The Numerical Simulation Study On The Evolution Of Stream-Groundwater Relationships During Pumping

The evolution of the hydrologic relationship between streams and aquifers resulting from groundwater pumping (or drainage) near a stream.is of great theoretical and practical significance to deepening understanding of the formation of groundwater resources along the river lots, and also to developing and innovating the groundwater movement theory and research methods.This paper dose the numerical simulation research on evolution of stream-groundwater relationships and the factors affecting the evolution process with GMS software. The evolution model is built based on the saturated-unsaturated seepage theory, guided with the indoor sand tank experiment. The main content of paper as follow:1. Discuss the relationship between stream and groundwater and flow characteristics, and taking experimental studies as an example, explore the evolution of the hydrologic relationship between streams and aquifers from the hydrological connection to disconnection, resulting from groundwater pumping near a stream.2. Construct the Mathematic Model for simulating the evolution of stream-groundwater relationships driven by a pump, design the simulation programs according to different factors, and get the Simulation Results by using GMS software.3. Analyze and summarize the simulation, and reveal the dynamic process of evolution of stream-groundwater relationships driven by pumping.4. Comparatively analysis the simulation results, point out the factors of the aquifer characteristics, clogging layer in the streambed, the aquitard, and the stream geometries on the evolution process.(1) The evolution of the hydrologic relationship between streams and aquifers was strongly affected by discharge stage rather than aquifer character.(2) Streambed-clogging blocking river water infiltration made the evolution of the stream-groundwater relationship from the hydrologic connection to disconnection been easy, the critical groundwater level increase, groundwater discharge rate decrease, and the thicknesses of the inverted saturated zone reduce. Once the aquifer disconnect from the stream, the gradient of the regional water table increases lightly with further lowering discharge stage.(3) Aquifer-clogging blocking ground water flow made the evolution of the stream-groundwater relationship from the hydrologic connection to disconnection been easy, the critical groundwater level increase, and groundwater discharge rate decrease. When the clogging located near the recharge zone the influence is big. Otherwise the influence is small as the clogging located near the discharge zone.When multi-layer clogging existing in the aquifer, the one that mainly inhibit the evolution of stream-groundwater relationships is the first layer blow the streambed center. Other layers affect the flow as well, but the influence is very small.(4) Leakage area of the triangular streambed is smaller than rectangular streambed, so the stream leakage flux and the discharge flux is little, and the critical groundwater level is high. Once the aquifer disconnect from the stream, the inverted saturated zone of the rectangular streambed show a hemicycle, and that of rectangular streambed show a vertical rhombus.