A Unified Runoff Generation Scheme for Applicability Across Different Hydrometeorological Zones

Abstract

Runoff generation in humid and arid regions are usually saturation-excess-driven and infiltration-excess-driven respectively, whereas semi-humid regions is confronted with complex nonlinear rainfall-runoff process influenced by both of them. In this study, we proposed a unified runoff generation scheme to delineate the mixed runoff generation processes by integrating a modified Horton infiltration module with the saturation excess runoff generation module of the Xin'anjiang model at the grid scale, and a new distributed hydrological model, grid-Xin'anjiang-infiltration-excess (GXAJ-IE) model was developed. The model was tested in four watersheds and two models with single runoff generation mode were set as benchmarks for comparison. The results indicate that GXAJ-IE model has higher flexibility and robustness in reproducing flood hydrographs, especially flood peaks in semi-humid watersheds. It achieves comparable performances with the benchmark models in humid, arid and semi-arid regions. Overall, GXAJ-IE model shows potential for universal application in flood simulation in different hydrometeorological regions.

Keywords: semi-humid regions, saturation excess and infiltration excess mechanisms, unified runoff generation scheme, grid-Xin'anjiang-infiltration-excess (GXAJ-IE) model, universal application, flood forecasting