墨西哥城的城市河渠 ? 俞孔堅
擁堵不堪的達卡市區和嚴重污染的城市河流 ? 俞孔堅
曼谷現已沒落的水上街市 ? 俞孔堅
Work with and by Nature:The Essence of Territorial Spatial Planning and Ecological Restoration
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, 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. 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. 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.
 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
 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
 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.