A former center of China's fossil fuel industry puts its economy on a cleaner, sustainable track, as Zhu Lixin reports from Huaibei, Anhui.

In the southern suburbs of Huaibei, a city in the eastern province of Anhui, there are large areas of water, which resemble natural lakes and serve as wetland parks.

However, these "lakes" are the result of subsidence. They are a reminder that the city, one of China's largest coal production bases, has struggled to eradicate the economic and environmental problems created by mining, which was once its dominant industry.