The Necessity of Building Sponge Cities
Release Time:
2016-05-16
Source:
The Necessity of Building Sponge Cities
In modern cities, stormwater runoff and the resulting flooding caused by heavy rainfall have become severe natural disasters that pose significant challenges to urban development. Traditional stormwater management practices are confined to a “pipe–retention basin” infrastructure network, which channels rainwater through pipes, catch basins, curb inlets, and drainage ditches. This approach lacks resilience and the capacity to handle excessive loads, while also exacerbating the spread of pollutants. Given the current prevalence of urban flooding, substantial losses of rainwater resources, depletion of groundwater supplies, and the increasingly severe urban heat island effect, the use of permeable paving materials in urban public spaces represents a strategic response to the intensification of urban spatial density and the growing proportion of impervious surfaces.
Once implemented, sponge cities can effectively reduce stormwater runoff, improve rainwater quality, enhance rainwater infiltration, and make full use of rainwater resources, thereby alleviating pressing urban challenges such as urban flooding, stormwater runoff pollution, and water scarcity. Moreover, for urban residents, the preservation and restoration of urban vegetation, wetlands, ponds, and streams in sponge cities can significantly increase green space, mitigate the urban heat island effect, regulate the local urban microclimate, and improve the overall living environment.
The construction of sponge cities cannot be accomplished by a single department or institution alone; it requires the concerted efforts of the entire society. The government bears primary responsibility for sponge-city development and should coordinate and integrate the work of relevant departments, including urban planning, land resources, drainage, road infrastructure, transportation, and landscaping, while fully leveraging the guiding role of the city’s master plan to set control targets tailored to local conditions. At the same time, the general public should serve as supporters and active participants in sponge-city initiatives—for example, by creating rain gardens, green balconies, micro-wetlands, and rooftop vegetable gardens in their own yards and on their rooftops.
The proportion of annual rainfall that is captured and retained by a city to reduce runoff is known as the total stormwater runoff control rate. As sponge city initiatives continue to advance, this rate may become a mandatory performance indicator. The root cause of urban flooding is that the volume of runoff generated by heavy rainfall exceeds the capacity of the drainage infrastructure; therefore, a range of engineering measures must be implemented to reduce runoff from intense storms, such as: lowering the degree of impervious surface coverage in urban areas and increasing permeable pavements to enhance rainwater infiltration and thereby reduce surface runoff; developing urban green spaces and wetlands and constructing depressed detention basins to improve the capacity for regulating and storing stormwater; and protecting urban river and lake systems.
