Sensitivity of Flood Hazard and Damage to Modelling Approaches

Charlotte E Lyddon,Andrew J Plater,Nicoletta Leonardi,Jennifer M Brown

doi:10.3390/jmse8090724

Charlotte E Lyddon, Andrew J Plater + Show 2 more

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https://doi.org/10.3390/jmse8090724

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Abstract

Combination of uncertainties in water level and wave height predictions for extreme storms can result in unacceptable levels of error, rendering flood hazard assessment frameworks less useful. A 2D inundation model, LISFLOOD-FP, was used to quantify sensitivity of flooding to uncertainty in coastal hazard conditions and method used to force the coastal boundary of the model. It is shown that flood inundation is more sensitive to small changes in coastal hazard conditions due to the setup of the regional model, than the approach used to apply these conditions as boundary forcing. Once the threshold for flooding is exceeded, a few centimetres increase in combined water level and wave height increases both the inundation and consequent damage costs. Improved quantification of uncertainty in inundation assessments can aid long-term coastal flood hazard mitigation and adaptation strategies, to increase confidence in knowledge of how coastlines will respond to future changes in sea-level.

Highlights

The combined effect of astronomical high tides, storm surges, wind and waves during hurricanes and violent storms can temporarily increase sea level at the coast to exceed critical hazard thresholds, and lead to flooding, damage to infrastructure and potential loss of life
The combined effect of astronomical tides, meteorological storm surges, wind and waves can increase flood hazard in heavily populated and industrialised estuaries, which are the focal point of coastal megacities, critical infrastructure and economic activity
Accurate predictions of high water level and high water significant wave height are required to develop hazard maps or warning systems to mitigate the negative effects of combined flood hazards

Summary

Introduction

The combined effect of astronomical high tides, storm surges, wind and waves during hurricanes and violent storms can temporarily increase sea level at the coast to exceed critical hazard thresholds, and lead to flooding, damage to infrastructure and potential loss of life. This is critical in heavily populated, industrialised estuaries and deltas, which are the focal point of coastal megacities and hubs for transport, trade and critical infrastructures [1,2,3]. Typhoon Hato caused 12 fatalities and up to USD 4.34 billion of flood damage in the city of Macau on the south coastline of the Pearl River Estuary on 23 August 2017, as observed tides were 6.14 m above predicted level; a 2.79 m meteorological storm surge was exacerbated by 127.9 km/h winds generating large wind setup [11]

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