Simulation of snowmelt runoff and sensitivity analysis in the Nyang River Basin, southeastern Qinghai-Tibetan Plateau, China

The water-runoff in the plateau mountainous areas is mainly contributed by precipitation, snowmelt and glacial meltwater; the different runoff components result from different mechanism of runoff generation. Plateau mountainous areas have not only a unique hydrological cycle mechanism but also are sensitive to climate change. Glacier and snow meltwater in the plateau mountainous areas have a large proportion in runoff and are a main water resources for industrial, agricultural and domestic water use in the basin. Two commonly used model, HBV and SRM, were selected for the quantitative analysis of snowmelt runoff contribution and the hydrological response to climate change scenarios in the Nyang River Basin in the southeastern part of the Qinghai-Tibet Plateau. Based on the characteristics of the models, the HBV model was used to analyze the runoff composition, while the SRM model was used to analyze the runoff in climate change scenarios. The results showed that both models have a good performance in modeling the hydrological processes in the basin. The snow melts mainly concentrate in May, in the average annual precipitation, rainfall and snowfall accounted for 85% and 15%, respectively. From the results of sensitivity analysis, the increase in temperature would accelerate the melting of snow in April and May and turns the snowfall into rainfall in October. However, the change in precipitation mainly affects the runoff in July, August and September, when precipitation is dominated by rain. The results indicate that the timing of the effects of temperature and precipitation on the runoff process is different.