Land subsidence and countermeasures for its prevention in China

Abstract

Land subsidence is a type of regional geologic hazard which is usually caused by irrational pumping water. It is characterized by its damage ingravescence, vast environmental and economic losses, and difficulty of controling. Ground fissure often accretes to land subsidence. Since 1950's, the total losses are over 450～500 billions RMB due_to land subsidence and ground fracture in China. The annual average is about 90～100 billions. Among them, the annual direct losses are about 8～10 billions. Three major zones, the Yangtze Delta region, the Northern China Plain and the Fen(River)_Wei(River) graben are suggested to take the following prevention measures in the future 10～15 years: 1^synthetically researching quaternary system structure, aquifer structure and conservation environment of groundwater, bedrock topography and fault_block properties by the 3D digitized geologic platform; 2^ detailedly investigating the distribution and evolvement law of land subsidence, assessing the risk of subsidence hazards and ascertaining the safety function of different land subsidence; 3^working up the monitoring networks of subsidence and fracture; 4^putting land subsidence prevention in practice, strictly restricting the pumping of groundwater, reconstructing the aquifer in subsidence area. The typical prevention measures, such as prohibiting and limiting of groundwater pump, reasonably choosing exploitation aquifer, utilizing the shallow phreatic water, artificial water recharging etc, are concluded in the paper.