Integrating hybrid runoff generation mechanism into variable infiltration capacity model to facilitate hydrological simulations

Abstract

Hydrological models of simulating the process of runoff generation play a pivotal role to predict the dynamic hydrological fluxes and states. In order to describe the process of runoff generation, three mechanisms (i.e., Dunne, Horton and Subsurface flow mechanisms) have been developed and widely applied in hydrological model. Due to the heterogeneity of underlying surface conditions (e.g., soil properties, topography and antecedent soil moisture) and meteorological factors, a complex runoff generation process pattern formed by more than one mechanism can often be found at different spatiotemporal scales. A novel hybrid runoff generation mechanism has been proposed to simultaneously incorporate Horton, Dunne and Subsurface flow mechanisms and describe the dynamic processes of runoff generation. And a modified variable infiltration capacity (VIC) model based on this novel hybrid runoff generation mechanism has been developed to simulate more authentic rainfall-runoff generation processes. In order to test the performance of our modified VIC model, the upper reach of Hanjiang River basin with varying climate conditions is selected as a case study. Results show that the modified VIC model not only performs as well as the benchmark model with respect to streamflow simulation, but also the complex dynamic process of rainfall-runoff generation can be clearly described based on the hybrid mechanism. Our study reinforces model development on the authentic processes of rainfall-runoff generation in distributed hydrological models.