The Numerical Simulation Of Evolution Of Relation Between River And Groundwater

Close hydraulic connection and high frequent conversion relationship exist between river and groundwater. In recent decades, the rapid developments of industry and agriculture in our country have caused an increasing demand for water resource. But because of the influences of the overdraft of ground water and some natural factors, the relationship has been complicated, water cycle has been varied, and series of negative effect in ecological environment has been induced. Such as the expanding of the funnel caused by overdraft of ground water, the sea-water encroachment, the contamination of groundwater, land desertification, rivers drying up and so on. All of these have made the water resources and ecological problem highlighted. The relationship and its evolution are one of the most important problems of the interaction between river and groundwater, and are parts of the basic research contents of maintaining mechanics of river and reproducible capability of groundwater.On the water-supplying field, the water usually is drafted near the river, and the river as an important source recharge to groundwater. As difficult field conditions complicated operation, the evolution of relationship between the river and groundwater research was done by adopting the method of integrating theoretical analysis, lab experiments and numerical simulation and the combined use of percolation theory, the soil water dynamics, porous medium theory, numerical analysis, and more interdisciplinary approach .Based on the analysis of factors affecting the evolution of the relationship between the river and groundwater, numerical simulation of the evolution that from there is the uniform water table line between the river and groundwater to the line is out of joint , and discussing the regulation of the evolution, the following results can be concluded :(1) The dynamic process of evolution of relations between the rivers and groundwaterWhen the evolution that from there is the uniform water table line between the river and groundwater to the line is out of joint beginning, water table become sunken gradually, and will be out of the joint eventually, and an impendent zone of saturation comes into being in the mean time. Between the impendent zone of saturation and the water table, there is the zone of aeration spreading with drainage of the groundwater. At the last stage of the evolution, there is a system of river - impendent zone of saturation - zone of aeration - zone of saturation to be formed.(2) Numerically simulating the evolution of the relationship between the river and groundwaterThe system of river and groundwater is modeled mathematically based on the theory of saturation and unsaturated flow. And its dynamic process of the evolution is simulated in the GMS SEEP2D module. The simulation results inosculate the measured results beautifully, represent the phenomenon and the rules that come from lab experiments, and reflect the evolution correctly.(3) Factors that affect the evolution of the relationship between river and groundwaterThere are many factors that affect the evolution of the relationship between river and groundwater. Combining lab experiments, using numerical simulation, this text mainly explore the influence factors, including the riverbed shape, river level, drainage level, and semipervian layer under riverbed and in aquifer, which affect the evolution of the relationship between river and groundwater.Above research has provided the scientific basis for the evaluation of the groundwater resources along the river land sector and the appraisement of sustainable use and the ecological environment protection.