Effects of topography and snowmelt on hydrologic simulation in the Yellow River's source region

To quantify the effect of topography and snowmelt on hydrologic simulation, the (Soil and Water Assessment Tool (SWAT) model is employed for the hydrological simulation in the Yellow River's source region for the period 1960—1990. The topographical effect is determined through the partitioning of subbasins into elevation bands. While, the snowmelt effect is simulated using a snowmelt module. A series of simulations is conducted. The result shows that a satisfactory result of model simulations can be obtained when the snowmelt module applied alone or jointly with the consideration of elevation bands. The model will have a better performance if the topography effect is considered, indicating that topography plays a dominant role in water balance simulations. The model temperature is more sensitive to the partitioning of subbasins than precipitation. A reduced temperature value will lead to the reduction of evapotranspiration from subbasins, and hence increases the water yield of subbasins. Groundwater will get the most yield increase and followed by surface water and lateral flow. The influence of topography and snowmelt is likely to change to the source of groundwater recharges. An excellent simulation result can be obtained through calibrating model groundwater parameters that consider the effect of topography and snowmelt. The study provides valuable information for other hydrologic simulation in mountainous watersheds.