International Association of CIP Professionals

Natural disasters are estimated to cause an average of over $300 billion in direct asset losses every year; this estimate increases to $520 billion when considering the well-being (or consumption) losses experienced by people (Hallegatte et al. 2017). While each country faces its individual set of natural hazards – including cyclones, earthquakes, or wildfires – floods are one of the most common and severe hazards to disrupt people’s livelihoods around the world. Especially in lower income countries where infrastructure systems – including drainage and flood protection – tend to be less developed, floods often cause unmitigated damage and suffering. Recent events, ranging from Bangladesh and Nigeria to the United States and Vietnam, illustrate that the threat is a global reality. Not only rare and major floods, but also smaller and frequent events can revert years of progress in poverty reduction and development. In the coming years, land subsidence, rapid coastal urbanization, and climate change are bound to result in increasing exposure of people and their livelihoods.

A new report findings suggest that :

The exposure of people to flood risk is substantial: We find that 2.2 billion people, or 29 percent of the world population live in areas that would experience some level of inundation during a 1- in-100 year flood event. About 1.46 billion people, or 19 percent of the world population, are directly exposed to inundation depths of over 0.15 meter, which would pose significant risk to lives, especially of vulnerable population groups.

Of the 1.47 billion people who are exposed to flood risk, 89 percent live in low- and middle-income countries. 132 million people are estimated to live in both extreme poverty (under $1.9 per day) and in high flood risk areas.

While flood risks are global, East and South Asia stand out: Flood risks are a near universal threat, affecting people in all countries covered in this study – albeit at different scales. The largest number of flood exposed people live in East and South Asia (1.36 billion people). In several subnational areas of East and South Asia, more than two-thirds of the population is exposed to significant flood risks.

When considering poverty among the flood exposed population, risks are largest in Sub-Saharan Africa. At least 71 million people in Sub-Saharan Africa are estimated to live in both extreme poverty (using a $1.9 a day definition) and significant flood risk – thus making them particularly vulnerable to prolonged adverse impacts on livelihoods and well-being. Globally, between 132 million and 587 million poor people are exposed to flood risks (depending on which poverty definition is used). About 1.2 billion flood-exposed people live in lower- and uppermiddle-income countries.

These findings are based on high-resolution flood hazard and population maps that enable global coverage, as well as poverty estimates from the World Bank’s Global Monitoring Database of harmonized household surveys.