2003 Volume 47 Pages 193-198
Topography has dominant effects in hydrological modeling. The purpose of this study is to explore a proper subdivision level for distributed hydrological model BTOPMC (Block-wise use of TOPMODEL with Muskingum-Cunge method), so that simulation uncertainty due to basin subdivision could be reduced to quite a low level. The Pfafstetter subdivision algorithm was successfully integrated into the model and related problems and solutions were discussed. Using this BTOPMC, the effects of sub-basin scale on runoff simulations were investigated for the Fuji-kawa and the Nakagawa basin, respectively. It was found that as the average area of sub-basins becomes smaller, the simulated total runoff usually tends to be increased in flood/wet period and decreased in dry period, this is considered as the effect of averaging scale of the topographic index in the model. However, the results indicated that model performance appears stabilized when average sub-basin scale is about 1/150 of the entire basin.