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Calculating the Cost of River Floods in an Age of Climate Change

A new interactive tool estimates the economic, urban, and demographic risks through 2030.

Last September, India and Pakistan experienced devastating floods made deadlier because of shoddy urban planning and sluggish disaster management. About 600 people died, roughly 300 on either side of the border, as the river Jhelum flooded. Thousands were displaced, and many of those who lost their homes are still dealing with the aftermath of the disaster.

According to the World Resources Institute, river floods affect 21 million people in the world every year. In 2030, that number could rise to 54 million, with climate change driving the increase (hear that, Florida?) and urbanization putting more people in harm's way:

By 2030, the World Resources Institute estimates a 2.6-fold increase in the number of people affected by floods. (World Resources Institute)

To assess global disaster risk, WRI has designed an interactive tool that estimates the urban, demographic, and economic costs of river floods. Tianyi Luo, one of the research analysts behind the tool, says it can help government, disaster management, development, and other organizations highlight regions where they need to focus their resources. Globally, 15 countries—a majority of them in South and East Asia—account for 80 percent of the population vulnerable to river floods:

Countries with fewer resources and high rates of urbanization are more vulnerable. (World Resources Institute)

To work the tool, you first pick a country, state, or river basin in the world. Let's take the United States. WRI has assigned the U.S. a 100-year flood protection level, for example, because it has the resources to protect against floods at and below a 100-year magnitude. Users can adjust these levels for different levels of protection, ranging from 10 to 1,000. (WRI has assumed these flood protection values based on economic and other data and assigned them to all countries listed here.)

Once you adjust for protection capability, the tool pulls up the current flood-related costs based on 2010 data. To continue with the U.S. example, the tool calculates that over the course of a year, urban damage from river floods in the U.S. could amount to $36.8 billion on average. But the 100-year flood protections will have saved an estimated $512 billion in additional damage.

By varying individual factors that drive the impact of floods, such as climate change, population shifts, and urbanization, the tool also projects a range of future scenarios:

Just like it did for urban damage, the tool can calculate the current and future effect of a flood on economic activity (below, top) and population (below, bottom) in the selected region:

Flooding could cost the United States $7 billion in interrupted economic activities. (World Resources Institute)
And 167,000 people could be affected by flooding. (World Resources Institute)

Densely populated cities with rivers running through them are vulnerable to floods for obvious reasons. That's why WRI soon plans to add a data layer that estimates flood risks for the 100 biggest "megacities" around the world. Until that happens, the wonk in you can play around with the present version of the flood risk analyzer tool, here.

About the Author

  • Tanvi Misra
    Tanvi Misra is a staff writer for CityLab covering demographics, inequality, and urban culture. She previously contributed to NPR's Code Switch blog and BBC's online news magazine.