AUTOMATION OF WBNM HYDROLOGIC MODELING USING GIS AIDED TOPOGRAPHIC PARAMETERISATION

This paper describes the development of a GIS interface which can be used to construct lumped hydrologic models for flood estimation on natural and urban catchments. The interface is currently being implemented with the runoff routing model WBNM, but is a general procedure and could be used with a range of flood hydrograph and daily flow models. The GIS interface utilises digital contour and watercourse data to automatically delineate subcatchments, to measure generalised subcatchment attributes, and to allocate lag times to the subcatchments. The key algorithms in the GIS interface are compared with traditional manual map interpretation techniques, and to some currently available GIS procedures. The GIS interface dramatically reduces the time required to delineate subcatchments and measure their topographic and hydrologic attributes. It also has significant potential to increase the reproducibility and accuracy of streamflow prediction, while reducing the inherent user subjectivity involved in more traditional methods.