Numerical Mdeling Of Groundwater Flow In Daxing District Based On FEFLOW

With an area of 1030km2 and convenient transportation, DaXing district is located in southern Beijing, which also is one of the cities that under programming in Beijing. As a result of groundwater over- exploitation, water table is keeping declining and water resources couldn't get enough recharge. Besides, over-exploration leads to the risk that surface polluted water migrating to deep groundwater, as Quaternary is widely spread and developing well here. Therefore, it's very necessary and urgent to optimize the framework of water utilization in DaXing district.Firstly,the paper presents the differences of theory analysis of Feflow software which is based on finite element methods and Modflow software which is based on finite differential methods in dealing with hydrogeologic problems simulation. And then I introduced the simple process of finite element methods.Feflow is applied in the simulation of groundwater dynamic changes of DaXing district. Using hydrogeologic parameters derived from kinds of tests during January 2005 and December 2006,a 3D hydrogeologic model is established. The depth considered here is 300m. In the vertical direction, a unconfined aquifer and two confined aquifers is divided, and the first confined aquifer is treated as the main exploration formation. With identification and validation of hydrogeologic parameters, flow field simulation and process curve, when balanced calculation results is consistent with the real hydrogeologic conditions, we do groundwater balancing analysis, assessment of resources quantity as well as prediction of water table. Then according to numerical model that has been identified and validated, we proposed three suggestions about the maxim exploitation quantity refer to water usage mode for the time being in DaXing. In the simulation process, the total recharge is about 1.83×10~8m~3and the total discharge is 2.95×10~8m~3,and therefore caused a negative balance state with -1.12×10~8m~3.The maxim exploitation quantity is proposed as a potential suggestion to alleviate the conflict of water utilization in DaXing district when over- exploitation is serious here.