Development of GIS techniques for automated topographic and hydrologic analysis

This thesis describes a research project which focuses on improving the accuracy, and extending the capabilities of topographic and hydrologic analysis algorithms. These algorithms can be applied within GIS frameworks for parameterisations of hydrologic models. In this research project, several new algorithms were developed to overcome the observed deficiencies in current algorithms for GIS based analysis of raster Digital Elevation Models (DEMs). These algorithms were used to develop a software product CatchmentSIM which has been made freely available to researchers and practitioners. CatchmentSIM allows for interpolation of a DEM from contour and streamline data, removal of flat and pit cells, catchment delineation, automated catchment break-up, analysis of impervious areas, modelling of urban catchments, and the hydrologic and geomorphologic analysis of subcatchment properties. Following the application of CatchmentSIM to a DEM, a simple internal macro language can be used to automatically create files in any binary or text file format. This allows coupling with a full range of Australian and international hydrologic models, including RAFTS-XP, WBNM, RORB, URBS, DRAINS and HEC-HMS. The algorithims developed during this research were verified by comparative analysis against current approaches, as well as verification in two case studies. CatchmentSIM enables users to build on the increasingly comprehensive information available in todays GIS world, while avoiding the traditional shortcomings of conventional raster GIS techniques, and maintaining tight coupling with existing industry standard modelling approaches.