A preliminary comparison of snowmelt models for erosion prediction
The United States Department of Agriculture, Water Erosion Prediction Project (WEPP) is developing a process-oriented prediction technology based on hydrologic and erosion sciences (Rawls et al., 1987). The major components of this are: climate and precipitation, snow accumulation and melt, infiltration, runoff, channel routing, erosion, soil moisture, crop growth, plant residue and tillage. The authors describe the work we have done on the modeling of snow melt in the application of WEPP which is being developed by the Forest Service. The rate of delivery of meltwater and its spatial distribution is critical for the prediction of erosion. During the melt phase the melt rate varies with the diurnal cycle of temperature and solar radiation. In many instances, erosion is due to short duration high intensity flows. Therefore, the modeling of erosion for snowmelt must be simulated with short time steps. In this study, we have used one hour and six hour time steps. To capture the spatial distribution of snowmelt delivery, models that are capable of calculating snowmelt at each point on a hillside or small basin are necessary. Models that may have provided good estimates of catchment wide average runoff will not necessarily work well at the point scale required for the estimation of erosion.