Study on the transformation of surface water and groundwater in the water source area of Baima-Jili River Basin

Abstract

Abstract The exploitation of groundwater in a riverside water source area is a complex process of conversion of surface water and groundwater. At present, the numerical model for simulating the exploitation of riverside water sources often generalizes rivers to the specified head boundary (CHD) or the river boundary (RIV). The CHD generalizes the river into an infinite supply of water, which is obviously unrealistic for seasonal rivers, and the RIV does not have the function of the river confluence. The above two methods directly affect the calculation accuracy of river water and groundwater conversion amount due to inherent loopholes, so the simulation of the riverside exploitation amount has some errors. This study uses the Streamflow-Routing (SFR) model to generalize the Baima-Jili River. By calculating the stream flow, the upstream, and downstream water levels of the rainy, normal, and dry seasons through the permeability parameter between river water and groundwater (parameters such as riverbed permeability coefficient, riverbed thickness, water depth, and cross-sectional shape), a coupling model of surface water and groundwater is established. In order to verify the accuracy of the SFR model simulation, the CHD and RIV conditions are used to generalize the river, and the simulation results of the three models are compared. The results show that the available groundwater exploitation simulated by the SFR model, the CHD, and the RIV boundary conditions are 27.798 × 106, 35.11 × 106, and 25.76 ×106 m3/a, respectively. The known available groundwater exploitation in the study area is 2,870 × 104 m3/a. Therefore, the SFR simulation results are more realistic, indicating that the SFR model is more suitable for coupling simulation of the surface water and groundwater interaction in riverside water sources of a seasonal river.