變遷中的島嶼
——韌性城市形態(tài)

著：（德）彼得·鮑斯文（美）馬蒂亞斯·康道夫 （美）帕特里克·韋伯 譯：李詩瑤

1 《羊城山水形勝圖》，1892年（琶洲島和黃埔碼頭位于圖像的最右側(cè)）Guangzhou Landscape, 1892 (Pazhou Island and the Whampoa Anchorage are seen on the far right of the image)

2 1786年關(guān)于底格里斯（虎門）的測(cè)繪（琶洲島和黃埔碼頭位于圖紙上方）Survey of the Tigris (Humen) from 1786 (Pazhou Island and the Whampoa Anchorage are seen on the top of the survey)

琶洲島位于珠江前航道和廣州的黃埔運(yùn)河之間。該島已成為廣州金融、媒體、技術(shù)、貿(mào)易和展覽區(qū)的一部分，并逐漸成為粵港澳大灣區(qū)的重要中心。自2003年以來，該島中部新建成的琶洲會(huì)展中心成為廣交會(huì)的舉辦場(chǎng)地。珠江新城毗鄰琶洲島西部，位于其中的廣州塔是為迎接2010年廣州亞運(yùn)會(huì)開幕而建成的著名地標(biāo)。琶洲島西部目前已成為互聯(lián)網(wǎng)創(chuàng)新集聚區(qū)。對(duì)比之下，該島東西部發(fā)展呈現(xiàn)出不均衡的態(tài)勢(shì)，對(duì)東部的開發(fā)已導(dǎo)致環(huán)境惡化和生態(tài)系統(tǒng)受損[1]。將重點(diǎn)介紹該島的東部。將基于一個(gè)城市設(shè)計(jì)實(shí)驗(yàn)來對(duì)比2種規(guī)劃方案，并將在文中呈現(xiàn)二者的結(jié)果預(yù)期。第1種方案是開發(fā)該島東部的所有可用土地，第2種方案則只發(fā)展可用土地的2/3，并保留所有現(xiàn)有低洼地不做開發(fā)，利用其儲(chǔ)蓄臺(tái)風(fēng)暴雨等帶來的降水。這2種方案都可以保護(hù)島嶼不受洪水與潮汐的影響。通過回顧琶洲島的自然與文化歷史，計(jì)算2個(gè)方案下島嶼所需的蓄水總量來證明我們的實(shí)驗(yàn)。

珠江三角洲的河流有著非常復(fù)雜的歷史。現(xiàn)在的三角洲有8個(gè)相互連接的潮汐河口。而在2世紀(jì)，這里仍然是一片淺內(nèi)陸海。廣州的發(fā)展始于這大片海域的北岸，即中國南海的一個(gè)海灣。這座城市選址很好，因?yàn)樗晨坑^音山（越秀山）的南坡，地處洪水淹沒不到的高地。隨著時(shí)間的推移，內(nèi)陸海逐漸轉(zhuǎn)變?yōu)橛上髋c潮汐涌組成的水文脈絡(luò)。羅伯特·馬克斯（Robert B. Marks）在他的《虎、米、泥、絲——帝制晚期華南的環(huán)境與經(jīng)濟(jì)》（Tigers, Rice, Silt and Silk: Environment and Ecology in Late Imperial）一書中展示了該地區(qū)的迷人景象。深入研究過去，記錄了河流環(huán)境是如何在自然力和人力作用下形成的。書的標(biāo)題中提到了老虎，因?yàn)槿侵拗車耐恋卦敲艿纳?，老虎頻繁地出現(xiàn)在當(dāng)?shù)氐牡孛袜l(xiāng)村傳說中。大米則是由于繁榮的水稻種植文化（一年兩熟）在由當(dāng)?shù)剞r(nóng)民建造的堤壩和池塘中蓬勃發(fā)展。河流從山上運(yùn)來了淤泥，農(nóng)民使用這種材料，打造出越來越平坦且易種植的島嶼。清代，農(nóng)民們?cè)诘虊紊戏N植桑樹，以采集利用桑葉為依托的絲綢產(chǎn)業(yè)應(yīng)運(yùn)而生[2]。

許多島嶼都是由地表巖石背面沉積物的堆積而逐漸形成。琶洲島就是這樣一個(gè)島嶼，因沖積沉積物積聚在2塊露出表面的巖石之間而形成。明朝海鰲塔，即如今的琶洲塔就坐落在其中一塊巖石上方。當(dāng)時(shí)從虎門河航行到黃埔港港口的遠(yuǎn)洋帆船以3座寶塔為重要地標(biāo)，琶洲塔是其中一座（圖1、2）。黃埔村位于歷史悠久的港口上方，占據(jù)了第二塊露出地表的巖石。黃埔村嚴(yán)格來說不是一個(gè)農(nóng)業(yè)村莊。它是一個(gè)因與外國人通商而興盛的聚居地。在這里，貨物被轉(zhuǎn)運(yùn)到舢板上，并通過河流和運(yùn)河運(yùn)輸?shù)絻?nèi)陸（圖3、4）。

1 與雨洪共生

縱觀歷史，洪水改變了島嶼岸線的輪廓。清代的記載報(bào)道了從1736—1839年間的44次大洪水[3]，平均每2.4年發(fā)生一次大洪水。這些洪水裹挾的泥沙，大部分沉積在廣州等三角洲地區(qū)。洪水重塑了三角洲，因此島嶼的形狀和范圍隨著大洪水的每次來臨而變化，由此產(chǎn)生的沖積島嶼一直處于低海拔區(qū)域并持續(xù)遭受洪水侵襲。

與珠江三角洲的其他島嶼一樣，琶洲島受到的洪水威脅主要有2個(gè)來源：當(dāng)?shù)貜?qiáng)降雨帶來的洪水（“in-flooding”）和超出防護(hù)堤壩的防洪水位的汛期河水或風(fēng)暴潮（“outflooding”）。保護(hù)這2種不同的威脅需要不同的策略。第1種類型的洪水基本上是由降雨量超過可排水量所造成的，會(huì)導(dǎo)致城市街道淹水。在河流水位過高或漲潮期間，琶東這樣被東、南、北側(cè)堤壩環(huán)繞的盆地就像一個(gè)浴缸，堤壩外水位高于內(nèi)部，不能排出所有集聚的雨水。使用水泵是一種解決方法，但泵的排水量可能跟不上強(qiáng)降雨期間積水的速度，并且如果沒有可靠的應(yīng)急發(fā)電機(jī)，水泵在電源故障時(shí)將變得毫無用處。

3 琶洲塔和黃埔村Pazhou Pagoda and Whampoa Village

4 帆船在黃埔港裝載轉(zhuǎn)運(yùn)Sailing ships trans-loading at Whampoa Harbor

5 琶洲島東部的潮汐涌、運(yùn)河和池塘Tidal sloughs, canals and ponds on Eastern Pazhou Island5-1 現(xiàn)狀Present condition5-2 1947年的琶洲島東部Eastern portion of Pazhou Island in 1947

在強(qiáng)降雨期間，400 hm2土地上的徑流被6條規(guī)模可觀的、穿過琶洲島東部的潮汐涌所吸收（圖5）。這些河涌通常依照對(duì)角線流經(jīng)過去及現(xiàn)在仍在使用的農(nóng)田。位于東南部的年豐涌仍然在堤壩上種滿了喬木和灌木。由于潮汐作用，該河涌在島嶼兩側(cè)的入河口處是雙向流動(dòng)的，通過機(jī)械操控的閘門控制。從前，新洲和合興涌與黃埔村外圍運(yùn)河相連。2條河涌都與年豐涌匯合，它們共同排出黃埔村南向斜坡上的積水。黃埔村北向斜坡將水流排入大涌和沙涌，它們的潮汐水流也由琶洲島北岸的2個(gè)閘門控制。只要周邊堤壩外的河流水位保持相對(duì)較低，這些潮汐涌就可以在降雨后將水排出島嶼。但是，如果河流中的洪水水位持續(xù)保持高位，或是遇上漲潮，則雨水將無法外流，因?yàn)榈虊瓮獾乃蝗匀桓哂诘虊蝺?nèi)水位。

因此在島嶼的低洼地區(qū)，在洪水沒有破壞建筑物的情況下，具備足夠的蓄水能力是在強(qiáng)降雨下保持可持續(xù)性的一個(gè)極其重要的策略。由于周邊堤防外較高水位所產(chǎn)生的水力梯度的驅(qū)動(dòng)，根據(jù)土壤滲透性，堤防內(nèi)的水也可能會(huì)從土地向上滲透。我們通過將強(qiáng)風(fēng)暴中預(yù)期的降水深度乘以降水所在的區(qū)域來計(jì)算蓄水需求。對(duì)于這種計(jì)算，假設(shè)根據(jù)預(yù)期的高地下水位和土壤飽和條件，滲透到土壤中的水可以忽略不計(jì)。我們使用了1981—2017年在中山大學(xué)測(cè)量的年均24 h最大降水記錄（表1、2）。僅在37年的記錄中，24 h降雨總量超過210 mm的情況已有4次，這表明這種降雨量的頻率大致為10年一次。

根據(jù)這37年的降水頻率分析表明：百年一遇的降水量將為264 mm（岡貝爾極值分布）或265 mm（對(duì)數(shù)皮爾遜分布）。這場(chǎng)百年一遇的降水將帶來多少雨水量？如果以24 h降水量265 mm為例進(jìn)行計(jì)算，則琶東地區(qū)將有1 077 548 m3的雨水待處理（表3）。假設(shè)沒有雨水通過下滲流失（百年一遇的降水來臨時(shí)，預(yù)計(jì)地下水位極高），則所有雨水需要被儲(chǔ)存。那么需要多大的空間來儲(chǔ)存這些降水？若將這些雨水儲(chǔ)存在80 hm2的低洼土地與河涌?jī)?nèi)，則水深將達(dá)到1.34 m?，F(xiàn)有的地形高差基本能夠滿足這個(gè)深度，局部濕地外圍可能需要建設(shè)護(hù)坡堤來防止水流漫溢至建筑物密集區(qū)域。道路、停車場(chǎng)和建筑地下的儲(chǔ)水箱可以作為額外的儲(chǔ)水空間，但這種形式通常昂貴且難以維護(hù)。如果琶東土地被完全開發(fā)，而不保留80 hm2的濕地，那么地下儲(chǔ)水箱將可能是唯一的儲(chǔ)水辦法。洪水將給島上的投資開發(fā)帶來的嚴(yán)重威脅不容小覷。

關(guān)于雨洪的分析對(duì)未來琶洲島土地利用有重要的指示作用。現(xiàn)有的80 hm2低洼土地和河涌如果需要承受1.34 m的水位升高，則應(yīng)足以儲(chǔ)存1 077 548 m3（百年一遇暴雨24 h內(nèi)在琶洲島產(chǎn)生的降水總量）的降水量。相比之下，地下儲(chǔ)水箱則昂貴得多，且易出現(xiàn)故障。若能夠?qū)⑺袕搅鲀?chǔ)存在80 hm2的河涌與其毗鄰的低洼場(chǎng)地中，將得到更為可靠且經(jīng)濟(jì)的蓄水系統(tǒng)。這是應(yīng)當(dāng)保留這80 hm2土地的重要理由。當(dāng)然，由于氣候變化將帶來更嚴(yán)重的暴風(fēng)雨，維護(hù)現(xiàn)有天然蓄水設(shè)施，乃至新建額外的蓄水設(shè)施都是合理的。

2 應(yīng)對(duì)過高水位和涌潮

琶洲島東部沿岸地區(qū)受防洪堤壩的保護(hù)，然而沿岸的堤壩并不完整，并且局部堤防明顯過低。水務(wù)局的防洪標(biāo)準(zhǔn)要求堤壩高出海面8.68 m以上。而北岸島嶼防洪堤的實(shí)際高度僅8.05 m。在東南岸，堤壩高度甚至更低，為7.10 m與6.95 m[1]。東南沿岸的部分地區(qū)甚至沒有堤防，即使是相對(duì)較常見的小規(guī)模水災(zāi)也會(huì)使這些地區(qū)遭遇洪水泛濫問題。2018年9月15日，據(jù)中山大學(xué)驗(yàn)潮站（距琶洲島東部上游約10 km）監(jiān)測(cè)，臺(tái)風(fēng)“山竹”的最高潮位高于平均海平面8.227 m。當(dāng)涌潮和臺(tái)風(fēng)暴雨同時(shí)來襲，降水將無法排出，只能通過水泵使之越過堤壩排入相鄰的泛濫河流，但也可能會(huì)由于洪水淹沒過堤壩而造成大量漫溢。關(guān)于淹沒堤防的一個(gè)關(guān)鍵問題是堤壩的完整性，以及當(dāng)?shù)谭朗r(shí)可能面臨的災(zāi)難性后果——對(duì)人居環(huán)境造成致命危險(xiǎn)的滔天洪水將迅速席卷而來。近幾十年來，所謂“百年一遇洪水”的頻率有所增加[4]。并且隨著海平面上升的加速，即使是海拔8.68 m的連續(xù)完整堤防系統(tǒng)也必須在設(shè)計(jì)中考慮適應(yīng)未來的更高水位。目前尚不清楚水利管理當(dāng)局的防洪堤標(biāo)準(zhǔn)在多大程度上考慮了風(fēng)力驅(qū)動(dòng)海浪，即將堤壩高度提高至高于預(yù)期最高水位（即術(shù)語中的“freeboard”，在美國通常設(shè)為0.9 m）。當(dāng)然，在未來海平面上升和極端天氣模式的情況下，洪水水位上升似乎是不可避免的。因此建議將堤防提高至平均海平面以上至少9.50 m（圖6）。

表1 1981—2017年24 h廣州最大降水量記錄Tab.1 Max daily precipitation Guangzhou (1981—2017)

表2 基于1981—2017年24 h廣州最大降水量記錄的頻率分析Tab. 2 Frequency analysis of precipitation for Guangzhou based on max daily precipitation data from 1981 to 2017

表3 琶洲島東部的徑流計(jì)算Tab. 3 Run-off calculations for the Eastern Portion of Pazhou Island

3 琶洲島上的村莊

黃埔村是琶洲島上6個(gè)最大、最古老的村莊之一。自宋代以來，黃埔碼頭在世界各地的商賈中聞名。清代所有外國船只被禁止通過位于黃埔碼頭東南部的一座島嶼的山坡背風(fēng)面上的一個(gè)天然港口，因此被迫中止了往返琶洲島東南部的行程。帆船乘著6—9月的夏季風(fēng)抵達(dá)這里，并于11月—次年2月期間離開。船只?？奎S埔碼頭期間，貨物被轉(zhuǎn)運(yùn)到舢板上，并被帶到廣州。船舶和索具都可以在黃埔村當(dāng)?shù)剡M(jìn)行修理。與外國船員的接觸支持了村里的產(chǎn)業(yè)發(fā)展，并使之保持開放性，這樣的場(chǎng)景在其他村莊里都是前所未有的。因此，黃埔村與琶洲島上的其他5個(gè)村莊相異，有著獨(dú)一份的鮮明的特質(zhì)。

南部的石基村幾乎是黃埔的附屬。同樣，在廣州環(huán)城高速公路的另一側(cè)，東北面的楊青村則可以看到更多現(xiàn)代發(fā)展的痕跡。這3個(gè)村莊都采用梳式布局，房屋排成排，一幢在另一幢后面排列著。該布局之所以被稱為梳式布局，是因?yàn)橐慌排欧课荻家造籼脼閰⒄掌叫胁贾茫⑶掖怪庇谶\(yùn)河或池塘。這個(gè)布局遵循中國風(fēng)水理論，但也通過引導(dǎo)氣流從較冷的水面流向道路、庭院和房屋的方式來改善微氣候。黃埔村的梳式結(jié)構(gòu)比其他村莊更復(fù)雜。以不同方向面對(duì)池塘和運(yùn)河的祠堂決定了村莊的整體結(jié)構(gòu)[5]。

6 保護(hù)島嶼外圍片區(qū)Protecting the island perimeter6-1 外圍堤防，不同標(biāo)高的平臺(tái)適應(yīng)不同的水位線Perimeter dike with platforms adapting to different water levels6-2 外圍堤防，面向河流側(cè)為斜坡，以減輕溢流Perimeter dike with a slope towards the river to mitigate overtopping6-3 堤防Embankment6-4 浮橋式結(jié)構(gòu)，保護(hù)漁民新村Boardwalk-type structure to protect the New Fisherman’s Village6-5 堤防面向河流側(cè)為大面積緩坡，以防止溢流Dike with extensive slope to prevent overtopping6-6 潮汐涌穿過低洼地帶的主閘口和次級(jí)閘口Tidal slough traverses low-lying land with primary and secondary sluice gates6-7 將水排放到低洼地帶所通過的水閘Sluice gate to allow discharge onto low-lying land6-8 低洼地帶Low-lying land6-9 外圍堤防以外設(shè)置廣泛的可灌溉（可被淹沒）土地Extensive floodable land outside perimeter dike6-10（穿越水面或濕地的）堤道Causeway

與梳式村莊相比，島嶼東端的新洲村遵循嚴(yán)格的線性布局。新洲村與珠江后河道有直接關(guān)聯(lián)。如今的珠江后河道仍然作為跨河、跨海航行的通道被充分利用著。黃埔以北的東圍村地處于歷史悠久的農(nóng)業(yè)片區(qū)中，它的北面是一片菜地，這個(gè)村莊也遵循梳式結(jié)構(gòu)布局（圖7）。

由于社會(huì)和自身方面的原因，漁民新村沒有一個(gè)正式名稱。這個(gè)村莊位于朝南的海岸，因此會(huì)直接暴露于浪潮與臺(tái)風(fēng)的危險(xiǎn)之中。這些村民與琶洲島上的其他社群相隔離，也沒有正規(guī)道路作為連接，只能通過步道和水相連。高達(dá)4層的結(jié)構(gòu)建在船上，水在下方流動(dòng)。漁民新村是疍家人的聚居地，疍家人在粵語中是用來描述“船屋住民”的貶義詞。流行的理論認(rèn)為疍家人是自史前時(shí)代以來居住在中國南方的少數(shù)民族——“百越族”的成員。當(dāng)漢族人在宋代從中國東部遷移到三角洲時(shí)，百越人則流亡到廣闊的河流上，在船只和舢板上生活[6]。村民們現(xiàn)居住于陸地上，但在日常運(yùn)作與宗教信仰上仍與水保持著密切關(guān)系。村里年長(zhǎng)的居民也仍以在碼頭和船只上釣魚為生（圖8）。

琶洲島的東部有一個(gè)造船廠，在20世紀(jì)70年代末改革開放之前曾用于制造漁船。造船廠和工人宿舍現(xiàn)已閑置。目前，一些廠房被改造用于新技術(shù)產(chǎn)業(yè)。島上其他地方的其他輕型制造和后勤設(shè)施已被拆除或重新用于與設(shè)計(jì)有關(guān)的活動(dòng)或其他活動(dòng)。

我們難以準(zhǔn)確估計(jì)6個(gè)村莊的現(xiàn)有人口。因?yàn)榇迩f里包括大量的租戶，他們?nèi)员Ａ艮r(nóng)村戶口，流動(dòng)到廣東尋找就業(yè)機(jī)會(huì)。在我們的設(shè)計(jì)中，按照琶洲東區(qū)未來有30 000居住人口的預(yù)期進(jìn)行設(shè)計(jì)[1]。作為設(shè)計(jì)目標(biāo)，建議保留（并在可能的情況下改善）所有村民的賴以生計(jì)的工作，并避免重新安置現(xiàn)有的租戶。島上的低收入居民就業(yè)機(jī)會(huì)將增加，并為目前年輕務(wù)工人員保留足夠的供出租房屋。如果島上所有可用的土地都用于開發(fā)新的商業(yè)用途，則可能無法滿足該人口預(yù)期下的住房需求?；诖?，筆者于2019年1月進(jìn)行了一次實(shí)驗(yàn)性設(shè)計(jì)。

4 城市設(shè)計(jì)作為檢驗(yàn)政策影響的工具

廣東省和廣州市目前的政策是集中利用琶洲東部作為新興廣州多核心灣區(qū)的就業(yè)中心。地鐵線和輕軌線延伸段的建設(shè)已獲批資金。從琶洲展館到機(jī)場(chǎng)和廣州南站的快速列車線路也在修建當(dāng)中。島上也計(jì)劃增建幾條隧道，以輔助現(xiàn)有的位于島嶼最東端的兩座橋，滿足往來車流量的需求。

在實(shí)驗(yàn)性設(shè)計(jì)中，建議政府不僅應(yīng)支持商業(yè)辦公的開發(fā)，也應(yīng)更多地支持住宅用地建設(shè)，來創(chuàng)造一個(gè)與已建成亟待建成的公交系統(tǒng)充分結(jié)合，而對(duì)汽車依賴性更小的社區(qū)。通過建設(shè)覆蓋全島的公共交通，給出開車出行的替代方案。對(duì)于這2種開發(fā)方案，都假設(shè)未來的商業(yè)和住宅樓面積比將為6∶4。

廣州環(huán)城高速以東總面積306 hm2。黃埔村和歷史港口占地37.5 hm2，二者都受到遺產(chǎn)保護(hù)條例的保護(hù)，應(yīng)從總面積中剔除。黃埔村包含大量“不可移動(dòng)的文物”，它們受到嚴(yán)格的規(guī)章保護(hù)。剩下的5個(gè)村莊占地總面積92 hm2，但受到保護(hù)的級(jí)別與黃埔村并不相同。因此，可以在環(huán)城公路以東開發(fā)270 hm2。如果在環(huán)城公路的西北部增加72 hm2的東圍村土地，可開發(fā)土地總面積將達(dá)到340 hm2。由于政府當(dāng)下已經(jīng)在與東圍村民談判購買村里集體所有的土地，因此將東圍村土地納入規(guī)劃藍(lán)圖是切合實(shí)際的。另一方面，340 hm2土地同時(shí)進(jìn)行開發(fā)也是不現(xiàn)實(shí)的。因此，對(duì)2個(gè)方案進(jìn)行比較：第1種方案將開發(fā)270 hm2，并留下70 hm2作為部分村莊自主發(fā)展用地。第2種方案將170 hm2土地用于開發(fā)，并將保護(hù)所有村莊現(xiàn)有的低洼農(nóng)田。通過對(duì)季風(fēng)時(shí)節(jié)雨洪量的計(jì)算，得出島嶼東部所有適宜蓄水（包括水道、池塘和濕地）的低洼土地的范圍。該類土地面積約80 hm2，是2種方案下對(duì)土地面積利用率的主要差異。2種方案中都采用了相同的建筑覆蓋率與平均容積率（0.25）。

2種方案都使商業(yè)開發(fā)集中在地鐵站附近。方案1在未來的3個(gè)地鐵站周邊都采用了商業(yè)集中開發(fā)模式，形成脊?fàn)罱Y(jié)構(gòu)的超高層建筑群。方案2則在中央地鐵站周圍形成了一個(gè)山丘狀超高層建筑群。擬建的地面輕軌服務(wù)將延伸至島的東端，并可能繼續(xù)延伸形成完整環(huán)狀交通。在2種方案中，輕軌都將為島上的居民服務(wù)（圖9）。

這2種方案在治水策略上有所不同。方案1依賴于道路、開放空間與停車區(qū)域地下的儲(chǔ)水箱儲(chǔ)水。百年一遇的暴雨將會(huì)給琶東帶來1 077 548 m3的降水量。將這些雨水儲(chǔ)存于道路、停車場(chǎng)和建筑地下將需要極大容量且極昂貴的蓄水箱。更可持續(xù)而不易發(fā)生故障的是方案2，它將保留現(xiàn)有的80 hm2河涌與低洼土地來儲(chǔ)存雨水。這80 hm2的低洼土地足以儲(chǔ)蓄上述的所有降水，水深為1.34 m。然而，徑流路徑需要被設(shè)計(jì)以適應(yīng)現(xiàn)實(shí)中水流的集聚，這意味著部分無法及時(shí)排水的地區(qū)需要建設(shè)一些蓄水設(shè)施。地表徑流可以被引流至砂濾器過濾后排入潮汐涌。

5 結(jié)論：應(yīng)對(duì)氣候變化的原因和后果

以上2個(gè)方案都會(huì)遭到當(dāng)權(quán)者的質(zhì)疑。現(xiàn)有的琶洲島東部未來藍(lán)圖中，只有商業(yè)辦公樓的開發(fā)，而沒有新的住宅開發(fā)項(xiàng)目。文中闡述的2種方案都包括了新住宅社區(qū)的建設(shè)。同樣，文中所示的以街道為核心的城市形態(tài)與中國當(dāng)代城市開發(fā)模式并不一致。在我們的設(shè)計(jì)中，以街道為核心的城市形態(tài)，弱化以往特定街區(qū)的單一高層塔樓周圍常見的開放空間。積極地利用街區(qū)外圍的道路將促使人行道更多地被行人使用。該設(shè)計(jì)方案鼓勵(lì)人們沿著綠樹成蔭的街道行走，并且街道兩側(cè)有面向街道的住宅入口或有商鋪開放。住宅與辦公結(jié)合開發(fā)，并提高街區(qū)的步行方便程度，將降低人們對(duì)汽車的依賴性；若兩者共同應(yīng)用，將使琶洲島未來的新發(fā)展更為低碳可持續(xù)。

也許有人會(huì)提出更進(jìn)一步的質(zhì)疑：村莊附近的低洼土地目前被視為未來城市發(fā)展中具有潛力的開發(fā)區(qū)域。然而，如方案2中所提出的保留所有低洼土地用于蓄水的觀點(diǎn)與目前的發(fā)展戰(zhàn)略相矛盾。關(guān)于這一點(diǎn)，在我們的設(shè)計(jì)過程中，的確有人提出，琶洲島的未來發(fā)展應(yīng)符合世界級(jí)標(biāo)準(zhǔn)。世界范圍內(nèi)的三角洲地區(qū)，發(fā)展戰(zhàn)略正在發(fā)生出乎意料的變化[7]。氣候變化要求必須為應(yīng)對(duì)雨洪災(zāi)害而考慮設(shè)計(jì)的適應(yīng)性。這些曾經(jīng)被認(rèn)為極端和罕見的自然狀況，現(xiàn)在更為頻繁地發(fā)生。琶洲島需要的世界級(jí)設(shè)計(jì)，必然應(yīng)長(zhǎng)遠(yuǎn)地為未來可能的災(zāi)害做好準(zhǔn)備。因?yàn)檫@樣的遠(yuǎn)見將有助于預(yù)防實(shí)體層面以及社會(huì)層面上的災(zāi)難。

縱觀歷史，由珠江水系至南海間的平緩坡度[3]使遠(yuǎn)洋航行的輪船能夠到達(dá)位于距離海洋120 km內(nèi)陸上的廣州。每天2次漲潮使船只能夠乘浪上升，而黃埔港的錨地也因此欣欣向榮。未來的每一天仍將潮起潮落，潮水亦會(huì)日復(fù)一日地來到廣州。但由于海平面上升的緣故，海潮之于廣州將由優(yōu)勢(shì)轉(zhuǎn)變?yōu)橐环N負(fù)擔(dān)。在暴風(fēng)雨后，河流系統(tǒng)中更高的水位對(duì)蓄水量的需求將十分巨大。方案1中將270 hm2用于開發(fā)，雨洪防護(hù)幾乎依賴于路面地下的蓄水箱來完成，建造和維護(hù)成本很高。方案2則只允許在170 hm2的土地上進(jìn)行開發(fā)，并保留琶洲島上的80 hm2低洼土地作為濕地以儲(chǔ)存雨水，直至堤壩外水位下降后排放進(jìn)入河流系統(tǒng)中。

根據(jù)實(shí)驗(yàn)，筆者建議采取以下治水策略：

1）在東部琶洲島內(nèi)滿足其自身蓄水需求。

該政策下將保護(hù)目前用作農(nóng)田的所有現(xiàn)存低洼土地。在未來，這片土地將要作為濕地并被設(shè)計(jì)成能夠在暴風(fēng)雨后儲(chǔ)水的形式。這將意味著我們需要重新設(shè)計(jì)琶洲島外圍的水閘和潮汐涌斷面。

2）保護(hù)琶洲島周邊免受浪潮威脅以及預(yù)防洪水淹沒堤壩、海堤或防護(hù)堤。

本策略意味著將島外圍堤壩強(qiáng)制性高度從目前海拔8.68 m提高到海拔9.50 m。外圍防護(hù)的設(shè)計(jì)有多種方式，本文已對(duì)它們進(jìn)行了解釋說明（圖10）。

致謝：

文中所提及的工作內(nèi)容得到了琶洲概念性城市設(shè)計(jì)國際工作坊，孫一民工作室與華南理工大學(xué)的鼎力支持。合著者：Eleni Oikonomaki、Andrew Salmon、施德松、Preeti Shrinivasan、孫思晗、陳碧琳、王登月、薛明琦、朱明熙、懷露、羅苑菁、盧培駿、李凡姝、蔡梓煜，圖像處理：李詩瑤。

圖表來源：

圖1作者梁石友（廣東省中山圖書館藏）；圖2?香港科技大學(xué)；圖3?The Picture Art Collection / Alamy Stock Photo；圖 4?Niday Picture Library / Alamy Stock Photo；圖5～10為作者繪；表1～3為作者繪。

Pazhou island is located between two branches of the Northern Pearl River and the Whampoa Canal in Guangzhou. The island has become part of the city’s financial, media and technology, trading and exhibition district. The ambitions go further to make the island an important center in the emerging Guangzhou, Shenzhen, and Hong Kong, Macao polycentric metropolitan region, referred to as the Greater Guangzhou Bay Area. Since 2003, the island’s central portion has hosted the Canton Fair inside new mega structures, Zhujiang New Town followed to the west of Pazhou Island with the Canton Tower as Guangzhou’s prominent landmark that opened for the Asia Games in 2010. The western portion on Pazhou Island is currently developed into a New Technology and Internet — Media concentration. By contrast,development on the eastern portion of the island is officially characterized as unbalanced with a deteriorating environment and a damaged eco system[1]. This article focuses on the eastern portion of the island. We report on an urban design experiment to test two contrasting development scenarios. The first utilizes all land available on the eastern portion of the island, the second scenario develops only two thirds of the available land and leaves all existing low-lying land undeveloped,to accommodate water from intense typhoonal rains. Both scenarios protect the island from riverine flooding, and tidal surges. We justify our experiment by reviewing the natural and cultural history of Pazhou Island and by computing the water storage needs of the island under the two development scenarios.

The fluvial history of the Pearl River Delta is highly complex. What is now a delta with eight interconnected tidal estuaries, was a shallow inland sea in the second century AD when Guangzhou originated at the northern shore of this large body of water, a bay of the South China Sea. The location for the city was well chosen because Guangzhou originated on the south-facing slope of the Guanyin Mountain, on higher ground above the reach of floods. Through time the inland sea transformed into a hydrographic net of steams and tidal sloughs.Robert Marks (1998) gives a fascinating portrait of the region in hisTigers, Rice, Silt and Silk:Environment and Ecology in Late Imperia.Taking a long range view into the past, the book documents how the riverine environment was shaped by natural forces and anthropogenic changes. Tigers are mentioned in the title of the book, because the land around the delta was once densely forested,and tigers lived on in place names and village folklore. Rice is because of the prosperous rice growing culture (supporting two harvests a year) that flourished in the dike and pond landscape created by farmer-built levees. The rivers transported silt from the mountains. Farmers used the material and cultivated more and more flat and easy to cultivate islands. Lastly in the Qing Dynasty, the silk industry emerged utilizing leaves from Mulberry trees that farmers planted on the levees[2].

Many islands grew as deposits in the lee of rock outcrops. Pazhou Island is such an island,alluvial deposits having accumulated between two outcrops. One outcrop served as the foundation of the Ming Dynasty Hai-o, or Pazhou, Pagoda, which was one of three pagodas that directed sailing ships on their ascent up the Humen (Tigris) Estuary to Whampoa Harbor (Fig. 1, 2). Whampoa Village,just above the historic port, occupies the second rock outcrop. Whampoa was not strictly speaking an agricultural village; it was a settlement oriented to trade with foreigners. Here cargo was transloaded onto sampans and shipped further inland on rivers and canals (Fig. 3, 4).

7 5個(gè)村莊及它們毗鄰的低洼地帶都在圖中展示出來。低洼地區(qū)的總面積，包括方案2中的“中央公園”，面積為80 hm2The five villages are shown with their associated low-lying land. The land area of all low-lying land, including the“central park” in Scenario TWO amounts to 80 hm27-1 楊青村Yangqing village7-2 東圍村Dongwei village7-3 石基村Shiji village7-4 新洲村Xinzhou village7-5 漁民新村New Fisherman’s village 7-6 黃埔村Whampoa village

1 Living with Rain Water and Floods

Throughout history floods changed the contours of the island’s shore. Records from the Qing Dynasty report 44 major floods from 1736 to 1839[3], an average of a major flood every 2.4 years. These floods carried sediments from the river basin, much of which was deposited in the delta reaches such as Guangzhou. The floodwaters rearranged previously deposited sediments, so that island shapes and extents changed with each large flood. The resulting alluvial islands are low-lying and continue to be subject to flooding.

Like other low-lying alluvial islands in the Pearl River Delta, Pazhou Island is threatened by floods from two sources: local urban floods from intense rains (“in-flooding”) and overtopping of protective dikes by high river stage or storm surge(“out-flooding”). Protecting against these two distinct threats requires different strategies. The first type of flood is essentially a matter of more rain falling than can be drained away, resulting in urban “street flooding”. During high river stage or high tide, the eastern portion of Pazhou Island functions like a bathtub, protected by levees on the north, east and south sides. Because water levels outside the levees are higher than the land inside the levees, it is not possible to drain out all the accumulating rain water. Pumps can be used, but pumps may not be sized to keep up with the rate of water accumulation during intense rains, and without reliable emergency generator power, pumps become useless in the event of power failure.

8 海堤對(duì)漁民新村的保護(hù)（設(shè)想手繪圖，基于謝光源拍攝的無人機(jī)照片繪制）Protection of the New Fisherman’s Village by a seawall. (Sketch based on a drone photo by Aaron Xie)

During intense rains, run-off from a land-area of approximately 400 hm2is now absorbed by six sizeable tidal sloughs that dissect the eastern portion of Pazhou Island (Fig. 5). The sloughs generally run in a diagonal pattern through former and still used agricultural fields. The Nianfeng Tidal Slough in the south east is still lined with trees and shrubs on levees. Depending on tidal action, this slough has a two directional flow to its outlets on both sides of the island, where tidal flow can be controlled by mechanically operated sluice gates. In the past the Xinzhou and Hexing Tidal Sloughs connected to the Whampoa Village perimeter canal. Both sloughs meet the Nianfeng Slough, and together they drain the south facing slope of Whampoa Village. The north facing slope of Whampoa Village drains into the Da Tidal Slough and Sand Tidal Slough, where tidal flow is also controlled at two sluice gates on the island’s northern shore. These tidal sloughs work well to drain the island after rains so long as river levels outside the perimeter dikes remain relatively low. However, if flood stage in the river persists, and during tidal surge,rain water cannot drain because the water level outside the dikes remains higher that the water level within.

Thus having the capacity to retain to retain water in low-lying areas of the island can be a critically important strategy to survive intense rains without floodwaters damaging buildings.Depending on soil permeability, there could be seepage of water upward from the ground, driven by the hydraulic gradient created by the higher water levels outside the perimeter dikes. We have calculated the water storage needs by multiplying the depth of precipitation expected in an intense storm by the area over which the precipitation falls. For this calculation, we assume infiltration of water into the soil would be negligible, in light of the anticipated high water table and saturated soil conditions. The 37-year record of annual maximum 24-hour rainfalls from 1981 to 2017 (measured at Sun Yat-sen University, Tab. 1, 2) shows that 24-hour rainfall totals have exceeded 210 mm four times, suggesting such rainfalls are roughly decadal in return frequency.

9-1 方案1：利用270 hm2Scenario ONE utilizing 270 hm29-2 方案2：利用170 hm2Scenario TWO utilizing 170 hm2

What volumes of rainwater can we expect in this 100-year rainfall? A 24-hour rainfall of 265 mm over eastern Pazhou Island yields 1,077,548 m3(Tab.3).Assuming no water lost to infiltration (given the high water table likely during 100-year storm conditions),this full volume of water needs to be stored. We next ask how much room is required to store this water. Spreading this 100-year storm volume over the existing 80 hm2of slough and low-lying land would result in an average water depth of 1.34 m.The existing topographic differences between higher areas and the low-lying lands are sufficient that in most cases the water can be contained by existing topography, elsewhere small berms would be needed around the margins of the wetlands to prevent overflow into built-up areas. Additional storage could be developed in underground galleries beneath roads, parking lots, and buildings,but this storage would be expensive to build and more prone to malfunction in operation. If eastern Pazhou Island were to be fully built out, without preserving the existing 80 hm2of wetlands,such underground storage would seem the only remaining option to manage this stormwater.The stormwater cannot be ignored without grave threat to investments on the island.

Our analysis of storm water leads to an important implication for future land use on the island. The existing 80 hm2of slough and adjacent low-lying wetland, if flooded to an average depth of 1.34 m, should be sufficient to store the 1,077,548 m3of rainwater accumulated over a 24-h period in the 100-year storm. Storing water in underground culverts and reservoirs would be expensive, and would be more prone to failure than preserving wetlands to store water. If we can retain all the runoff in the 80 hm2of sloughs and adjacent lowlying land, the greater reliability and decreased costs seem like strong arguments for preserving them. In light of more intense storms anticipated with climate change, it would make sense to preserve existing natural storage and to build additional storage.

2 Protecting Against High River Levels and Tidal Surge

The perimeter of eastern Pazhou Island is protected from riverine flooding by dikes, but the perimeter of dikes is incomplete, and in places evidently too low. The water authority’s flood control standards call for a levee with an elevation of 8.68 m above sea level. The actual elevation of the flood control dike on the islands northern shore is only 8.05 m. On the south-eastern shore the levee elevations are even lower at 7.10 m,6.95 m[1]. In some places along the south-eastern shore, dikes do not exist, exposing these areas to flooding in even relatively small, frequent floods.The highest tide during typhoon Mangkhut on September 15, 2018 reached 8.227 m above mean sea-level at the Su Yat-sen University tide-gauge station, about 10 km upstream of eastern Pazhou Island). In a combined tidal surge and typhoonal storm event, with rainfall having nowhere to go except to be pumped up and over dikes into the adjacent flooding river, the dikes could overtop and extensive flooding could result. A critical issue with overtopping dikes is the integrity of the dikes, and the danger of their failing catastrophically, releasing a fast-moving wall of water that would be lethal to human settlements. In recent decades the frequency of so-called “100-year floods” has increased[4],and with acceleration of sea-level rise, even a continuous dike system at 8.68 m elevation would have to designed to be adapted to higher elevations in the future. It is not clear to what extent the water authority’s standards for flood control dikes include consideration for run-up of wind driven waves, commonly accounted for by increasing the levee height over the anticipated water level. (Height above the expected water surface is often termed“freeboard” and is commonly set at 0.9 m in the US.). Certainly under future conditions of higher sea level and greater extremes in weather patterns,higher flood levels seem inevitable. We therefore recommend to raise the dikes to at least 9.5 m above mean sea level (Fig. 6).

3 The Villages on Pazhou Island

Whampoa Village is the largest and oldest of the six villages on Pazhou Island. Since the Song Dynasty, the anchorage at Whampoa was well known to mariners around the world. During the Qing Dynasty all foreign ship were forced to terminate their journey to the south-east of Pazhou Island at a natural harbor in the lee of hills located on an island to the Southeast of the Whampoa anchorage. Sailing ships would use the monsoon winds to arrive here between June and September and depart in November to February. During their time at the anchorage cargo was trans-loaded to sampans and taken to Guangzhou. Ships and riggings were repaired locally at Whampoa village.The contact with foreign crews supported a local industry and an openness to the world different from what could be expected in rural villages elsewhere. As a result, the character of Whampoa Village remained distinct and different from the other five villages on Pazhou Island.

Shiji Village to the south is virtually attached to Whampoa. Likewise, across the elevated Guangzhou Beltway, Yangqing Village to the north east is integrated with more recent development.All three villages follow a comb shaped layout with houses constructed in rows, one behind the other.The layout is referred to as combs because the rows are organized in parallel lines following ancestral halls and arranged perpendicular to perpendicular to canals or ponds. The layout follows Chinese geomancy, but also provides improvements to micro-climate by allowing for an ambient windflow to move from the cooler surface above water to the lanes, courtyards and homes. The comb structure of Whampoa Village is more complex than in other villages. Ancestral halls with varied orientations to ponds and canals gave shape to the overall structure of the village[5].

In contrast to comb shaped villages, Xinzhou Village on the eastern tip of the island follows a strictly linear layout. This village has a direct relationship to the Zhujiang Back Channel, which is still heavily used by river and ocean going navigation. Dongwei Village to north of Whampoa exist in the historically agricultural setting with vegetable fields to the north. This village also follows the comb structure layout (Fig. 7).

Remarkable for social and physical reasons,the New Fisherman’s village does not have a proper name. Located on the south facing shore this village is directly exposed to tidal surge and typhoonal rain events. The villagers live isolated from the communities on Pazhou Island, not connected by formal roads, but connected only by foot-path and water. Structures of up to four stories in height are built on pylons with water flowing below the ground floor. The fishing village has the reputation of being home to Tanka people, a derogatory label used in Cantonese to describe “Boat Dwellers”. The prevailing theory considers the Tanka as members of an ethnic minority known as Baiyue who lived in Southern China since prehistoric times. The Baiyue people took refuge in the extensive river system to live on junks and sampans, when Han Chinese migrated to the delta from eastern parts of China during the Song Dynasty[6]. The villagers live now on land but maintain a strong functional and probably also a ritual relationship to the water. Fishing from jetties and boats continues to provide income to the older village members (Fig. 8).

The eastern portion of Pazhou Island included a shipyard where fishing boats were built prior to the opening of China’s economy in the late 1970’s. The shipyard and the dormitory for its workers stays empty. Some buildings are currently repurposed for new technology industries. Other light manufacturing and logistics installations elsewhere on the island have been demolished or repurposed for design-related or other activities.

An accurate estimate of the current population in all six villages is difficult to obtain because of the large number of residents who rent living space in the villages, but maintain their residency registration in the rural districts from where they migrated to Guangdong Province in search of employment. During our work we used estimates of 30,000 inhabitants on the eastern portion of the island[1]. As a design objective,we propose to preserve (and where possible improve) the livelihood of all villagers, and avoid the relocation of the current rental population.Jobs on the island for lower income residents will become available and the current housing needs for a younger working population require the retention of sufficient rental units. It may not be possible to meet the housing needs of this population if all land available on the island is developed for new commercial land-use. This last observation brings us to the design experiment we conducted in January of 2019.

4 Urban Design as the Tool to Tests the Implication of Policy

10 一組闡述琶洲島蓄水策略的詳細(xì)示意圖A set of detailed drawings that illustrate water-storage strategies on Pazhou Island10-1 雙車道與地下儲(chǔ)水箱Storage vaults under a dual-lane road10-2 三車道與地下儲(chǔ)水箱Storage vaults under a 3-lane road10-3 六車道與地下儲(chǔ)水箱Storage vaults under a 6-lane road10-4 抬高的道路Elevated roadway10-5 與低洼河涌相鄰的雙車道Dual-lane roadway with slough10-6 河涌?jī)蓚?cè)的單車道Two one-way roadways with slough

The current policy of Guandong Province and the City of Guangzhou is to intensively use the eastern portion of Pazhou as an employment center in the emerging Guangzhou Polycentric Bay Region. Funding is committed for extensions of the Metro and light rail system. Rapid train service is under construction to connect the exhibition pavilions on the island to the airport and to Guangzhou’s new South Railroad Station. Several roadway tunnels are also planned to support vehicular access that is currently limited by the capacity of the island’s two easternmost bridges.

In our design experiment we recommended that the government not only permit commercial office development, but also include residential use to create a community that is less automobile dependent and more related to the significant transit investments that have already been made and are committed in the future. Distances on the island are manageable for transport that is alternative to single occupancy automobile traffic.For both development scenarios we assumed a 60 to 40 percent split between future commercial and residential floor space.

A total of 306 hm2is located to the east of the Guangzhou Beltway. The 37.5 hm2that Whampoa Village and the historic port occupy need to be subtracted. Both are protected through heritage conservation. Whampoa Village includes a large number of “immovable cultural relicts”,which are subjects to strict preservation rules. The five remaining villages occupy a total of 92 hm2of land, but do not necessarily enjoy the same protection. Thus 270 hm2could be developed to the east of the Beltway. If we add the 72 hm2of Dongwei Village land to the north-west of the Beltway, the total developable land would amount to 340 hm2. It is realistic to add the Dongwei Village land as the government is currently negotiating with the Dongwei villagers to purchase their collectively owned land. On the other hand,it might be unrealistic that all 340 hm2would be developed at once. We therefore decided to compare two development scenarios, one based on 270 hm2that would leave 70 hm2for “autonomous”upgrading of some villages. The second scenario utilized 170 hm2for development and would preserve all villages with their low-lying agricultural land. Informed by our calculation of flooding from torrential rains during the monsoon season, we computed the extent of all low-lying land on the eastern portion of the island that is suitable for water storage in the form of waterways, ponds and wetlands. This land includes approximately 80 hm2and accounts for the main difference in land area utilization between the two scenarios. The land coverage by buildings and the average floor area ratio of 1∶4 were kept the same for both scenarios.

Both scenarios concentrate commercial development around metro stations. Scenario ONE does so in utilizing the land around all three future station, thus creating a ridge like configuration of high-rise structures. Scenario TWO creates a hill configuration around the central metro station.The proposed surface light rail trolley service will continue to the eastern tip of the island and possibly beyond to form a loop. The light rail will serve the residential communities in both scenarios (Fig. 9).

The two scenarios differ with regard to water management strategies. The 100-year rainstorm of 265 mm (over 24 h) would yield 1,077,548 m3of water over the eastern Pazhou Island. Storing such volumes under roads, parking lots, and buildings (Scenario ONE) would be a massive and expensive undertaking. More sustainable and less prone to failure would be Scenario TWO, which would retain the existing 80 hm2of sloughs and low-lying land to store stormwater. The entire volume of the 100-year,24-hour storm could be accommodated by the 80 hm2of low-lying land with an average depth of 1.34 m. However, the likely flow paths would need to be modeled to properly account for actual accumulations of water, which might require some constructed storage in some areas that could not drain to the sloughs quickly enough. Road runoff could be directed to sand filters into the -sloughs.

5 Conclusion: Responding to the Causes and Consequences of Climate Change

Both development scenarios for the eastern portion of Pazhou Island will be met with skepticism by the permitting authorities. Only commercial office development and no new residential development is currently envisioned for the eastern portion of Pazhou Island. Both scenarios shown here include new residential communities. Likewise, the street oriented urban form illustrated here is not consistent with the contemporary development process in China.Our urban blocks with their street oriented urban form ignore the customary open-space around a single high-rise tower on a given urban block. In our view, however the active use of streets around the perimeter of urban blocks is necessary in support of pedestrian activities on sidewalks. The designs illustrated here encourage walking along tree-lined streets that have an active frontage with entrances to residences and commercial activities.The inclusion of residential uses with office development and greater walkability will lower automobile dependency; both together will reduce the carbon footprint of new urban development on Pazhou Island.

Skepticism will go further: the low-lying lands near villages are currently viewed as opportunity sites for future urban development.The preservation of all low-lying land for water storage purposes, as shown in the second scenario,contradict current development strategies.During our work, we were reminded that future development of Pazhou Island should meet worldclass standards. In delta regions world-wide,development strategies are changing in ways that have not been considered in the past[7]. Climate change will call for adaptability of designs to anticipate flooding conditions. These conditions,once considered extreme and rare, are now more frequently occurring. A world-class design of Pazhou Island would take a long range view that prepares urban districts for catastrophic events,simply because such foresight will help prevent physical and social disasters.

Throughout history, the extremely low gradient of the Pearl River system towards the South China Sea[3]allowed ocean going vessels to reach Guangzhou, 120 km inland from the sea. The twice daily incoming tide made that ascent possible, and the anchorage at Whampoa harbor thrived. In the future high tides will continue to reach Guangzhou, but rising tides due to sea-level rise will turn this historic advantage into a liability. Higher water-levels in the river-system will require substantial water storage capacities after storm events. The first scenario that makes 270 hm2available for development would depend on extensive storage vaults below all streets which are costly to construct and to maintain. The second scenario would only allow development on 170 hm2and preserve 80 hm2of low-lying lands on Pazhou Island to serve to store run-off water until it can be discharged after the water level in the riversystem outside the levees recedes.

As a result of our experiment we recommend the following water management policies for consideration:

1) Manage Water Storage Needs Locally on the Eastern Portion of Pazhou Island.

Implied in this policy is the preservation of all existing low-lying land that is currently used as farmland. In the future this land will be needed as wetlands to be designed for water storage after typhoonal storm events. The work will imply a redesign of the sluicegates around the island perimeter and a redesign of tidal slough cross-sections.

2) Protect the Perimeter of Pazhou Island from Tidal Surges and the Associated Over-Topping of Levees, Sea-walls or Embankments.

Implied in this policy is the raising of the perimeter elevation from the currently mandatory 8.69 to 9.5 m above sea-level. A variety of perimeter designs are possible, and they have been illustrated in this article (Fig.10).

Acknowledgments:

The work described in this article received generous support from the International Conceptual Urban Design Workshop for Pazhou Area, Professor Sun Yimin’s Studio,South China University of Technology.

Co-authors: Eleni Oikonomaki, Andrew Salmon, SHI Desong, Preeti Shrinivasan, SUN Sihan, CHEN Bilin,WANG Dengyue, XUE Mingqi, ZHU Mingxi, HUAI Lu,LUO Wanqing, LU Peijun, LI Fanshu, CAI Ziyu, and image processing by LI Shiyao

Sources of Figures and Tables:

Fig.1 by Liang Shiyou (Guandong Provincial Zhongshan Library); Fig. 2? Hong Kong University of Science and Technology; Fig. 3? The Picture Art Collection / Alamy Stock Photo; Fig. 4? Niday Picture Library / Alamy Stock Photo; Fig. 5-10 by authors; Tab.1-3 by authors.