Hydrologic Modelling On A Catchment ScaleUsing GIS And Remote Sensed Land UseInformation

Abstract

A spatially distributed hydrologic model is presented for simulation of runoff in a river basin. The generation of runoff is triggered by the rain intensity and soil moisture status, and is calculated as the net precipitation times a runoff coefficient, which depends upon slope, land use and soil type. The runoff is routed through the basin along flow paths determined by the topography using a diffusive wave transfer model, that enables to calculate response functions between any start and end point, depending upon slope, flow velocity and dissipation characteristics along the flow lines. All these calculations can be performed with standard GIS tools. The model is tested on a catchment in Belgium for which topography and soil data are available in GIS form, while the land-use and soil cover is obtained from remote sensed images. The resulting calculated discharges compare favourably with measurements, without any need to model optimisation. Next a 100 year series of hourly precipitation data is processed with the model and the resulting hydrograph is analysed statistically to determine the characteristics of extreme floods.