Policy Research Working Paper 9447
This study provides a global estimate of the number of people who face the risk of intense fluvial, pluvial, or coastal flooding.
The 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.
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.