Application of the URBS-Monte Carlo Simulation Technique to Urban Catchments: A Case Study for the Coomera River Catchment in Gold Coast Australia

In recent years in Australia, there has been significant research and interest in the development and application of a more holistic approach of design flood estimation such as the Monte Carlo Simulation Technique. The advantage of the Monte Carlo Simulation Technique is that this considers the probabilistic nature of the model input variables in explicit manner as opposed to the Design Event Approach. This paper presents the application of the Monte Carlo Simulation Technique to the Coomera River Catchment in the Gold Coast region Australia. This identifies the probability distributions of rainfall duration, rainfall intensity, rainfall temporal pattern and initial loss from the observed pluviograph and streamflow data in the catchment and applies URBS model to simulate ten thousand streamflow hydrographs to determine derived flood frequency curve for the catchment. It has been found that the URBS-Monte Carlo Simulation Technique (UMCST) provides a robust means for providing a range of inflows to hydraulic/floodplain models to assess the impact of ‘100 year’ storms on the floodplain. Further it is noted that the UMCST technique provides design peak flow rates similar to the Design Event Approach using the temporal patterns derived from the local pluviograph stations.