ABSTRACT
The world is changing from A (Atomic age) to B (Bit age) due to C (Computer). Bit, as a basic unit of information, is replacing atom, and becomes a basic element of the human society. In 1998 the concept of Digital Earth was proposed, which is a multiresolution, three-dimensional representation of our living planet. Terrain is regarded as only one of the many kinds of data with which we can interact. The development of computer science and digital techniques such as DEMs provide a solid technical foundation for the revolution of hydrological modeling (Ren and Liu, 2000). The spatial distribution of land surface characteristics, such as topography, land cover, soil, watershed divide, drainage network, or catchment area, could be expressed digitally, so as to avoid using the conventional manual method. Thus the digital hydrological model emerges (Ren and Liu, 2000b). The digital hydrological model is a modern, physically based modeling technique containing a large amount of information. It is a DEM-based distributed model, and the combination of grid-based runoff generation model with streamflow routing model.
