The Research On Coupling Simulation Of Flow Exchange And Solute Transport Between River And Groundwater

Effective water resources assessment and management must attach great importance to the contact of the surface water and groundwater.The interaction between river and groundwater is both related to many factors such as topography,physiognomy,aquifer lithology changes,and also changes with seasons,which transform to each other both in time and space,is an indivisible whole.During the water exchange between the two system,the solute dissolved in the water also will also migrate at the same time.In previous studies on groundwater and river,they usually analyzed and calculated the two system respectively as an independent subsystem,it may cause the error of water resources evaluation become bigger,and lead to not fully rational use of water resources.This simulation uses the latest groundwater simulation software FEFLOW 6.1 and the one-dimensional river simulation software MIKE 11 to make an coupling simulation,implements the quantitative analysis of water exchange and solute transport between river and groundwater,regard river and groundwater respectively as a complete system to research,rather than regard river as a source and sink term of groundwater in the previous studies.Coupling the river model with third type of boundary(Cauchy boundary)in the groundwater numerical model can simulate the drainage relationship between river and groundwater more reasonable,and then study the influence of river water variation on groundwater aquifer.This simulation takes Shenyang as an example,builds an accurate one-dimensional river numerical model by using MIKE 11 based on the actual flow characteristics of Hun River;uses FEFLOW to establish a non-homogeneous and isotropic three-dimensional groundwater flow model according to the hydrogeological conditions and balance parameters of the study area at the same time.By using the plug IFMMIKE11 2.0 through the interface management(IFM)in the groundwater model FEFLOW,this simulation coupled one-dimensional river model and groundwater model.Through the simulation we can calculate the relationship of the Hun River and groundwater recharge and discharge accurately and quantitatively,and also can got the groundwater aquifers balanced.This article mainly consider the affect of ammonia in groundwater belong to Hun River.Select ammonia nitrogen as the characterized component and the Hun River as the major pollution source of ammonia nitrogen of groundwater,we establish the river-groundwater solute transport model of study area on the basis of the water flow coupling model.Simulation results show that the sphere of influence of ammonia nitrogen in the groundwater of the study area is wild,water wells close to the Hun River has largely been affected,and some water wells are out of limits:the influence area of ammonia nitrogen width is relatively small in Hun River upstream,probably between 300-900m,and the concentrations are relatively low;there is a significant increase of the influence area of ammonia nitrogen in the midstream of Hun River,the influence width is about 2000m,the ammonia nitrogen concentration values near the river are up to 16mg/l;the influence width of ammonia nitrogen decreases,which is about 300-500m.And the model forecasts the distributed situation of ammonia nitrogen after 5 years,10 years,20 years in study area under steady flow field conditions.The prediction results show that the influence and exceeded area will rise slightly and steadily over time,the influence area after 5 years,10 years and 20 years is respectively 243.24Km2,278.22Km2 and 308.34 Km2;and the exceeded area is respectively 95.44Km2,107.64Km2 and 118.57Km2.