The Simulation of Snowmelt Runoff in the Headwater Region of Yangtze River by Satellite Data and SRM

It is theoretically and practically important to study snowmelt runoff simulation in alpine regions. The headwater region of Yangtze River is a typical plateau where snow melt water is an important composition of its channel runoff during snow melt period. This study aims to apply the Snowmelt Runoff Model (SRM) for the headwater region of Yangtze River in the snow melt season (from March to August). Snow cover is a major input for SRM. As it is difficult to monitor and measure snow cover for such a large basin, satellite approximate images are used as an alternative to mapping snow cover. Based on MODIS (Moderate-resolution Imaging Spectroradiometer) snow product and DEM data, the snow cover ratio and its depletion curve of different altitudinal zones within study area were obtained. Besides, precipitation data is provided by TRMM (Tropical Rainfall Measuring Mission) and other meteo-hydrological data is from ground stations. Therefore a snowmelt runoff simulation for the snowmelt season in 2006 was set up based on WinSRM version 1.10. Nash Sutcliffe coefficient of determination (R2) and volume difference (DV) are used for quality assessment of the SRM. The result shows a good correlation between the measured and computed runoff in the headwater region of Yangtze River. In addition, the sensitivity of the main variables (snow cover depletion curves, temperature and precipitation) and parameters (degree-day factor, recession coefficient, runoff coefficients, time lag, critical temperature and temperature lapse rate) were analyzed. These findings will be useful for hydrological cycle research in the headwater region of Yangtze River.