IWRA Proceedings

AbstractIn recent years, geological disasters such as floods, slope failures, and debris flows caused by heavy rainfall have occurred frequently around the world. The runoff process plays a vital role in the generation of these disasters. The simulation of distributed runoff depth is an important means to evaluate geological hazards. At present, the distributed runoff depth is often obtained by solving the shallow water equation or its approximate form through numerical simulation. However, the time-consuming model establishment and solution process sets up obstacles for the rapid acquisition of runoff depth and then creates obstacles to the prediction and timely warning of geological disasters. Based on the hydrological model and two-dimensional hydrodynamic model, this paper aims to propose a very simple and practical method for estimating distributed runoff water depth in mountainous areas, so that the calculation efficiency of distributed runoff water depth in mountainous areas can be greatly improved while meeting the accuracy requirements of the results. Through the hydrophysical model, the balanced relationship between the total input rate (rainfall intensity), the total water storage growth rate, and the total output rate (outflow rate, infiltration rate) in the catchment area are established by using the law of conservation of mass. At the same time, according to the 2D kinematic-wave hydrodynamic model, the hydraulic connection between the outflow velocity of the section and the average water depth of the section is established. Then according to the outflow velocity at the catchment boundary and the total water storage in the catchment calculated by the hydrological model and the hydrodynamic model should be equal at all times, a distributed runoff model is established that can describe the relationship between runoff water depth, catchment area, and rainfall history at any position in mountainous areas, which provides a simple and practical method for rapid estimation of distributed runoff water depth. This solves the problems of the existing hydrological models, hydrodynamic models, and hydrological-hydraulic coupling models with huge calculation amounts and long calculation times. The proposed distributed model is proven will effectively shorten the time for converting real-time rainfall values obtained from meteorological monitoring into runoff depth distribution results, and improve the early warning efficiency of the geological disasters occurrence.