Thailand: Fighting floods with 'sponge cities'
By Ignacio Ortinez, Matthew McCartney and Priyanie Amerasinghe
Bangkok and other Thai cities are seeing serious floods with increasing regularity. Udon Thani, one of the major cities in the northeast region of Isan, has been a prime target. Almost every year during the monsoon, the city's drainage system is overwhelmed. Large areas are inundated, homes and other buildings are flooded, and roads become impassable. Because sewage mixes with flood waters, city flooding brings increased health risks -- so there is a direct human, as well as a financial, cost to the flooding.
As with many Thai cities, Udon Thani continues to grow rapidly and solutions are urgently needed to alleviate the increased flood risk. The Bangkok-based planning and design firm estudioOCA has a vision for the future of Udon Thani as a "green" city, mitigating flooding by using natural infrastructure, as it is known, including wetlands, trees and parks. In a year-long project, landscape architects, engineers and scientists have tested the feasibility of natural infrastructure to soak up excess water. Using a hydrological model, in combination with design and engineering tools, they have designed a natural infrastructure network that links green areas across the city. This work has shown that the wetlands and green areas "buffer" water flows; reducing flooding by slowing water flow during storms and increasing infiltration. In essence, they act as a sponge to mop up floods before they occur.
Research in Asia by the International Water Management Institute (IWMI) has highlighted the value of urban wetlands, particularly for the urban and suburban poor. For example, wetlands within the city boundary of Hyderabad in India support the growing of rice, vegetables and cattle fodder that are sold in the city markets -- a major contribution to the livelihoods of many subsistence farmers. Similarly in India's northeast, the wetlands of Kolkata not only help reduce flooding in the city, but also support 32,000 people who fish for a living – all while treating the city's sewage.
In recent years, urban development in Thailand and most of Southeast Asia has largely outpaced proper urban planning. Now is the time to recognise that wetlands are an integral part of urban landscapes; a key component of natural infrastructure that provide numerous benefits. As such they must no longer be neglected. Wetlands must be incorporated explicitly in urban planning. The vision for Udon Thani illustrates what can and must be done. Using wetlands to create "sponge cities" is a crucial step on the way to the greener, healthier and less flood-prone cities of the future.