Numerical Simulation Research Of Coupled Groundwater-Surface Water Based On HydroGeoSphere In Da-XiaoLing River Fan, LingHai City

Daling-Xiaoling river's alluvial and flood fan is the major aquifer for Linhai City groundwater, there are seven perennial concentrated exploitation water source area distributed in the fan, in which have a total exploitation quantity of 42.5×104m3/d, and it serve as main water source for area's agricultural irrigation and rural life water demand. With the rapid development of local economic, industrial and agricultural water consumption increase gradually, as well as extremely uneven distribution for annual and seasonal precipitation, the contradiction between supply and demand has became one of the main constraint factors for the region socio-economic sustainable development. As long-term unreasonable and excessive exploitation in groundwater, there are groundwater drop funnel appeared in local area. At the same time, because of a large number of industrial and domestic wastewater directly into surface water and groundwater in the upstream City-Linghai and Jinzhou, as well as unreasonable using of pesticides and fertilizers, all of which have caused water pollution to surface and groundwater in a certain extent, human health and ecological environment at risk. As a result, the scientific management and planning has become an urgent task.In response to the shortcoming of the traditional water resource simulation, this study considered various hydrologic factors, taking groundwater-surface water as a integer in basin hydrologic cycle, and established a coupled simulation model for flow and solute transport to groundwater-surface water.The main study contents of this paper are as follows:①Firstly, this paper introduced the research status at home and abroad, problems and trends for the coupled groundwater and surface water, classifying the existing coupled models. Then expatiated on the times and lithology to the stratum, divided the aquifer group and the using type of surface, analyzed the recharge, run off, discharge of groundwater on the basis of the full collection and analysis of the local meteorological and hydrogeology condition, At last, established the conception and mathematics models for groundwater and surface water.②In accordance with lithology of the aquifer and pumping test data, establishing the initial value of van Genuchten and hydrogeologic parameter, establishing the initial value of surface hydraulic parameter according as surface using type, coupling the surface and groundwater model through dual-node approach, then HydroGeoSphere was used to solve the coupled model.③Adopting the state flow approach to acquire the transient flow initial condition, and make model calibration and verification respectively. The result shows that the coupled model based on HydroGeoSphere for groundwater-surface water can represent the base hydrologic and hydrogeologic conditions. Then analysis and forecast the area groundwater and surface water in 2008-2010.④On the base of the area flow model, established mathematical model for groundwater and surface water respectively, advection effect was considered only in the process of groundwater and surface water solute transport coupling. Choose the nitrogen as simulation objection, generalizing the area boundary condition and source and sink, developing a coupled groundwater-surface water solute transport model, and adopting the soft HydroGeoSphere to solve the model.⑤Through the analysis of flow and solute transport simulation result, we can get following conclusions: The quantity of groundwater and surface water can maintain the stability of many years, but because of seasonal distribution of precipitation, there are local groundwater drop funnel appeared in the area which caused by over-exploitation in dry season; in the high water season, the groundwater get fully recharge and water level get restored; the main pollution of the nitrogen is polluted water, in the next place, the pollution source of the area is the industry pollution, the region municipal wastewater and agricultural non-point source pollution have a slight effect to the nitrogen distribution.⑥It can acquire more actual process to water resource remove and distribution which take groundwater and surface water as a integer, and having more exact simulation and forecast results, to providing more reliable evidence for local water resource management and planning.