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Estimating Floodwater Depths from Flood Inundation Maps and Topography
Author(s) -
Cohen Sagy,
Brakenridge G. Robert,
Kettner Albert,
Bates Bradford,
Nelson Jonathan,
McDonald Richard,
Huang YuFen,
Munasinghe Dinuke,
Zhang Jiaqi
Publication year - 2018
Publication title -
jawra journal of the american water resources association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.957
H-Index - 105
eISSN - 1752-1688
pISSN - 1093-474X
DOI - 10.1111/1752-1688.12609
Subject(s) - flood myth , digital elevation model , environmental science , lidar , hydrology (agriculture) , flooding (psychology) , elevation (ballistics) , 100 year flood , scale (ratio) , remote sensing , flood stage , geographic information system , geology , cartography , geography , psychology , geotechnical engineering , geometry , archaeology , mathematics , psychotherapist
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.