Asian cities are struggling to handle the influx of urbanization, and the growth is expanding into flood-prone regions. The recent floods in Mumbai were blamed partly due to an unregulated expansion of wetlands, and the construction of hurriedly constructed cities is affected by floods all over India, Nepal, and Bangladesh. This isn’t a trend just in the developing world; floods in Houston, USA, highlighted the dangers of growth in areas that are environmentally sensitive and low-lying. A massive storm in Beijing destroyed the city’s transportation infrastructure, and in 2016, floods caused flooding to the drainage system at Wuhan, Nanjing, and Tianjin. The issues are evident.
Waterway degradation, groundwater over-extraction, and urban flooding are forcing cities in China to confront the vicious cycle. Urban sprawl and the use of waterproof materials hinder soil from absorbing rainwater whi, which is causing further investment in infrastructures that typically impede natural processes and intensify flooding impacts.
“China’s “sponge city initiative” aims to stop this cycle by the use of permeable pavements and green infrastructures. However, the plan is facing two obstacles: the inexperience of local authorities to effectively manage and integrate this complex array of activities and financial constraints.
The idea
Engineering solutions are a popular way to address the issue, but they aren’t able to eliminate flood risk by piping it away. To deal with the problem, the Chinese Sponge City initiative has a lofty objective: by the year 2020, 80 percent of urban areas will absorb and recycle 70 percent of the rainwater.
In 2015, the initiative was launched across 16 towns. The initiative aims to lessen the impact of rainwater runoff by enhancing the capacity for absorption and spreading it more evenly across the targeted areas. The resultant groundwater replenishment improves the availability of water for a variety of applications. This strategy not only helps reduce flooding but also enhances the security of the water supply.
The idea is akin to the North American concept of low-impact development (LID), which, according to the United States Environmental Protection Agency (EPA), mimics natural processes to ensure the quality of water.
The situation of Lingang, an urban plan in Shanghai’s Pudong district, shows typical city-wide measures of sponge construction. This includes rooftops that are covered with plants, wetlands that are scenic to store rainwater, as well as porous pavements that hold excess runoff water and permit the evaporation of heat to moderate temperatures.
In pursuit of becoming China’s biggest sponge city, the Lingang city government has poured USD 119 million into retrofits and new technologies that could serve as an ideal model for the large majority of Chinese cities that lack modern infrastructure for water.
Chinese cities make notable efforts. In a promise to expand the green spaces in urban areas, Shanghai announced in early 2016 the creation of 400 square meters of green roofs. The project is a cooperative initiative between city regulators property o,wners, as well as engineers. Projects in the Sponge cities of Xiamen Wuhan and Wuhan have been successful throughout the heavy rain.
