Abstract: In the lumped hydrological model the temporal hydrological process can be simulated very well with no concern to the spatial distribution and spatial variation of the hydrological variable and hydrological parameters. With the increase of the spatial data and the development of spatial discretion technology, the distributed hydrological model, in which the spatial distribution is concerned, is the research focus in the recent years. In this paper the discretion method, which is used to discrete the computational domain of the distributed hydrological model and flood routing model, is discussed in detail. In the distributed rainfall runoff models there are several computational domain discretion methods, such as representative elemental areas, or REA; hydrological response unit, or HRU; grouped response unit, or GRU; and aggregated simulation areas, or ASA. In the runoff routing model, the computational domain can be discreted into structured mesh and unstructured mesh. The structured mesh can be regular mesh and irregular mesh. In addition, we also elucidate the role of Geographical Information System technology and Remote Sensing in the hydrological model and its computational domain discretion. GIS technology can be used to generate and adjust the irregular and unstructured mesh for the computational domain. In addition, RS can provide the information of relief map and landuse map. Based on the GIS and RS, some necessary hydrological parameters can be derived from the relief map and landuse map.

Key words: Basin hydrological model, Computational domain, Discretion method, Distributed hydrological model, Geographical Information System