How often throughout the year do you notice sudden weather changes in the city where you live—or in more urban places you visit—that clearly affect your mood? At times, it seems as though we don’t even know what we want: when it rains, we long for sunshine; when it’s hot, we dream of shade.
Yet, if we look more closely at weather patterns, it becomes clear that the problem lies not only in our desires. Climate change is bringing something we are struggling to adapt to—sudden and intense shifts in weather. Moderate transitions are becoming shorter and rarer: periods of extremely high temperatures and drought are quickly followed by heavy downpours, which sometimes cause floods, and at other times evaporate rapidly, leaving behind heavy, humid air.
Our emotional response to the weather has become a reflection of these changes—uncertain, changeable, and at times frustrating. And it is precisely here, between rain and sunshine, that the story begins of how cities can learn to become sponge-like.
Although my first association—half jokingly—was Bikini Bottom, the city where SpongeBob lives, this is in fact a very real concept that originates from China. It was first proposed in 2013 by Professor Kongjian Yu of Peking University. His idea was simple yet powerful: cities do not have to fight nature—they can cooperate with it. A sponge city, as he explained, absorbs and retains excess water from rainfall, storms, or floods within its green spaces—essentially functioning like a giant sponge.
Such urban environments include a high proportion of trees, parks, lakes, and green areas. However, nature alone is not enough, as many urban surfaces are covered by sidewalks, roads, and buildings. That is why green spaces are combined with smart infrastructural solutions: permeable pavements and streets that allow rainwater to pass through, green roofs that absorb water, and specially designed retention lakes—artificial or natural—that collect excess water during heavy rainfall.
Sponge cities are not designed solely to manage floods. They function like urban reservoirs: excess rainwater is absorbed, stored, and released when needed. In this way, collected water can be used for irrigation or other urban needs during dry periods, reducing pressure on municipal water systems and drinking water supplies.
The first cities to seriously implement this concept are located in China, where the risk of flooding is particularly high. According to data from 2018, as many as 98 percent of large and medium-sized cities in the country are affected by flooding. Shanghai is one of the pioneers in applying the sponge city concept, and the Chinese government has selected 30 pilot cities to test this ambitious program.
As the world continues to face increasingly extreme weather events, the Chinese example shows that sponge cities can become a key element of sustainable urban planning.
Katarina Vuinac
