Parameterization Using ArcView GIS in Medium and Large Watershed Modeling

摘要

This paper describes the development of a comprehensive subcatchment parameterization method for medium and large-scale watershed modeling based upon the fully distributed WetSpa model. A simplified approach is used in order to take advantage of the existing spatial analysis function within ArcView GIS and its Spatial Analyst and hydrological modeling extensions. The model combines elevation, soil and land use data within a GIS framework, and predicts flood hydrograph and water balance over the catchment. The method of diffusive wave approximation is applied in tracing water for both overland flow and channel flow, while the water and energy budget are maintained for each very small watershed derived from the high resolution DEM. Hydrographs at each subcatchment outlet are firstly calculated using the GIS derived subcatchment response function and then routed to the basin outlet using the channel response function. Model parameters and meteorological data input for each subcatchment are obtained by integration of the values from all cells of that subcatchment, allowing for the internal drainage structure within each subcatchment. The method was applied to the Alzette river basin, an 1176 km2 medium-size watershed in the Grand-duchy of Luxembourg, for which topography and soil data were available in GIS form, and land use data was obtained from remote sensed images. Calibration and validation were performed on hourly basis using observed rainfall and discharge data from December 1996 to December 2000. Good agreement between the predicted and measured hydrograph has been achieved according to the graphical comparison and statistical assessment