Effects of Cave Filling on Seepage and Hydraulic Parameters of Aquifers

In the karst area of Southwest China, water and soil leakage is serious, and topsoil fills and plugs the aquifer storage structure, changing the hydrodynamic parameters of the media field. In order to explore the influence of cavern plugging on aquifer seepage, a three-dimensional physical model of karst fissure-cavern was designed, and experiments on water storage-release seepage from karst fissures under different plugging rates and rainfall conditions were carried out. The results show that the karst water flow shows a three-stage decline pattern during baseflow recession. The initial flow rate and recession coefficient are affected by aquifer thickness, water level drop and permeability coefficient of media field. Clogging prolongs the storage time and accelerates the rate of water level fallback at the end of rainfall; At a clogging rate of more than 50%, there is a large reduction in the storage space, and the clogging medium retards the drainage significantly, slowing down the rate of water level fallback. Clogging rate and permeability coefficient K and water storage coefficient S is an exponential function of the relationship between the two parameters at the beginning of the plugging rapid decrease. Numerical simulation results show that the decrease of parameters K and S will cause the groundwater level to be elevated, leading to the instability of the groundwater level at the beginning and the end of rainfall, and weakening the ability to regulate the groundwater in karst aquifers.