Integrated Modeling of Storm Drain and Natural Channel Networks for Real-Time Flash Flood Forecasting and Stormwater Planning and Management in Large Urban Areas

For accurate prediction of flash flooding and effective stormwater planning and management in urban areas, it is necessary to model both natural channel and storm drain networks. In this presentation, we describe a modular storm drain model that may easily be coupled with existing gridded distributed hydrologic models for such applications. A salient feature of the model is the use of the equivalent storm drain network which approximates the actual network on the same grid as the distributed hydrologic model for direct coupling. The integrated model is applied to a 144.6 km² area consisting of five urban catchments in the Cities of Arlington and Grand Prairie in Texas, U.S., and the impact of the storm drain network is assessed via a combination of simulation experiments, sensitivity analysis and limited comparison with observed flow. We demonstrate how the integrated model may be used to assess the effectiveness of storm drain network over a large area and how areas of potential concern for flooding may be identified under the existing conditions and under increased imperviousness.