| Land subsidence is an environmental geological phenomenon in which the surface elevation slowly decreases.The over-exploitation of groundwater is an important cause of land subsidence.The unreasonable exploitation of groundwater in Guangrao County of Dongying City has caused certain land subsidence and secondary disasters,which has become one of the most serious subsidence areas in Shandong Province and has seriously restricted the sustainable development of the city.It is of great significance to monitor the current situation of land subsidence in Guangrao County,analyze the dynamic evolution law of regional groundwater flow field,predict the development and evolution trend of land subsidence and propose targeted scientific prevention and control measures for land subsidence to ensure the safety of residents,sustainability of water resources and the development of urban economy.In view of the shortage of numerical simulation of regional land subsidence and the lack of quantitative research on the correlation analysis between groundwater level and land subsidence,this paper takes Guangrao County as the object of study.On the basis of fully collecting groundwater and land subsidence monitoring data,a three-dimensional seepage model of regional groundwater and a three-dimensional fluid-solid coupling numerical model of land subsidence were constructed by means of theoretical analysis and numerical simulation.The dynamic evolution law of groundwater flow field was analyzed,the development process of land subsidence was restored,and the evolution trend of subsidence under different groundwater exploitation schemes was predicted.The influence of groundwater level change of different aquifers on land subsidence was quantified in the spatial scale,and the corresponding prevention measures of land subsidence were put forward.The main research work and results are as follows:(1)The groundwater monitoring network and level monitoring data were used to analyze the development history of groundwater funnels and regional land subsidence in different aquifers.Based on GIS platform,the SBAS-InSAR technology was used to restore the subsidence evolution law of Guangrao area from 2017 to 2021,and the level monitoring data were combined for verification and verification.According to the regional geological background and hydrogeological conditions,the causes of land subsidence were analyzed and summarized,and the main factors inducing land subsidence in Guangrao County were determined.(2)Based on the hydrogeological and engineering geological conditions in the study area,and combined with the hydrological monitoring network and satellite meteorological data,the three-dimensional groundwater flow field model of the study area was established.The spatial distribution characteristics and dynamic evolution law of groundwater in different aquifers were analyzed,and the dynamic change trend of groundwater level in the next 10 years under different mining conditions was predicted.A three-dimensional fluid-structure coupling numerical model for the whole process of groundwater and land subsidence in the study area was constructed,and the differential change of land subsidence under different groundwater exploitation schemes was studied,so as to comprehensively reveal the evolution law of land subsidence and the development trend of land subsidence in the next 10 years.(3)Based on InSAR remote sensing satellite data and coupled model calibrated annual groundwater level and land subsidence data.Geographically Weighted Regression(GWR)model and Ordinary Least Square(OLS)model for land subsidence and groundwater level change in the study area were developed.The contribution of different aquifers to land subsidence was analyzed,and the corresponding modes of land subsidence to different aquifers were summarized.The subsidence area was classified according to the subsidence rate as the control index,the influence degree of different land subsidence areas was discussed,and corresponding prevention and control measures were proposed. |
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