Hydrodynamic Characteristics of Shallow Groundwater in River Banks and Shoals Under Rainfall

Taking a riverbank beach in Shanxi, the middle reaches of Cao'e jiang River, as the research object, according to the characteristics of water level fluctuation caused by rainfall confluence, simultaneously monitor the change process of water level and temperature in the riverbank beach, analyze the process of water level fluctuation, calculate the lateral subsurface flow exchange volume of the riverbank beach, and establish the response relationship between the lateral unit width subsurface flow exchange volume and the river water level. The results show that under the action of rainfall, the shallow groundwater level in the riverbank beach fluctuates frequently, and the lag effect of the water level fluctuation in the far water end is obvious, the amplitude of the water level fluctuation is weak, and the phase lags behind; From the river bank to the river direction, the total volume of water exchanged by # 1 and # 0, # 2 and # 1, # 3 and # 2 per unit width is 1.28 m ³ , 0.37 m ³ and 0.10 m ³ respectively. The far water end is recharged by rainfall infiltration, and the total volume of water exchanged by # 4 and # 3 per unit width is 1.87 m ³ ; The beach is supplemented by transverse inflow, and the exchange volume of unit width subsurface flow between the shallow groundwater and the river channel and the river water level show a clear counterclockwise “rope sleeve relationship”.