基于基塘系統的珠江三角洲多尺度水敏設計研究

孫傳致 （荷）斯特芬·奈豪斯 （英）格雷戈里·布拉肯

珠江三角洲（簡稱珠三角）是世界上城市化最快的三角洲之一，具有潛力的同時也面臨著挑戰：如洪水風險增加、生態和社會價值的喪失等。珠三角位于中國東南沿海地區，西江、北江和東江是其主要的河流動脈，經歷了1 000多年的自然過程，如淤積和沉積[1]，珠三角形成了2個次級三角洲以及一個河口的地形地貌特點。由于土壤肥沃，珠三角長期以來一直非常適合農業生產。人類干預始于大約1 000年前，通過開發一種被稱為基塘系統的綜合水陸農業養殖模式[2]13，逐漸將珠三角轉變為中國最富裕的農業區之一。這種基于基塘所形成的獨特的景觀是水利、農業、生態、工業和居住聚落之間歷史悠久而錯綜復雜的關系的結果（圖1）。西江次級三角洲——順德區域，位于易發洪水的低地，在該地這種景觀清晰可見，是當地人們長達幾個世紀解決洪水和暴雨內澇問題、通過實踐取得的成果。然而，長時間的筑堤圍墾、硬化河道以及城市化所帶來的傳統基塘大量消失，不僅導致了蓄洪能力的喪失和洪水風險的增加，更威脅到了整個三角洲的水安全問題。為了解決這些問題，急需一種更具適應性的城市化戰略：一種以社會生態介入、更具水敏感性和包容性的多尺度方法[3]。為了總結這一方法，須重點研究傳統的區域特定水陸農業實踐以及歷史水管理方法，以便得出可以為當代空間發展戰略提供幫助的設計和規劃原則。

筆者通過對順德傳統基塘系統的分析，結合該地區多尺度的生態水利系統的歷史發展與進化，發掘隱藏在這一獨特景觀表象之下的豐富設計原則。由于這些原則是基于該地區悠久的歷史與獨特的水文、生態與人文社會結構總結而出，它們有極大的潛力成為未來適應性城市規劃和設計的工具。隨后，這些原則將以設計規劃實踐的形式被應用于改善當代的雨洪消納能力、修復河道生態以及重塑和凸顯城市的獨特文化個性。最后，本文筆者將討論該研究在珠三角其他地區應用的適應性與普遍性，以建立更廣泛的聯系。

1 綜合水陸農業養殖實踐

西江和北江之間的農業低地在雨季期間容易發生洪水，造成上游河流排水達到峰值。洪水主要發生在6—8月，往往雨洪同期發生，因此內部積水由于外江水位較高而無法排放到外河。這種自然的水文環境孕育了肥沃的土壤，從而形成一種特殊類型的水陸農業養殖模式——基塘系統，作為當地經濟生產的基礎（圖2、3）[2]30。

基塘系統發展于14世紀，由堤壩上種植的果樹及中心魚塘組成，是當地居民在易發洪水的自然條件下發明的一種獨特的農漁混合耕種模式。17世紀初，這一系統變成了桑樹與魚塘中四大家魚的組合，形成了絲綢綜合漁業的經濟模式。從那時起，這種農業水產養殖模式繼續繁榮發展，直到20世紀20年代達到頂峰。在此之后，全球絲綢市場的蕭條以及日本侵略極大地打擊了珠三角地區的生絲市場，絲綢價格急劇下跌，最終人們不得不尋求其他替代絲綢的基塘作物組合（香蕉、甘蔗）。基塘系統因其擁有能量和物質合理循環的優點而享譽世界，它不僅是一種自足且高效的土地利用方式，也體現了對該地區特殊地貌的有效利用（圖4）。人們利用從池塘中挖出來的塘泥來建造周圍的堤壩，并在堤壩上種植桑樹以養蠶，蛹以及吃剩的葉子和蠶糞是非常好的飼料，可以被回收以喂魚。塘中，魚吃剩的飼料與魚糞富含有機物，這些有機物被塘內微生物分解落到池塘底部增加了塘泥的肥力。最后，人們通過每年挖掘塘泥并將其堆回堤壩，又增加了土壤肥力從而為桑樹提供營養。然而，這個綜合系統直到1350年左右[4]66才被開發出來。隨著水利系統的發明，在古代河口周圍的河岸地區已經開始建設堤壩，以保護低于河岸低地的農業地區。由于其優良的抗洪能力和高產能力，這種土地利用方法集中在西江和北江之間易發洪水的低地。此后，基塘系統遍布珠三角，并成為綜合水利系統中重要元素之一。因此，我們需要了解整個系統才能正確理解這種特殊的農業水產養殖模式如何起到防洪的作用。

2 多尺度的水利系統

1 基塘景觀展示了水利、農業、生態、工業和居民點之間錯綜復雜的關系Dike-pond landscape showcasing the intricate relationships between water management, agriculture,ecology, industry, and settlements

珠三角歷史悠久，形成于6 000多年前，在當時，順德仍然是南海的一部分。到了宋代（960—1279年），三角洲中心的大部分由于沉積作用已逐漸形成。此時西江的分流加快了土地圍墾的速度，形成了順德西南的杏壇、均安等地[5]32。1450年，清代建立順德縣，以防止富農和貧困漁民之間由于稀缺土地資源而產生沖突。土地持續開墾導致漁民逐漸失去生存空間，而富農希望進一步加速開墾以獲利。因此，順德縣政府的成立平衡了這一矛盾，同時也保護了整個區域的農業免受洪水侵害，建立了各鄉各堡的合作原則。該地區的行政區劃以水利防洪為基礎，倡導包括40個縣和297個村的通力協作[6]。通過來自不同縣、村和部族人們的共同努力，保護河岸及其腹地免受洪水侵襲，這種以合作為導向的區劃體系幫助建立了跨區域、系統性的水利管理方法。該水利系統包含4個級別的防洪干預：區域、縣、村和建筑（圖5）。這4個尺度彼此之間有著密切的關系，并共同發展形成一個整體系統，起到防洪、促進居住區建立、發展農業生產和形成社會結構的作用。因此，理解不同的水管理原則以及它們如何通過這些尺度相互關聯非常重要。

2.1 區域尺度的水敏設計

區域規模包括40個縣，297個村莊。每個縣有20%～50%的邊界毗鄰西江或北江[5]24，每個縣的縣界都以平衡優勢與分攤泛洪風險為原則，即平衡沿河的生產和運輸利益，同時分擔水利措施建設以保護整個區域免受洪水的危險。幾個世紀以來，洪水一直是順德區的主要威脅。明清兩代（分別為1368—1644年和1644—1911年）平均每年記錄在冊的有3次洪水，不包括季風季節（4—9月）幾乎每月發生的小洪水。堤防建設一經發明便成為該地區防洪的主要措施之一。然而，由于缺乏技術和人力資源，當時的大型堤壩建設不僅需要縣或村內進行合作，而且需要長期的努力（圖6）[7]。

2 順德區：珠三角西江和北江之間的一個易發洪水的低地，擁有數百年的傳統，通過綜合農業水產養殖系統與水為生Shunde district: a flood prone lowland between the PRD’s Xijiang River and Beijiang River with a centuries’ old tradition of working with water via integrated agri-aquaculture systems

3 典型的帶有農舍的堤壩結構，2019年Typical dike-pond structure with farmhouses, 2019

從宋代開始一直到清代，區域堤防建設逐漸發展出了幾個防洪原則。在宋代近3個世紀中，人們在西、北、東江沿岸建造了大量的堤壩（共28個）[8]39，特別是在西江，桑園圍是當時最大的堤圍系統[4]32。堤防的主要功能是保護定居點免受河流洪水的影響，其主要原則如下[5]45：利用自然地形（使其成為堤壩的一部分，利用上游和下游之間的高度差進行排水）；2）保持堤圍與河流的足夠距離；3）在堤壩完成后，于其旁邊修建寺廟（紀念和作為未來治水、議會的場所）。

在元代（1271—1368年），舊堤壩的高度被增加并加固，包含11個縣的西江沿岸繼續新建堤防，最終形成34個新堤圍[8]13。然而，由于下游河口的延伸和淤積加劇了上游的洪水堵塞，施工往往集中在河流的上游岸線部分。同時，通過使用石制水閘和堤壩，施工技術也得到了改善。

明代人口與經濟的繁榮意味著這一時期堤防建設和土地圍墾達到了頂峰。人口和經濟空前繁榮，對土地的需求也劇烈增加，而同時人們發現堤防建設有利于促進自然淤積從而形成陸地，于是人們利用這種方法開始進行大規模的圍墾。歷朝歷代都主要采用線性堤防，在島嶼的西部和東部建造以防止洪水，但在明朝期間，由于開墾和淤積導致海水倒灌，人們不得不尋求新的堤圍修建方法。因此，修建原則從開口堤圍建設以防止河水泛濫，變成了封閉的堤防系統以防止海潮泛濫，例如明代初期通過在東南部增加堤壩而關閉了桑園圍[5]55。然而，這一系列的封閉式堤防結構加劇了腹地的洪水問題，特別是在強降雨無法有效排放時的季風季節。正是在此期間，基塘系統被發明出來，并且作為一種特殊的農業用地，通過吸納多余雨洪緩解這一內澇問題。

這種在明代末期出現的基塘系統一直繁榮發展到清代中期[8]36。農業的蓬勃發展鼓勵了更多的土地圍墾、堤防建設。然而，由于河道渠化導致河床空間大量減少，從而導致大型堤圍內的河流容易在雨季發生更嚴重的洪水。因此，人們開始在較大的堤壩內部建造小的堤圍以保護村莊免受內部洪水的影響，最終形成了嵌套的環狀布局。與此同時，為了防御來自外部河流的洪水，不同的堤壩被連接起來形成更大、更堅固和更安全的堤圍，并在其中建造水閘以控制排水。最終，形成了一個環環相套的整合式水利基礎設施，由一個大型的堤圍和內部較小的堤圍組成。反思通過漫長過程逐步建立的區域水利系統時，研究了解到以下關于水敏設計的原則：1）水利系統需要協同合作：防洪系統只有通過不同層級的政府機構（鄉—堡—都—圍）和學科團隊合作，并從區域角度共同規劃、設計和建設時才能卓有成效；2）在對當地水文的理解中，要認清每種水資源（例如海水、河水和雨水）都有各自隨時間的動態變化規律（例如，整個季節的排水量不斷變化），并且對于水利的方法有特定的要求；3）通過對當地水文的增量學習，當地人發現為雨水和洪水消納提供足夠的空間是非常重要的：通過引入天然水流和水體來為洪水提供更大的緩沖空間；在筑堤時需要和河流之間保持一定距離；利用自然地形建造堤防并分配布置排水（灌溉）的溝渠和運河。

2.2 縣（堡）尺度的水敏設計

區域范圍內的水利系統涉及外部洪水的管理與疏導，而縣（堡）尺度干預措施則側重于調節內部水患。“堡”這一行政區劃僅在順德區被發現使用，它是一個基本的治水單位，其防御的兩個主要威脅分別為洪水和海盜[9]。堡內的水利設施由3個部分組成，形成有效的系統：堤圍、水網和不同的連接通道（圖7），這3個要素密切相關。傳統的水利單位劃分可歸納為“外海、外堤、內河、海灣、運河、溝渠、排水系統”[10]。

4 桑基魚塘的循環系統Circular system of dike-fishponds

5 4種尺度的水利措施Scheme showing four scales of water management

堡尺度的水利系統包括汛期的排水和旱季的蓄水，與每日和每月的水量變化密切配合。例如，在汛期，沿著主要河道建造的大型堤壩將防止來自外部河流或海洋的洪水，而大雨引起的內部洪水可暫時存儲在內河、運河、小溪、海灣和基塘中。在退潮期間，當外部水位降低時，這些水可以通過排水孔從基塘排入溝渠與運河，然后流入內河、小溪中。最后，隨著外堤上水閘的打開，多余的洪水可以排入外河。在干旱季節，這個系統可以反過來用于儲存雨水以及農業灌溉。有了這個可以隨時調整的雙向系統，堡內的定居點和農業能夠積極地應對洪水和干旱。因此，該水利系統不僅能夠防洪，還能夠進行灌溉和運輸，為農業提供了灌溉用水和有機土壤，同時建立了便捷的交通。

基于以上理解，可以總結得出關于水敏設計的原則：1）通過建立龐大的供水網絡以緩沖和臨時儲存洪水：不同的水要素連接在一起形成一個網絡，為臨時儲存雨洪提供足夠的空間，并可以用于灌溉和排水；2）堡尺度水網的多層次結構可以通過不同水體之間的動態控制實現自適應性的雨洪管理，從而可以隨時調節水位，其中排水孔、溝渠、運河和水閘等調節系統都在整個系統中起著至關重要的作用；3）需要形成一個完整且多功能的水利系統：洪水防御、蓄水、農業和交通都被認為是系統的組成部分，為農業生產發展、定居點發展以及加強社會交往提供了條件。

2.3 村莊尺度的水敏設計

除了保護整個堡免受洪水侵襲的水利系統外，村莊也擁有與防洪相關的選址、布局和建筑技術原則。這些原則不僅有助于降低洪水風險，而且形成了與水為生和以水為鄰的特殊范式，并側重于不同地理條件下的村莊布局，蓄水和排水方法以及社會結構等方面。首先，本文確定了兩種主要的村莊類型，其名稱來自其地理條件：依山村落和平原村落。

依山村落通常垂直于等高線布置，以利用高低差地形進行排水和集水（圖8）。此外，垂直排布于建筑之間的排水通道，被稱為“冷巷”，促進通過空氣壓力差而進行的冷暖空間循環。這個原則產生了“梳式”布局[11]，其中主要的排水渠通過小巷中的溝渠連接垂直于它們布置的房屋，有助于快速排水。這些排水通道有時也與公共建筑物（如寺廟、學院和學校）前面的池塘相連，稱為“風水”池塘。該類池塘不僅用于收集雨水，還象征著財富和祝福。此外，這些池塘周圍還設有公共空間（如小廣場），為集會、交流和傳統節日提供場所。從這個意義上講，該類池塘具有儲水和促進社交聯系的多種功能。除了風水池塘外，在山地村落周圍還發現了基塘，通過排水孔與運河或河流相連。池塘內的水可以通過下部排水孔輕易地排入運河或河流中，同時，水也可以通過上部排水孔從運河河流中注入池塘。用于農業生產和住宅的小屋位于池塘堤壩上，為灌溉、施肥和收獲提供便利。村莊內部的運河大多渠化，并作為交通、社會交流和防洪的重要骨架。市場、港口和周圍的寺廟都分布于這些運河沿岸。

平原村落也遵循這些關于布局、排水和社會結構的原則。然而，與山地村落有2個重要的區別：1）水網通常更密集，有時在村邊界挖掘運河，以防止洪水和海盜；2）在平原村莊內有更多的風水池塘和基塘緊鄰建筑用于收集多余的雨水（而在山地村落中，基塘通常都與定居點分開設置，圖9）。

根據這些信息，可以從村莊尺度的研究中得出以下經驗教訓：1）基于地形的定居點組織與開發，其中自然地形作為建筑環境的分配和布局的基礎，包括排水、蓄水和農業；2）公共建筑和公共空間與主要水體有關，例如運河或風水池塘，以刺激社會交流與互動。

6 不同朝代的堤防建設過程Process of dike construction in different dynasties

7 縣（堡）尺度水利系統要素的解構Deconstruction of water-management element at the county scale

2.4 建筑尺度的水敏設計

寺廟、民居和農舍是3種典型的建筑類型，在該地區的整體水利系統中發揮著重要作用。雖然它們具有不同的功能，但有相似的排水和儲水原則。寺廟通常位于運河旁或風水池塘后面（圖10）。這樣的布局有很大的排洪優勢：從建筑物中排出的雨水能夠便捷快速地流入運河或被儲存在風水池塘中供日常灌溉等使用。內部庭院作為雨水排蓄緩沖區，通常低于建筑平面以收集從屋頂（釉面瓷磚覆蓋）落入其中的雨水。民居通常有一個較小的庭院，中間有一個水箱，可以收集雨水以供日常使用（圖11）。云母制成的天窗可以自由開關，有利于引入日光同時可以有效防雨。通常在建筑物之間布置排水溝以收集雨水，將其輸送到較大的溝渠或運河。農舍用于與農業生產相關的活動，通常修建在基塘上，靠近運河，以利用運輸資源。建筑材料也取自在基塘上種植的作物，如桑樹的枝條或稻殼。此外，屋頂的雨水和生活污水可以直接排入池塘進行灌溉和施肥。建筑尺度的水敏設計原則：1）建筑物的分配、定位、布局和材料基于對氣候模式（降水量/蒸發強度，風力強弱和溫度高低）以及水利的深刻理解，以通過儲存在不同形式（包括蓄水池、庭院池或吸水的材料）中的水體提供降溫效果和淡水供應；2）水是循環自給自足系統的一部分（例如飲用水、冷卻水、污水處理、象征/宗教用水等）。

3 水敏感規劃設計的特點

通過解讀隱藏在順德區典型水陸農業景觀中的知識，歸納總結出不同尺度的設計原則，這些原則共同協作從而使整個系統成功運作。基于對該地區傳統水利和水陸農業養殖實踐的理解，可以確定水敏規劃和設計的某些關鍵特點。這些特點可以被提取，并作為減輕洪水風險的基礎原則，同時也可以促進可持續的城市化建設。這些原則不僅能被運用于順德區，而且能服務于整個珠三角。

3.1 長期發展過程

其中一個關鍵特征是水敏感景觀是長期發展所形成的結果。如上所述，順德區的水利系統是上千年不斷累積的試驗和觀察的結果，這一特點使其成為現今和未來水敏城市建設的寶貴水利系統模范，并能從中提取適應雨洪的地方性基礎知識。然而，當代的水利措施主要集中在水利工程解決方案方面，這些系統通常在短時間內，建立并且完全依賴于人造的、單功能的城市排水網絡和堤防建設。事實證明，這種方法是無效的，隨著近年來洪水事件的頻頻發生，這種完全摒棄舊有的歷史水利系統而用與其無關的城市肌理取而代之的建設模式帶來了更多麻煩而非利益。從這個意義上講，考慮景觀的長期發展過程應該被予以足夠的重視，因為在這一原則中，景觀被視為一個多層級且含有不同過程的系統，這些過程不僅具有不同的自我變化動態，更相互影響、相互作用[12]。在珠三角，由于自然沉積和侵蝕等力量，以及通過水利和農業的人為干預不斷地改變景觀，景觀動態和轉變成為景觀研究和設計的關鍵問題[13]。

3.2 多尺度視角

另一個特征是水敏景觀的發展強調多尺度的干預，這些不同尺度一起構成互補系統。這一點可以通過“堡”中的系統組成和防洪機制很好地說明：堡規模的水利系統是具有不同水體的密集水網絡。該系統通過在2個方向（即排水和儲存）中調節河流、運河和基塘中的水，使其對洪水具有彈性與適應性。此外，它通過將大型堤圍與內部較小的堤防相結合，提供多層級的防洪保護，因此可以保護人們免受外部和內部洪水的侵害。通過將水系統和堤防系統劃分為較小的系統，以減輕特定的洪水危險（例如外堤圍防河洪、內堤圍防雨洪），這個原則將珠三角的水利系統視為一個復雜的問題，因此我們不應該通過一個單一的解決方案來解決每一個要素（河流、溪流、海灣、基塘）的問題。這使得多尺度的視角不僅在防洪方面發揮著重要作用，而且在提供更大的靈活性方面也起著重要作用（如儲水和保留洪水區）。現代實踐中常常看到的建造一個單一巨大的水利工程堤防以保護整個縣的做法是失敗的，相反，一個多尺度協調合作、對不同雨洪問題更有針對性的水利系統不僅更有效，而且對于建設適應性的城市景觀規劃至關重要。

8 山地村落水利系統Water management in mountain villages

9 平原村落水利系統Water management in plain villages

3.3 協同作用

正如順德區的案例所示，水敏感規劃設計需要當局、專家和其他利益相關者之間協作，與不同的堡或村莊共同合作努力，這對區域范圍內的水敏設計也是至關重要的，當涉及整個地區的洪水時，單個縣或村莊做出的單獨決定是不夠的。其原因在于整個地區中，河流、潮汐、沉積物以及其他需要區域共識和宏觀層面決策的能源或物質密切相關，因此需要從全局的角度出發才能解決問題。區域戰略必須由不同的地方政府共同制定，以便根據當地的不同情況進行調整，并將措施付諸實踐。這需要多個學科，當局和其他利益相關方的合作，以便為更具彈性的水利系統制定共同的理解和戰略。

3.4 了解地形條件

如上所述，地形條件，如地形、水文和土壤決定了定居點的分配和布局。這些特點決定了場地是否容易發生洪水。因此，傳統村莊通常位于丘陵或山脈的山腳下、天然河堤上或基塘系統的堤壩上。這些地點可以保證定居點免受洪水侵襲，同時還可以提供足夠的水資源。該布局不僅提供了一種有效的排水方式，并且創造了小氣候效益，例如引進風和水蒸發帶來的冷卻效果。然而，現代的開發實踐中通常以發展基礎設施（交通運輸）為優先，其他的開發則依從于這一交通框架，因為該框架帶來了便利的運輸和外部資源。這種開發方法有利于快速發展，但忽略了自然地形和特定布局，使得其往往不能夠抵御雨水和河流引起的洪水。通過重新確定由交通優先轉變為地形或水網絡發展優先的戰略，未來將在遠離洪水風險的更安全地區發展。

3.5 自然做功以及納水滯洪空間

了解景觀系統及其水文和生態過程是水敏感規劃設計的另一個重要特征。由于水和植被有其自身的發展動態，并遵循一定的發展過程和周期，因此在不同的時間尺度（日、月、年）為其提供生長發展、演替變化的機會以及靈活彈性的空間是很重要的。為水位消漲、河流和生態系統創造更多自我消納與修復的空間將緩解整個水利系統的防洪壓力，同時還可以增加生物多樣性，刺激肥沃土壤的沉積以利于農業發展，并且創造更多自然環境以滿足人們的娛樂休閑需求，最后，還為發展特定地點（不同的地形、土壤和水位消落環境）的住房類型提供了合適條件。然而，旨在嚴格控制水位變化以達到防洪目的的現代水利工程方法限制了水和自然的動態變化，并且使得水利（堤壩、渠道）局限于單一的功能，這一系列的做法最終增加了洪水風險并加劇了生態破壞。與水相關的自然過程需要開放和包容的設計策略，而不是制定一個藍圖式的設計策略。相反，提供一個可調整并尊重自然和水文過程的框架指導開發，將為適應性開發和規劃設計未來的水敏感（城市）景觀創造極好的條件。

3.6 多功能水利系統

10 寺廟的水利系統Scheme of water management in temples

11 農舍的水利系統Scheme of water management in cottages

順德地區歷史水利系統的另一個重要特征在于多功能性。順德區的水利系統不只用于防洪，同時集防御、商業、社會交流、農業和城市發展于一體。這樣一個龐大的供水網絡還促成了一個廣泛連接的交通網絡，提供不同村莊之間的交通運輸和交易。市場往往設置在水閘或堤壩旁，以利用其運輸優勢。這一原則不只將防洪和水資源管理問題視為一種威脅或者是工程措施，而是將其視為一種為人們提供新的水上生活、水上通勤、與水為樂的范例。因此，這些不同功能之間相互促進，為人們提供了三角洲生活的全新體驗。在動態使用公共空間的做法中我們也能看到關于多功能使用的考慮，如風水池塘和私人庭院空間不同狀態（雨、旱）的利用。多功能使用的做法還考慮了天氣和季節的變化，并將這些變化轉變為多功能使用公共、半公共空間的優勢。這種做法將社交、娛樂和其他公共生活或活動等與排水和儲水相結合，使對洪水消長的利用成為人們日常生活的一部分，為人們帶來了景觀和水位的季節性變化。不僅為人們提供了景觀的美麗動態變化，還警示人們：洪水的風險就在身邊。在這方面，規劃者和設計者應利用水利措施與其他開發的整合，以鼓勵多功能使用并提供更多的適應性。

3.7 再生和循環

傳統上，基塘景觀是再生和循環利用的典范。循環原理在于重新使用灰水和黑水進行凈化、灌溉、施肥和其他用途。以基塘系統作為循環中心，來自庭院或屋頂的雨水以及河水可以成為池塘補給水的來源，而這些池塘中的水也可以用來灌溉基塘上的作物。來自房屋的污水也可以流入魚塘作為肥料。之后，經過一系列生物降解過程，營養物質將被植被或水中的微生物吸收并凈化。這種循環原理不僅可以成為一系列雨水收集和凈化系統的設計原則，而且可以在不同季節充分利用雨水。

綜上所述，分析得到的水敏規劃和設計方法特點有：1）長期發展過程：將景觀理解為具有不同動態的長期過程；2）協作：政府以及具有不同學科背景的專家和其他利益相關者共同努力，為更具彈性的水系統制定協同戰略；3）多尺度的景觀設計：從區域尺度到建筑尺度的防洪集水解決方案；4）了解地形條件：景觀系統及其地形條件是村莊、建筑和土地利用的分配、組織和布局的基礎；5）自然做功以及納水滯洪空間：修復河流與降雨的系統并恢復其自然的生態過程，如演替、沉積和侵蝕等；6）多功能水利系統：不僅關注水利，還包括規劃設計中的生態、社會、文化和經濟方面；7）再利用和循環：促進水循環的發展，在建筑、村莊、縣和地區的尺度上推動雨洪的收集和再利用。

這些特征是綜合水利系統的基礎，水利系統不僅起到防洪的作用，而且還是生態發展、循環、交通、農業生產、聚落、社會聯系和政府管理的驅動力。從這個角度來看，水成為增長和繁榮的主要條件；通過水敏規劃設計，水成為文化性和地方性的催化劑。這一設計理念不僅汲取了歷史“技術”的經驗教訓，而且還具有構成珠三角強大區域特征即地方性和適應性的內在文化品質。

3.8 水敏原理在順德規劃設計中的應用

通過對歷史水利和生態堤防——基塘系統的研究所學到的水敏原理將被應用于杏壇縣，以實現更具彈性的城市景觀設計。運用上述原則，該設計中構建了一個強大的水網系統，可以引導過量洪水，并且通過一系列雨洪調控將其儲存起來，通過凈化過程實現再利用，并將修復一條歷史溪流，改造成新的中央洪泛平原，以幫助消納該縣內運河和小溪帶來的過量雨洪（圖12）。此外，通過恢復河流的自然漲落動態和泥沙沉積過程，修復了其生態功能，加速自然界物質能量循環并增加了生物多樣性（圖13）。因此，這些天然泥沙沉積物可用于加強該地區的農業。作為新洪泛平原的一部分，該方案還提出了一個多功能的水利基礎設施，包括現有的道路系統：新的公共交通、自行車道和人行道。這個新的交通體系不僅是連接所有村莊、城鎮和其他主要道路或高速公路的主干道路系統，同時也作為新型堤防住宅的交通基礎。通過擴展基礎設施并逐漸發展新的“交通分支”，這一生長的交通體系還為兩棲住宅（可建于洪泛平原）和漂浮住宅增加了可達性，并利用現有的農業水產養殖模式進行水循環和減輕洪水威脅（圖14）。總之，該方法為珠三角地區的城市發展提供了嶄新的視角，利用從生態基塘和水利方法中提取的原則，將其轉化為現代規劃和設計語言以進行實踐。此外，這一方法探索了城市化新的可能性：使我們有可能將傳統的水陸農業養殖模式轉變成為具有適應性和彈性的景觀基礎設施并能夠促進可持續的城市化發展。

12 新的杏壇綜合區域計劃（宏觀尺度），該計劃基于可持續的水利和基礎設施框架，考慮水系統，新基礎設施，生態系統，農業和住房的發展A new integrated regional plan that takes the development of the water system,new infrastructure, ecosystem, agriculture, and housing into consideration based on a sustainable water and infrastructure framework

13 中觀尺度水敏景觀的時序規劃。這一注重過程性的規劃著重于恢復水動態并建立一個彈性生長的基礎設施系統Phasing plan of water-sensitive landscape development in middle scale. This process-oriented plan focuses on restoration of the water dynamics as well as building up a growing system of flexible infrastructure

4 結論

本研究最重要的貢獻是提供在珠三角地區城市化實踐的嶄新視角，將傳統的水陸農業養殖（基塘）系統知識與未來城市發展聯系起來，架構了地方性、歷史性設計原則與現代雨洪城市設計的橋梁。在這種可持續轉型發展的視角之下，景觀被視為空間戰略和干預的基礎。由于一些地方歷史地圖的不準確性（即在某些情況下缺乏原始數據），這項研究面臨著資料不完整的困難。然而，該研究確實為更加注重動態雨洪防范的方法提供了新的思路：其中包括上面列出的水敏規劃方法特征。通過學習傳統的水陸農業養殖實踐，可以開發出水敏規劃設計的新原則，這些原則可以減輕洪水風險，同時也可以促進可持續的城市化和農業發展。這些方法將不僅僅能夠被應用于順德區，而且可以擴展至整個珠三角。這種觀點需要規劃者正確理解景觀及其背后的設計規劃原理，并以此為基礎制定發展戰略，而不是應用中國近現代城市化進程中出現的“白紙式”的發展模式（與這種方法相關的問題也是如此）。總之，恰如其分地應用和適應上述原則和特征不僅可以為城市景觀發展提供嶄新的視角，而且還可以為規劃和設計更具彈性和適應性的珠三角提供新的范例。

圖片來源：

圖1由招力行攝；圖2由斯特芬·奈豪斯繪；圖3由孫傳致攝；圖4、5、8～14由孫傳致繪；圖6由孫傳致基于參考文獻[7]繪；圖7由孫傳致基于《順德縣志》繪。

14 基于杏壇基塘系統轉型而成的水敏社區闡釋了一種新的與水而生的范式，同時結合了公共空間，濕地與新的住房類型Elaboration of a new water-sensitive community transformed from the dike-fishpond pattern in Xingtan County that implies a new paradigm of water life with public space, wetland, and new housing typologies

The Pearl River Delta (PRD) is one of the world’s fastest urbanizing deltas, with all the related challenges and potentials that this entails (e.g.increasing flood risk, loss of ecological and social values, etc.). The PRD is located in the southeast coastal region of China, with the Xijiang River,Beijiang River and Dongjiang River being its main riverine arteries. This river-dominated delta has been formed by natural processes, such as siltation and deposition, for more than a millennium[1]. The resulting lowland is characterized by two sub-deltas(Beijiang River/Xijiang River) and an estuary. The PRD is an area that has long been well suited to agriculture because of its rich soil. Human intervention, which began around 1,000 years ago, gradually transformed the delta into one of the richest agricultural regions in China by developing an integrated agri-aquaculture, known as the dikepond system[2]13. This unique landscape is the result of an historic and intricate relationship between water management, agriculture, ecology, industry, and settlement (Fig. 1). In the sub-delta of the Xijiang River, a flood prone lowland near Shunde, this is clearly visible via its centuries’ old tradition of coping with river floods and excessive rainwater. However,the ongoing process of dike-ring construction and the channelization of watercourses, as well as the partial disappearance of the dike-pond system due to urbanization, has led to a dramatic decrease in flood storage capacity and has seriously increased flood risk from rivers and rain water, not only in this region, but in the PRD as a whole. In order to address these issues a more adaptive urbanization strategy is required: a multiscale approach that is more water sensitive and inclusive in a socio-ecological way[3]. In order to develop such an approach, it is important to study traditional region-specific agricultural practices as well as historical water-management methods in order to derive design and planning principles that can inform contemporary spatial development strategies.

The objective of this paper is to identify landscape architecture principles for multiscale water-sensitive design based on traditional agriaqucultural practices and historical development of ecological water management in the sub-delta of the Xijiang River (in particular the dike-pond system) in order to increase flood storage. Since these systems were formed gradually and refined by residents through practical lessons learned over centuries, there is wealth of accumulative knowledge hidden in the landscape that can be used for flood protection, ecology, and the cultural formation of contemporary urban development.After that, this tacit knowledge which is as yet largely unexplored but proven useful, would be applied for adaptive urban planning and design in order to illustrate how these principles can be put into practice in contemporary situations. Finally,the link between this research and its possible application in the PRD will be discussed, while connecting it to a wider context.

1 Integrated Agri-aquaculture Practice

The agricultural lowlands of the area between the Xijiang River and Beijiang River is flood prone due to heavy rain which causes a peak river discharge from upper parts of the river basins. Floods occur mainly between June and August, a time when these two flood dangers happen at the same time, causing internal floods that cannot be discharged to the outer river due to the higher level of the water. This natural hydrological circumstance resulted in a fertile soil which in turn led to a particular type of agriaquaculture known as the dike-pond system, which became the basis for local economic production(Fig. 2, 3)[2]30.

The dike-pond system developed in the 14th century with fruit trees being planted on dikes around fish ponds at their centre. This changed in the early 17th century into a combination of mulberry and four major fish species, creating a local silk and fisheries economy. Since then, this agriaquaculture pattern continued to grow and prosper until it hit a peak around the 1920s. After this time, the worldwide depression, and later Japanese aggression, led to market changes with other alternatives being explored and developed. The dikepond system had been well-known as a self-sufficient and productive use of land because of its closed energy and material circulation (Fig. 4). It makes use of soil dug from the pond to build the surrounding dikes, on which the mulberry was planted to feed silkworms. After the worms had been reared,their chrysalis, along with the leaves and silkworm excrement, were returned to feed the fish, providing very good forage. The forage that was left then combined with fish manure and other rich organic matter, which was decomposed by microorganisms and fell to the bottom of the pond as fertilizer. By the digging the organically enriched mud two to three times a year and putting it back onto the dike it also offered nutrients to the mulberry trees.

However, this integrated system was not fully developed until around 1350[4]66, by which time water-management methods were in place and dike construction already begun in riparian areas around the old estuary to reclaim the low tidal flat for agriculture. Because of its excellent flood tolerance and high productive capacity, land use was concentrated in the flood-prone lowland between the Xijiang River and Beijiang River. Later it sprawled all over the PRD as a result of the region’s watermanagement system and also became one of the most important elements in an integrated watermanagement system. A look at the whole system is required to properly understand how this special agri-aquaculture pattern functioned as a floodprotection system.

2 Multiscale Water-management System

The Pearl River Delta is ancient, having been formed more than 6,000 years ago, a time when Shunde was still part of the South China Sea. By the Song Dynasty (960—1279), a large amount of the central part of the delta had been formed very gradually from sedimentation. The diversion of the Xijiang River at this time accelerated the speed of land reclamation, forming Xingtan,Jun’an, and other places to the southwest of Shunde[5]32. In 1450, the Qing Dynasty established Shunde county partly in an effort to prevent conflict over scarce land resources between rich farmers and poor fishermen, which had resulted from the continuous land reclamation, but also to protect agriculture from flooding, thereby establishing a principle of cooperative flood defence. As a result, the administrative divisions were based on cooperation for water management and included 40 counties and 297 villages[6]. This classification system helped build up a systematic water-management system thanks to the joint efforts of people from the different counties,villages, and clans to protect both the waterfront and its hinterland from flooding. This historical water-management system contains interventions at four levels of scale: regional, county, village,and building (Fig. 5). These four scales have a strong relationship with each other and developed together to form an integral system that functions as a flood defence, as well as for settlement establishment, agricultural production, and social structure. It is, thus, very important to understand the different water-management principles, and how they are interrelated through these scales.

2.1 Water-sensitive Design at the Regional Level

The regional scale includes 40 counties, which manage 297 villages. Each county has 20 to 50 percent of its boundary abutting either the Xijiang River or Beijiang River[5]24, and each tries to balance profit with danger, i.e. balance production and transportation along the river while protecting from the danger of flooding.Flood has been a major threat in the Shunde district for centuries. Floods were recorded on average three times a year during the Ming and Qing Dynasties (1368—1644 and 1644—1911 respectively), and this did not include the frequent small floods that happening nearly monthly during the monsoon season (usually April to September). Once invented, dike construction became one of the main measures against flooding. However,due to a lack of technique and human resource at the time, the building of large dikes required cooperation not only within a county or village, but also their joint efforts over a long time period (Fig. 6)[7].

Regional dike construction evolved several flood-defence principles, starting in the Song Dynasty and continuing through the Qing Dynasty.During the nearly three centuries of the Song Dynasty, people built a large number of dikes(28 in total) along the banks of the Xijiang River,Beijiang River and Dongjiang River[8]39particularly along the Xijiang River, where the Sangyuan dike was the largest at that time[4]32. The main function of the dike was to protect settlements from river floods using three main principles[5]45: 1) Utilize natural topography (i.e. make it part of the dike to make use of height difference between upstream and downstream for drainage); 2) Keep enough distance from the river; 3) Build temples besides the dikes (for commemoration and as places of deliberation).

In the Yuan Dynasty (1271—1368), old dikes had their heights raised and were reinforced, and new construction of dikes continued along the Xijiang River in 11 counties, resulting in 34 new dikes[8]13. At this time construction tended to focus on the upstream parts of the river due to the more serious floods caused by the extension and siltation of the estuary downstream. Construction techniques were also improved by using stone for the sluices and dikes.

The flourishing of both population and economy during the Ming Dynasty meant that this period saw the largest extent of dike construction and land reclamation. Population and economy were witnessing a prosperity which led to an increased demand for land, thus reclamation was widely carried out using dike construction to capture natural sediment. While in former dynasties the dikes were mainly linear, constructed on the west and east sides of islands to protect from river floods, during the Ming this was inverted because reclamation and siltation had caused tidal water infusion from the sea. Thus, the principle changed from open dike construction, to prevent river flooding, to a closed dike-ring system against sea flooding, for example, the Sangyuan dike was closed in the early Ming Dynasty by adding dikes on its southeast[5]55. However, this series of closed dike-ring constructions caused further flooding problems in the hinterland, especially during the monsoon season, when heavy rainfall could not be discharged effectively. It was at this time that the dikepond system was invented as a special agricultural land use to mitigate this problem by providing capacity for extra excess water.

This dike-pond system, which appeared in the late Ming Dynasty, prospered into the middle of Qing Dynasty[8]36. The burgeoning of agriculture in this period encouraged more land reclamation downstream, which required more dike construction and connections. However, this caused more serious flooding from the river inside the large dike rings because there was less space for water. As a result, smaller dike rings were constructed inside the large ones to protect settlements from internal floods, which led to a nested loop-like layout. At the same time, to defend from floods from the external river, different dikes were connected to form large stronger and safer dike rings, and sluices were built in them to control drainage. Finally, the whole water-management system was formed into an infrastructure of large connected dike rings with smaller dike rings inside them.

While reflecting on the long-term development of the regional water-management system, the following lessons for water-sensitive design can be learned: 1) Water management is a collaborative effort:flood defence can only be effective when different authorities and disciplines team up and jointly plan,design, and construct the water-management system from a regional perspective; 2) It is important to acknowledge that each water source (e.g. sea, river,and rain water) has its own temporal dynamic in the amount of water in each (e.g. changing levels of discharge throughout the seasons) and have specific requirements for water management; 3) As a result of an incremental learning process in this region it was considered important to provide enough space for water and flood storage by incorporating natural water streams and water bodies, have a certain distance between dike and river, and utilize natural topography to build dikes and allocate and orient drainage/irrigation ditches and canals.

2.2 Water-sensitive Design at the County (Fort)Scale

Water management at the regional scale deals with external water; at the county scale(also known as the Fort scale) interventions focus on regulating internal water. The name “Fort”for a county is used only in Shunde district and highlights a basic unit of division which is strongly related to defence from the two main enemies: flood and pirates[9]. Water management inside a Fort consists of three main components in order to form an effective system: dikes, rivers,and connectors (Fig. 7). These three elements were closely interrelated. The traditional division of the water management can be summarized as “external river, outer dike, internal river, bay,canal, ditch, drainage system”[10].

The water-management system at the Fort scale consists of drainage in the flood season and water storage in the dry season, which also works closely with the daily and monthly tidal change.For example, in the flood season, floods from the external river or the sea will be prevented by the large dikes constructed along the main river course,while the internal flood waters caused by heavy rain can be temporarily stored in internal rivers, canals,creeks, bays, and dike-ponds. During low tide,when the outer water table is lower, this water can be drained from the ponds through drainage holes into canals and thence to internal rivers, creeks, or rivulets. Finally, with the opening of sluices on the outer dikes, it can be drained into the outer rivers. In the dry season this system works conversely to store rain water, using it and river water for irrigation.With this double-sided and regular system, that could be adjusted at any time, the settlements and agriculture inside the Fort were able to deal with both flood and drought. As a result, this water system was not only capable of flood protection,but also of irrigation and transportation. It provided agriculture with water as well as rich sediment and convenient transportation.

Based on this understanding the following lessons can be learned for water-sensitive design:1) Buffering and storing water through a water network: water elements are connected and form a network that provides enough space for temporary storage of rain and river water for irrigation and drainage; 2) The hierarchy in the water network enables adaptive water management through dynamic control between different water bodies enabling the regulation of the water table at any time; the drainage holes,ditches, canals, and sluices all play key important roles in the whole system; 3) Water management requires an integral approach; the water system is multifunctional:flood defence, water storage, agriculture, and transportation are all considered integral to the system and provide conditions for the development of agricultural production, settlement development, as well as enhancing social communication.

2.3 Water-sensitive Design at the Village Scale

Besides the water-management system that protects the whole Fort from flood risk, the village also has its principles of site selection, layout, and building techniques related to flood protection.These principles not only help people reduce flood risk, but also form a special paradigm for living and interacting with water, and focus on aspects such as the layout of villages in different geographical conditions, methods of water storage and drainage,as well as social structure. First, two main village types are identified in this article, taking their names from their geographical conditions: the mountain village and the plain village.

The mountain village is usually arranged perpendicular to the contours of the terrain to make use of it for drainage and catchment (Fig. 8). In addition, small alleys are reserved as drainage aisles between perpendicular rows of buildings, which are called “cold alleys” since they aid the circulation of cool air from the water body thanks to differences in air pressure. This principle results in what is known as a “tomb” layout[11]where a main drainage canal is connected to a number of perpendicular houses via the ditches in the alleys that help drain water quickly.Sometimes these drainage aisles are also linked to ponds in front of public buildings like temples,colleges, and schools. These are known as “fengshui”ponds. This type of pond is used not only for rain water collection but also symbolizes wealth and blessings. In addition, public spaces (e.g. small plazas)are arranged around these ponds, offering a place for assembly, communication, and traditional festivals.In that sense they have the multifunctional purpose of storing water and allowing for social connection.Besides the fengshui pond, dike-fishponds are also found surrounding the mountain villages and are connected to canals or rivers via drainage holes.The water inside these ponds can be easily drained into the canals or rivers through the lower drainage hole and, conversely, water can also be poured into the ponds via an upper drainage hole. Cottages for agricultural production, as well as dwelling, are located on pond dikes which offer convenience for irrigation,fertilization, and harvesting. The canals in the village are always channelized and regarded as an important framework for transportation, social communication,and flood prevention as can be seen by the markets,ports, and temples surrounding them.

The plain villages also follow these principles regarding layout, drainage, and social structure.However, there are two crucial differences with the mountain village: first, the water network is usually denser and sometimes a canal was excavated around the village boundary to protect against flooding and pirates; second, there are more fengshui ponds and dike-fishponds inside the plain villages for the collecting of excess water (in mountain villages,dike-fishponds are usually separated from the settlements, Fig. 9).

Based on this information the following lessons can be derived from the village scale:1) Terrain-sensitive organization and development of settlements, where the natural terrain serves as the basis for the allocation and layout of the built environment, including drainage, water storage, and agriculture; 2) Public buildings and public spaces are related to the main water bodies, e.g. canals or fengshui ponds, which stimulate social interaction.

2.4 Water-sensitive Design at the Building Scale

Temples, folk houses, and cottages are three of the typical building types that play a significant role in the integral water management of the region. Though they have different functions, they share principles of water drainage and storage.Temples are usually located besides canals or behind fengshui ponds (Fig. 10). This helps the rain water that runs off the building to be easily drained into the canal or stored in fengshui pond for daily irrigation use. The inner court serves as a water buffer zone, with a lower-level surface to collect rainwater that drops into it from the roof(which is covered in glazed ceramic tiles). Folk houses usually have a smaller courtyard with a water tank in the middle to collect rain water for daily use (Fig. 11). Skylights made of mica can be opened or closed to let in sunlight or keep out rain.A drainage ditch is usually laid out between the buildings to collect water and deliver it to a larger ditch or canal. Cottages are typically buildings used for activities related to agricultural production and are usually built besides the dike-ponds and canals to prioritize transportation. Their building materials are also taken from the crops grown on the dikes,like the branches of mulberry tree or rice husks. In addition, the rainwater from the roof and domestic sewage can be drained directly into ponds for irrigation and fertilization.

Lessons for water-sensitive design at the building level: 1) Allocation, orientation, layout, and materialization of buildings are based on a deep understanding of climate patterns (precipitation/evaporation, wind, and temperature) as well as water management to provide for cooling effects and fresh water supply via water storage in many different forms, ranging from cisterns,pools in courtyards, or to materials that absorb water; 2) Water is part of a circular, self-sufficient system (e.g. drinking water, cooling water, sewage treatment, symbolic/religious water, etc.).

3 Characteristics of Water-sensitive Planning and Design

By interpreting the accumulative knowledge hidden in the typical agri-aquaculture landscape of Shunde district, design principles can be identified for each scale that, working together, make them collaborate successfully. Based on an understanding of traditional water-management and agriaquacultural practices in this district, certain key characteristics of water-sensitive planning and design can be identified. These characteristics could serve as a basis for mitigating flood risk while also allowing for increased but sustainable urbanization,not only in the Shunde district but also for the Pearl River Delta as a whole.

3.1 Long-term Development Process

One of the key characteristics is that a watersensitive landscape is the result of a long-term development process. As has been shown above, the water-management system of Shunde district was the result of incremental experimentation and observation over a millennium, which makes it a valuable basis on which to build for today and the future. However,current practice is focused on fixed engineering solutions, often built in a short time frame and depending exclusively on manmade mono-functional urban-drainage networks and dike construction. This approach has proved to be ineffective, as illustrated by increased flooding events in recent times. In fact, it has brought more trouble than benefits by demolishing the historical water-management pattern, replacing it with an urban texture that has no relation with the existing water network. In that sense, taking into account the long-term development process is vital because it regards the current landscape as a layered entity where different processes and systems influence each other and have a different dynamic of change[12].In the PRD, natural forces like sedimentation and erosion, along with human intervention through water management and agriculture, have constantly changed the landscape, which makes landscape dynamics and transformation a key issue in landscape research and design[13].

3.2 Multiscale Approach

Another characteristic is that the development of a water-sensitive landscape addresses multiple scale levels that, taken together, make for a complementary system. This might best be illustrated by the following:the water-management system at the Fort scale is a dense water network with different water bodies. This system, by regulating water in rivers, canals, and dikeponds in both directions (e.g. drainage and storage)makes the settlement more resilient to flooding.In addition, it offers multiple flood defences by combining the large dike ring with the smaller dikes inside, so they protect people from both external and internal flooding. By dividing the water system and the dike system into smaller systems that work to mitigate specific flood dangers (e.g. the outer dike for river flooding, the inner against rain flooding), this principle see water management in the PRD as a complicated issue that should not be addressed by one single solution. Every single element (river, rivulet, bay, dikefishpond) plays an important role not only in flood defence but also in accommodating greater flexibility(for things like water storage and reserved flood zones). Thus, instead of modern practices which see the construction of one single dike to protect a whole county, which has proved subject to failure, a water system that addresses multiple scales is not only more effective, but is vital for adaptive urban-landscape planning.

3.3 Collaborative Effort

As illustrated by the Shunde district case, a water-sensitive approach requires a collaborative effort between authorities, experts, and other stakeholders. Their joint efforts, by working together with the different Forts or villages, is also crucial in the regional scale because it reminds us that separate decisions taken by a single county or village will not be enough when it comes to floods in the whole region. The reason for this is that the whole region is closely connected by rivers, tides, sediment,and other energy or material flows which require regional consensus and decisions taken at the macro level. Regional strategies have to be formulated by different local governments working together to put things into practice depending on their different local situations. This requires a collaboration of multiple disciplines, authorities, and other stakeholders to develop common understandings and strategies for a more resilient water system.

3.4 Understanding Terrain Conditions

As highlighted above, terrain conditions such as topography, water courses, and soil determine the allocation and layout of settlements. As a result, the site determines if a settlement is prone to flooding.Traditional villages were therefore usually located at the foot of hills or mountains, on natural river levees, or on the dikes of an agri-aquaculture system.These locations keep the settlements safe from flooding, but at the same time provided access to water, which acted as an effective way of draining rainwater and provided microclimatic benefits, such as the cooling effects of wind and evaporation.However, modern practice usually privileges transportation in its development framework, since this brings convenience and external resources. This approach is beneficial for rapid development but ignores the natural terrain and the specific layout that makes it resilient to flooding caused by rain and river. By reprioritising from a traffic — to a terrain — or water-network-development strategy,future development will have the advantage of being located in places that are safer from flooding.

3.5 Working with Nature and Space for Water

Understanding the landscape system and its hydrological and ecological processes is another important characteristic of water-sensitive planning and design. Since water and vegetation have their own dynamics of development, and follow their own processes and cycles, it is important to provide space for development, change, and flexibility in different temporal scales (diurnal, monthly, yearly,etc.). Space for fluctuating water levels, room for rivers, and the development of ecosystems will ease pressure on the water system as a whole, increase biodiversity, stimulate sedimentation of fertile soil for agriculture, create possibilities for recreation,and open up opportunities for the development of site-specific housing typologies. However, modern engineering methods that aim at making strict controls limit the dynamic of water and nature and result in a mono-functional system that contributes to increasing flood risk and ecological damage.Working with natural processes connected to water demands open and inclusive design strategies, not blueprint designs, aimed at guiding development and creating conditions for a more adaptive and water-sensitive (urban) landscape.

3.6 Multifunctional Water Management

Another important characteristic lies in multifunctionality. The water system of Shunde district integrated defence, business, social communication,agriculture, and urban development and was, thus, not merely used for water protection. The water network also contributed to a widely connected transportation network for communication and trading between different villages. Markets were arranged beside sluices or on dikes to make use of their transportation advantages. This principle regarded the issues of flood protection and water management not only as a threat or an engineering problem, it also saw it as an opportunity to offer a new paradigm of living with water, commuting with water, and generally enjoying life with water. As a result, these combined functions promoted each other to provide people with a new experience of delta life. Multifunctionality was also visible in the dynamic use of public spaces,like the fengshui ponds and the private courtyard spaces. It also took fluctuation of weather and seasons into consideration, transforming these into advantages for multiple uses. It combined activities like social communication, recreation, and other public life or events with water drainage and storage and made it part of people’s daily life. It brought the seasonal changes in landscape and water to the people, which not only warned them of possible flooding but also provided beautiful scenery. In that respect, the integration of water management with other developments should be utilized by planners and designers to encourage multifunctional use and accommodate more adaptation.

3.7 Re-use and Circularity

The agri-aquacultural landscape was traditionally one of re-use and circularity. The circulation principle lies in the re-use of grey and black water for irrigation,fertilization, and other purposes. Taking the dikepond system as the circulation centre, rain water from the courtyard or roof, as well as river water, could be a source of water replenishment for the ponds while the water in these ponds could also be used to irrigate crops on the dike. Sewer water from houses could also flow into the dike-fishpond to act as fertilizer.Later, after a series of bio-degradation processes,nutrients would be absorbed by vegetation or by microbes in the water and purified. This circulation principle could be the inspiration for a series of water collection and purification systems that make the best use of water during the dry season today.

To sum up, a water-sensitive planning and design approach is characterized by: 1) Longterm development process: understanding the landscape as a long-term process with different dynamics; 2) Collaboration: collaborative efforts of authorities, multiple experts with different disciplinary backgrounds, and other stakeholders to develop a common understanding and strategies for a more resilient water system; 3) Multiple scale levels:complementary water solutions ranging from the regional scale to the building scale; 4) Understanding terrain conditions: the landscape system and its terrain conditions are the basis for the allocation,organization, and layout of settlements, buildings,and land use; 5) Working with nature and space for water: employing natural river and rain-water systems and processes, and also make use of natural processes such as ecological succession, sedimentation, and erosion, etc; 6) Multifunctional water management:not only focused on water management but also includes ecological, social, cultural, and economic aspects in planning and design; 7) Re-use and circularity: stimulating the development of closed loops of water, re-use of water at the levels of scale of building, village, county, and region.

These characteristics are the basis for an integrated water system that not only functions as flood defence but also serves as a driving force for ecological development, circularity, transportation, agricultural production, settlement advancement, social connection,and governance. From this perspective, water becomes the main condition for growth and prosperity; it boosts culture through water-sensitive planning and design,because not only does it apply “technical” lessons learned but also carries the intrinsic cultural qualities of local adaptations that make up the strong regional identity of the PRD.

3.8 Application of Water-sensitive Principles in Shunde

By applying the water-sensitive principles learned through the study of historical watermanagement and the ecological dike-fishpond system to Xingtan county for a more resilient urban landscape design, this approach creates a robust water network that could allow excessive water to be guided,stored, and purified through a series of processes and controls. It is proposed that a historical creek will be renovated as a new central flood plain that could help absorb heavy rainwater brought by canals and rivulets inside the county (Fig. 13). In addition, by bringing water fluctuation and sedimentation back to the river,this intervention also restores its ecological function,like circulation and biodiversity, through natural processes (Fig. 12). As a result, this sediment could be utilized for enhancing agriculture in this region. A multifunctional water infrastructure which consists of existing road systems, new public transportation, as well as biking and pedestrian paths is also proposed as part of the new flood plain. This not only serves as an arterial road system that connects all the villages,towns, and other main roads or highways, but it is also the basis for a new type of dike house. By extending the infrastructure and creating new “branches”through this development process, it also offers accessibility to the amphibious houses, terp houses,and floating houses that make use of the existing agriaquacultural pattern for water circulation and flood mitigation (Fig. 14). In conclusion, this approach offers a transformative perspective that makes use of the principles extracted from the ecological dikefishpond and water-management methods and converts them into practice with modern planning and design language. In addition, the exploration provides us with a possibility of transforming and adapting the traditional agri-aquaculture into a more resilient and sustainable urban landscape.

4 Conclusion

The most vital contribution of this paper is to build a bridge between traditional practices in agriaquaculture and future urban development to offer a transformative perspective that takes landscape as the basis for spatial strategies and interventions.The difficulty with this research consists in the incompleteness of some of its information due to the inaccuracy of some local historical maps(even a lack of these in some cases). However,the research does provide clues for a more watersensitive approach that includes the characteristics listed above. By learning from traditional agriaquacultural practices new principles for watersensitive planning and design can be developed which can mitigate flood risk while also allowing for increased but sustainable urbanization and agricultural development, not just for the Shunde district but the PRD as a whole. This perspective requires a proper understanding of landscape, and the principles behind it, to build on such a system,instead of taking a tabula rasa-development model,which can be seen everywhere in China’s recent urbanization (as can the problems associated with this approach). In conclusion, a proper application and adaptation of the above-mentioned principles and characteristics would not only provide a transformative perspective for urban landscape development but would also offer a new paradigm for planning and designing for a more resilient and adaptive Pearl River Delta.

Sources of Figures:

Fig.1 ? Zhao Lixing; Fig.2 ? Steffen Nijhuis; Fig.3-5, 8-14? Sun Chuanzhi; Fig.6 Sun Chuanzhi draw based on the reference [7]; Fig. 7 Sun Chuanzhi draw based onShunde County Annals(《順德縣志》).