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Implications of Using Global Digital Elevation Models for Flood Risk Analysis in Cities

Lookup NU author(s): Dr Fergus McClean, Professor Richard Dawson, Professor Chris Kilsby

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

As urban populations grow, it is increasingly important to accurately characterize flood risk in cities and built up areas. Global digital elevation models (GDEMs) have recently enabled flood risk analysis at broad scale and worldwide, but their accuracy and its impact on modeled flood risk in cities has not been fully investigated. We compare flood extents, hydrographs, depths, and impacts between hydrodynamic simulations, using five spaceborne GDEM products and an airborne LIDAR product. Benchmark observations of a historical flood event in Carlisle (UK) were used to assess the accuracy of each simulation. GDEM simulations are shown to perform significantly less accurately than the airborne LIDAR‐based simulations. No DEM outperforms the others across all metrics; the MERIT DEM is the best predictor of flood extent, but TanDEM‐X performs best for discharge. However, the impacts of flooding from GDEM simulations are consistently overestimated, 2 to 3 times higher than those from LIDAR simulations. Until a high resolution, accurate, global DEM is available, multiple products should be used concurrently to enable the full uncertainty range to be quantified and communicated, to ensure flood risk management decisions are not misinformed.


Publication metadata

Author(s): McClean F, Dawson RJ, Kilsby CG

Publication type: Article

Publication status: Published

Journal: Water Resources Research

Year: 2020

Volume: 56

Issue: 10

Print publication date: 01/10/2020

Online publication date: 23/09/2020

Acceptance date: 06/09/2020

Date deposited: 21/10/2020

ISSN (print): 0043-1397

ISSN (electronic): 1944-7973

Publisher: Wiley-Blackwell Publishing, Inc.

URL: https://doi.org/10.1029/2020WR028241

DOI: 10.1029/2020WR028241


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