When climate change is bringing on harsher and deadlier natural disasters, cities must be prepared. Instead of fighting floods with concrete, flood walls, and pipes, Yu Kongjian, a Chinese landscape architect, recommends working together with nature to combat flood damage. Yu has advocated for “sponge cities”, which replaces concrete surfaces with greenspaces purposefully designed to absorb excess water. If architects try to control the water using grey landscaping, it will be costly, high maintenance, and largely ineffective. However, using low maintenance local plants will help soak up flood water that would otherwise not be soaked up by concrete structures. Yu states: “If it rains, the earth and plants soak up the water and prevent some (or even all) of it from flooding nearby areas. Any excess water that is not absorbed will at least be slowed by the vegetation — unlike concrete, which can instead dangerously speed up water flow.”
Implementing sponge cities isn’t a “one size fits all” policy; it is a very flexible program. The best way for a city to become “spongy” will depend on other factors in the city, such as rainfall levels and topography. Cities can incorporate green roofs, urban wetlands, permeable surfaces, and many more to accomplish the task. Many cities have transformed the ground of abandoned buildings and factories into man made wetlands. When these wetlands are utilized, they absorb flood water from surrounding areas as well, whereas if they had been left abandoned, the concrete would be an impermeable surface for flood water to stay atop of.
Implementing sponge cities can help environmental concerns beyond just flooding. There have been studies done showing that as the biodiversity in an area helps to soak up flood water, they are also releasing up to hundreds of tonnes of carbon into the air. This in turn improves the city’s air quality and lowers the temperature. If a city also struggles with drought, they can install water harvesting systems to collect water that the greenspaces would soak up and clean through natural processes, providing drinking water to citizens, and leaving out contaminated water.
Sponge cities are an excellent way for urban areas to combat harsher effects of climate change in a unique and creative way. As more and more cities incorporate these ideas into their urban planning, we will hopefully see less lives affected due to devastating floods.