Effect of karst conduit topological structure on the estimation accuracy of water storage variation

In this study, we systematically investigated how changes in the topological structure of karst conduits affect the accuracy of karst water storage variation (KWSV) estimation. As primary groundwater pathways, karst conduits significantly control groundwater flow dynamics and influence water resource assessment accuracy, especially in heterogeneous aquifer systems. We developed a coupled equivalent porous medium–conduit groundwater flow numerical model to simulate conduit topology variations typical of late-stage karst aquifer evolution. Two critical topological parameters—vertex degree and branch conduit angle—were selected to represent structural variations. Spring flow recession data were analysed using exponential fitting methods to characterize the recession behaviours under varying conduit structures. By comparing simulated spring recession curves with fitted results, we clarified the mechanisms by which conduit topology regulates groundwater dynamics and influences KWSV estimation accuracy. Our findings provide essential insights for improving the reliability of karst groundwater resource assessments and contribute to theoretical advancements in karst hydrology research.