The living polders- East rural area of suzhou in YRD

Living WEITIAN

Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

Hongxia Pu MaUSP Master of Urbanisam and Strategic Planing EMU European Master of Urbanism Faculty of Engineering Science and Department of Architecture

Living WEITIAN

ACKNOWLEGEMENTS

Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

Foremost, I would like to express my deep appreciation to my thesis promoter Kelly Shannon and copromoter Paola Viganò and Qingyi Zhang, for the inspiring insights, constructive critiques, patient guidance, and encouragements. Without your valuable guidance and comments, this thesis would not exist.

Hongxia Pu Thesis submitted to obtain degree of European Master of Urbanism [EMU] / Master of Urbanism and Strategic Planning [MaUSP] Promotor Kelly Shannon Co-promotor Paola Viganò Qingyi Zhang

I am grateful to Professor Bruno De Meulder, Christian Nolf, Paola Pellegrini, Alvise Pagnacco, both for their time and contribution to the thesis research.

I would like to thank all my colleagues in KU Leuven, IUAV, from which I have learned a lot during the last two years. In particular, I would like to express my appreciation to my studio teammate Marlies Aerts, Bindi Raditya Purnama, Maria Skordouli, Katerina Eleftheriou, Rayan Al-Gareeb, Maher Nimer Mohammed Alabed for the valuable and dense discussion.

I would like to thank my teammate and best friends Yuying Sun and Yuxi Wu, for the inspiring teamwork and encouragements. I would also like to thank my friend Zhijian Yang for the helpful data processing.

Above all, my gratitude goes to my parents and my family for their love and support.

Thesis Reader Bruno De Meulder(KU Leuven) Paola Viganò(IUAV) Alvise Pagnacco(IUAV) Christian Nolf(XJTLU) Jianxiang He(O-office) Gregory Bracken(TU Delft) © Copyright by K.U.Leuven Without written permission of the promoters and the authors, it is forbidden to reproduce or adapt in any form or by any means any part of this publication.

Requests for obtaining the right to reproduce or utilize parts of this publication should be addressed to K.U.Leuven, Faculty of Engineering- Kasteelpark Arenberg1.B3001 Heverlee(België). Tel:+32-16-32 13 50& Fax.+32 -16-32 19 88.

A written permission of the promotor is also required to use the methods, products, schematics and programs described in this work for industrial or commercial use, and for submitting this publication in scientific contests. All images in this booklet are, unless credit are given, made or drawn by authors.

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Table of Contents

00 Abstract& Design Methodology

02 Climate change threats in YRD

03 Lakes and Ponds Systems(50km x 50km Square)

05 Zooms

2.1 Climate Change in Yangtze River Delta

3.1 Framework (Systems of Lakes and Ponds)

2.2 Predominance of Water in the Delta

5.1 New Protection System in a Polder Unit-Garden Communities 5.2 New Seasonal Water Reservoir

3.2 Landscape Structure

01 Atlas-Reading the Territory

2.3 Engineered Water Systems

3.3 Flooding and Water Pollution

1.1 Yangtze River Delta -Taihu Basin

2.4 Flooding in Yangtze River Delta 2.4.1 Three big conflicts in terms of flood control

3.4 Design the Hinterland as a Sponge System

1.2 Historical Evolution of the Delta 1.3 Socio-economic Shifts in the Delta

04 Testing the Research Through Design: Luzhi Watertwon

06 Bibliography

4.1 Historical layers in luzhi 4.2 Existing structures 4.3 Design

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Abstract This project delves into questions in relation to the recent intensification of flooding extremes and massive urbanization in rural polder landscapes. People can easily claim that the Yangtze river delta(Taihu lake basin) is geomorphologically lower than the sea inducing the frequent flooding, therefore leading the ecological complexity and human conflicts. However, since Tang and Song dynasty(618-1279AD), the highly developed natural and engineered flood control system on the delta scale and the extremely intelligent water conservancy project have enabled the entire region not only to successfully manage floods, but also in turn have made these fertile water resources as its advantages and cruciality of urban development and the prosperity of rice-based food industry. At the same time, it also formed water cities in which fabricated the traditional gardens centering around the water landscapes such as Suzhou gardens.

However, the very causes from which frequent flooding and intensified conflicts take over are over-exploiting activities and inappropriate urban expansion which destroy the water and forest ecologies. Since the end of the 1980s, many large cities such as Suzhou and Shanghai have adopted the method of super dikes encircling the city to protect the city, but to flood the rural villages as compensations. The expenses and quantity of work are unprecedented than the natural river drainage projects. However, with the industrialization and urbanization of rural areas, many villages have been built higher dikes (from5-year flood to 20-year flood) in order to protect their enterprises and populations. This increase flood water levels provoking intensified contradiction between villages and cities.

At the same time, the climate change uncertainty, which causes the change of rainfall pattern, sea level rise, and temperature rise result in severe flooding problems in YRD.

THE LIVING POLDERS Post-graduate Design Thesis Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta Hongxia Pu

The thesis intervenes within the massively industrialized and urbanized water town along Suzhou Creek in the periphery, where floods occur most frequently. It explores the approaches responding to the intensified flooding as a way to re-sew new emerging urban landscapes with the unique rural polder landscapes and re-integrate the vernacular strategies to fabricate waterscapes and typologies of traditional Chinese gardens to meet the increasing populations and housing demand in the developing rural area.

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“The city is a fact in nature, like a cave, a run of mackerel or an ant-heap. But it is also a conscious work of art, and it holds within its communal framework many simpler and more personal forms of art. Mind takes form in the city; and in turn, urban forms condition mind.�

-"The Culture of Cities". Book by Lewis Mumford. Introduction, 1938.

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Design Methodology

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01 Atlas：Reading the Territory

Suzhou Creek

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Yangtze River Delta -Taihu Basin General Introduction The Yangtze River Delta is a stable delta landform formed since the Holocene 10,000 years. After 10,000 years, it extended more than 200 kilometers to the east, forming the current form(Yang,Belkin, Zhao. 2003). From a larger spatial scale, the sediments deposited by the Yangtze River have a wider range of sediments. The thickness of the main delta near the estuary is 40-60 m, and the coverage of the sediments of the Yangtze River is hundreds of kilometers to the east. The north and the Yellow River sediments form a mixed sedimentary zone.(Liu.2007) Taihu Lake experienced a coastal plain landscape cut by gullies and evolved into a lagoon. Later, due to changes of its inlets and outlets, the lagoon evolved into Taihu Lake. The Taihu Lake Basin is located on the south side of the lower reaches of the Yangtze River. The whole terrain is high in the west and low in the east. The Danyang-XiangyangYixing-Huzhou-Hangzhou line divides it into two parts: the plain and the mountainous hills. The Taihu Lake Basin has been the most important economies since the Tang and Song Dynasties due to its highly developed water system and market system.

[Fig.01-1]Historical map of Yangtze River Delta-1920 Source: Whangpoo Conservancy Borad.[1920].Earth Sciences and Mpa Library.University of California, Berkeley)

14 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

[Fig.01-2] Coastal sedimentary accretion at the Yangtze River Delta

[Fig.01-3] The formation of Yangtze River Delta Source: Yang,(2003).Estuarine coastal and shelf science.

Source: Seavitt(2013). Yangtze River Delta Project

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The Kangxi emperor's tour of Jiangnan in 1699.

The water as a main infrastructure connects market towns. Villages are located on the higher ground of a polder linking by bridges. 《Imperial Inspection Tour to the South》

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Depicting the bustling urban life of Suzhou by Xuyang, 1759.

The agricultures are in the lower area of a polder. The dikes around the polder are not only as protections but also as social, public spaces. 《Prosperous Suzhou 》

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Historical Layers Timeline

Source1: Edit by author based on Nolf.

C.(2017).NSFC research report.

Source2: Fei, X.T(1939) 2.Image of weitian：Zhang.T.(1742)

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Historical Layers Tang Dynasty(618-907)

[Fig.01-5] The water system in YRD in Tang dynasty Source:Edit by author based on Wang, Jiange. (2019).

The west of Taihu plain is located at the lower east side which has contributed to the pattern of overflowing from the lowlands to the highlands and then into the sea. It made the Jiangnan area become an ideal rice farming area. There are no similar streams in China and other large river basins in the world. Most rivers flow from high to low, and the area of rice that is benefited is limited to the floodplain of the main river. The overflow area of ancient Jiangnan covered the Suzhou, Hangzhou, Huzhou, Yangzhou area, which became the important economies in China. In the lowfield areas, it is necessary to build a dike to prevent flooding. Otherwise, agricultural production is not guaranteed. The Tangpu polder was created and cooperated with the lake embankment and seawall project to form a complete water conservancy system.

The Tangpu polder consists of the lowland agricultural area and highland agricultural a r e a . T h e Ta i h u L a k e e f f l u e n t e n t e r s t h e lowland polder(weitian) network, and lowland polder(weitian) drains water into the Suzhou Creek which forms a complete irrigation and drainage system. At that time, Tangpu polders were quite large, reaching between 8.6 and 17.2 km2. It is called the Danwei ancient system. Fan Zhongyan discussed in the article " Jiangnan's West Water Conservancy" that "there are old fields in the south of the Yangtze River. Each side has dozens of miles, such as in the big city, there are river channels in the middle, and there are gates outside.�(Fan, Z.Y.,1020) He directly compares the Tangpu polder with the city.

[Fig.01-4] The polder landscape in Tang dynasty Source:Edit by author based on You,Z. (2011). China Economic history report.

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Water

Water towns

Agriculture in lowlands

Changing shoreline

The grand canal

Agriculture in highlands

[Fig.01-6] The polder city in Luzhi in Tang dynasty Source: Figure by author

Luzhi, as one of the most important water towns, is also in a large polder(weitian) city of about 13.4km2.

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Historical Layers Song Dynasty(960-1279AD)

[Fig.01-8] The water system in YRD in Song dynasty Source: Figure by author

For the transportation of the Grand Canal, the Northern Song Dynasty repaired the Wujiang Long Bridge at the Taihu Lake outlet. The main drainage river in Tang dynasty-Suzhou Creek was silted up by the construction. The slowing down of the water at the key points and the strengthening of the siltation have caused a global change. After the water environment was destroyed, the highlands benefited from the high water level, while the lowlands were destroyed by the flood. The lowlands benefited from the low water level, while the highlands were destroyed by the drought. Moreover, due to changes in the land system, the contradiction between large and medium-sized polders, irrigation and drainage, maintenance and management was intensified. In the Taihu basin, the large-scale system of Tangpu was gradually disintegrated, and the thousands of acres of large ancient polders were mostly divided into small polders bounded by Weibin. The Bin ( ćłž ) as the core of small polders were formed. .

[Fig.01-9] The separated small polder in Luzhi in Song dynasty [Fig.01-7] The polder landscape in Song dynasty Source1: Edit by author based on Nolf.C.(2017).NSFC research report

Water Changing shoreline

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Devlopment of water towns

Source: Figure by author

Smaller-scale polders

The grand canal

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historical layers 50s

Historical Layers 1950s

After 1949, the polders were massively united to have efficient engineered flood management. A mechanized drainage system has been established in the polder, and a large number of drainage rivers have become inland rivers. However, after the union of polders, the Jiangnan water towns were unified and standardized and the water flow was straight and fast. Floods and droughts have been greatly weakened, but the flow of living water has also been greatly reduced.

[Fig.01-11] The water system in YRD in 1950s Source: Figure by author

Especially afterW the formation of the Wangyu canal and the Taipu canal, the difficulty of drainage in Taihu Lake has been greatly reduced.

The successful drainage of the two rivers changed the dynamics of the water flow. In early Taihu Lake, the water is not directly discharged into the Yangtze River. It flows southward through Suzhou Creek into the Yangcheng Lake and other areas. In addition, after the 50s, the great investment into township industry and modern agriculture was massive.

The rivers and fields after the union are not like the overflowing hydrological ecologies in traditional times. When the flood or precipitation exceeds the normal situation, electromechanical pumping can drain the water quickly, and the river is often dry and stagnant. It is different from the ancient times, whereas the irrigation and drainage were based on the natural flow.

[Fig.01-12] The united super polder in Luzhi in 1950s Source: Figure by author

[Fig.01-10] The polder landscape in 1950 Source1: Edit by author based on Nolf.C.(2017).NSFC research report

Water The construction Taipu river and wangyu river

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Urbanization United super polders

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Socio-economic Shifts in the Delta Timeline

[Fig.01-13] Social-economic shifts in Yangtze River Delta Source1: Wan. X.D.(2008).SUN YAT-SEN UNIVERSITY

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02 Climate Change Threats in Yangtze River Delta

Suzhou Creek

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Climate Change Threats in Yangtze River Delta

The climate change in general which cause the change of rainfall patterns, sea level rises and temperature rises (the linear annual temperature increase rate of the Yangtze River Delta region is 0.6°C/10 years(Chaolin,2011)) result in severe flooding problems in YRD. In the meantime, the increased impervious area reduces the storage capacity of water and resilience to the water fluctuation.

Secondly, the lowering water table and risk of salinization with sea level also cause a lack of water in the drought period.

[Fig.02-2] Water pollution Source: Edit by author based on Taihu Basin &Southeast River Water source Bulletin

[Fig.02-1] Climate change threats in Yangtze River Source1: Edit by author based on Nolf.C.(2017).NSFC research report

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[Fig.02-3] Flood risk Source: Edit by author based on Chen, W.(2012) Research and preliminary practical exploration of landuse zoning and spatial governance of river basin.

[Fig.02-4] Urban heat island

[Fig.02-5] Land subsidence

Source: Edit by author based on Chen, W.(2012) Research and preliminary practical exploration of landuse zoning and spatial governance of river basin.

Source: Edit by author based on Liu.(2013). Regional land subsidence simulation in Su-Xi-Chang area and Shanghai city, China.

Thirdly, the severe pollution of water (mainly from industry and agriculture) and the dead-end water result from the fragmentation and covering of the infrastructure. First and foremost, the polluted and unstable water system results in the ecological degradation and diminution of coastal sedimentation ecosystem.

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Predominance of Water Water Network Density Comparison& 4 Main Water Systems The Taihu Lake Basin with an area of 36,500km is characterized by a dense river network, containing numerous lakes. The area of water reaches 6,134km and the water surface rate is 17%, in which the canals and a lake each occupying half. There are 189 lakes with an area of 0.5km. The total length of the river channel is 12×10km, and the river channel density in the plain area is 3.2km/km.(Lu, Dong.2009) As can be seen in the comparison of two deltas, the water network is much denser than in Rhine-Meuse-Scheldt Delta.

[Fig.02-6] Water network density in Yangtze river delta

[Fig.02-8] The Taihu lake system

[Fig.02-10]The the hudang‘ 湖荡 ’system（lakes and ponds）

Source: Edit by author based on Openstreetmap data

Edit by Lamberts,M.(2019) based on Openstreetmap data

[Fig.02-7] Water network density in Rhine-Meuse-sceldt Delta

[Fig.02-9] The Grand canal system

[Fig.02-11]The Grid system

Edit by Avella,R.(2019) based on Openstreetmap data

Edit by Lamberts,M.(2019) based on Openstreetmap data

Source: Edit by author based on Openstreetmap data

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Edit by Lamberts,M.(2019) based on Openstreetmap data

There are four types of water bodies in one water system. The Taihu lake, the hudang‘ 湖 荡 ’system （lakes and ponds）, the grand canal system and the grid system.

The Taihu lake is the fundamental role to provide the drinking water for Suzhou and for shanghai.

The the hudang‘ 湖荡 ’system（lakes and ponds） consists of the large lakes, small ponds and villages that are punctuating the territory of suzhou. this is incredible asset for the metropolitan area.

The grand canal is the important structure for whole of China. In the part of Suzhou is mainly companied by industrial areas. Comparing to the 15yeas changes, there are massive investment in infrastructures in industrial areas.

The grid system is mainly in the ancient Suzhou which has been constructed on this mesh of waters and canals but also the modern city is constructed at the same type of mesh which is superposed with the road system.

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[Fig.02-12] Raining season: high water level in TaiLake( high water in dark grey) Edit by author based on Zhang.Q.Y(2019) water city report.

[Fig.02-14] Raining season: high water level in Yangtze river( high water in dark grey) Edit by author based on Zhang.Q.Y(2019) water city report.

Water as a Machine Natural&Engineered Water Systems

[Fig.02-13] Raining season: high water level in TaiLake( high water in dark grey)

[Fig.02-15] Raining season: high water level in Yangtze river( high water in dark grey)

Edit by author based on Nolf.C.(2017).NSFC research report

Edit by author based on Nolf.C.(2017).NSFC research report

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Conflicts in Flood Control Existing Conditions The construction of united super polders in Suzhou was carried out under the condition that the governance of Taihu Lake Basin was long-term stranded, and regional flood control governance was separated from river basin governance. It was not until the big flood in Taihu Lake in 1991 that the governance reached a consensus. However, the construction of super polders was a foregone conclusion, while the first round of the Taihu lake plan focused on the union of polders project, and did not put forward an overall requirement for how the construction of the super polders should adapt to the rivers basin and canal system management. The construction can only continuously improve the ability of flood control on the original model. The higher the levee is, the stronger the drainage capacity, and thus the weaker the capability of its natural river drainage systems is.

The conflicts between urban and rural flood control: Since the end of the 1980s, the towns in the lower reaches of Taihu Lake have suffered from floods. Therefore, flood control projects have been built in most cities since the late 1980s. For example, Wujiang urban area and Jiaxing urban area have adopted the method of super dikes encircling the city, especially the area of Jiaxing, nearly 100 square kilometers area was protected by the big encircled dikes. The expenses and quantity of work are unprecedented than the natural river drainage projects. In large cities such as Suzhou and Shanghai, the cost of reducing the threat of flooding is often overwhelmed by farmland and villages that are of no value.

However, with the industrialization and urbanization of rural areas, many villages have been building higher dikes(from5-year flood to 20-year flood) in order to protect their enterprises and populations. This increases water flood levels, which has intensified the contradiction between villages and cities.

Conflicts between united super polders and natural polders: As more and more super polders are united and built, the water level in the river is gradually increasing, and the duration of flood is prolonged. In the case of heavy rains, many polders are bound to be broken, causing extreme floods. On the other hand, a large amount of urbanization has led to a reduction in the internal water storage capacity. In the past 20 years, the water surfaces in urban area has been reduced by about 10%(Lu. Dong. 2009). The paddy fields and low-lying lands in the city have become rigid roads, urban areas and factories, which have weakened the storage capacity of rainwater. According to the research, the water layer in the paddy fields is maintained at nearly 10 cm. In the case of heavy rain, it can reach 15 cm. The calculation of 1 million hectares of paddy field in Suzhou can store 280 million m3(Chaolin, 2011).

Image from Gao, Y.H, 2-1

Adaptation vs. Mitigation: Flooding projects in most cities are now dominated by pumps and gates. Every year, the energy used for flood discharge in Suzhou is enormous. Although it solves the problem of urban flood control well, whether it affects the overall efficiency of the natural river systems and whether it will aggravate the surrounding flood disasters is worth further exploration. Meanwhile, the projects of adaptation and resilience are very rare.

[Fig.02-16] Extreme flood in Jiangxi Province.

Image from Gao.Y.H.2017. Flood in Jiangxi province

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United Weitian Vs. Smaller Weitian

The Conflicts Between Urban and Rural Flood Control

As more and more super polders are united and built, the water level in the river is getting higher and higher. The research shows that under the condition of the same daily rainfall, the water level of the outlying river increases with the water surface rate decreases. When the standard is 20year flood, the water level of 1.0% water surface is 4cm higher than of the water surface rate of 1. 7%.

Under the condition of the same outflow rate and daily rainfall, the water level of the river is raised with the increase of the polder area. The maximum occurs at a water surface rate of 1.0%, the water level of the river with a polder area of 100% is 13 cm higher than the water level of the river with a polder area of 20%. (Xu.2009)

Large cities such as Suzhou and Shanghai have adopted the method of super dikes encircling the city to protect the city. However, the cost of reducing the threat of flooding is often overwhelmed by farmland and villages that are of no value. However, recently, with the industrialization and urbanization of rural areas, many villages have been building higher dikes (from 5-year flood to 20-year flood).

The research shows that under the same outer water surface rate and daily rainfall, when the standard of flood control in a single polder is raised, the water level of the outlying river increases. The maximum occurs at a water surface rate of 1. 0%. The 20-year flood standard of a single polder is 4 cm higher than the 5-year flood standard(Xu, J.Y.2009). This increased flood water levels, which has intensified the contradiction between villages and cities.

[Fig.02-17] Diagram of the flood protection in urban and rural area

[Figure 02-18] Map of polders and rivers before the union of polders in Linjiacao Village, Suzhou.

Source: Wang, J.G.(2019).Peking university.

Before

Before

Soure: Figure by author

Before

[Figure 02-19] Map of Polders and rivers after the union of polders in Linjiacao Village, Suzhou.

Source: Wang, J.G.(2019).Peking university.

Now

Before Now Now Now

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Flooding

Adaptation vs. Mitigation Flood Control

High Risk of Flood in The Central Hinterland(Hudang system)

At present, climate change response strategies are divided into two aspects: mitigation and adaptation. The focuses of two strategies are on direct reduction of climate change incentives and long-term defense against climate hazards respectively. As one of the carriers of climate change strategies, cities have a more concise political system and a more flexible response to climate change measures than the broader global and national political levels.

Floods in the Yangtze River Delta region are mainly caused by long-term and high-intensity rain. In addition, because it is located in the alluvial plain of the Yangtze River Delta, the surrounding areas are higher, the central part is the lowest comprised with the richest lakes and ponds(as can be seen in the flooding map). And the river discharge is affected by the tidal water which caused the flooding lasted for a long time. Therefore, once a large-scale and high-intensity precipitation occurs, this phenomenon is likely to cause flooding.

I n te r m s o f f l o o d co n t ro l, t h e m i t i g a t i o n emphasizes control of the flood by engineering methods such as flood gate (as barrier and barrage systems), flood defense (rock revetments) etc.

But adaptation focus on the long-term natural management of floods and the way people live with nature and water. The strategies can be the wetland parks, flood storage systems, green roofs, and bio-swales.

Flood control projects in most cities in China are now dominated by pumps and gates. Every year, the energy used for flood discharge in Suzhou is enormous. There are 3,467 water gates and 1,941 drainage stations in Suzhou. Due to the low engineering standards and long-term operation, the project has been out of service, and the efficiency of the installation is low. Nearly 40% of the pumping station installation efficiency below the provincial and ministerial standards which casued severe energy waste. In the latest urban planning, Suzhou plans to build 87 new gates with a length of 138.99km. Although it solves the problem of urban flood control well, whether it affects the overall efficiency of the natural river systems and whether it will aggravate the surrounding flood disasters is worth further exploration. The projects of adaptation and resilience are very rare..

On the other hand, the rapid development of urbanization induced increasing precipitation in urbanized areas. In the urban-rural transition zone, the existing flood control and drainage capacity are relatively low. In addition, as the birthplace of China's township and village enterprises, the rural industries in the delta are mostly developed.

A large number of surfaces are transformed into impervious surfaces. The reduction of water bodies such as rivers and lakes decreases the water storage capacities and increases the total water volume in peak time which causes a serious flood in the developing rural area.

[Fig.02-20] Diagram of the mitigation and adaptation Soure: Sustainability&CRS insights(2013).

[Fig.02-23] 100-year Flood prediction in Yantze River Delta Source: Figure by author based on Openstreetmap.

[Fig.02-24] Flood frequency in Yantze River Delta [Fig.02-21] Diagram of the mitigation approach of flood control [Fig.02-22] Diagram of the adaptation approach of flood control Source:Baca Architects（2014）

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Source:Baca Architects（2014）

Source:Xu, Mao(2002). Lake Tai Water History Editing Group.

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03 Hudang' 湖荡 'System(Lakes and Ponds) 50km x 50km

Suzhou Creek

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Framework(50km x 50km) Hudang‘ 湖荡 ’ System(Lakes and Ponds )

The Hudang‘ 湖 荡 ’system(lakes and ponds) consists of the large lakes, small ponds and villages that are punctuating the territory of Suzhou. It is a natural storage reservoir in extreme flooding events. Suzhou's natural wetlands account for 31.66% of the total area of Suzhou. There are three major categories of natural wetland resources in Suzhou, namely, marsh wetland (7.02%), lakes and ponds wetland (69.89%), and riverine wetland (23.09%). (Zhang, Zhu.2016) According to the distribution, there are three types: Taihu Lakeside wetlands in the west, riverine wetlands in the north(along Yangtze river) and the Hudang wetlands in the south and east area (around Yangcheng lake and Suzhou Creek which is in the 50x50km square). Historically, large lakes and small ponds have been formed due to the lowest position between the Taihu Lake and the coastal highlands.

Water

However, the surrounding areas of Hudang(lakes and ponds) are generally dominated by villages and towns. With the rapid development of the rural economy, the surrounding land is heavily invaded by urban development and monoculture farming. The activities of fish/shrimp farming of the lakes and ponds greatly reduced the lake surfaces making the water storage capacity drastically decline. At the same time heavily polluted the lakes and ponds caused irreversible damages on soil and subsoil. In addition, the over-exploitation of wetlands has changed the wetland ecosystem, narrowing and endangering the living space of aquatic animals and plants, reduce productivity.

Villages Fish/shrimp ponds [Fig.03-1] The hudang‘ 湖荡 ’system（lakes and ponds）

46 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

Water in Hudang area

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 47

Hudang Culture' 湖荡 文化 ' (Lakes and Ponds )

Landscape Structure Disruption of Ecologies(Infrastructure)

Existing Conditions

The Hudang wetlands in the south and east area (around Yangcheng lake and suzhou creek which is in the 50x50km square). Historically, large lakes and small ponds have been formed due to the lowest position between the Taihu Lake and the coastal highlands.

The water culture here is different from the lake culture in the Taihu Lake Basin, the Yangtze River Basin culture in the north, and the Grand Canal culture. Since ancient times, people had to live with lakes and ponds and built villages above the reeds.

[Fig.03-6] Disruption of Ecologies(Infrastructure) Source: Photo by author

Suzhou creek Drinking water reservoir Suzhou creek

Taihu Lake

Lakes

Water in Hudang area East-west infrastructures

Drinking water reservoir Ponds

North-south water systems

[Fig.03-2] The hudang‘ 湖荡 ’system（lakes and ponds) in 50x50km

[Fig.03-3] The hudang‘ 湖荡 ’system（lakes and ponds) Source: Photo by author

[Fig.03-5] Disruption of Ecologies(Infrastructure)

[Fig.03-4] The historical map of hudang‘ 湖荡 ’system（lakes and ponds) Source: Painting of the Grand Canal to the Forbidden City in Beijing (17c)

48 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

In the past, Suzhou creek was the main connection between the Tai lake and the east sea. The extra water from Tai lake can be transported into the whole lower ground via north-west water system.

Now, the massive construction of the south-east infrastructures in order to connect Suzhou and Shanghai disrupted the ecology of the connected watersystem.

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 49

Landscape Structure

Landscape Structure

Forest & Wetland

Agriculture & Villages The surrounding areas of Hudang(lakes and ponds) are generally dominated by villages and towns. With the rapid development of rural economy, the surrounding land is heavily invaded by urban development and mono-culture farming.

The activities of fish/shrimp farming of the lakes and ponds greatly reduced the lake surfaces making the water storage capacity drastically decline. At the same time heavily polluted the lakes and ponds caused irreversible damages on soil and subsoil.

The forest and green land in the region are mainly along with the infrastructure. The system of the urban forest is disorganized and scattered, leading to the urban heat island effect in Suzhou metropolitan area. The wetlands are encroached and segregated tremendously by the urban expansion provoking the degradation of water ecologies. There are only fragments remained mainly along the lakes providing for drinking water

Drinking water reservoir Water in Hudang area

Taihu Lake Water in Hudang area

Wetlands

Fish/shrimp ponds

Forests

Agriculture [Fig.03-7] Map of Forest & Wetland

[Fig.03-11] Map of agriculture&villages

[Fig.03-8] Forest occupied by agriculture

[Fig.03-12] Agriculture land and shrimp ponds close to villages Source: Photo by author

[Fig.03-9] Diagram of linear forest

[Fig.03-10] Diagram of dispersed wetlands along lakes

Source: Photo by author

50 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

[Fig.03-13] Diagram of Lakes encroached by urban development, shrimp farming and agriculture

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 51

Design the Hinterland as a Sponge System

Design the Hinterland as a Sponge System

Strategy1- Suzhou Creek as a Main Connection to Re-bind the Water Systems

Strategy2- Increasing Water Surfaces&Purification

Suzhou Creek has been the main river channel draining the water from Taihu Lake to the East sea since 600A.D. It is also an important river channel connecting Yangcheng Lake in the north and the lakes and ponds in the south. The Taihu Lake effluent enters the lowland polder network, and the lowland polder network drains into the Suzhou Creek. The pattern of overflowing from the lowlands to the highlands is connected and discharged by the Suzhou Creek. It made the Jiangnan area become an ideal rice farming area which covers an enormous part of the area. There are no similar streams in China and other large river basins in the world. Most rivers flow from high to low, and the area of rice that is benefited is limited to the river basin.

In Hudang area, the lakes and ponds system was crucial for absorbing floods from Taihu lake until the colonization of water surfaces by industrial agriculture and shrimp farming. Therefore, it is necessary to properly return the fields to the lake to create porous and permeable territories that allows water to move in the ways that it moves in the hydrological cycle. The increasing small lakes act as sponges that soak up water before a flood occurs.

The strategy is not only to contain the water at the origin but also to purify and infiltrate the rainwater by different qualities of wetlands before it goes into the water bodies.

Th e re fo re, t h e S u z h o u Cre e k a s t h e m a i n co n n e c t i o n n e e d s to b e re s to re d a n d re naturalized. The reconnection of the north-west axis of waterways which are currently fragmented and disrupted by the south-east infrastructures increases the water capacity. And redistributing the extra water into the surrounding lowlands which can revitalize the characteristics of the water towns and irrigate the surrounding paddy fields especially when it is dry season.

Suzhou creek Exiting drinking water reservoir New drinking water reservoir Lakes with protected wetland Enlarging water surfaces Sponges with wetland park [Fig.03-14] Map of Re-binding the Water Systems

Ponds Lakes

[Fig.03-15] Map of sponge and wetland systems Before

North-south water connections Suzhou creek Now

52 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 53

Design the Hinterland as a Sponge System

Design the Hinterland as a Sponge System

Strategy3- Separating the Super Polders and Preserving the Smaller Polders

Integrating All Strategies as One System

Since the 50s, the polders have been massively united to have efficient engineered flood management. The rivers and fields after the union are not like the overflowing hydrological ecologies as in ancient times. When the flood or precipitation exceeds the normal situation, electromechanical pumping will drain the water quickly which leads no water circulation in the territory.

The Hudang (lakes and ponds) system and water ecologies are recently suffering from development pressure due to the industrialization and mechanization of agriculture, causing the intensified flood frequency. The first strategy is to reconnect the lakes with the main river channelSuzhou Creek. by doing so, creating a connected water system and allowing water to flow in the ways that it flows in the hydrological cycle.

The second strategy is to enlarge the existing lakes meanwhile creating the smaller lakes inside each unit to contain the water at a local scale and increase the water storage capacity. The different qualities of wetland alongside the main rivers and lakes can purify the rainwater and in essence, provide people new landscapes and public spaces.

The last but not the least is to separating the existing super polders into smaller one in order to give more space for outer water to be connected and moved.

The three strategies related to resilient flood control attempt to re-integrate different water ecologies through linear waterways and cluster of polder landscape mosaic thus creating an interrelated and porous interfaces. .

Therefore, in the lowlands of Hudang area, the united super polders can be dismantled accordingly, and some independent smaller polders can be restored, and the dikes of each smaller polders can be raised. Since some of the traditional polders close to small lakes and traditional water conservancy facilities remain, the cultural heritage of this water conservancy and ecology should be preserved on a large scale and rebuilt on a large scale.

[Fig.03-16] Map of separating super polders

Suzhou creek

Suzhou creek

Separated polders

Existing drinking water reservoir

Exiting drinking water reservoir

North-south water connections

New drinking water reservoir

New drinking water reservoir

Separated polders

Lakes with protected wetland

Lakes

Enlarging water surfaces

Ponds

54 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

[Fig.03-17] Map of overall strategies

Next chapter will take one area(5x5km) located in - between suzhou creek and three big lakes as an example to further explore the design strategies.

Sponges with wetland park

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 55

04 Testing The Research Through Design: Luzhi Water Town

Suzhou Creek

56 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 57

[Fig04-1] Luzhi satellite map 2000

[Fig04-2] Luzhi satellite map 2018

Source: Google maps

Source: Google maps

58 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 59

Existing Conditions Massive Urbanization & Industrialization Luzhi is a historical water town surrounded by five large lakes and Suzhou Creek shaped its north boundary. Because of the blooming of township enterprises in YRD, Luzhi is also developed by rural industries and massive migration. Over the past 20 years(see in the satellite map), Unprecedented pace of urbanization and industrialization in Luzhi presents the drastically decline of agriculture and water surfaces and emerges vast monotonous gated communities and high energy-cost and water-cost polluted industries

[Fig.04-4] Monotonous gated communities Source: Photo by author

Famers house

Less polluted industries

Alsphat

Ditches

Elevated highway

Vegetables

Heavily polluted industries

Water systems Shrimp ponds Urban fabric

Road

Commercial building

Parking along the canal

Agriculture Land

Less polluted industries Canal polluted by industries

Dumpsites

Fenced waterfront

Agriculture [Fig.04-3] Existing vector map of Luzhi water town

60 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 61

Landscape Structure Influenced by the Massive Urbanization Drastically Decline of Agriculture Land & Water Pollution Since the 1980s, the township enterprises have been prospered, employing most of the local villagers, which caused the encroachment and abandonment of the agriculture land. The diagrams show that from 2000 till now, about 68% of agriculture has been transformed into industries and infrastructures that serve urban development.

Due to the increasing number of migrants and relocation of villagers, massive arable land is occupied by the growing monotonous gated communities which exacerbated the pressure of arable land. Meanwhile, the disordered expansion of unqualified industries has severely deteriorated water ecologies.

Polluted industries Normal industries Lightly polluted water

Water systems

polluted water

Agriculture [Fig.04-5] Map of agriculture land in 2000

[Fig.04-7] Map of Industires and infrastructures in 2000

[Fig.04-6] Map of agriculture land in 2018

[Fig.04-8] Map of Industires and infrastructures in 2000

62 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

Highly polluted water [Fig.04-9] Water pollution(mainly from indsturies and infrastructures, 2018

Water systems

Gated communities

Infrastructures

Water systems

Industries

Infrastructures [Fig.04-10] Map of gated communities 2000

[Fig.04-11] Map of gated communities 2018

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 63

Changing family structures

Urban Morphologies

Shifting from the Extended Family to the Nuclear Family

Agriculture Shrimp ponds Villages Canals

Disppearance of Villages

Villages

As Jiangnan Water Towns are close to the most developed metropolis such as Hangzhou, Shanghai and Suzhou, the urbanization has given a great impact on the Luzhi. The Jiangnan Water Town, known as the “Southern Jiangsu Development Model�, has experienced rapid economic development over the decades. Rapid industrialization has driven the rapid expansion of the township, resulting in the disorderly urban spatial structure. The township enterprises have undergone many changes in the use of agricultural land. The rural landscape has been replaced by the emerging disordered urban landscape. The landscape of traditional villages and farmland is separated by privatized green land, thus the losing regional landscape integrity.

The rural landscapes have become a fragmented island. The characteristics of Jiangnan water towns are gradually dying out.

Luzhi water town is also facing this dilemma of inconsistent urban strategies, heavy traffic and water town life eroded by modern industry. From the urban morphologies research on the right, it can be seen that the farmland surrounding most of the villages are occupied by factories and gated communities due to the cost of occupying farmland less than the cost of the village. The villages which have its unique rural polder landscapes have been or will be immediately encroached by factories or gated communities.

The villages are now being immensely demolished and spatial qualities of remained ones are in decline.

The intensification of industries and rapid process of urbanization (extension of road networks and buildings) and massive migration to Luzhi result in the large demands of new housing. At the same time, the family structures are shifting from extended family to nuclear family especially, in Luzhi, which has diverse income groups and customs of locals and migrants leading the increasing social conflicts.

Traditionl water-town

Agriculture [Fig.04-14]Relocated communities Gated communities [Fig.04-12] Traditional villages with polders

Industries

Villages

Gated communites

Agriculture [Fig.04-15]Villages surrounded by gated communities Villages

Before 18C Extended family with compound courtyard.

[Fig.04-16]Villages occupied by small industries in the peripherals

[Fig.04-13] Villages surrounded by Industries Industries

64 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

Agriculture Villages

50s After land reform and Hukou system, one generation live together.

Before 18C 50s [Fig.04-17] Diagram of Changing family structures in Luzhi Extended family with compound Land reform and Hukou system, courtyard. one generation live together.

80s After one-child policy , farmers migrate to cities for work

80s one-child policy , farmers migrate to cities for work .

90s Township enterprises booming, migrants came in.

90s Township enterprises booming, migrants came in.

2000s Villages are disappearing and gated community are massively built.

2000s Villages disappearing, development of gated community.

Changing family structures

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 65 Shifting from extended family to nuclear family

.

Research Questions

Agriculture Vs. Urbanization In Luzhi water town. about 735 hectares, 68% of the agriculture land is converted into built-up areas in 18 years.Traditional relations with agriculture has been dramatically changed. Which new morphological relationships can be designed between productive landscapes and peri-urban settlements in order to revalue the rich agriculture heritage and simultaneously create protective landscapes which can respond to climate change threats Flooding How can abandoned underlying water structures be integrated into the new emerging urban landscapes and reconnect to the ground water systems (rivers and lakes) in order to alleviate the increased flood risk

Conflicts between diverse social groups Which new urban typologies need to be redesigned to relate to the emerging family structures that are shifting from the extended to nuclear family and growing aging population—all which is increasing conflicts due to the diversity of income groups, and customs of locals and migrants

[Fig.04-18] Different waterfront qualities in Luzhi

Villages

Gardens

Canal

Polders

Ponds

[Fig.04-19] Section of the relations among villages, canals and agriculture lands

66 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 67

Scenario(5x5km) Strategy1- Linking The Water Systems& Increasing Water Surfaces

Luzhi water town located in the crucial connection between Suzhou creek and Cheng lake. The strategy first aims to revive the water systems in hierarchies and create more water surfaces to increase the flood resilience. Re-naturalizing the Suzhou creek and its tributary to bind to the new drinking water reservoir as well as giving more space to the water in other two tributaries on the east which anchor to the other two small ancient lakes named Wanqian lake and Yangmingtian lake.

[Fig.04-21] Diagram of re-naturalizing the triburary of Suzhou creek

[Fig.04-22] Diagram of creating lake and ponds system

Secondly, creating a new seasonal lake on the abandoned and polluted industrial quarters according to the 50x50km scale strategies in order to accomplish the regional sponge system. The smaller ponds inside each polder will not only increase the water resilience but also give citizens a new waterfront landscapes at local scale.

It is also crucial to bring back the small-scale canals covered by the infrastructures inside the polders to have a circular water flow. Above three strategies in relation to water attempts to have an independent and efficient flood control inside each protected polder.

Re-naturalized canals/ Suzhou creek New sponges Recovered canals The New seasonal lake Canals connected to other lakes Agriculture [Fig.04-20] Plan of linking the water systems& Increasing water surfaces [Fig.04-23] Diagram of re-covering the canals

68 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 69

Scenario(5x5km) Strategy2-Purification with Diversified Ecosystems

The water pollution mainly results from the disordered expansion of unqualified industries and inappropriate human activities such as dumping the domestic waste directly to the river, the chemical pollutants from agricultural activities.

The design proposes to have diversified functional wetlands in different conditions.

[Fig.04-25] Diagram of protected wetlands

Firstly, the protected wetland with less accessibility along the Cheng lake and Suzhou creek guarantee the water quality in the drinking water reservoir and main linking water channel.

Secondly, the wetland park are designed along the main water spines(tributaries of Suzhou creek) binding to three important lakes(Cheng lake, Wanqian lake and Yangmingtian lake). The public spaces close to the park can be reintegrated into the larger continuous public spaces.

[Fig.04-26] Diagram of wetland parks

Lastly, the waterfront in the periphery are mainly agriculture lands or shrimp ponds. The idea is to transformed these land into seasonal wetlands for birds and aquatic animals, which can be cultivated of rice for one season. The Mulberry trees on the dikes will contributes a circular ecologies(see in the section below)

Leaves

Mulberry

Wetland parks (more accessible) Protected wetlands (less accessible) Public spaces [Fig.04-24] Plan of purification systems

70 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

Seasonal agricultural wetland

Silkworm

Mulberry

Silkworm

Sluge as natural fertilizer Fish and shrimps

Mature

Mulberry

Shrimp and �ish

Organic(shell�ish,mussels)

Nutrient zone

Inorganic(seaweeds)

Silkworm

[Fig.04-27] Diagram of sesonal agricultural wetlands Sluge as natural fertilizer

[Fig.04-28] Section of mulberry- fish ecological pond

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 71

Scenario(5x5km) Strategy3- A New Flood Protection System The most urgent issue in Luzhi is the increasing flood frequency and intensity and the growing population.

[Fig.04-30] Diagram of new typologies as flood protection systems Existing

Proposal

Since the two large cities close to luzhi(Suzhou and Shanghai) have increased the flood protected metropolitan area due to its rapidly expansion of cities, it exacerbates the flood pressure in the drainage river channel which is the Suzhou creek.

After the completeness of the 200-year flood dikes protecting a lager urban areas, the water level in Suzhou creek will raise 40cm maximum in the extreme events. Meanwhile, the climate change inducing the sea level rise and changing rainfall patterns also result in the higher water level.

So the project is to strategically protect the existing landscapes in Luzhi by building new housings on the dikes at the boundary of polders. This strategy is based on thousands of years of Chinese wisdomWeitian(polder) system and Chinese gardens.

The existing houses on the dike will be protected by the new development on the raised ground.

The way to fabricate the new communities is to provide the same spatial qualities as the Suzhou gardens, which is the water as the central object surrounded by the encircle buildings to form a private courtyard. The central pond is connected to the outside water system which form a flowing landscapes.

Wetland parks (more accessible) Protected wetlands (less accessible) Public spaces Seasonal agricultural wetland Existing buildings New typologies [Fig.04-29] Plan of new flood protection systems

72 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 73

To kunshan

To Suzhou

Re-naturalized canals/ Suzhou creek

To Shanghai

New sponges

To Wujiang

Recovered canals The New seasonal lake Canals connected to other lakes Agriculture Wetland parks (more accessible)

[Fig.04-31] Plan of soft mobility and public transport system Soft mobility system Centralities

Planed Subway

Protected wetlands (less accessible) Public spaces Soft mobility system Water transports

Seasonal agricultural wetland

Centralities

Existing buildings

Downgraded roads

New typologies

Planned subway(2050)

74 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

[Fig.04-32] Overall plan

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 75

05 Zooms

Suzhou Creek

76 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 77

Zoom1-Comparing Suzhou Garden with One Polder Unit The scale of the small separated polder is larger than that of the Suzhou garden, but they are both water-based living space. Therefore, it is very necessary to learn the traditional Suzhou gardens for the way of fabricating the waterscapes, the spatial qualities and the architecture layout.

Suzhou gardens are generally centered on water, and the buildings are arranged around the water to form a private courtyard space. And the water flows through the interconnection of the creek and the lake, forming a flowing landscape.

In the selected polder, the lowest point in the middle has formed an open water surface, and the small-scale forest is still present. The edge of the polder has partially been encroached by the gated community.

0 [Fig.05-1] Learning from Traditional Chinese Gardens Source: Edit by author based on Peng,Y.G(1986). Xinhua Publishing House.

78 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

100

200

300

400 m

[Fig.05-2] Satellite map of zoom1 [Fig.05-3] Map of zoom1

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 79

Zoom1-New protection system in a polder unit New Garden Communities as the Continuous Protection System The design proposes to have new housing typologies on the existing dikes along the edge of the polder in order have a continuous protection system. The new ponds connecting o u te r r i ve r s a re c re ate d i n e a c h g a rd e n communities to increase the water storage capacity as well as a better living quality.

[Fig.05-5] Diagram of new typologies integrating with the existing villages

[Fig.05-6] Diagram of Forest and wetlands

New water landscape layer

Continuous protection system layer

A-A

Existing water and villages layer Agriculture New development on raised ground as new protections

New waterscape in the garden comunities also storage water

Trees along the each garden community

Existing forest

[Fig.05-4] Plan-New Garden Communities as the Continuous Protection System

80 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

[Fig.05-7] Diagram of the landscape structure 0

100m

200m

[Fig.05-9] Delayering the protecting system and landscape structure

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 81

SectionA-A Existing

SectionA-A Proposal

82 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 83

The window with a view

84 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 85

Zoom2- The Changing Islands New Wetland Park and Seasonal Water Reservior

The second zoom is along the tributary of Suzhou creek which connects Suzhou creek with Cheng lake. The polluting industries along the one side of the canal massively contaminate the water. The villages and agriculture on the other side with fragile dikes have high risks of flooding.

[Fig.05-11]Plan -The changing islands(normal condition)

SectionA-A Existing 0

100

200

300

Permanent flooded ponds

Buildings

Seasonal flooded ponds

Elevated path connecting islands

Only flooded when extremes happen

Floodable wetland park

Islands

400 m

SectionA-A Proposal

[Fig.05-10] Existing conditions of zoom2

86 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 87

Zoom2- The Changing Islands New Wetland Park and Seasonal Water Reservoir

The design proposes to create a floodable wetland park benefiting from its natural topography on the one side since it is a crucial connection between Suzhou creek and Cheng lake. And on the other side, transforming the most polluted industrial site into a seasonal flooded lake which the existing housing and new development can be the islands that connected by the elevated soft mobility system when it is the extreme events. The lake is also linking to the large sponge system and forming the porous interfaces on the territorial scale.

[Fig.05-12]Plan -The changing islands(rainy season) SectionB-B Existing

SectionA-A Rainy season

Buildings Elevated path connecting islands Floodable wetland park

SectionB-B Proposal SectionB-B Rainy season

88 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 89

[Fig.05-12]Plan -The changing islands(Extreme flood event) SectionA-A Extreme flood

Buildings Elevated path connecting islands Floodable wetland park

SectionB-B Extreme flood

The window with a view

90 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 91

06 Conclusion

Suzhou Creek

92 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 93

Conclusion As“the continual interaction of human settlements with the productive landscape for necessity and survival has evolved over the millennia into a complex system of balance.”[Shannon2004] This thesis explores the landscape potentials of Hudang‘ 湖 荡 ’(lake and ponds)system and polder landscapes as territorial water infrastructure to response to flooding extremes and massive urbanization and industrialization in rural area of Yangtze River delta.

ponds)in the hinterland, the covered water systems and the polder structure.Through this connectionincrementally transforming the Hudang area as a sponge system and porous territory.

At the polder scale, the united super polders will be separated into smaller ones. The new typologies surrounding each polder unit to meet the increasing housing demands will be the new protection system and continuous public spaces for a better living space.

Since the end of the 1950s, The over-exploiting activities and inappropriate urban expansion has destroyed the natural water ecologies in Yangtze River Delta, especially in Hudang area where it has the densest network of lakes and ponds. In many large cities such as Suzhou and Shanghai have adopted the method of super dikes encircling the city to protect the city, but to flood the rural villages as compensations. The expenses and quantity of work are unprecedented than the natural river drainage projects. However, with the industrialization and urbanization of rural areas, many villages have been built higher dikes (from5year flood to 20-year flood) in order to protect their enterprises and populations. These increase flood water levels provoking intensified contradiction between villages and cities.

The project developed in this thesis test the hypothesis that the intelligent polder water conservancy can be the opportunity for achieving better integration of urban development and ecological diversities as it was in ancient times.

A synergy can be constructed via revitalizing the connections between the water systems at the territorial scale and the Hudang system(lakes and

94 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 95

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[Fig.01-1]Whangpoo Conservancy Borad.[1920].Earth Sciences and Mpa Library.University of California, Berkeley)

[Fig.01-2] Seavitt(2013). Yangtze River Delta Project. Scenario journal [Fig.01-3] Yang,(2003). Delta response to decline in sediment supply from the Yangtze River: evidence of the recent four decades and expectations for the next half-century: Estuarine coastal and shelf science, v. 57, p. 689-699.

[Fig.01-4] Edit by author based on You,Z. (2011).

Development of the water network in the low-lying plains of the Song and Yuan Dynasties。China Economic history report.

[Fig.01-5] Edit by author based on Wang, Jiange. (2019). Historical Experience and Realistic Countermeasures of "Water Flows in the South of the Yangtze River".

[Fig.01-6] figure by author.

[Fig.01-7] Edit by author based on Nolf.C.(2017).NSFC research report [Fig.01-8] Figure by author [Fig.01-9] Figure by author [Fig.01-10] Edit by author based on Nolf.C.(2017).NSFC research report [Fig.01-11] Figure by author [Fig.01-12] Figure by author [Fig.01-13 ]Wan. X.D.(2008). Comparison between Migrant Workers in Pearl River Delta and Yangtze River Delta.SUN YAT-SEN UNIVERSITY [Fig.02-1] Edit by author based on Nolf.C.(2017).NSFC research report.

[Fig.02-2] Edit by author based on Taihu Basin &Southeast River Water source Bulletin [Fig.02-3] Edit by author based on Chen，W.(2012) Research and preliminary practical exploration of landuse zoning and spatial governance of river basin.

[Fig.02-4] Edit Edit by author based on Chen，W.(2012) Research and preliminary practical exploration of landuse zoning and spatial governance of river basin.

[Fig.02-5] Edit by author based on Liu.(2013). Regional land subsidence simulation in Su-Xi-Chang area and Shanghai city, China.

[Fig.02-6] Edit by author based on Openstreetmap data [Fig.02-7] Edit by author based on Openstreetmap data [Fig.02-8] Edit by Lamberts,M.(2019) based on Openstreetmap data [Fig.02-9] Edit by Avella,R.(2019) based on Openstreetmap data [Fig.02-10] Edit by Lamberts,M.(2019) based on Openstreetmap data [Fig.02-11] Edit by Lamberts,M.(2019) based on Openstreetmap data [Fig.02-12] Edit by author based on Zhang.Q.Y(2019) water city report.

[Fig.02-13] Edit by author based on Nolf.C.(2017).NSFC research report.

[Fig.02-14] Edit by author based on Zhang.Q.Y(2019) water city report.

[Fig.02-15] Edit by author based on Nolf.C.(2017).NSFC research report.

[Fig.02-16] Image from Gao.Y.H.2017. Flood in Jiangxi province Retrive from https://www.google.com/search?q=%E6%B1%9F%E8%A5%BF%E6%B4%AA %E6%B0%B4&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi0vqKbhfniAhXJ JlAKHTLnDHgQ_AUIECgB&biw=1536&bih=674#imgrc=0jGshJoC420G2M:

96 LIVING POLDERS-Luzhi Water Town, Polder Area East of Suzhou, Yangtze River Delta

[Fig.02-17] Figure by author [Figure 02-18] Wang, J.G.(2019).Peking university.

[Figure 02-19] Wang, J.G.(2019).Peking university.

[Fig.02-20] Sustainability&CRS insights(2013).

[Fig.02-21] Baca Architects2014) [Fig.02-22] Baca Architects(2014) [Fig.02-24] Xu, Mao(2002). Lake Tai Water History Editing Group.

[Fig.02-23] Figure by author based on Google maps.

[Fig.03-3] Photo by author.May,1.

[Fig.03-4] Painting of the Grand Canal to the Forbidden City in Beijing (17c) [Fig.05-1] Edit by author based on Peng,Y.G(1986). The analysis of traditional Chinese gardens. Xinhua Publishing House.

KU LEUVEN - EMU Graduation Thesis- Hongxia Pu 97