeds and sedges, and finally rainwater storages and water networks are built to irrigate swamp forests and bog reserves.

Figure 37. Establishment of surface water storages and netwroks that feed cattails (paludiculture type A)

Nutrients pH

Figure 38. Establishment of groundwater storages and netwroks that feed reeds and sedges exclusively (paludiculture type B), and other paludicrops in part

Nutrients pH

Figure 38. Establishment of rain water storages and netwroks that feed swamp forests (paludiculture type C), other paludicrops and the new nature zone 35

Water Storage Examples The water storages can play a role in promoting nature, economic productivity, and innovative ideas. The figures below and on the next page show a few ways in which these

storages can become more than just a place to store water. For example, a rain water storage can be accompanied by a bioswale that can catch the surplus rain safely in heavier downpours, and be part of the nature. The groundwater storages

occupy larger surfaces because the need for them in paludiculture is greater. Due to the strong winds in this area, large water bodies may produce strong waves. One solution is to put smaller islands in the water to mitigate the waves and wind, and to host nature away from land.

Bioswale Storage Lake

Storage Tanks Peat Subsurface

Figure 39. Example of rain water storage with bioswale and storage tanks

Storage Lake

Small Nature Islands

Peat Subsurface

Figure 40. Example of groundwater storage with small nature islands to break waves and wind and host biodiversity away from threats in the land 36

The surface water storages can be used for making fisheries and promoting aquaculture production. Moreover, they can host housing and leisure activities. Housing on water is already being practiced and invested on in the Netherlands, as the housing demands are high and space is scarce.

Small Fisheries Aquaculture Plants

Sand/Clay Subsurface

Figure 41. Example of surface water storage used for fisheries and aquaculture for economic gain

Housing, Leisure, etc.

Storage Lake

Figure 42. Example of surface water storage used as medium for housing, leisure, etc.

Landscape Sections These sections show how different parts of the design are situated in the landscape and in relation with each other. For example, in the overall section it can be seen that cattails (paludicrops type A) are situated at the lowest level in the landscape - where soil subsidence has had the strongest impact. Cattails have the highest rate of peat accumulation and help building up the soil faster. Boezem

Reeds and sedges are paludicrops type B and are situated in the midlevel grounds and are occasionally flooded. The swamp forest composed of mainly willow, alder, and birch trees are paludicrops type C that sit on highest grounds inside the agricultural area, as they need relatively drier mediums for their roots to grow. The overal higest areas are designated as the new nature zone, where existing peat bogs are reserved and nature is allowed to

Canal

Village

maintain its natural succession. Also, it can be seen that roads and settlements sit on top of dikes to be protected from floods and always be accessible. The overal section at the bottom of the page shows how the saline groundwater is pushed back by the freshwater underneath project zone, as a result onot draining the water constantly and instead using crops that are suitable for wet mediums. Ditch

Dike

Grassland Pasture

Saline Seepage

Figure 43. Section A-A, existing situation (vertical heights are exagerated and not in scale)

The Adjustable Dams

Widening of the Ditches

Water Nutritional Profiles

The adjustable dams in the ditches allow controlled flooding of the land. The swamp forest trees flourish in a land that has water fluctuations - not always flooded or dry - and the dams are a means to control the desired water levels.

The regular ditches on current grasslands are widened and have a more dynamic shape, sometimes wide enough to create a small water pond, where certain species of willows can flourish better.

Different paludicrops need different nutritional profiles that are obtained from a variety of different water sources. In this diagram, the water sources required for cattail production is given as an example.

Adjustable Dams

Widened Ditch

Rainwater Storage (low nutrient profile) Ground water (medium nutrient profile) Surface water (high nutrient profile)

Boezem

Village Water Storage

Canal

Swamp Forest on higher grounds Grassland Pasture

Cattails immersed in water in lower grounds

Fresh Groundwater

Saline Seepage

Figure 44. Section A-A, design proposal (vertical heights are exagerated and not in scale) 38

Protected Nature Zone Grassland Pasture

Grassland Pasture

Fresh Groundwater

Saline Seepage

Figure 43. Section A-A, existing situation (vertical heights are exagerated and not in scale)

The Double Ditch System The protected peat meadow landscape is hydrologically buffered from the rest of the farm with a double ditch system. the inner ditch is basically a pond, with an impervious layer that retains the water in the pond, and acts as a retention basin.

1:10,000

When water surmounts the capacity of the pond, it is directed to the second ditch through pipes. This second ditch has an adjustable dam to drain water in winter and retain it in summer.

Bog Peat

Retention Pond 1st Ditch 2nd Ditch with adjustable dam

Protected Nature Zone Grassland Pasture

Reeds on ocasionally flooded land

Fresh Groundwater

Figure 44. Section A-A, design proposal (vertical heights are exagerated and not in scale) 39

1:10,000

Natural Succession The new nature zone reinforces the existing protected raised bog area and closes the gap between two main natural patches. This new zone focuses on restoring the peat ecosystem. However, unlike the existing protected area, it offers a diverse palette of habitats of the lowland and highland peat meadow.

This is a shifting, dynamic landscape in which sucession can be resetted and experienced in all its stages. It is a living labratory to be explored. Grazors (cows, sheep, and goats) are introduced from time to time to maintain this dynamic. Therefore, this land parcel maintains to some level its agricultural productivity.

Agriculture Agriculture

Lakes & Spontaneous Perennials

Wild Grassland

Lakes & Spontaneous Perennials (Lowlands)

Cattails

Lakes & Spontaneous Perennials

Reeds & Sedges Fen Peat Fen Peat

Wild Grassland (Highlands)

Swamp Forest

Wild Grassland

Cattails

Wild Meadow

Reeds & Sedges

Moss Peat

Grassland Pasture Parcel diversity: 1 Monoculture Monofunctional Flat

New Nature Zone Parcel diversity: 9 Diverse Patches Multi-functional Changing Topography

Figure 45. Natural succession in the new nature zone

Forest Patch

A DETAILED FRAME OF THE LANDSCAPE This map shows a detailed frame of the design masterplan. The water storages can be seen as the first defensive layer in the landscape. The larger ones are groundwater reservoirs that feed most paludicrops.

The darrk green area represents the swamp forests made of Alder, Willow, and Birch trees as paludiculture type c, that can be used for their timber. The creme-yellow areas represent Reed and Sedge areas

as paludicrops type B, and the bright green areas show Cattail areas that are paludicrop type a. The new nature zone is separated from paludiculture zone with a double-dike system all around its perimeter.

Figure 46. A detailed frame from the landscape masterplan LEGEND Cattails

Cranberries

Reeds and Sedges

Willow, Alder, Birch

New Nature Zone

Protected Nature Area

Water Storages

Wooden Wander Trails & Platforms

1:25,000

N 41

THE LANDSCAPE PERCEPTION These frames try to visualize the perception of this landscape from the perspectives of visitors. In the end, the goal has been to design a productive landscape that is part of nature itself, offering the same experience, spontaneity, and serenity that is associated with these lowlying peat meadows of the north.

This new mode of agriculture has a potential for agritourism and can attract many visitors and volunteers. This landscape is an ideal place for birdwatchers, photographers, and nature enthusiasts.

and adapt to a landscape that people and nature both can enjoy and thrive.

All of this diversity and dynamic is owed to the effort to restore peat,

Figure 47. Walking through the new nature zone, connected to the exisitng nature park

Figure 48. The wandering trails and platforms are important elements in experiencing this landscape

Figure 49. A farmer is harvesting the cranberries. The swamp forest trees can be seen on the horizon

Figure 50. A farmer is harvesting the reeds. This new agriculture holds potential for agritourism 42

CONCLUSION Peatland restoration in the context of Netherlands imposes several challenges. Intensive agricultural production takes place on the fertile peat soil in this country by draining the peat and lowering the groundwater level to a suitable level for crops. In fact, Netherlands is a major global exporter of agriculture and dairy products, and a considerable part of its economy depends on this production. A large portion of the land here is composed of peat soil that has formed through thousands of years. Nowadays, most of this peat soil has vanished; yet in part that it remains, an established land use that has developed through generations continues the cycle of harm on peat.

tackling environmental issues in the region and climate mitigation. The landscape history and soil had the main influence in shaping the design strategy. As Netherlands is a country where land is scarce and precious, a particular challenge in this proposal was to develop a design that makes room for nature by fully realizing the potential of a given land parcel and maintaining its economic productivity. Therefore, multi-functionality has replaced mono-functionality, and the complex relationship between these functions gave birth to creative spatial solutions.

The actors that covered vast areas of this land with peat are the same actors that alarmingly threat to flood the land and disrupt agricultural production and the conventional lifestyle on peat. Envisioning a more sustainable, innovative, and diverse utilization of this landscape is increasingly projected in efforts to restore and promise balanced living on the land. A gradual shif in the current unsustainable agricultural practices seems to be the inevitable prospect. Moreover, the unpredictability of droughts and peak discharges due to climate change means that a new water system needs to be developed for this landscape. In this regard, the aim of this design proposal has been to envision a more sustainable, innovative, and diverse utilization of the peat landscape in Groningen that focuses on peat regeneration as well as

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