Rainfall-Runoff Process Simulation in the Karst Spring Basins Using a SAC-Tank Model

Rainfall-runoff simulation is the basis of basin flood forecasting and water resource planning. However, karst basins are highly nonhomogeneous. With the intermittent uplift of the Earth's crust, karst landscapes with large depressions and nonhomogeneous vertical orientations have developed in many places, with the surface being covered with depressional soil layers and surrounded by hills. Thus, the springs are recharged in various ways. To better represent the transformation relationship between rainfall, soil water, fissure water, and conduit water, we proposed a conceptual hydrological model called the karst Sacramento (KSAC) model to simulate the rainfall-runoff processes in karst basins. The model couples Sacramento (SAC) and tank models to simulate rainfall-runoff processes in the soil layer of karst depressions and exposed carbonate rock areas, respectively. The KSAC model was applied to the simulation of rainfall-runoff in the Yuquandong (YQD) karst spring basin in central China. The simulation results revealed that the proposed model achieves satisfactory performance in simulating hourly rainfall-runoff processes. The model was further applied to water cycle processes and water resource evaluation studies in the basin. A comparison of models revealed that depressions were more effective in regulating karst groundwater circulation processes. This study can improve our understanding of complex and variable hydrological processes that occur in karst basins.