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World’s 15 Countries with the Most People Exposed to River Floods

This blog was co-written with Hessel Winsemius and Philip Ward. Hessel is a researcher at Deltares. Philip is a senior researcher at the Institute for Environmental Studies of the VU University Amsterdam.


Last September, Hamberton Nongtdu woke to a loudspeaker at a nearby mosque blaring a warning: Floods were coming.

Nongtdu, a Kashmiri resident, barely had time to rush to the third floor of her house before water burst through her gate and inundated the first and second floors. Nongtdu and her family survived, but unusually heavy monsoon rains in September 2014 triggered floods in India and Pakistan that claimed more than 500 lives. It was the year’s costliest catastrophe.

Those floods may have been the most dramatic of recent river floods, but the threat extends well beyond Southeast Asia. More people are affected by floods than by any other type of natural disaster. New analysis shows that approximately 21 million people worldwide are affected by river floods each year on average. That number could increase to 54 million in 2030 due to climate change and socio-economic development.

Quantifying and Visualizing River Floods Worldwide

The Aqueduct Global Flood Analyzer, a new online tool, quantifies and visualizes the reality of global flood risk. WRI co-developed the tool with four Dutch research organizations: Deltares, the Institute for Environmental Studies of the VU University Amsterdam, Utrecht University and PBL Netherlands Environmental Assessment Agency, supported by the Netherlands’ Ministry of Infrastructure and the Environment. The Analyzer estimates current and future potential exposed GDP, affected population and urban damage from river floods for every state, country and major river basin in the world.

We ranked 164 countries by the number of people affected by river flooding. We found that the top 15 countries account for nearly 80 percent of the total population affected every year. These countries are all considered least developed or developing. Roughly 167,000 people in the United States, the highest-ranked high-income country, are affected every year.



River Flooding Affects GDP

WRI analyzed which countries have the highest percentage of total GDP affected by river flooding on average per year, and each of the top 20 is classified as least developed or developing. India has by far the most GDP exposed, at $14.3 billion. Bangladesh is a distant second, at $5.4 million.

We judged the potential national economic consequences of river floods to be highest in countries with the largest percentage of affected GDP. China and Brazil, for example, would fall first and fifth respectively on a list ranked by gross GDP affected. However, their national incomes are so large that they drop off a list of countries ranked by percentage of GDP exposed.



GDP Exposure in 2030: Disparity between the Developed and Developing Countries

Our analysis shows a clear trend across the world. In lower and middle-income countries, socio-economic development is expected to concentrate more people, buildings, infrastructure and other assets in vulnerable regions. So, the developing world is expected to see more GDP exposed to flood risks in 2030, driven largely by socio-economic change.

India, for example, faces more potential change in exposed GDP than any other country. Using a middle-of-the road scenario, the Analyzer estimates that India’s current $14 billion in GDP exposed annually could increase more than 10-fold to $154 billion in 2030. Approximately 60 percent of that increase could be caused by socio-economic development.

In the developed world, Australia, Croatia, Finland, Portugal, and Israel are expected see more GDP exposed to floods in 2030, driven primarily by social-economic change. On the contrary, countries like the Netherlands, Slovenia, Belgium, Ireland, and Switzerland will likely see increased GDP exposure driven primarily by climate change.

Climate Change Will Expose More People to River Floods

Climate change is a greater driver of change in population exposure to river floods than socioeconomic development, because both the frequency and intensity of river floods is expected to increase due to climate change in many areas. This phenomenon would expand flood-prone areas, and make floods more likely to occur in those areas more often.

Climate change drives populations at risk in the developed and developing world alike – there is no clear distinguishing pattern. In Ireland, for example, 2,000 people face flood risks currently. By 2030, 48,500 more people could face river flood risk, and 87 percent of that difference would be driven by climate change. From the developing world, 715,000 people in Pakistan are at risk today. By 2030, river floods could affect 2 million more people, with climate change driving 70 percent of that increase.



A Tool for Awareness and Action

The risks may be escalating, but public and private sector decision makers can do more to prevent catastrophic damage before it happens.

Sharing the Analyzer’s easily accessible data with public and private sector decision makers will immediately raise their awareness about current and future river-flood risks. Armed with the right information, decision makers can then prioritize risk reduction and climate adaptation projects, and implement the most viable, cost-efficient options (see sidebar).

It will take decades and many billions of dollars to protect the tens of millions of people at risk from river floods and coastal storm surges. But starting now and following the direction of tools like the Global Flood Analyzer will help decision makers in international relief organizations, reinsurance companies, multinational companies, and many others build advanced protection systems to protect people and infrastructure.

For more on the ranking and methodology behind this analysis, access our data sets or test the tool.

Comments

It is a fact that the frequency of flood events globally has increased by a factor of 4 since 1980. The increase in losses is especially driven by rising values in exposed regions, which is particularly true of fast-growing countries in Asia.
Flooding is considered to be the natural hazard for which precautions have the greatest loss-mitigating effect. Particularly with floods, an increased hazard – such as more frequent heavy rainfall events – need not necessarily result in higher losses. Such a rise in losses can be prevented by better flood control. It is therefore important to sharpen risk awareness. Appropriate flood control measures can help flood waves to disperse without causing serious damage. And the flood risk needs to be considered in the designation of land for industrial or residential areas

Would be useful to say a sentence or two more about WHY climate change causes more flooding, e.g., "As the earth's atmosphere warms, it holds more moisture."

This another study showing us the consequences of climate change.

We should increase efforts to decrease the amount of Green House Gas (GHG) released in the atmosphere.

Each and everyone of us can become a model on how to use less fossil energy.

This is a very interesting post and provides a great perspective about the extent to which the negative effects of floods can reduce economic productivity throughout the world, and how these negative effects may worsen due to both climate change and socioeconomic development in vulnerable areas. However, this blog post does not discuss or even mention the benefits of flooding. Floodplain agriculture is a major economic engine in many of the countries most vulnerable to flood damages, including the ones in the Ganges and Mekong basins that comprise four of the five most economically vulnerable countries (Bangladesh, Laos, Cambodia and Vietnam). In the Mekong basin, the average annual benefits of floodplain agriculture have been estimated to be over 100 times greater than the average annual damages (Mekong River Commission 2010 State of the Basin Report). To make sound management decisions, both the benefits and costs of flooding must be considered!

It is true that flooding of river banks provides much needed replenishment of nutrients to surrounding land. It is human folly that allows construction of permanent buildings and infrastructure within the 'flood zone' of rivers everywhere. Why not change planning/building control to only allow building of structures that can withstand the large flood events (such as elevated, platform style building) that will happen as a result of both 'normal climate and human induced climate change and global warming
It would not be difficult to establish 'buffer zones' of areas where permanent building is not allowed. This buffer zone could be determined with analysis and modelling of local hydrology and precipitation data. This is what 'Planning and Development' should be all about.
If we argue about moderating our behaviour due to the considered/perceived 'costs' of those changes - such as reducing GHG emissions and conversion to renewable energy sources we are missing the inclusion of the costs involved in doing nothing as made extremely obvious in articles and research such as this. It really boils down to the reality that globally we cannot afford the true cost of not acting immediately and effectively to change our behaviour, at personal, local, national and global levels. Come on people, let's stop walking around naked admiring the emperor's new clothes and lets get down to the business at hand - demanding from our governments the sensible policies that will see immediate and radical reductions in production of GHG's and switch to renewable energy sources while transitioning away from major reliance on finite fossil fuels.

According to the above analysis, over 50 % of population exposed to river food risk worldwide lives in just 5 countries of South Asia i.e. Afghanistan, Bangladesh, India, Myanmar and Pakistan which is very alarming! With assistance from global partners, the governments of these countries should divert their sufficient resources to address this issue for improving flood-related DRR activities as well as to protect lives of their people.

would it not be better to take a stand to stop the ozone layer deteriorating further by cutting the numbers of cattle, no more breeding, stop all the the industrial countries polluting,such as china. we can i am sure for the next 20 years or so get on very nicely without eating beef, and having new vehicles on the road, and stop all manufacturers using cfc in products. and why is there not more free solar panels etc, and why is there not more money on research to get a affordable hydrogen powered vehicles.

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