Yaghoub Norouzi Banis
Soil Conservation and Watershed Management Research Center
Ministry of Jihad-e-Sazandeghi, Tehran, Iran
E-mail: aquasoil@neda.net.ir

Rate of raindrop erosion in most of physically based erosion models is a non-linear function of rainfall intensity. Owing to some practical constraints rainfall input data used in these models do not often represent the spatial and temporal variations of rainfall storms as important factors in simulation of raindrop erosion. Therefore the used rainfall input data are either spatially averaged or their spatial and temporal resolutions are not desirable for this purpose. In the present study the effect of spatial averaging of rainfall data and random selection of rainfall stations on the simulated rate of raindrop erosion in four catchments with different sizes (ranging from 1.4 to 1600 km²) using SHETRAN model were investigated. It was found that for frontal type rainfall data (generated by MTB method) the effect of spatial averaging of rainfall on simulated raindrop erosion in small catchments is much less than that in larger catchments. It was also found that the raindrop erosion can be simulated with enough accuracy where the rainfall data from at least four randomly selected rainfall stations across the catchment is used.