A continental scale hydrological model using the distributed approach and its application to Asia

Continental scale hydrological models are important for improving the land surface scheme of the General Circulation Model (GCM) and for downscaling applications of GCM predictions for regional water resources assessment. A grid-based distributed hydrological modelling approach cannot be applied at a continental scale by simply increasing the grid size due to factors such as the spatial heterogeneity and nonlinear nature of soil-vegetation-atmosphere transfer processes. Sub-grid parameterization is required to capture the spatial variability of hydrological behaviour within a large grid. On the other hand, water resources management is usually implemented at the basin scale. The methodology presented in this study expands a grid-based distributed hydrological model to the continental scale, and addresses both sub-grid hydrological parameterization and basin-based water resources assessment. A continental scale model with a 0.5degrees spatial resolution is developed based on a number of available global data sets. The model performance is examined through application to the Asian Continent. The regional and temporal variability of hydrological characteristics and water resources is discussed in this paper. Copyright (C) 2003 John Wiley Sons, Ltd.