The Study On Land Subsidence Prediction In Groundwater Overdraft Areas Of Jining City

Land subsidence is defined as natural or man-made factors affecting the ground under the conditions of emergence of the phenomenon of lower elevation. Land subsidence is a natural disaster, it happened a certain geological factors. However, with the economic and social development, land subsidence area is growing and the hazard is also growing. Overall, in the process of development of land subsidence, the contribution of human factors are more prominent relative to natural factors. In the larger urban,which over exploite groundwater, land subsidence phenomenon is more evident.With economic and social sustainable development, the demand for water resources is increasing in Jining City. Because long time overexploiting deep groundwater, regional depression cones of groundwater was formed and it induced land subsidence which lead to decreased ability to of urban flood control, ground crack, crack houses, urban pipeline rupture, road deformation and other hazards.At present, land subsidence has restricted the economic and social sustainable development and become one of the environmental geological problems which need to urgent solve.By depth study hydrogeological and the engineering geological conditions of jining city,quasi-three dimensional groundwater flow-one-dimensional land subsidence numerical model has been established, calculating the the source and sink terms of the groundwater flow model.The mathematical model is solved by Processing Modflow and carrying subroutine package Interbed-storage Package.By repeatedly adjusting parameters and calculation,reasonable hydrogeological parameters are obtained, which can be more accurately simulate the situation of land subsidence in Jining City.The land subsidence mathematical model can be used to predict trend to 2020 under the cases groundwater mining conditions constant and the groundwater extraction is slowed down. Prediction results show that: â‘ Mining in 2005 to maintain the level forecast in 2020 under the conditions of the head and changes in the settlement.The groundwater funnel center is rapid decline ,ground subsidence is also growing, and the land subsidence funnel center 220mm in 2005 to down to 480mm.â‘¡In the South-North Water Diversion and other water projects to achieve the use to reduce groundwater exploitation by 10%, falling water tables have eased,and land subsidence funnel center from 220mm in2005 down to 296mm.From the predicted results, for the special geological conditions in Jining city, with the mining has decreased, the grim situation of land subsidence will greatly reduce, settlement rate will slow down, settlement will reduce.If the water table is restored, the land subsidence even have a small amount of rebound phenomenon.Finally, the countermeasures to control land subsidence were proposed from the point of optimization the program of groundwater pumping and strengthening use and management of groundwater.