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.

模拟径流产生过程的水文模型在预测动态水文通量和状态方面起着关键作用。为了描述径流的产生过程，已经开发了三种机制（即，Dunne，Horton和地下流机制）并将其广泛应用于水文模型中。由于潜在的地表条件（例如，土壤特性，地形和先前的土壤湿度）和气象因素的异质性，通常可以在不同的时空尺度上发现由多种机制形成的复杂径流产生过程模式。已经提出了一种新颖的混合径流产生机制，以同时纳入霍顿，邓恩和地下流机制，并描述径流产生的动态过程。基于这种新颖的混合径流产生机理，开发了一种改进的可变入渗能力（VIC）模型，以模拟更真实的降雨径流产生过程。为了测试我们改进的VIC模型的性能，以气候条件不同的汉江流域上游为案例研究。结果表明，改进后的VIC模型不仅在流模拟方面的性能优于基准模型，而且可以基于混合机制清楚地描述降雨径流产生的复杂动态过程。我们的研究加强了分布式水文模型中降雨径流生成的真实过程的模型开发。