January 25, 2004
The eastern plain in north China’s Hebei Province has a long record of groundwater over-exploitation. Now it finds itself home to the world’s largest acreage of subsidence.
Local economic development and the lives of ordinary people have been adversely affected. Geological experts have been urging the authorities to introduce effective and comprehensive measures to address the problem as the ground continues to subside.
Citing the example of the province’s Cangzhou City, geological experts warn of a catalogue of very real dangers brought about by the subsidence:
* The safe operation of important arterial communication links such as the Beijing-Shanghai Railway and major highways is being affected;
* The bed of the South Canal has dropped, threatening the eastern line of the South-to-North Water Diversion Project;
* The flood carrying capacity of rivers flowing through the city has been degraded and urban flooding intensified;
* Dust-storms are becoming more of a problem;
* The economic development of coastal regions is being seriously affected by tidal waters;
* The frequent appearance of cracks in the earth leaves buildings unsafe in both urban and rural areas;
* Industrial development is being held back;
* Much extant survey data is now rendered invalid by falling levels; and
* Last but not least, the daily lives of many ordinary citizens are being affected.
According to geological experts from the Hebei Provincial Geological Prospecting Bureau, the underground water table in the eastern plain has dropped some 40 to 60 meters. And what’s more, long-term over-exploitation of the groundwater has led to the formation of seven subsidence funnel areas totaling 43,915 square km.
Falling groundwater levels have meant widespread subsidence and 48,550 square km of the eastern plain have dropped by at least 200mm. Within this grand total over 6,430 square km have seen 500mm subsidence and 755 square km have dropped over a meter.
Urban areas are most severely affected. Amazingly the whole of Cangzhou city proper is now over 2 meters lower and the worst affected part of the city is recorded as having sunk by 2.236 meters.
The program of measures put forward in the Geological Disaster Survey and Evaluation of Earth Subsidence in Cangzhou City Proper in Hebei Province has now been approved by the state and a detailed plan has been prepared.
Implementation of the plan will see the provision of facilities dedicated to subsidence monitoring and prevention in the Hebei Plain. This will lay a sound scientific foundation on which a comprehensive control system can be built.