Comparison of different distributed hydrological models for characterization of catchment spatial variability

Most physically-based hydrological models rely on either spatially distributed or lumped characterizations of topography and other spatial variations. Three disturbed hydrological models with different treatments of topography, namely the MIKE SHE, TOPMODEL and GB model (geomorphology-based hydrological model) are discussed in this paper. A regular square grid system is used by MIKE SHE for representation of catchment spatial variability and as the fundamental computation units. TOPMODEL characterizes the topography using a distributed topographic index, ln(a/tan β). The areas with the same ln(a/tan β) are assumed to be hydrologically similar. Then, the catchment is divided into a number of segments corresponding to the topographic index intervals. The GB model employs the catchment area function and width function to lump the topography and divide the catchment into a series of flow interval-hillslopes. The catchment spatial variations are averaged over each flow interval and represented by one-dimensional distribution functions with respect to the flow distance from the catchment outlet. The hillslope elements are the fundamental computational units in the GB model. The above three models are applied to the Seki River in Japan. The model structure and performance are compared and discussed in the paper. Copyright © 2000 John Wiley & Sons, Ltd.