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RMS® Global Flood Maps are already generating a wealth of insight. Over a series of two blogs, I will be highlighting five interesting points about flood risk – by combining the maps across multiple return periods with country population data from various censuses and river basin data.

In this blog, we’ll focus on the first two points by looking at the global flood trends and the regions that are the most disproportionately affected by flooding. These regions often have significant and growing levels of exposure.

1) 1.375 Billion People Are at Risk of Flooding at the 200-Year Return Period

Flood is the most prevalent global peril. Where there is precipitation, there is potential for a flood. According to RMS analysis, almost one-in-five people globally – some 1.375 billion people – are at risk of inland flooding at the 200-year return period (Figure 1).

Global population at risk of flooding over various return periods
Figure 1: Global population at risk of flooding over various return periods; the bars show the population at risk in millions of people (left axis), the yellow line shows the percentage of the global population at risk (right axis)

As you’d expect, this number varies significantly across the array of available return periods, starting with about 550 million people (7.4 percent) at risk at the lowest (10-year) return period, extending to 1.9 billion (25 percent) at the 1,000-year return period.

Global population at risk of inland flooding at the 200-year-return period
Figure 2: Global population at risk of inland flooding at the 200-year-return period; the bars represent the population in millions (left axis), and the gray line represents the percentage of the global population (right axis)

Looking at the 200-year return period over 40 years (1975-2015), the proportion of the population at risk has been steadily increasing, from 16.9 percent to 18.4 percent (Figure 2). This highlights how the development of property in flood-prone areas is becoming increasingly commonplace around the world.

Over the same time frame, the global population increased by about 80 percent, from 4.1 billion to 7.5 billion, and the absolute number of people at risk increased by 97 percent (from approximately 700 million in 1975 to 1.375 billion in 2015). But as might be expected, some regions are more adversely affected than others.

2) Southeast Asia Is Disproportionately Affected by Flooding

Of all the regions in the world, Asia-Pacific is the most disproportionately affected by flooding relative to the rest of the world. Of the 1.375 billion people that we have identified as falling within the 200-year flood extent, 934 million live in Asia, compared with 150 million in Europe, and 290 million in the Americas.

Asia is home to China and India, and this region is the most populous. However, it has approximately a 70 percent share of the overall population at risk of flooding, compared with only 55 percent of the world’s population. Yet, the two regions of Europe, Middle East, and Africa (EMEA) and the Americas have less than their fair share. Some 22.5 percent of Asia-Pacific’s population is at risk of flooding, above the global average of 18.4 percent.

Flood risk at the 200-year return period for global regions
Table 1: Flood risk at the 200-year return period for global regions

Diving deeper into the sub-regional level, Southeast Asia stands out with over one-in-four people at risk of flooding at the 200-year return period (Table 1). And although regional variation still exists, in countries such as Cambodia, Thailand, and Vietnam almost 40 percent of the population is at risk.

2011 Thailand Floods

Why is it important to examine flood risk in Southeast Asia? The 2011 Thailand Floods still stand as the costliest pure flood event in history on an economic basis. According to the World Bank, the floods caused over US$45 billion in damages. The widespread inundation of seven industrial parks, including one high-tech industrial plant where all 130 factories were inundated with water, saw losses extend beyond the physical boundaries of Thailand.

Over 30 percent of Thailand’s US$250 billion in annual exports are electronics. The 2011 floods caused widespread disruption to global supply chains, from hard drives to semiconductors. Questions should be asked of other areas – such as Vietnam – that could have the potential for a similar event.

Vietnam’s exports also include a significant proportion of electronics. As in Thailand, large global players such as Intel have recently invested another US$500 million at a high-tech park in Vietnam. The country is of course no stranger to significant flood events, and effective risk management should be considered to ensure a 2011 style catastrophe does not occur again.

Regional Flood Trends

The RMS Global Flood Maps open many interesting insights and perhaps this blog has highlighted things you didn’t know about global flood risk. In the second blog, I will examine specific regions of the globe, from Scandinavia to the Middle East, and what RMS analysis is telling us about flood trends.

Please contact us if you would like to talk more about how RMS can help your business look at new opportunities or potential hot spots in what is a complex world of flood risk.

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Oliver Smith
Oliver Smith
Senior Product Manager, Data Product Management

Based in London, Oliver is a Senior Product Manager within the data product management team, responsible for overseeing the development and release of RMS data offerings across multiple peril regions and delivery vehicles. Oliver joined RMS in 2013 and has held roles in the Global Knowledge Center and Model Product Strategy teams prior to joining Product Management in 2016. Oliver is a Certified Catastrophe Risk Analyst and holds a bachelor's degree in Economics and Finance from Keele University.

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