Risk Assessment Of Land Subsidence In Hebei Plain

As one of the regions with higher economic level in my country,the Hebei Plain has the characteristics of dense urban distribution,large population and complete transportation facilities.With the development of society in this area,the amount of water extraction has been increasing year by year,and the phenomenon of land subsidence has become increasingly serious.It has become a geological disaster that cannot be ignored,hindering the economic,living,and urbanization development of the Hebei Plain.Therefore,revealing the main causes of land subsidence and evaluating the risk of land subsidence has become an important research topic,providing a theoretical basis for reasonable and scientific proposals for corresponding prevention and control measures.This study combines the history and current status of land subsidence,the natural and human factors affecting land subsidence were analyzed,and it was concluded that excessive exploitation of deep groundwater was the main cause of land subsidence in the Hebei Plain.On the basis of this research,combined with the actual situation of the area,8 indicators are selected: cumulative land subsidence,land subsidence rate,shallow aquifer group,deep aquifer group,main mining layer cohesive soil thickness,GDP per unit area,Population density,land or planning function type.Using AHP-fuzzy comprehensive evaluation method,establish an index evaluation system including hazard and vulnerability to comprehensively evaluate the risk of land subsidence in the study area.Using the spatial analysis function of GIS platform,the land subsidence risk in the study area is divided into four grades : low,medium,high and high.The results show that the hebei plain as a whole has a higher risk of land subsidence.The low-risk areas accounted for 21.19% and medium-risk areas for 19.41%,which were mainly distributed in shanqian plain south of Beijing and Tianjin,north three counties of Langfang,Jidong Plain,Huanghua-Yanshan-Haixing,Gucheng County,Linxi-Guantao,Wei County-Daiming and other places.The area with high risk accounted for 44.04%,including the central plain south of Beijing and Tianjin,The southwest of Fengnan-Caofeidian New Area,the north of Langfang city,Baoding-Shijiazhuang-Xingtai-Handan.The high risk area covers 15.36% of the total area,including the urban area of Langfang,the southeast corner of Xiongan New District,the urban area of Cangzhou,the urban area of Hengshui and the county-level urban planning area.In view of the risk partition of land subsidence in Hebei plain,the paper puts forward some Suggestions on strengthening the investigation,monitoring and water resources management of land subsidence,which is of great practical significance in slowing down the development trend of land subsidence,preventing and reducing disasters,protecting geological environment and promoting economic development.