Explainer-What are China's 'sponge cities' and why aren't they stopping the floods?

economictimes.indiatimes.com:

The initiative was launched to boost flood resilience in major cities and make better use of rainwater through architectural, engineering and infrastructural tweaks. But cities remain vulnerable to heavy rain. In July alone, floods and related geological disasters caused 142 deaths and disappearances, destroyed 2,300 homes and caused direct economic losses of 15.78 billion yuan ($2.19 billion), China's emergency ministry said on Monday.

Following is an explainer about the sponge city scheme.WHY WAS THE INITIATIVE LAUNCHED? China has long sought to improve the way it handles extreme weather, and make highly populated cities less vulnerable to flooding and drought. The «sponge city» initiative was designed to make greater use of lower-impact «nature-based solutions» to better distribute water and improve drainage and storage. Those solutions included the use of permeable asphalt, the construction of new canals and ponds and also the restoration of wetlands, which would not only ease waterlogging, but also improve the urban environment.

Breakneck urbanisation has encased vast stretches of land in impermeable concrete, often along banks of major rivers that traditionally served as flood plains. With wetlands paved over and nowhere for surplus water to settle, waterlogging and flooding was commonplace. According to 2018 data, 641 out of 654 large- and medium-sized cities in China were vulnerable to flooding and waterlogging, with 180 facing flood risks every year.WHAT HAS BEEN DONE SO FAR? Studies show that many of the local pilot initiatives launched so far have had a positive effect, with low-impact projects like green roofs and rain gardens reducing run-offs.