资源环境科技发展态势分析平台

Most karst aquifers behave as a dual-flow system composed of a highly conductive karst conduit embedded in a low-permeability rock matrix. Simplified physically based models suitable for such a karst system are presented herein. The physical processes consist of a pressurized flow in a conduit that is interacting laterally with the groundwater flow in the surrounding matrix. The conduit is subject to a concentrated recharge at its upstream end, while the groundwater aquifer is subject to a diffuse recharge over its contributing surface area. The resulting mathematical model is a coupled system of equations that describe one-dimensional flow processes in a two-dimensional domain. The governing differential equations are solved using the Laplace transform method after an appropriate linearization of the nonlinear coefficient. The derived spring discharge expressions are a function of three dimensionless parameters: the lumped conduit parameter gamma, the aquifer parameter eta, and the recharge parameter mu. The simulation results highlight the importance of the conduit-matrix interaction on the functioning of the karst system, and the application of the flow models to various karst aquifers demonstrates their effectiveness in reproducing the observed spring hydrograph with parameter values within the acceptable range of observed field data.

Plain Language Summary Karst aquifers are a major supply of potable water in many countries around the world. They are especially vital in areas where water resources are limited during a significant part of the year. The proper management and protection of the groundwater resources is therefore essential to meet increasing water demands. One key tool in support of that endeavor is a mathematical model that can replicate the observed flow processes. The derived flow models in this work are based on physical considerations, relatively simple in form, and accurate enough to produce realistic outcomes. They are an efficient alternative for the simulation of karst responses than more complex numerical models and proved to be successful in simulating the spring outflow from real karst systems.