Enhancing runoff modeling with GIS

Runoff modeling is used to predict the effect that rain falling somewhere in a catchment will have elsewhere in the catchment. Engineers use it to estimate floods, and therefore design dams, spillways and retarding basins. However, engineering runoff models are not well suited to the process of environmental planning: substantial hydrological expertise is required to run them. It takes many hours to run a single test, and visual display of the planning scheme for the catchment is rudimentary. Geographic Information Systems (GIS) have the potential to overcome all these problems. In this paper, we describe how we integrated RORB, the runoff model most widely used in Australia, with a GIS. Results obtained with the integrated GIS/RORB system were not significantly different from those obtained by conventional use of RORB by hydrological engineers. Model operations using the linked system took only around one quarter of the time and, as would be expected with GIS, the visual display capability was excellent.