戴偉 孫一民 （荷）韓·梅爾

隨著世界城市化進程，臨近海岸的三角洲地區(qū)成為城市群的集聚地帶。三角洲地區(qū)的人口密度高，并在世界生態(tài)系統(tǒng)以及全球經(jīng)濟中具有重要地位。一方面，三角洲地區(qū)本身自然基底脆弱，加上長期城市建設(shè)對自然基底層的忽視，使城市生態(tài)系統(tǒng)功能日漸衰退。粗放式的土地利用方式使得土地資源更加短缺，土地增量難以為繼，環(huán)境承載能力下降。另一方面，近20年來，雨洪災(zāi)害、地質(zhì)災(zāi)害、環(huán)境污染等多種自然災(zāi)害頻發(fā)。例如，在珠江三角洲流域，1994 年、1998 年、2008 年發(fā)生的3次特大洪水災(zāi)害，2006 年以來10 多次強風(fēng)暴潮和40 多次大型災(zāi)害性赤潮，1994—2009 年幾十次大型地面塌陷和地面沉降等都給珠江三角洲造成重大損失[1-2]。再如，2005 年美國路易斯安那州新奧爾良遭遇卡特琳娜颶風(fēng)，導(dǎo)致雨洪災(zāi)害與地質(zhì)災(zāi)害并發(fā)，使新奧爾良幾乎被毀[3]。1993 年與1995 年， 荷蘭遭遇2次特大洪水，使得荷蘭政府不得不重新考慮全域空間規(guī)劃布局與空間資源統(tǒng)籌[4]。

三角洲地區(qū)環(huán)境承載能力較低、生態(tài)系統(tǒng)脆弱、加上頻頻受到自然災(zāi)害的擾動，因而成為生態(tài)環(huán)境敏感地區(qū)。習(xí)慣于勾勒以經(jīng)濟發(fā)展為單一目標(biāo)的規(guī)劃，難以適應(yīng)三角洲地區(qū)未來的發(fā)展。因此，三角洲地區(qū)應(yīng)該高度重視氣候變化引發(fā)的自然災(zāi)害等不確定性擾動，迫切需要改變現(xiàn)有規(guī)劃的思維模式，將提升三角洲地區(qū)未來發(fā)展的韌性作為重要目標(biāo)，使得三角洲地區(qū)在面對各種擾動時，能夠抵御擾動并在災(zāi)后快速進入新的穩(wěn)定狀態(tài)。

1 三角洲地區(qū)的景觀特征

三角洲地區(qū)具有特殊的景觀格局。自然基底為社會經(jīng)濟活動提供了發(fā)展空間和必要的物質(zhì)基礎(chǔ)。自然基底是三角洲地區(qū)各類空間要素形成和生長的物質(zhì)載體，是塑造基礎(chǔ)設(shè)施網(wǎng)絡(luò)層及城鄉(xiāng)占用層形態(tài)的依托。河流、湖泊、山體等不僅是三角洲地區(qū)景觀格局的重要特征， 也是引導(dǎo)城市空間擴展方向、職能、空間布局的主要因素，為網(wǎng)絡(luò)層、城鄉(xiāng)占用層的形成和發(fā)展奠定了基礎(chǔ)。從自然流動過程角度看，三角洲地區(qū)可分為河控、浪控和潮控3種類型[5]，分別代表以徑流沉積物輸入、波浪能量和潮汐能量為主導(dǎo)的三角洲海陸岸線塑型過程（圖1）[6]。三角洲海陸岸線不同的自然過程依照自身節(jié)律而變化，作用的尺度范圍也有相當(dāng)大的區(qū)別（表1）。因此，自然過程成為三角洲地區(qū)空間格局塑造與再塑造的重要組成部分。只有深入了解三角洲地區(qū)空間的時空演變過程，規(guī)劃思想才能從“抵抗災(zāi)害”到“適應(yīng)自然”轉(zhuǎn)變，主動適應(yīng)地域環(huán)境、氣候變化和未來發(fā)展。

2 韌性規(guī)劃核心能力和特點

基于上述理解，筆者認為韌性規(guī)劃可以作為三角洲地區(qū)規(guī)劃轉(zhuǎn)型的新理念，以回應(yīng)三角洲地區(qū)自然基底脆弱、外部擾動頻繁、城市持續(xù)擴展與土地供應(yīng)不足的矛盾等特點。

“韌性”一詞近年來高頻次出現(xiàn)在城市規(guī)劃領(lǐng)域，最早來源于拉丁語“resilio”，本意是“物體受損后回恢復(fù)到原來狀態(tài)”，后來演化為現(xiàn)代英語中的“resile”。自霍林20世紀(jì)70年代在生態(tài)學(xué)領(lǐng)域提出該概念以來，韌性一詞得到廣泛應(yīng)用并沿用至今[7]。許多著名的國際研究機構(gòu)相繼闡述了韌性的含意。如國際政府間氣候變化專門委員會（IPCC） 認為：“韌性用來描述一個系統(tǒng)能夠吸收干擾，同時維持同樣基本結(jié)構(gòu)和功能的能力。 ”[8]

韌性概念經(jīng)歷了工程韌性、生態(tài)韌性和演進韌性幾個階段，追求的目標(biāo)也從最初的“單一穩(wěn)態(tài)” 到強調(diào)持續(xù)不斷的適應(yīng)，研究對象從線性拓展到非線性系統(tǒng)。韌性內(nèi)涵的發(fā)展體現(xiàn)了學(xué)術(shù)界對韌性的理解從“恢復(fù)能力”“保持能力”到“適應(yīng)能力”“轉(zhuǎn)換能力” 的過程[9]。筆者認為， “恢復(fù)能力” 和“保持能力”主要體現(xiàn)了系統(tǒng)的魯棒性（robustness）、底線性（babaseline）， 而“適應(yīng)能力”則體現(xiàn)在系統(tǒng)規(guī)劃時的預(yù)判性（preparation），使系統(tǒng)受到擾動后，具有應(yīng)對擾動、適應(yīng)環(huán)境的能力。“轉(zhuǎn)換能力”體現(xiàn)在從應(yīng)對擾動的經(jīng)歷中學(xué)習(xí)、吸收經(jīng)驗和教訓(xùn)，并轉(zhuǎn)化為指導(dǎo)下一次設(shè)計的能力。筆者認為：魯棒性、適應(yīng)性、學(xué)習(xí)—轉(zhuǎn)化能力是三角洲地區(qū)韌性規(guī)劃的核心能力。

韌性規(guī)劃與現(xiàn)有其他規(guī)劃方法相比，具有一些鮮明的特點。

1）韌性規(guī)劃更加尊重自然，結(jié)合自然做功， 強調(diào)在底線保障基礎(chǔ)上積極尋求高效的發(fā)展與保護路徑。具有韌性的系統(tǒng)能夠在受到擾動時依靠自身能力維持系統(tǒng)的核心功能，使系統(tǒng)正常運轉(zhuǎn)，并盡快進入新的穩(wěn)定狀態(tài)。

2）韌性規(guī)劃對未來不確定的擾動要有預(yù)判性。要根據(jù)歷史上發(fā)生的災(zāi)害頻率、影響范圍、損失大小、原生災(zāi)害引發(fā)的次生災(zāi)害、災(zāi)后恢復(fù)時間等多種因子進行綜合評價，結(jié)合現(xiàn)狀基礎(chǔ)設(shè)施的標(biāo)準(zhǔn)，從基底安全性、設(shè)施安全性和環(huán)境安全性角度， 對潛在風(fēng)險的類別、環(huán)境敏感性、系統(tǒng)抗災(zāi)能力進行評估，對重點防御的擾動制定針對性的解決方案。

3）韌性規(guī)劃具有超前意識，需要準(zhǔn)確辨識未來城市的主要發(fā)展情景。未來的發(fā)展要從多種可能的發(fā)展情景中，結(jié)合地域的自然條件、生態(tài)環(huán)境、社會經(jīng)濟發(fā)展現(xiàn)狀、在區(qū)域中的地位作用，確定發(fā)展目標(biāo)、發(fā)展策略，并作為空間規(guī)劃的指導(dǎo)。

4）韌性規(guī)劃需要采取一系列有利于提高系統(tǒng)魯棒性、適應(yīng)性和學(xué)習(xí)—轉(zhuǎn)化能力的特色規(guī)劃策略，需要在傳統(tǒng)規(guī)劃方法的基礎(chǔ)上廣泛應(yīng)用多樣性、多功能性、冗余度、模塊、多尺度網(wǎng)絡(luò)和連通性等規(guī)劃原則。

5）韌性規(guī)劃與其他規(guī)劃不是對立的。韌性規(guī)劃強調(diào)對自然條件、社會、經(jīng)濟多因素驅(qū)動力有更全面深刻的了解，立足于對基底和發(fā)展趨勢的綜合把握。但不同于傳統(tǒng)規(guī)劃方式，韌性規(guī)劃不僅保留對歷史與現(xiàn)狀的總體與專題評估，而且增加對未來風(fēng)險與防災(zāi)專題探討。在綜合明確空間問題后，提出前瞻性的解決方案。需在設(shè)計思想上從單純地抵抗擾動轉(zhuǎn)向容擾，將外部不確定擾動視為常態(tài)。須通過對大數(shù)據(jù)等新規(guī)劃技術(shù)的引入，不斷提升空間物質(zhì)層面的韌性標(biāo)準(zhǔn)。也須通過加強民眾參與等非空間物質(zhì)層面的行為，協(xié)同增強韌性反饋機制。

3 三角洲地區(qū)韌性規(guī)劃的思維特性

3.1 系統(tǒng)性

三角洲是一個復(fù)雜的、具有較強不確定性的人與自然共存的系統(tǒng)，涉及宏觀、中觀、微觀不同尺度。應(yīng)堅持從系統(tǒng)的角度出發(fā)，通過分析系統(tǒng)的結(jié)構(gòu)和功能，研究系統(tǒng)、要素、環(huán)境三者的相互關(guān)系和變動的規(guī)律性，對系統(tǒng)與要素、要素與要素、結(jié)構(gòu)與功能、系統(tǒng)與周圍環(huán)境之間的相互作用和相互制約關(guān)系進行充分的分析研究，跳出空間割裂、孤立、封閉的狀態(tài)，從多尺度、多維度思考問題。綜合考慮社會經(jīng)濟發(fā)展與自然支撐力，將局部工程治理置于全域統(tǒng)籌考慮，將每個項目、每個子域的特征上升到整體關(guān)系中進行把握和認識。

表1 三角洲地區(qū)常見自然過程Tab. 1 Common natural process in delta areas

3.2 協(xié)同性

三角洲空間的適應(yīng)性體現(xiàn)在與其賴以生存的環(huán)境相適應(yīng)，達到人與人、自然、環(huán)境的和諧，提高空間韌性，增強空間發(fā)展活力。當(dāng)前，由于發(fā)展階段、發(fā)展條件不同使得地域之間存在巨大差異，系統(tǒng)內(nèi)各種要素互相交疊，利益多元，因此，區(qū)域間協(xié)調(diào)性顯得更加必要。三角洲地區(qū)韌性規(guī)劃只有運用協(xié)同的方法，才能促使系統(tǒng)產(chǎn)生空間、時間、功能上的協(xié)同。

系統(tǒng)與協(xié)同理念可體現(xiàn)在跨尺度多功能的防災(zāi)網(wǎng)絡(luò)規(guī)劃中，例如BIG 事務(wù)所系統(tǒng)地考慮海平面上升、氣候變化及城市發(fā)展中的不確定因素，提出針對曼哈頓主島濱水區(qū) “U”形保護系統(tǒng)，對防災(zāi)網(wǎng)絡(luò)加以優(yōu)化，重塑場地，并高度適應(yīng)生存、社會、經(jīng)濟環(huán)境（圖2）。從系統(tǒng)多功能的結(jié)構(gòu)與功能出發(fā)，既解決當(dāng)前防災(zāi)問題，又統(tǒng)籌考慮平時作用的發(fā)揮。打造多樣化的景觀空間，為該區(qū)域的未來韌性海岸建設(shè)和城市發(fā)展描繪出嶄新的圖景，不僅回應(yīng)了三角洲地區(qū)的防洪需求，也滿足使用者對于自然環(huán)境的當(dāng)前需求和未來期許。

3.3 底線性

保障三角洲地區(qū)在面臨未來擾動時具有維持核心功能的系統(tǒng)底線。韌性規(guī)劃要立足于底線保障。主動適應(yīng)未來氣候變化， 確保地區(qū)在面對風(fēng)險時能夠抵御擾動，保障系統(tǒng)核心功能地正常運轉(zhuǎn)。

底線辨識可分為靜態(tài)式底線保障和基于自然的動態(tài)式演進的解決方案（圖3）[10-11]。靜態(tài)式底線保障強調(diào)對以生存敏感性、生態(tài)系統(tǒng)服務(wù)功能為核心的自然基底格局進行多因子疊加分析，構(gòu)建能夠保障自然承載力的、具有穩(wěn)定性的自然基底格局。例如“千層餅”式自然底線評估方法、現(xiàn)今的景觀生態(tài)安全格局，都屬于靜態(tài)式底線保護。但靜態(tài)式底線保障不利于各類信息、能量的交互。近年來歐盟等提出的基于自然的動態(tài)式解決方案，在規(guī)劃中引入自然要素，增強動態(tài)性，充分利用自然過程的優(yōu)勢，不僅保障了自然底線，而且塑造了一種新的自然基底[12]。可綜合利用潮汐、沙、風(fēng)等自然過程實現(xiàn)規(guī)劃與自然動力的結(jié)合，形成穩(wěn)態(tài)基底。

3.4 預(yù)判性

預(yù)判性是韌性規(guī)劃的重要屬性。在面對未來不確定的擾動、特別是強擾動時，需要防患于未然。預(yù)判性的實現(xiàn)需要通過構(gòu)建與評估可能的遠期情景，作為近期規(guī)劃方案的線索，并比選方案。評估未來面臨的各種發(fā)展情景、風(fēng)險可能造成的破壞程度，重視灰、綠色基礎(chǔ)建設(shè)結(jié)合， 將三角洲地區(qū)韌性規(guī)劃作為持續(xù)的行動，注重承前啟后和發(fā)展整體性。例如，三角洲地區(qū)協(xié)同化規(guī)劃與設(shè)計項目（Integral Planning and Design in the Delta，IPDD），根據(jù)對荷蘭三角洲的歷史演進、現(xiàn)狀和對未來預(yù)測，通過對自然風(fēng)險高、城市化增強與自然風(fēng)險低、城市化減弱2種情景背景的模擬、分析，制定了相應(yīng)的空間布局方案，以期為區(qū)域發(fā)展路徑提供不同可能性（圖 4，表 2）[13]。

3.5 韌性原則的應(yīng)用

結(jié)合上述4種思維特性，韌性規(guī)劃在三角洲地區(qū)的實現(xiàn)需要基于不同場所、不同景觀特征，運用相應(yīng)的規(guī)劃策略。積極應(yīng)用多功能性、冗余性、網(wǎng)絡(luò)化、模塊化等空間布局原則。圖5顯示了荷蘭若干基于上述原則的典型項目。鹿特丹水廣場項目（Rotterdam Watersquare）在實現(xiàn)對雨水沖擊的緩沖、吸納、儲存的同時，提高了場地的多種功能，提升了公共活力[14]；還河流以空間項目奈梅亨節(jié)點（Room for Rivers-Nijmegen）通過適度冗余策略，增加人工支流，設(shè)置溢流堤，擴大泛洪區(qū)，后退原有堤岸，打造具有休閑游憩價值的濱水公共空間[15]；還河流以空間項目諾德伍德節(jié)點（Room for Rivers-Noorward）適應(yīng)自然，通過網(wǎng)絡(luò)化策略，還田于水，成功實現(xiàn)對河流水位的控制[16]；補沙引擎項目（Sand motor）充分發(fā)揮地域性優(yōu)勢，讓自然做功固沙，防止岸線沙土被海浪侵蝕[17]；馬肯湖—瓦登海人工島項目（Marker Waddern）增加生態(tài)網(wǎng)絡(luò)連通性，不僅吸收了周邊環(huán)境的污染物，同時創(chuàng)造了棲息地的多樣性，為候鳥遷徙、 魚群回游提供生態(tài)踏腳石，增加生態(tài)網(wǎng)絡(luò)連通性，同時創(chuàng)造了生物多樣性[18]；馬斯弗拉克特二號碼頭項目（Maasvlakte II）根據(jù)地域性特點，將港口外輪廓線設(shè)計與洋流動態(tài)緊密結(jié)合，確定了預(yù)發(fā)展深水航道， 引入零污染和零地下水開采的產(chǎn)業(yè)，帶動港口工業(yè)地區(qū)的能源轉(zhuǎn)型[19]。

1 不同類型三角洲演進Delta evolution of different dominated natural powers1-1 河控型三角洲演進——以美國密西西比三角洲為例Fluvial-dominated delta evolution — Mississippi River Delta1-2 浪控型三角洲演進——以越南湄公河三角洲為例Wave- dominated delta evolution — Mekong River Delta1-3 潮控型三角洲演進——以荷蘭三角洲為例Tidal-dominated delta evolution — Dutch Delta

4 構(gòu)建跨尺度的“格局—連通—關(guān)鍵點”三角洲地區(qū)韌性規(guī)劃框架

4.1 土地利用格局

以提升城市空間韌性能力為出發(fā)點，系統(tǒng)地研究整體格局。將基于機理驅(qū)動預(yù)測、地理空間形態(tài)模擬與水文生態(tài)模擬相結(jié)合，預(yù)測空間結(jié)構(gòu)可能的演變趨勢與風(fēng)險場所。通過情景分析，利用已知的不確定性， 減少“未知不確定性”，從多個可能性中尋找空間發(fā)展的潛力，探索應(yīng)對不同情景規(guī)劃的可行性。加強區(qū)域合作和協(xié)同， 應(yīng)基于綜合自然邊界的劃定，綜合生態(tài)安全格局和全域基礎(chǔ)設(shè)施，將自然要素落實到土地利用總體規(guī)劃中。重視項目對系統(tǒng)整體功能實現(xiàn)的支撐性作用，在尊重景觀格局的前提下，讓自然要素成為重要的設(shè)計語言， 合理選擇開發(fā)與保護用地。

4.2 空間連通性

構(gòu)建“流動性”載體。藍綠網(wǎng)絡(luò)具有不可替代的作用，是實現(xiàn)“流動性”的重要載體。特別是水系、綠廊，更是成為塑造城市空間形態(tài)的重要因子。當(dāng)前，快速城市化過程中存在的一個突出問題是由于土地粗放利用、缺少統(tǒng)籌，導(dǎo)致空間完整度低，原本有強烈自然肌理的三角洲自然基底幾乎消失殆盡，造成了嚴(yán)重的生境損失。由于交通系統(tǒng)的發(fā)展，藍綠廊道被渠化、切斷，導(dǎo)致原有自然徑流被大幅度改變。因此，藍綠網(wǎng)絡(luò)建設(shè)的主要目標(biāo)是將空間中現(xiàn)存的、潛在的生態(tài)斑塊、生態(tài)踏腳石連接起來，利用自然自我修復(fù)的機制，逐步形成新的生態(tài)格局，提供更多的生態(tài)系統(tǒng)服務(wù)，以起到防災(zāi)作用。同時，交通網(wǎng)絡(luò)要富有韌性，具有較強的抗干擾、抗沖擊能力，要協(xié)同交通網(wǎng)絡(luò)與藍綠網(wǎng)絡(luò)、灰色網(wǎng)絡(luò)， 在軟硬件方面具有足夠的適應(yīng)能力，增加市民使用的可選擇性，保持不同空間組團之間的暢通。

表2 不同遠期情景假設(shè)條件下荷蘭三角洲地區(qū)空間布局解決方案策略解析Tab. 2 Analysis of applied spatial strategies of sub-systems in planning proposals under different background of long-term scenarios

4.3 關(guān)鍵點策略

加強對韌性技術(shù)在各類空間節(jié)點的研究和應(yīng)用。針對三角洲敏感性高、經(jīng)濟發(fā)展迅速、雨洪—生態(tài)韌性低、易受外部擾動的特點，從空間、時間和功能3個維度開展韌性技術(shù)系統(tǒng)研究，探討關(guān)鍵性要素及其組合方式對系統(tǒng)目標(biāo)實現(xiàn)的驅(qū)動機理，研究不同控制要素間的耦合機制及對系統(tǒng)目標(biāo)的集成影響。需要結(jié)合場地的實際情況，編制相應(yīng)的規(guī)劃內(nèi)容。要將有利于提高系統(tǒng)韌性的一些原則，如地域性、多樣性、多功能性、冗余性、網(wǎng)絡(luò)化、模塊化等規(guī)劃原則應(yīng)用到三角洲地區(qū)各關(guān)鍵點的工程實踐中。結(jié)合空間網(wǎng)絡(luò)， 打造關(guān)鍵點“海綿體”。

4.4 集成應(yīng)用傳統(tǒng)生態(tài)智慧與現(xiàn)代技術(shù)

合理利用人工介入和生態(tài)智慧，使得三角洲地區(qū)跨尺度空間形成一個整體，協(xié)同應(yīng)對未來氣候與發(fā)展情景的變化。例如，圩田區(qū)域地勢平緩、泥沙極易沉降。順?biāo)鵀?、適度改造是圩田類空間規(guī)劃的核心理念。在充分尊重自然匯水過程的基礎(chǔ)上，將低洼處無序的水流塑造成自然的水網(wǎng)，實現(xiàn)疏浚排水，盡可能將圩田河渠連通形成網(wǎng)絡(luò)。利用現(xiàn)代技術(shù)將圩田水渠貫通，使其具有排水、調(diào)蓄、航運、灌溉、景觀等綜合功能。定期疏浚河道，將淤泥用于墊高圩堤和戧岸，修復(fù)被破壞的圩田。需要設(shè)置多重防災(zāi)體系，形成一定的防災(zāi)冗余條件， 實現(xiàn)分級防災(zāi)體系，分區(qū)排澇。

4.5 跨尺度協(xié)同與管理措施

生態(tài)規(guī)劃管理、防洪規(guī)劃管理、智能化預(yù)警系統(tǒng)、應(yīng)急調(diào)度管理等方面，建立跨尺度、跨部門的統(tǒng)一協(xié)調(diào)機制。改變僅以局部視覺美學(xué)和空間構(gòu)成學(xué)為依據(jù)的傳統(tǒng)城市規(guī)劃的評價標(biāo)準(zhǔn)。

5 小結(jié)與展望

韌性規(guī)劃作為三角洲地區(qū)規(guī)劃轉(zhuǎn)型的新理念，通過對自然基底的保護，對自然過程的引入，對空間格局的重塑，應(yīng)對未來“社會—經(jīng)濟—生態(tài)”三者的挑戰(zhàn)，形成更加合理的“生產(chǎn)、生活、生態(tài)” 的城市空間，并能夠與國土空間規(guī)劃“三區(qū)三線”技術(shù)性指南劃定形成有機聯(lián)系，迎合生態(tài)文明建設(shè)發(fā)展的要求。

盡管目前關(guān)于三角洲地區(qū)韌性規(guī)劃的研究尚處于起步階段，但從“抵抗自然”走向“與自然合作”的趨勢已經(jīng)顯現(xiàn)。當(dāng)前在實踐中要特別注意以下4點。

1）高度重視三角洲地區(qū)自然基底的脆弱性，深刻認識韌性思維的系統(tǒng)性、協(xié)同性、底線性和預(yù)判性，從一味依賴技術(shù)力量這一現(xiàn)象轉(zhuǎn)變?yōu)閷鹘y(tǒng)生態(tài)智慧與現(xiàn)代技術(shù)相結(jié)合。

2）基于預(yù)判式過程。以情景作為線索，構(gòu)建更加合理的規(guī)劃方案。未來環(huán)境變化具有不確定性。對情景的展望可以減少“不確定性”情景發(fā)生的概率，為構(gòu)建合理的近期規(guī)劃方案提供科學(xué)依據(jù)。要結(jié)合地域特點，積極探索土地利用方式和空間格局，合理設(shè)置土地擴展的閾值。

3）兼顧魯棒性與適應(yīng)性的功能分區(qū)管控體系。魯棒性分區(qū)指該分區(qū)在外力作用下不易發(fā)生形態(tài)和功能上形變的空間分區(qū)。適應(yīng)性分區(qū)指該分區(qū)在外力作用下發(fā)生形變、但不損壞空間的分區(qū)。在魯棒性空間分區(qū)，主要采用以靜態(tài)式的底線保障方案，以“千層餅”式自然底線評估方法繪制景觀生態(tài)安全格局。在適應(yīng)性空間分區(qū)，可以采用基于自然的動態(tài)式演進的解決方案，確保景觀要素的“流動性”。在近期規(guī)劃中采用兼容魯棒性與適應(yīng)性的規(guī)劃導(dǎo)則，保證空間結(jié)構(gòu)自身的穩(wěn)定性，以適當(dāng)手段吸收和緩沖外界變化導(dǎo)致的形變。

設(shè)計導(dǎo)向，基于自然過程的動態(tài)性原則，優(yōu)化生態(tài)系統(tǒng)，應(yīng)拿捏好規(guī)劃中自然、農(nóng)田、城市等多種重要的環(huán)境系統(tǒng)，通過整合人工與自然力量，塑造海陸統(tǒng)籌的三角洲地區(qū)空間景觀格局，適應(yīng)未來動態(tài)變化以及發(fā)展需要。

致謝：

感謝華南理工大學(xué)建筑學(xué)院林廣思教授、荷蘭代爾夫特理工大學(xué)斯特芬·奈豪斯副教授、Taneha Bacchin 對本文的指導(dǎo)。

圖表來源：

圖 1-1、1-2 來自參考文獻 [5]；圖 1-3 來自參考文獻[6]；圖 2 來自 Rebuild by Design (http://www.rebuildbydesign.org/)；圖 3 翻譯自參考文獻[10]；圖 4 來自參考文獻 [13]；圖 5 為作者自繪；表1、3 為作者自繪；表2 改繪自參考文獻 [10]。

With rapid urbanization process in the world,delta areas have made remarkable achievements in urban construction, as a result of rapid development in recent decades. However, the ecological problems accumulated over the years have also become more prominent, especially for the increasing spatial vulnerability. Extensive land use and reclamation caused scarce land resource, lowering environmental carrying capability. On the one hand, ecological system services were declining, as a consequence of the destructive original natural basement. On the other hand, various natural disasters, such as heavy precipitation, river flooding and tidal invasion,geological hazard, environmental pollution, etc.occurred frequently in recent years. For instance,in 1994, 1998, and 2008, several major floods hit the Pearl River Delta[1-2]. More than 10 times storm tides and 40 times heavy red tides have invaded since 2006. Land subsidence, as secondary disasters also happened for several times between 1994 and 2009, causing significant property losses in the Pearl River Delta. New Orleans suffered from Hurricane Katrina in 2005[3], leaving the city almost in ruins, as a result of the flooding and land subsidence. In 1993 and 1995, the Netherlands suffered from two severe flooding, which resulted in heavy losses in both human life and properties,and made the Dutch government reconsider spatial planning strategies for the future[4].

Due to weaker environmental carrying capacity and frequently challenging natural disasters, delta areas have become ecological sensitive places that seem hard to be developed, with constant pressures of increasing population growth social-economic requirements. Current planning theory and methodolgy in delta areas are required to be shifted to enhance resilient capacity. When looking back our experience, the traditional economic-oriented pathways with deterministic blueprint planning outcomes seems not enough to adapt to potential future challenges either in macro strategies or local practices. Uncertain disturbances such as natural disasters caused by climate change urge planners to change their thinking mode, by making advantages of dynamic landscape and preparing for future risks. Only in this way can delta areas withstand the destabilization and have abilities to quickly return to stable states after disasters.

1 Characters of Delta Landscape

The delta area has a special landscape composition with dynamic mechanism. The natural basement, being the carrier of the formation and development of other spatial elements, provides space, materials and acts for shaping infrastructure networks and urban-rural occupations. Green-blue systems are not only important spatial networks of generating stable landscape in delta areas, but also are main indicators to guide actions for urban-rural patterns’ development, protection or remove. The complex landscape of delta area can be classified into three categories according to their dominated natural power, namely fluvial dominated delta,wave-dominated delta and tidal-dominated delta[5],representing the shaping processes of delta areas dominated by sediment input, wave energy and tidal energy (Fig.1)[6]. Delta areas are constrained by themselves’ natural laws, and thus, different natural processes in delta areas vary between each other according to specific rhythms. The speed of these processes can be fast or slow, with quite different operational scales and principles (Tab.1), which can greatly affect shaping and reshaping spatial layout for the future. Therefore, it is necessary to first have an in-depth exploration of the spatialtemporal evolution of the delta area, to understand the dynamic operation of the system in natural basement, infrastructure networks and urban-rural occupations, and then to transform our value from“resisting disasters” to “adapting nature”, in order to optimize the situation of existing site.

2 Core Capabilities and Characteristics of Resilient Planning

Based on the above understanding, we believe that the resilient planning in delta areas can be applied as a new concept for the transformation of planning paradigm in response to the special landscape composition with dynamic mechanism, meanwhile overcoming conflicts between urban-rural expansion and insufficient environmental capacity.

The term “resilience” , originated from Latin word “resilio”, often appears in regional or urban planning in recent years, which means “returning to its original state after an object is disturbed”and evolves into “resile” in modern English. Since Holling[7]first proposed it in 1970s, the concept of resilience has been widely used. Many famous international research institutions have elaborated the meaning of resilience during their practices. For instance, International Intergovernmental Panel on Climate Change (IPCC) described that“resilience is the ability of absorbing interference and maintaining the core structure and function of system”[8].

The concept of resilience has experienced several development stages from engineering resilience, ecological resilience to evolutional resilience, in pursuit of concept from single steady state to a more emphasis on continuous adaptation, by shifting the research objective from linear to nonlinear system. Evolution resilience reflects the process from recovering and maintaining ability to adaptive and learning/transforming ability[9]. It is believed that recovery and maintenance ability reflects from the system’s robustness of its baseline, while adaptive ability reflects the prediction of system when it comes to the ability to cope with the sudden disturbances and to adapt to the surrounding environments.learning ability from the experience of dealing with disturbances and transforming these lessons into planning actions, in order to guide next planning actions. Shortly, the capabilities of robustness,adaptability, and learning/transformation can be regarded as core competencies of resilience planning in delta areas.

Compared with the other current planning methods, resilient planning in delta areas has five distinctive characters, together with the necessary knowledge inputs of complex system. Resilient planning aims to constantly organize with natural and unnatural elements, scales, short and long term spatial visions, exploring balanced relationship between each of them. First, resilient planning highlights the principles of natural basement.When there are conflicts between natural and unnatural areas, it is important to leave space for nature according to its self-organization functions.That means, the better way to develop in delta areas should emphasize the baseline combining with the nature, especially water and green system. Second,resilient planning should comprehensively evaluate various impact factors of future uncertainties. The overall evaluation factors including the disaster frequency, defensiveness, affected regions, losses,the secondary disasters as well as the recovery time of the catastrophe in history needs to combine with the layer of current states, in order to make predictions for challenging places in space by mapping technologies. Third, resilient planning requires to consider about possible scenarios,as background but important information for planning “No-regret” strategies. Scenarios can provide tendencies to be thought about. Then different spatial strategies with related spatial layouts to respond to these scenarios can be used to present different possibilities for the long-term future. “No-regret” strategies for spatial layouts can take a series of distinctive principles for improving the robustness, adaptability, and learning/transformation capabilities, such as diversity, multifunctionality, redundancy, modularity, multi-scale networking and connectivity. Fourth, resilient planning is not the opposite of other planning theories and methodologies. Resilient planning relies on the comprehensive master of the baseline and trend highlighting the further understanding of natural condition, social and economic-driven factors. The concept of resilience should shift from the resisting the disturbance to allowing the disturbance, taking the uncertain disturbance as normality to work with. With new planning techniques such as “big data” introduced, the opportunities for realizing these resilient criteria with well-prepared scientific spatial layouts and typical sections can be achieved.

2 “BIG U”方案體現(xiàn)系統(tǒng)性、多尺度協(xié)同規(guī)劃設(shè)計的觀念Systematic, multi-scale collaborative planning and design— Example of “BIG U”

3 傳統(tǒng)的“千層餅”底線格局研判方法Research and judgment method of the traditional “multilayer steamed bread” bottom line pattern

4 不同遠期情景下的荷蘭南三角洲方案：STEAM（左）與REST（右）Scenarios thinking in South Dutch Delta：STEAM (Left)and REST (Right)

3 Thinking Characters of Resilience

3.1 Systematic Thinking

The delta area is a complex system involved in scales with strong uncertainty, which coexists with nature and unnatural actions. Planning outcomes,such as new spatial layouts with typical sections are required to include the information of multi-scale spatial researches, such as multi-scale water, green system understanding, etc. Planners should build up their understandings, by reduction drawings of different specific subsystems and elements, then to reconstruct new understanding of relationships based on studying the interactions among whole system, subsystem, elements, outside environments.

3.2 Integrative Thinking

Integration reflects harmonious relationship between human and nature to improve space resilience. Due to the overlapping of various elements of system and the diversity of different interests, integration is necessary. Integrative thinking also means that the different subsystems have their own freedom to develop within the limits of whole system interest.

A famous practical example can be learned is in New York, deriving from competition outcomes of “Rebuild by design” with several planning proposals for multi-scale and multi-functional disaster prevention networks. For instance, “U-shaped”system of 14 km Manhattan waterfront boundary proposed by BIG team is of great interests to the resilient concept (Fig.2). Their proposals was made by systematically considering the climate change and uncertain surrounding communities’ development,with technic prediction of spatial mappings to find out both opportunities and challenges for future.Based on those, their proposal optimizes the disaster prevention networks, from a bare hard-surface dyke system to vivid public waterfront areas, by making the highly adaptive framework with three key parks and several suggestions for both roads and waterfront sections. Their proposal solves both the current spatial issues and provides strategies for future disaster prevention, by transforming high risk waterfront areas to a multi-function public area that citizens can involve. Furthermore, different typical sections’ models are suggested to complete with this new “U-shaped” spatial layout. Like guidelines, the selection of these sections will be decided by different users’ of surrounding communities.

3.3 Baseline Thinking

The resilient planning is based on baseline thinking in order to keep system stable even if system is subjected to great disturbance, by understanding the self-organization characters of delta natural landscape. It should be based on natural basement by actively adapting to future climate change, with making advantages of landscape and introducing natural language into new spatial layout.

In planning practice, there are two ways to identify sensitive natural baseline based on the theory of landscape ecology. One is based on static layer-based perspective and the other is natural-based solution based on dynamic evolution perspective, which means that dynamics of natural power can also be applied for planning languages (Fig.3)[10-11]. The static method emphasizes on the analysis of layering of multiple spatial factors for the evolution of comprehensive maps to find challenges and opportunities, however, the static method is not conducive to coping with dynamic changing of the environment and the interaction of various types of material, information and energy transformation. In recent years, the natural-based solution introduced the processes of natural elements in planning process by utilizing the advantages of natural processes, which can use the power of nature to replace the artificial technology[12]. An example in the coastline shows how the concept of “natural-based solution” can work in practice.

3.4 Scenarios Thinking

It is essential to prepare strategies aiming at different future possibilities. In scenario thinking,“No-regret” strategies should be established based on the understanding of existing situations as well as different possibilities of long-term scenarios,where the green, blue and grey infrastructures will be combined under the background of the sustained action. For example, Integral Planning and Design for the Delta (IPDD) project has simulated 2 scenarios(High natural risk with high urbanization; Low natural risk with low urbanization) and corresponding 2 spatial solutions in Dutch Delta based on the knowledge of historical evolution, current status and future projections. (Fig.4, Tab.2)[13]. They are useful to establish more comprehensive “No-regret” strategies with process-based spatial layout, with the feedback evaluation in finding both similar and changeable places in both scenarios.

3.5 Adapting to Local Conditions, Based on Above Four Thinking Characters

Apart from traditional planning principles,resilient planning needs to apply special principles to distribute a new spatial layout, Fig.5 show typical projects with related landscape features in the Netherlands. Project “Rotterdam Watersquare”enhanced the public vitality of the site by buffering,absorbing and storing rainwater impacts[14]; Project“Room for Rivers - Nijmegen” reduced peak water discharge through creating a by-pass channel. Related strategies like expanding floodplain, retreating the original embankment, and creating a waterfront public space with leisure recreation value[15]. Project“Room for Rivers - Noorward” adapted to nature,through depoldering technologies by returning agriculture land to the water body[16]; Project “Sand Motor” made use of advantage of regional natural processes to fix sand and prevent coastline sand from being eroded by waves[17]; Project “Marker Waddern” not only absorbed pollutants from surrounding environment, but also created habitat diversity by providing ecological stepping stones for bird and fish migration and increasing the surrounding biodiversity[18]; Project “Maasvlakte II” was based on regional characteristics. The outer contour of the port was closely integrated with the dynamics of ocean currents, which defined the deep water channel and introduces zero pollution and zero groundwater mining industries[19].

4 Research Framework of “Pattern-Connectivity-Strategic points”

4.1 Land Use Pattern

It is important to systematically study overall landscape pattern to make balance between protection and development of land use by highlighting the ability of resilience. It is necessary to combine techniques like geographic big data simulation, GIS database, and spatial hydrological simulation to predict the backbone of spatial structures. The natural elements are used as important language for planning,with selected strategic points.

During this process, the corresponding spatial evaluations, such as environmental carrying capacity evaluation, land suitability evaluation, and space risk assessment, can provide a reference for delineating the final scientific land use pattern.They are essentially systematic and scientific spatial mapping outcomes, which are basis for guiding the final spatial layout into the right direction. When there is a contradiction in the space demarcation, it is necessary to abide by the principle of ecological priority and reserve buffer space for future growth.

4.2 Increasing Connectivity for Flowspace

Connectivity can be achieved by building“flowspace” carriers. The blue-green networks are important carriers for generating flowspace. Blue corridors and green corridors are elements for shaping new spatial structures. At present, a serious problem is that green-blue networks are fragmented,which causes runoffs blocked and habitat loss.Therefore, the main goal of blue-green network reconstruction is to connect potential green spaces,water bodies and wetlands to form large context.

4.3 Strategic Points for Resilience

5 典型節(jié)點項目分布Spatial distribution of typical projects

Strengthen the research and application of resilient technology in various strategic points. In view of the high sensitive delta areas, the researches for various strategies which adapt to local scale should be carried out from three dimensions of space, time and element. It is necessary to integrate the actual situation of each strategic point to compile whole planning. At the same time, some technologies such as regionality, diversity, redundancy, network,and modularity, etc. are helpful to improve systematic resilience should be applied in practices.

4.4 Collaboration with Management Measures

In the aspects of infrastructure construction,ecological planning management, flood control management, intelligent warning system,emergency dispatch management etc., unified coordination mechanism between cross-scale and multi-sector should be built. Planners should pay attention to the coordination of the project with the regional environment and urban landscape.The evaluation criteria of planning based on visual aesthetics should be changed into “social-economicecological” comprehensive goals.

4.5 Robust and Adaptive Zones

Resilient planning of the delta area should take into account both robust and adaptive zones for different ways of guidelines. Robust zone refers to the spatial zone that is not easily deformed in structure and function under external disturbances.Adaptive zone refers to the spatial zone that can be changed in structure and function under external disturbances, but it still keeps abilities of selforganization. They can be set in high risk areas with high ecological vulnerability. We believe that in robust zones, the static methods for generating baseline can be used to draw the landscape ecological security pattern with the “l(fā)ayer model”. In adaptive zones, natural-based solutions can be used to ensure the “flowspace” of landscape elements. At the same time, it is possible to take into account the phase setting to connect the behavior of adaptive zones with long-term scenarios. Appropriate means can be applied to absorb external disturbances.

5 Conclusions

The new concept of resilient planning has been proposed for delta areas recently, which has developed a more rational delta space characterized with harmonious relationship of “production, living,ecology” zones in accordance with the requirement of ecological civilization construction by protecting natural baseline, connecting the natural processes,reshaping the spatial pattern in the face of the“society-economy-ecology” challenges.

The resilient planning of delta areas helps to promote the implementations of Substitutability.First, the problem is compounded by its fragility of natural baseline to delta areas, and it is necessary to deeply understand the systematic, integrative, baseline and scenarios thinking, and to combine the traditional ecological wisdom with modern technologies instead of relying on the data and techniques blindly.Scenarios can help to build “No-regret” spatial strategies and corresponding spatial layouts. The increasing expectations of long-term scenarios are good for reducing the probabilities of uncertainty and providing a scientific basis for scientific planning in the short-term. Second, it is important to provide spatial principles of both robustness and adaptation into a comprehensive spatial layout map. Robust zone refers to the spatial zone that is not easily deformed in structure and function under external disturbances. Adaptive zone refers to the spatial zone that can be changed in structure and function under external disturbances, but it still keeps abilities of selforganization. Third, manipulating landscape pattern with dynamic mechanism can be shaped to adapt the dynamic change and development need accompanied by integrating the artificial and nature power in the important environmental systems such as nature,rural, urban areas.

Although the characteristics of resilient planning are still in cognitive stage, the trend has emerged. The guiding value has shifted from“Resisting against disaster” to “working with nature”. It is time to combine traditional ecological wisdom with modern technologies for resilient development of delta area.

Acknowledgements:

We would like to thank Prof. Lin Guangsi, the School of Architecture, South China University of Technology;Associate Professor Steffen Nijhuis and Taneha Bacchin,the faculty of architecture and build environment, Delft University of Technology, for their help to this paper.

Sources of Figures and Tables:

Fig. 1-1, 1-2 from reference [5]; Fig. 1-3 from reference [6];Fig. 2 from Rebuild by Design(http://www.rebuildbydesign.org/); Fig. 3 translated from reference [10]; Fig. 4 from reference [13]; Fig. 5 is made by author; Tab.1 are made by author; Tab. 2 is revised from reference [10].