Preprints
https://doi.org/10.5194/nhess-2021-329
https://doi.org/10.5194/nhess-2021-329

  12 Nov 2021

12 Nov 2021

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

Storm surge hazard over Bengal delta: A probabilistic-deterministic modelling approach

Md Jamal Uddin Khan1,3, Fabien Durand1,2, Kerry Emanuel4, Yann Krien5, Laurent Testut1,3, and A. K. M. Saiful Islam6 Md Jamal Uddin Khan et al.
  • 1LEGOS UMR5566, CNRS/CNES/IRD/UPS, 31400 Toulouse, France
  • 2Laboratório de Geoquímica, Instituto de Geociencias, Universidade de Brasilia, Brazil
  • 3UMR 7266 LIENSs, CNRS- La Rochelle University, 17000 La Rochelle, France
  • 4MIT, USA
  • 5SHOM, DOPS/STM/REC, Toulouse, France
  • 6IWFM, BUET, Dhaka 1000, Bangladesh

Abstract. Storm-surge induced coastal inundation constitutes a substantial threat to lives and properties along the vast coastline of the Bengal delta. Some of the deadliest cyclones in history made landfall in the Bengal delta region claiming more than half a million lives over the last five decades. Complex hydrodynamics and observational constraints have hindered the understanding of the risk of storm surge flooding of this low-lying (less than 5 m above mean sea level), densely populated (> 150M) mega-delta. Here, we generated and analysed a storm surge database derived from a large ensemble of 3600 statistically and physically consistent synthetic storm events and a high-resolution storm surge modelling system. The storm surge modelling system is developed based on a custom high-accuracy regional bathymetry enabling us to estimate the surges with high-confidence. From the storm surge dataset, we performed a robust probabilistic estimate of the storm surge extremes. Our ensemble estimate shows that there is a diverse range of water level extremes along the coast and the estuaries of the Bengal delta, with well-defined regional patterns. We confirm that the risk of inland storm surge flooding at a given return period is firmly controlled by the presence of coastal embankments and their height. We also conclude that about 10 % of the coastal population is living under the exposure of a 50-year return period inundation under current climate scenarios. In the face of ongoing climate change, which is likely to worsen the future storm surge hazard, we expect our flood maps to provide relevant information for coastal infrastructure engineering, risk zoning, resource allocation, as well as future research planning.

Md Jamal Uddin Khan et al.

Status: open (until 24 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Md Jamal Uddin Khan et al.

Data sets

Probabilistic-deterministic storm surge return level dataset for the Bengal delta Khan, M. J. U., Durand, F., Emanuel, K., Krien, Y., Testut, L., and Islam, A. S. https://doi.org/10.5281/zenodo.5614101

Md Jamal Uddin Khan et al.

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Short summary
Storm-surge induced coastal inundation constitutes a substantial threat to lives and properties along the vast coastline of the Bengal delta. We present here a robust probabilistic estimate of the storm surge hazard from a combination of numerical storm and storm-surge modelling. The estimated water level extremes vary with well-defined regional patterns. Our assessment shows that one-tenth of the coastal population in the Bengal delta is exposed to a once in a 50-year flooding.
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