Intensive Versus Extensive Events? Insights from Cumulative Flood-Induced Mortality Over the Globe, 1976\u20132016

Bo Chen,Peijun Shi,Jing Zheng,Fanya Shi,Tingting Lin

doi:10.1007/s13753-020-00288-5

Abstract

More attention has been paid to the cost of intensive but sporadic floods than the cost of extensive but frequent events. To examine the impacts of intensive versus extensive events, we investigated the loss structure of global flood-induced mortality by using the cumulative loss ratio, marginal benefit chart, and cumulative loss plot. Drawing on the flood-induced mortality data for four decades (1976–2016) from the international disaster database EM-DAT, we defined the levels of flood loss according to the frequency of flood-induced deaths, and calculated the cumulative mortality and the marginal benefits of flood loss prevention practices at different levels. Our analysis showed that for the world’s leading 30 countries with large flood-induced mortality and different levels of development: (1) 70% of them have the cumulative deaths from extensive floods exceeding half of those caused by intensive floods in the study’s four data decades; and (2) 80% of them tend to gain less marginal benefit with increasing levels of flood prevention, with their marginal benefits peaking at loss prevention levels of 2-year or 5-year flood-induced mortality. These results indicate that, in the long run, the cumulative deaths of extensive floods are comparable to that of intensive events, and prevention of loss from extensive events can be an efficient way to reduce the total loss. For flood risk management under conditions of climate change, extensive loss events deserve more consideration.

Highlights

Across the globe, floods have been proved to be (Jonkman and Vrijling 2008; Kundzewicz et al 2012; Stevens et al 2014; Kousky and Michel-Kerjan 2017) or are projected to be (Hallegatte et al 2013; Hirabayashi et al 2013; Jongman et al 2014) among the top-ranking destructive natural hazards in terms of economic losses and people affected
To examine the impacts of intensive versus extensive events, we investigated the loss structure of global flood-induced mortality by using the cumulative loss ratio, marginal benefit chart, and cumulative loss plot
We investigated the cumulative loss of human lives recorded in EM-DAT to explore (1) the relative importance of the cumulative flood-induced mortalities of extensive events to that of intensive events; and (2) the marginal benefits of different levels of loss prevention, so as to provide insights into the decision making of preventive strategies

Summary

Introduction

Floods have been proved to be (Jonkman and Vrijling 2008; Kundzewicz et al 2012; Stevens et al 2014; Kousky and Michel-Kerjan 2017) or are projected to be (Hallegatte et al 2013; Hirabayashi et al 2013; Jongman et al 2014) among the top-ranking destructive natural hazards in terms of economic losses and people affected. Floods are usually categorized into extreme, major, medium, and minor events in a relative sense, typically according to their hazard intensity such as return period (Moftakhari et al 2017) and magnitude, for example, water depth (Burgos et al 2018; Moftakhari et al 2018). The insurance industry, and some researchers categorize floods based on the severity of their impacts, including but not limited to areas affected and fatalities caused. The National Weather Service (NWS 2019) of the United States describes the severity of flood impacts using four categories: minor, moderate, major, and record flooding. FEMA (2015) interpreted repetitive loss structure as a National Flood Insurance Program (NFIP)-

Results

Discussion

Conclusion