中国的部分城市出现沉降

A recent civilian house collapse in China's Anhui Province, reportedly due to land subsidence, caused the death of three people. The incident has reignited concerns over land subsidence and erosion in China, and has many looking for possible solutions.

Land subsidence refers to the decrease in elevation of an area of land, either due to natural or human activity. Earlier this year, the Chinese government approved the nation's first Land Subsidence Prevention Project.

According to research conducted as part of the project, more than 50 cities in China are now suffering from considerable levels of subsidence. Zhang Zuochen, vice president of the China Institute of Geo-Environment Monitoring, says land subsidence can result in a number of negative consequences.

"Land sinking can lead to height reduction of ground buildings, drainage system failure. Uneven sinking can cause building ground setting, structural faults and damages in rail tracks, water and oil pipeline, bridges and communication lines."

Jiang Mingjing, a professor at Tongji University's Substructure Studies Department, says land sinking in China is largely the result of human activity.

"There are causes like ground water recession, buildings and contractions on surface and traffic loads."

Professor Jiang argues that the major cause of subsidence is the rapid depletion of underground water supplies, which has lead to land subsidence in more than 40 cities in China, particularly in northern provinces.

Cities in China's northern provinces have been facing severe water shortages for some time now. Due to a lack of rain precipitation, they rely heavily on underground water sources. According to official statistics, underground sources make up at least 80 percent of the total water supply for cities in China's north.

To improve the situation, Cangzhou city – a key grain-producing area in northern China's Hebei province that suffers severe land subsidence – has initiated an agricultural adjustment program. Fu Xuegong, deputy chief of the Cangzhou Hydrology and Water Resources Survey Bureau, explains the program further.

"The growing season for corn, peanut and cotton is summer, when rain is sufficient. But growing wheat needs manual irrigation using underground water. So we have been encouraging farmers to grow more corn and peanut, instead of wheat."

Experts suggest that to prevent erosion and land subsidence, cities should develop more sustainable plans for the use of underground water supplies: reducing the use of underground water for industrial cooling, for example, which would also make more water available for drinking.

For CRI, I'm Wang Wei.