Rapid Flood Extent Mapping for the Houston Metropolis

Flood is a natural hazard with considerable economic and social impacts on the population all over the world. Among different flood management strategies, proper control of flooding in metropolitan areas is of high priority, as such floods endanger the livelihood and cause huge damages. The topographic complexities that exist in urban areas, and the need for concurrent simulations of both urban stormwater drainage systems and surface runoff flooding have limited the application of urban flood modeling to fine-scale flood inundation mapping. Although, preparing an accurate flood inundation map at fine resolution is desirable, preliminary estimation of flood extents is crucial when there is a storm warning and limited time for evacuation. To address this limitation, this study proposes a rapid urban flood extent mapping approach for the metropolitan areas. We first propose an algorithm to rapidly extract a large set of detailed stormwater drainage system information required for the Storm Water Management Model (SWMM). Then, we utilize the surcharges provided by the SWMM as inputs to a rapid 2D flood extent method. We implement this approach for simulating flood extent areas generated by hurricane Harvey over the Houston metropolis and test its efficacy. Our results demonstrate that the proposed approach can be used as a key tool for emergency responders and flood managers who need a quick estimation of flood extent areas in metropolitan cities.