An investigation on the effect of geometric shape of streams on stream/ground water interactions and ground water flow

Ground water should be used efficiently and improved for sustainable water management plans. For this purpose, comprehensive ground water flow models are developed incorporating surface/ground water interactions. Typically, these models require a significant amount of hydrological parameters and the sensitivities of these parameters on interaction mechanisms need to be clarified. Therefore, in this study, the role of the geometric shape of the stream on stream/ground water interactions is investigated. First, an analytical solution for two-dimensional ground water flow is developed with sloping stream boundary in an isotropic and homogeneous aquifer. Then, ground water head distribution and hyporheic exchange flow between stream and aquifer are obtained by conducting sensitivity analyses with prototype models developed using Visual MODular Finite-Difference FLOW in order to observe individual effects of each stream property. Finally, by incorporating the highest possible stream/ground water interaction conditions into a conceptual stream-aquifer model, the combined effects of different stream shapes are interpreted. Results show that slope, abrupt slope change, and flow path of stream affect the interactions significantly. Moreover, interaction flow rates increase further under the combined effects of these stream properties. The outputs of this work will ultimately be used in site investigations and in forecasting ground water hydrology.