INTEGRATED HYDROLOGIC MODELING AND GIS IN WATER RESOURCES MANAGEMENT

The integration of a physically-based distributed model with a geographic information system (GIS) in watershed-based water resources management is presented, and an example watershed is chosen to demonstrate the spatial database and modeling system developed in this study. The spatial data is first processed by GIS. The model is then used to simulate runoff hydrographs. It operates at a daily time step on 1 3 1k m grid squares and simulates important hydrologic processes including evapotranspiration, snowmelt, infiltration, aquifer recharge, ground-water flow, and overland and channel runoff. Finally, the model result is displayed by using GIS. This study demonstrates that the integration of a physically based distributed model and GIS may successfully and efficiently implement the watershed-based water resources management. Not only does this process facilitate examination of a wider range of alternatives that would be impossible by using conventional methods, but it also provides a living management that could be modified and updated by water managers once the watershed condition is changed. watershed is presented. The soil, land classification, topogra- phy, and stream channel of catchment are geocoded into layers, and the attribute information for each layer is used to construct database attribute tables. The simulated result of the runoff hy- drograph is displayed by using the GIS as well. This approach implements a watershed simulation throughout the catchment, which maintains the natural runoff flow characteristics. The objective is that the model would be used by local water au- thorities to simulate the impact of proposed land development scenarios on water resources. The focus of this paper is to describe the application of the GIS and to illustrate the benefits produced by the use of GIS in watershed-based water resources management. The model, together with the GIS, are run on inexpensive microcomputers in an effort to facilitate more widespread usage and convenient digital data transfer. This study has shown that GIS can be effectively applied to the watershed-based water resources management. Joint applica- tion of a GIS with physically based distributed models would be helpful for the development and application of a spatial decision support system (SDSS), which will thereby satisfy the needs of water managers in devising cost-effective watershed- based water resources management strategies. MODEL REVIEW