COMPARISON OF DISTRIBUTED AND LUMPED HYDROLOGICAL MODELS

A physically based distributed model, consisted of grid cell-sub-model of SVAT type and river routing sub-model of linear reservoir type, is proposed. Grid cell-specific meteorological variables are produced by a special regression method and applied to the Fuji River basin divided into 3, 376 grid cells. On the other hand, the basin is regarded as one grid and a lumped model is considered, with its input being the averages of distributed data. Then these two models are compared as for differing situations. They give similarly good runoff process when rainfall on basin is large and relatively uniform. However they behave differently when rainfall is not large and very non-uniform in spatial distribution. The lumped model underestimates flood peak flows. And the distributed model is applied to analysis of hydrological response to possible landuse change, while it is difficult to do so with the lumped model. Conclusively distributed model could be more appropriate than lumped model for a large basin.