To tackle black odors caused by industrial pollution and the dumping of daily domestic garbage in the city's rivers, lakes and wetlands－and to fully implement the strategy of the authorities to build Hainan into a national demonstration zone for ecological civilization－Haikou has pioneered integrated planning for the restoration of its ecological resources.

It has issued strict guidelines to safeguard ecologically fragile areas, the overall quality of the environment and promote rational use of resources, and has introduced hard-hitting access limits for new industrial projects.

Choosing not to use conventional methods to reinforce the riverbanks, large-leaf oil grass and plants were grown on the river banks and mangroves were planted in the rivers, the first successful planting of mangroves in urban rivers in China. The trees and plants will help to naturally filtrate and purify the waters.

"The cost of such a practice isn't very high, but the effect is a lot better," said Yu Kongjian, dean of the College of Architecture and Landscape at Peking University.