Economic benefits

Much of the space saved has been used to build parks and other leisure facilities that meet residents' demands for recreation. Construction of some underground plants has been incorporated into the development of commercial complexes, resulting in significant economic benefits.

For example, commercial buildings, office blocks and sports facilities occupying a total area of 249,700 square meters, as well as parking lots that can accommodate more than 4,000 vehicles, stand above two of the plants built 30 meters underground, Liu said.

Hou Feng, president of China Water Environment, which is based in Beijing, said the company's mode of operation in Guiyang has won widespread recognition.

This mode has been used on Erhai Lake, Yunnan province, in Chengdu, capital of Sichuan province, and also in Beijing, Hou Feng said.

Following the environmental improvements, tourism has boomed in Nanming district, one of the central districts of Guiyang.

For example, locations near the Jiaxiu Pavilion, a landmark ancient building by the river, are often packed with tourists until late at night in summer.

Li Na, administration manager at the Xiyuan teahouse near the pavilion, said she has seen increasing numbers of tourists in the area since the environmental improvements were made.

The area is always busy during the peak summer tourism season, with most shops full of customers, she said, adding that many people choose to stay in her teahouse all afternoon to enjoy the pleasant riverside environment.