The Risk Evaluation Study On The Land Subsidence In Tianjin Binhai New Area Based On ArcGIS

Binhai New Area is located in the north of the North China Plain.It is located in the northeast of Tianjin.It is surrounded by the Bohai Bay.The two peninsula of Liaodong and Shandong confluence here.The Haihe River enters the sea from here.The northern part of the study area is the original Hangu,the central part is Tanggu,and the south is the Dagang.This area east of Bohai Bay,south of Hebei Huanghua District,there is four of Tianjin city of Ninghe,Dongli,Jinnan and Jinghai located in Tangshan West,Fengnan Province,north of Hebei.Geomorphic type is a relatively complete distribution rule composed of alluvial alluvial plains,marine alluvial plains and intertidal zones.Land subsidence is very serious in the area,which poses a great threat to the local residents' property safety and seriously restricts the economic development.The assessment of the risk of ground subsidence covers the assessment of risk,vulnerability and ability to prevent and reduce disaster.Taking Binhai New Area as the research object,based on the field geological hazard investigation and related data collection,the risk assessment model of risk(R)= hazard(H)* vulnerability(C)/ disaster resistance capacity(P)is determined.The results of the evaluation have important theoretical and practical significance for the prevention and control of ground subsidence disasters.The main achievements of this study are as follows:(1)Ground subsidence is the main geological hazard in the study area.Only one year in 2014,the average settlement was about 23 mm.The serious settlement occurred mainly in the north of Dagang,east of Hangu.It has seriously affected the economic and social development of Binhai New Area.Settlement has caused many harm.(2Natural factors and human factors are the two causes of such serious ground subsidence.In recent years,all kinds of human economic activities and production activities have gradually increased,and human factors gradually become the main inducing factor of ground subsidence.(3)On the basis of many investigations and researches on the Binhai New Area,the risk assessment system for land subsidence is constructed from the following aspects: the status of land subsidence,the exploitation of underground resources,the geological environmental conditions and the ground load conditions.The land subsidence rate and the cumulative amount of land subsidence and groundwater exploitation,the exploitation of oil and gas,geothermal exploitation,Cenozoic thickness,soft soil thickness,ground elevation,tectonic and seismic zoning,ground load conditions and other factors,using fuzzy comprehensive evaluation method to evaluate the risk of ground subsidence,the ground subsidence hazard into high,high,low,low grade 5.(4)In the premise of collecting and controlling the impact of land subsidence on the research area,we build vulnerability assessment system from four perspectives,such as population density,economic status,road traffic and functional zoning.The vulnerability of ground subsidence is evaluated by improved analytic hierarchy process(AHP),and the vulnerability is divided into 5 grades,which are high,high,medium,low and low.(5)The risk assessment model of risk(R)= risk(H)* vulnerability(C)/ disaster resistance(P)was used.By using the grid calculator function of ArcGIS,the risk zoning of the ground subsidence in Binhai New Area was completed.The risk of the settlement of Binhai New Area is divided into 5 grades,which are high,high,medium,low and low.The ROC curve was used to test the accuracy of the evaluation results.(6)In view of the present situation of the land subsidence in Binhai New Area,we put forward strict control measures for groundwater exploitation,limiting groundwater exploitation,developing new water sources,strengthening monitoring and conducting in-depth research on engineering land subsidence.