Snowmelt runoff modelling in an arid mountain watershed, Tarim Basin, China

The feasibility of simulating daily snowmelt runoff in an arid mountain watershed with limited hydro-meteorological measurements was explored with an enhanced temperature-index snowmelt runoff model (SRM) in which the degree-day factor (DDF) is varied on the basis of shortwave solar radiation and snow albedo. The model satisfactorily simulated snowmelt runoff with a model efficiency of 0.64 for the calibration year and efficiency values of 0.78 and 0.51 for two validation years. Analysis indicated that the model was sensitive to lapse rate and snow albedo parameterization. The distinct seasonal variation of lapse rate played a key role for successful simulation. Snow albedo parameterization, which directly sealed snow cover percentage into snow albedo, worked quite well for the watershed although further validation is needed. Eight-day snow cover data from the Moderate Resolution Imaging Spectroradiometer (MODIS) were used to feed the model. A frequency filter, which filtererd out the clouds and large fluctuation of snow cover from the MODIS snow cover data, also improved model performance. The model, however, did not simulate peak stream flows well as most of the model runs underestimated them. Copyright (c) 2008 John Wiley & Sons, Ltd.