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Measuring compound flood potential from river discharge and storm surge extremes at the global scale

Measuring compound flood potential from river discharge and storm surge extremes at the global scale
Measuring compound flood potential from river discharge and storm surge extremes at the global scale
The interaction between physical drivers from oceanographic, hydrological, and meteorological processes in coastal areas can result in compound flooding. Compound flood events, like Cyclone Idai and Hurricane Harvey, have revealed the devastating consequences of the co-occurrence of coastal and river floods. A number of studies have recently investigated the likelihood of compound flooding at the continental scale based on simulated variables of flood drivers, such as storm surge, precipitation, and river discharges. At the global scale, this has only been performed based on observations, thereby excluding a large extent of the global coastline. The purpose of this study is to fill this gap and identify regions with a high compound flooding potential from river discharge and storm surge extremes in river mouths globally. To do so, we use daily time series of river discharge and storm surge from state-of-the-art global models driven with consistent meteorological forcing from reanalysis datasets. We measure the compound flood potential by analysing both variables with respect to their timing, joint statistical dependence, and joint return period. Our analysis indicates many regions that deviate from statistical independence and could not be identified in previous global studies based on observations alone, such as Madagascar, northern Morocco, Vietnam, and Taiwan. We report possible causal mechanisms for the observed spatial patterns based on existing literature. Finally, we provide preliminary insights on the implications of the bivariate dependence behaviour on the flood hazard characterisation using Madagascar as a case study. Our global and local analyses show that the dependence structure between flood drivers can be complex and can significantly impact the joint probability of discharge and storm surge extremes. These emphasise the need to refine global flood risk assessments and emergency planning to account for these potential interactions.
1684-9981
489-504
Couasnon, Anais
3cd73383-6489-4baa-914f-1fd4ff4da620
Eilander, Dirk
01cd09ca-8639-4cd2-9acd-67c874298a0e
Muis, Sanne
abb9cf16-d84f-4006-8c9f-66202486dd88
Veldkamp, Ted I.E.
644baba8-7d4c-4847-8ef5-71703e8c0b0a
Haigh, Ivan D.
945ff20a-589c-47b7-b06f-61804367eb2d
Wahl, Thomas
6506794a-1f35-4803-b7f7-98702e57e667
Winsemius, Hessel C.
0934e633-e76e-4dfa-ad4a-2839fbe60f3a
Ward, Philip J.
ff039336-2f71-44da-b28f-feab4875a944
Couasnon, Anais
3cd73383-6489-4baa-914f-1fd4ff4da620
Eilander, Dirk
01cd09ca-8639-4cd2-9acd-67c874298a0e
Muis, Sanne
abb9cf16-d84f-4006-8c9f-66202486dd88
Veldkamp, Ted I.E.
644baba8-7d4c-4847-8ef5-71703e8c0b0a
Haigh, Ivan D.
945ff20a-589c-47b7-b06f-61804367eb2d
Wahl, Thomas
6506794a-1f35-4803-b7f7-98702e57e667
Winsemius, Hessel C.
0934e633-e76e-4dfa-ad4a-2839fbe60f3a
Ward, Philip J.
ff039336-2f71-44da-b28f-feab4875a944

Couasnon, Anais, Eilander, Dirk, Muis, Sanne, Veldkamp, Ted I.E., Haigh, Ivan D., Wahl, Thomas, Winsemius, Hessel C. and Ward, Philip J. (2020) Measuring compound flood potential from river discharge and storm surge extremes at the global scale. Natural Hazards and Earth System Sciences, 20 (2), 489-504. (doi:10.5194/nhess-20-489-2020).

Record type: Article

Abstract

The interaction between physical drivers from oceanographic, hydrological, and meteorological processes in coastal areas can result in compound flooding. Compound flood events, like Cyclone Idai and Hurricane Harvey, have revealed the devastating consequences of the co-occurrence of coastal and river floods. A number of studies have recently investigated the likelihood of compound flooding at the continental scale based on simulated variables of flood drivers, such as storm surge, precipitation, and river discharges. At the global scale, this has only been performed based on observations, thereby excluding a large extent of the global coastline. The purpose of this study is to fill this gap and identify regions with a high compound flooding potential from river discharge and storm surge extremes in river mouths globally. To do so, we use daily time series of river discharge and storm surge from state-of-the-art global models driven with consistent meteorological forcing from reanalysis datasets. We measure the compound flood potential by analysing both variables with respect to their timing, joint statistical dependence, and joint return period. Our analysis indicates many regions that deviate from statistical independence and could not be identified in previous global studies based on observations alone, such as Madagascar, northern Morocco, Vietnam, and Taiwan. We report possible causal mechanisms for the observed spatial patterns based on existing literature. Finally, we provide preliminary insights on the implications of the bivariate dependence behaviour on the flood hazard characterisation using Madagascar as a case study. Our global and local analyses show that the dependence structure between flood drivers can be complex and can significantly impact the joint probability of discharge and storm surge extremes. These emphasise the need to refine global flood risk assessments and emergency planning to account for these potential interactions.

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Accepted/In Press date: 16 November 2019
Published date: 21 February 2020

Identifiers

Local EPrints ID: 438937
URI: http://eprints.soton.ac.uk/id/eprint/438937
ISSN: 1684-9981
PURE UUID: f841f6f2-65f1-489c-82f9-c1eec6da9110
ORCID for Ivan D. Haigh: ORCID iD orcid.org/0000-0002-9722-3061

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Date deposited: 27 Mar 2020 17:30
Last modified: 28 Apr 2022 01:57

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Contributors

Author: Anais Couasnon
Author: Dirk Eilander
Author: Sanne Muis
Author: Ted I.E. Veldkamp
Author: Ivan D. Haigh ORCID iD
Author: Thomas Wahl
Author: Hessel C. Winsemius
Author: Philip J. Ward

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