Foreign media report that facing the dual challenges of rapid urbanization and extreme weather, China is adopting a new strategy: turning cities into giant “sponges”. 30 pilot cities are trying to retain more water to help address a range of issues from flooding to extreme heat and pollution.

According to a September 27 report on India's Scroll website, China's initiative relies on a series of innovative measures, from green roofs on buildings to more urban wetlands. It is praised as a bold step toward solving the environmental problems plaguing the world's most populous country.

Sunandan Tiwari, an expert at a global sustainable development organization, said: “This is a timely reminder that addressing urban climate challenges requires a holistic approach.”

Like many countries, China, while experiencing rapid urbanization——more than half of its population lives in urban areas——also faces extreme weather such as floods, water shortages, and heatwaves. Both issues could put more people at risk, but the sponge city initiative launched in 2015 aims to reduce this threat.

The report says pilot cities are tasked with finding ways to absorb, store, filter, and purify rainwater and retain it within their areas, releasing it for reuse when needed, rather than letting it run off through sewers and pipes.

These cities, including Beijing, Shenzhen, and Shanghai, have received financial support and practical assistance in re-planning their urban areas in a water-saving manner, with the goal of turning 80% of China's urban areas into “sponges” by 2030.

The report says the core of this ambitious effort is rainwater utilization and water resource conservation.

But as urban areas in China and around the world heat up, sponge cities have another major benefit: they can reduce the impact of heatwaves, especially in urban areas where large amounts of concrete and asphalt absorb heat.

Trees and other plants can absorb water and release it through evaporation. This creates a cooling effect, just like humans cool down by sweating.

Just as southern China was hit by heavy rain and floods, Shanghai, a megacity with a population of 24 million, was sweltering in temperatures of 40.9 degrees Celsius.

The purpose of building sponge cities is to address both issues and improve the lives of urban residents.

The report says sponge city initiatives include building green roofs and walls, creating urban wetlands and ditches, and filtering used water to recharge aquifers, irrigate gardens and urban farms, flush toilets, and clean rooms.

The report says Shanghai also announced last year that it would build 400,000 square meters of rooftop gardens and take other greening measures.