Compounding Effects of Fluvial Flooding and Storm Tides on Coastal Flooding Risk in the Coastal-Estuarine Region of Southeastern China

Weiwei Lu,Lihua Tang,Dawen Yang,Zhiwu Liu,Heng Wu

doi:10.3390/atmos13020238

Weiwei Lu, Lihua Tang + Show 3 more

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https://doi.org/10.3390/atmos13020238

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Abstract

In coastal areas of southeastern China, multiple flood drivers such as river flow, precipitation and coastal water level can lead to compound flooding which is often much greater than flooding simulated by one flood driver in isolation. Bivariate probability distributions accounting for compound flooding from river discharge and sea level were constructed based on MvCAT (Multivariate Copula Analysis Toolbox) combined with goodness of fit tests in 15 coastal-estuarine regions of Southeastern China. Flood typing-based bivariate probability distributions considering multiple flood-generating mechanisms were also built. Our results indicated that the performance of flood typing-based bivariate distribution was not significantly better than the bivariate probability distribution in coastal-estuarine regions based on the Mann–Whitney U test; the compounding effects of river discharge and sea level had limited impact on bivariate return periods, but had greater impact on coastal flooding risk in terms of design values. Ignoring compounding effects of river discharge and sea level leads to significant underestimation of design values. The results suggest that the compounding effect of river discharge and sea level should be considered when calculating design values in coastal flood risk assessment.

Highlights

Coastal flooding in the context of sea-level rise and more intense tropical cyclone activities is one of the most significant natural hazards in coastal-estuarine regions over the globe [1,2,3]
It can be seen that the seasonality of three flood types were different, which confirms the necessity to analyze the impact of mixed flood-generating mechanisms on bivariate probability distribution
Ignoring compounding effects of river discharge and sea level leads to significant underestimation of design values

Summary

Introduction

Coastal flooding in the context of sea-level rise and more intense tropical cyclone activities is one of the most significant natural hazards in coastal-estuarine regions over the globe [1,2,3]. In the coastal-estuarine region, coastal cities are widely distributed because the flat terrain, accessible transportation and adequate water resources provide convenient conditions for urban human settlements [9]. As those coastal cities have experienced much higher economic growth than the inner cities, together with higher population density, coastal flood damages in coastal-estuarine regions are expected to increase significantly [10,11,12]. In practical applications, coastal and off-shore structures may suffer from severe damages because of the occurrence of high fluvial flooding and high sea level. The coastal flood risk analysis provides new insights to policy makers and impose very stringent regulations on the design of hydrological coastal and off-shore engineering structures

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