Study on distributed rainfall-runoff model based on dynamic transformation of infiltration-excess and saturation-excess runoff in arid basin

Abstract

[Objective] The process of converting precipitation into runoff in arid regions is intricate, and accurately characterizing and simulating flood process triggered by rainfall presents a significant challenge for regional hydrological research. [Methods] A distributed rainfall-runoff model, designated as the GA-XAJ-CW model (hereafter referred to as the GX-CW model), was developed based on the adaptive transformation of infiltration-excess and saturation-excess runoff. This model takes soil field capacity and infiltration capacity as discriminant thresholds, and integrates the Green-Ampt model(GA), the Xin'anjiang model(XAJ), and a confluence method based on grid water drops(CW). For model calibration and validation, ten precipitation events that occurred between 2013 and 2019 in the Suyukougou watershed, situated at the eastern foothills of the Helan Mountain, were selected. The distributed Green-Ampt(Grid-GA) model served as a comparative benchmark. [Results] The result indicate that the GX-CW model, which is based on the adaptive transformation of infiltration-excess and saturation-excess runoff, has a better simulation effect. During the model calibration process, 80% of the fields exhibited relative flood errors within 20% and peak timing errors within 1 hour, with all achieving a Nash-Sutcliffe Efficiency(NSE) exceeding 0. 7. In the model validation phase, the performance was somewhat diminished compared to the calibration phase; however, 60% of the fields still maintained relative flood errors within 20% and peak timing errors within 1 hour, with 60% achieving a NSE above 0. 7. [Conclusion] Overall, the GX-CW model demonstrated significantly superior performance compared to the Grid-GA model,providing enhanced insights into rainfall-runoff processes. This model exhibits promising potential for simulating flash flood events in small catchments in arid regions.

Keywords

dynamic combination of infiltration-excess and saturation-excess runoff / flash flood forecasting / arid region / confluence method based on grid water drops / distributed hydrological model / runoff / rainfall / numerical simulation