A FRAMEWORK FOR QUANTITATIVE-ANALYSIS OF SURFACE-WATER GROUNDWATER INTERACTION - FLOW GEOMETRY IN A VERTICAL SECTION

A numerical model is used to examine groundwater flow in vertical sect ion, near surface water bodies, such as lakes, wetlands, ponds, rivers , canals, and drainage and irrigation channels. Solutions are generate d partly by superposition to achieve computational efficiency. A large number of flow regimes are identified, with their characteristics con trolled by regional water table gradients, recharge to the aquifer, wa ter body length, aquifer anisotropy, and the hydraulic resistance of t he bottom sediments. Different flow regimes are distinguished by the p resence and nature of groundwater mounds or depressions near the edges of a surface water body and by corresponding stagnation points. Range s of values for dimensionless flow parameters over which particular re gimes occur are determined for six representative geometries and prese nted in the form of transition diagrams. Increasing anisotropy or sedi ment resistance and decreasing the length of a water body relative to aquifer thickness are shown to have similar effects on flow geometry, the main effect being an increasing tendency for stagnation points to form in the interior of the aquifer. Flow-through behavior becomes mor e prevalent with decreasing anisotropy and sediment resistance and inc reasing water body length.