Estimating Floodwater Depths from Flood Inundation Maps and Topography |
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| Authors: | Sagy Cohen G Robert Brakenridge Albert Kettner Bradford Bates Jonathan Nelson Richard McDonald Yu‐Fen Huang Dinuke Munasinghe Jiaqi Zhang |
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| Affiliation: | 1. Department of Geography, University of Alabama, Tuscaloosa, Alabama;2. Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado;3. Geomorphology and Sediment Transport Laboratory, U.S. Geological Survey, Golden, Colorado;4. Department of Natural Resources and Environmental Management, University of Hawaii at Manoa, Manoa;5. Department of Civil and Environmental Engineering, University of Texas, Arlington, Texas |
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| Abstract: | Information on flood inundation extent is important for understanding societal exposure, water storage volumes, flood wave attenuation, future flood hazard, and other variables. A number of organizations now provide flood inundation maps based on satellite remote sensing. These data products can efficiently and accurately provide the areal extent of a flood event, but do not provide floodwater depth, an important attribute for first responders and damage assessment. Here we present a new methodology and a GIS‐based tool, the Floodwater Depth Estimation Tool (FwDET), for estimating floodwater depth based solely on an inundation map and a digital elevation model (DEM). We compare the FwDET results against water depth maps derived from hydraulic simulation of two flood events, a large‐scale event for which we use medium resolution input layer (10 m) and a small‐scale event for which we use a high‐resolution (LiDAR; 1 m) input. Further testing is performed for two inundation maps with a number of challenging features that include a narrow valley, a large reservoir, and an urban setting. The results show FwDET can accurately calculate floodwater depth for diverse flooding scenarios but also leads to considerable bias in locations where the inundation extent does not align well with the DEM. In these locations, manual adjustment or higher spatial resolution input is required. |
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| Keywords: | flood inundation water depth remote sensing flooding |
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