2020年1月10日 俞孔堅攝於泰國曼谷
運河曾是泰國首都曼谷生命機體的血脈，也是為城市提供源源不斷生態系統服務的基礎設施，與水為友、與水相適應的水上社區與街市應運而生。但近年來對機動車出行的依賴和水系連通性的人為阻斷，終結了城市與自然的共生關係，曾經繁榮的水上社區日漸凋敝。
基於自然，讓自然做功：
國土空間規劃與生態修復之本
俞孔堅
哈佛大學設計學博士；美國藝術與科學院院士；
北京大學建築與景觀設計學院教授
原文刊發時間：2020年2月
近兩個月來，我頻繁造訪了世界上人居環境頗具挑戰性的三個城市：墨西哥首都墨西哥城、孟加拉國首都達卡，以及泰國首都曼谷。
在墨西哥城，我隨當地的城市研究專家、國家水務局及市水務局的主管沿著溪流谷地走街串巷、長途踏勘。在溪流的源頭山林，我感受到了溪水的清澈與涼爽；而進入城市後，水流則變得渾濁並散發著惡臭；貪婪的城市建築和道路將溪谷脅迫得只留下一條窄縫；為應對季節性洪水的威脅，城市不得不斥巨資渠化河道、高築河堤，將本可優美流淌並給城市帶來巨大福祉的溪流直接排入粗大的水泥管道中，囚禁於黑色中窒息而亡，隨後與汙水一起從城市的另一端排出。各方人士對目前惡化的人居環境幾乎都束手無策，因而不得不跨流域調水以滿足城市供水需求，同時投資建設更龐大的管道系統。於是，灰色的鋼筋水泥工程不斷覆蓋綠色的自然生態基礎設施，自然的自我調節功能逐漸喪失，熱島效應加劇。這個曾經漂浮在湖泊中的城市，幾乎已經耗盡來自高原湖泊的水資源，接著又吸乾了地下水，導致城市逐年下沉[1]。由於地下水得不到補充，阿茲特克人富有特色的水上田園消失殆盡。
墨西哥城的城市河渠 俞孔堅
在達卡，剛下飛機的乘客隨即會被警告不能直接飲用自來水，因為幾乎所有的地表水都已遭到汙染，管道中的自然水源也無法保證未被汙水滲透[2]。隨後，在當地嚮導的引導下，我參觀了當地所謂環境最好的社區。這是一個安保森嚴的封閉社區，社區周邊的公園是達卡市中心唯一可觀的公園。公園中原有的河流被切割成孤立的水泊，黑臭水體經由汙水管道源源不斷地排入其中。在入水口處，水面露出一排魚嘴，魚兒們在掙扎地呼吸。儘管政府花費了很大的精力進行治理，卻收效甚微。然而，來此鍛鍊的人卻絡繹不絕，他們就如同探出水面拼命呼吸的魚兒一般，這裡成為了他們僅有的喘息之地。籌建中的新城選址於水泊對岸的田野上，這裡是平坦低洼的河漫灘，每逢雨季都會被兩米深的水流淹沒，偶爾會形成幾處長滿樹木的孤島，被奉為神聖的宗教場所。平原之上是蜿蜒的線性人造高堤，村莊大多建設於此，堤腳下是因取土而形成的水塘，兼做旱季水源之用。這一派田園牧歌的景象與隔河相望擁堵不堪的達卡市區相比，真有天壤之別。
擁堵不堪的達卡市區和嚴重汙染的城市河流 俞孔堅
在曼谷，我有幸參與了近年來當地最大的一項人居環境建設工程—政府付出巨大代價，遷出了一處有近一個世紀歷史的制煙廠，並將場地開闢為森林公園。然而，這樣的城市生態修復工程對這個擁有一千多萬人口的特大城市來說，無異於杯水車薪。來自世界各地的遊客大多被那些風情獨特的佛塔和寺廟所吸引，或迷戀於無微不至的泰式服務。當走出瀰漫著異國香水的酒店大堂，來到建築後方的街道或運河旁，一種完全不同卻更為真實的曼谷的氣息撲面而來。於是我踏上了別樣的考察路線，在當地專家的帶領下，乘船沿古老的運河深入城市和郊區，感受最真實的泰國。運河曾經是曼谷生命機體的血脈，有數百年歷史的寺廟不時映入眼帘，但兩岸的果園大多已荒廢，民房和商鋪凋敝，一些曾經的豪宅也因久無人煙而被熱帶植被所覆蓋。我心生疑惑，為什麼這樣有特色的水上街市衰敗如此？專家告知，這些運河原本非常繁榮，也是當地最受青睞的旅遊勝地[3]，但政府為了保護居民免受洪水危害，在河口修建了許多閘門，此舉在阻擋洪水的同時，也犧牲了行船的便利，因此遊客不再光顧，居民也遷至他方。另外，陸路交通和汽車的發展也取代了這座城市對水上交通的依賴，原本與水共生且獨具曼谷特色的水上社區和街市更為荒廢，隨之而來的城市道路擁堵和大氣汙染也日益加劇。
曼谷現已沒落的水上街市 俞孔堅
以上三個城市的魅力都在於城市與自然的和諧共生，而這一魅力的消失，或者說是悲劇的產生，都緣於和諧關係的終結—不論是阿茲特克人的水上田園，與洪水相適應的達卡聚落，還是曼谷的水上街市：城市建設侵佔湖泊及河流等關鍵自然系統空間；城市盲目擴張，超越了自然的承載力；過分依賴基於工業文明的灰色基礎設施，導致河道等生態基礎設施廢棄，可持續的生態系統服務隨之消失。究其本質，所有這些都是國土空間的規劃問題，其核心和關鍵是如何在自然基底中為發展中的城市選址，以及如何在城市的基底中保留和完善生態基礎設施，使其為城市提供高品質的生態系統服務。
緊接著的問題是，如何挽救由於人類的短視、無知或高傲而帶來的城市現狀，以及如何修補已經不適宜人類居住的城市。其核心是修復城市中的自然系統，包括為自然爭取更多的空間，重建「山水林田湖草」生命共同體的連續性和完整性，以及讓自然系統充分發揮生態系統服務。
國土空間規劃和生態修復之根本是讓自然做功，並收穫自然所提供的免費生態系統服務。這是人類福祉的基礎，也是城市可持續發展的根本出路。
以下為文章英文版本
引用格式及所在主題刊詳細信息見文末
Work withand by Nature:
The Essence of Territorial Spatial Planningand Ecological Restoration
YU Kongjian
Doctor of Design at Graduate School of Design, Harvard University; Honorary Foreign Fellow of the American Academy of Arts and Sciences; Professor of College of Architecture and Landscape, Peking University
Over the past two months, I have visited three cities facing severe and challenging living environment: Mexico City, Dhaka, and Bangkok, capitals respectively of Mexico, Bangladesh, and Thailand.
In Mexico City I was accompanied by local urban experts and heads from national and municipal water authorities to make a long site survey along the river valley. At the source of the river in the mountains, I enjoyed the clear and cool stream water. But, entering the city, the river became turbid and stinky. Sprawling urban buildings and roads transformed the meandering river into a narrow channel. Facing seasonal flooding, the city invested generous funds to channelize the river with high levees. The river that was once beautiful and had brought great benefits to the city now is imprisoned in thick concrete, dark pipes, drained as sewage. At the end of wits, the city is constructing a larger pipeline system to transfer water from other basins, as a costly solution to the deteriorating living condition, to meet the city’s daily need. Now any green ecological infrastructure is covered with reinforced concrete, degrading the river’s ability to self-regulate and causing severer heat island effect. The city, once surrounded by lakes, has almost used up its groundwater and the water from the adjacent sources and is suffering from subsidence year by year[1], not to mention the erased cultural landscape of the indigenous Aztecs.
In Dhaka, visitors are warned not to drink the tap water because the surface water, as well as the water from natural sources conveyed by municipal pipes, is almost contaminated[2]. Led by the local guide, I visited a gated community, thought to have the best living environment in the country, that was heavily fortified away from its surrounding. The park nearby the community was the only green space in central Dhaka. The river that passed through the park had been cut into isolated ponds, full of dark and stinky water. Rows of fish mouths emerged at the water inlet — the fish were struggling to breathe. Despite the great effort the government has made in water management, very little has affected. Surprisingly, large numbers of people come to the park, like the fish reaching their mouths out of the water trying to breathe. The park was the rare place where they could get relieved. A new city is in the works on the other side of the river, where currently a low-lying floodplain is often inundated with water two-meter deep in the rainy season. Occasionally, several tree-covered islands emerge and are regarded as sacred religion spots. A constructed levee separates villages from the floodplain. At the base of the levee there is a pond formed by the excavated dirt. It serves as the water source for the villages during the dry season. This idyllic scene and lifestyle is dramatically different from the crowded Dhaka across the river.
Finally, in Bangkok I revisited an urban design project of my team, which is also one of the largest resettlement projects in the city in recent years. The government relocated a 100-year-old tobacco factory and transformed the site into a forest park. However, such an urban ecological restoration action is utterly inadequate for a city with a population of over 10 million. Tourists from all over the world enjoy Bangkok’s rich architecture and culture a lot — the unique pagodas and temples, or the meticulous Thai service. However, when I walked out of fancy hotels with exotic aroma in the air, I experienced a completely different and more authentic Bangkok when passing through the streets and along the canals. Guided by local experts, I took a boat along an ancient canal that was once the lifeblood of Bangkok. Besides the temples with hundreds of years of history, what came into my view were the abandoned orchards on both sides, obsolete residences and stores, and derelict mansions covered by overgrown tropical vegetation. I wondered why such a unique water corridor had declined. Our guides explained that the canal was once the most popular destinations in the area[3]. However, to protect the local residents from floods, the government built estuary gates that resisted floods but also limited boating. As a result, tourists no longer came and the locals had moved elsewhere. Worse, auto infrastructure had replaced water transportation, and, along with the declined floating communities and markets, Bangkok is suffering from an increasing congestion of urban roads and heavy air pollution.
All of the three cities have strong historical connections with nature. Yet, in each the relationship has been cut off, whether it is the loss of the Aztec floating gardens, the decline of Dhaka settlements that can accommodate floods, or the fading of Bangkok’s floating markets. As urban construction encroaches on key natural systems, including lakes and rivers, urban growth often overpowers natural resiliency. In these cases, cities begin to rely on grey infrastructure rather than ecological infrastructure, resulting in a loss of sustainable ecosystem services. Cities must become better at territorial spatial planning and have the foresight to develop and grow while preserving and improving existing ecosystems.
The next question is how do we remedy the current urban challenges resulted from humans』 shortsightedness, ignorance or arrogance, and how do we repair urban landscapes that are no longer suitable for human inhabitation? The answer is to restore the natural systems in cities by preserving more room for nature; to restore the continuity and integrity of the natural system of mountains, waters, forests, fields, lakes, and grasslands; and to help maximize the ecosystem services of these natural systems.
Essentially, territorial spatial planning and ecological restoration is to work with and by nature that would provide generous ecosystem services for humans, and, eventually, to increase people’s well-being and enhance cities』 development of sustainability.
參考文獻
[1] Lemon, J. (2018, September 14). Mexico city is sinking while also running out of drinking water. Newsweek. Retrieved from https://www.newsweek.com/mexico-city-sinking-while-also-running-out-water-1122482
[2] Hasan, M. K., Shahriar, A., & Jim, K. U. (2019). Water pollution in Bangladesh and its impact on public health. Heliyon, 5(8), e02145. https://doi.org/10.1016/j.heliyon.2019.e02145
[3] Batra, A. (2014). Floating markets: Balancing the needs of visitors as a tourist attraction and locals way of life. A case study of Talingchan floating market, Bangkok Thailand. International Journal of Hospitality and Tourism Systems, 7(2), 1-8.
END
Source:
Yu, K. (2020). Work with and by Nature: The Essence of Territorial Spatial Planning and Ecological Restoration. Landscape Architecture Frontiers, 8(1), 4-9. https://doi.org/10.15302/J-LAF-1-010006
翻譯丨薩拉·雅各布斯 張健
製作丨田樂