For the sustainable management of water quantity and quality, a hydrological model that can simulate the hydro-environmental dynamics of river basins at arbitrary locations is valuable. There are several streamflow simulation models suitable for such a purpose. Yet the lack of data commonly poses a serious problem for their application. This is a serious problem encountered for the sustainable management of water resources at a basin scale. This paper describes a combination of TOPMODEL with the Muskingum-Cunge flow routing method to overcome the problem at least partially. The resultant block-wise version of TOPMODEL is used to simulate daily flows in the data-rich 3570 km2Fuji-kawa basin, central Honshu, Japan and in the data-poor 20 750 km2northern part of Minjiang basin above Dujiangyan, Sichuan Province, China. The results demonstrate the potential use of the model for hydro-environmental simulation in a large data-poor basin.