Preprints
https://doi.org/10.5194/nhess-2021-359
https://doi.org/10.5194/nhess-2021-359

  09 Dec 2021

09 Dec 2021

Review status: this preprint is currently under review for the journal NHESS.

Real-time coastal flood hazard assessment using DEM-based hydrogeomorphic classifiers

Keighobad Jafarzadegan1, David Muñoz1, Hamed Moftakhari1, Joseph Gutenson2, Guarav Savant2, and Hamid Moradkhani1 Keighobad Jafarzadegan et al.
  • 1Center for Complex Hydrosystems Research, Department of Civil, Construction, and Environmental Engineering, University of Alabama, Tuscaloosa, AL
  • 2US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, Vicksburg, MS, USA

Abstract. Deltas, estuaries, and wetlands are prone to frequent coastal flooding throughout the world. In addition, a large number of people in the United States have settled in these low-lying regions. Therefore, the ecological merit of wetlands for maintaining sustainable ecosystems highlights the importance of flood risk and hazard management in these regions. Typically, hydrodynamic models are used for coastal flood hazard mapping. The huge computational resources required for hydrodynamic modeling and the long-running time of these models (order of hours or days) are two major drawbacks that limit the application of these models for prompt decision-making by emergency responders. In the last decade, DEM-based classifiers based on Height Above Nearest Drainage (HAND) have been widely used for rapid flood hazard assessment demonstrating satisfactory performance for inland floods. The main limitation is the high sensitivity of HAND to the topography which degrades the accuracy of these methods in flat coastal regions. In addition, these methods are mostly used for a given return period and generate static hazard maps for past flood events. To cope with these two limitations, here we modify HAND and propose a composite hydrogeomorphic index for rapid flood hazard assessment in coastal areas. We also propose the development of hydrogeomorphic threshold operative curves for real-time flood hazard mapping. We select the Savannah river delta as a testbed, calibrate the proposed hydrogeomorphic index on Hurricane Matthew and validate the performance of the developed operative curves for Hurricane Irma. Validation results demonstrate that the operative curves can rapidly generate flood hazard maps with satisfactory accuracy. This indicates the high efficiency of our proposed methodology for fast and accurate estimation of hazard areas for an upcoming coastal flood event which can be beneficial for emergency responders and flood risk managers.

Keighobad Jafarzadegan et al.

Status: open (until 10 Feb 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on nhess-2021-359', Anonymous Referee #1, 02 Jan 2022 reply
  • RC2: 'Comment on nhess-2021-359', Anonymous Referee #2, 16 Jan 2022 reply

Keighobad Jafarzadegan et al.

Keighobad Jafarzadegan et al.

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Short summary
The high population settled in coastal regions and the potential damages imposed by coastal floods highlight the need for improving coastal flood hazard assessment techniques. This study introduces a topography-based approach for rapid estimation of flood hazard areas in the Savannah river delta. Our validation results demonstrate that, besides the high efficiency of the proposed approach, the estimated areas are accurately overlapping with reference flood maps.
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