Population at risk of extreme flood is ten times higher than previously thought, finds Cloud to Street

Research by flood mapping platform Cloud to Street reveals that the proportion of global population exposed to floods has grown by 24% since the turn of the millennium, a tenfold difference from what scientists previously thought. Growing exposure and a growing number of flood events are behind the rapid increase.

Bessie Schwarz, CEO and co-founder of Cloud to Street, said: “More people and more assets are impacted by flooding than any other climate-fuelled disaster. The Global Flood Database will help insurers understand the changing nature of flood risk and offer more competitive insurance coverage.”

The researchers looked at daily satellite imagery to estimate both the extent of flooding and the number of people exposed to over 900 large flood events between 2000 and 2018. They found that between 255 and 290 million people were directly affected - and between 2000 and 2015, the number of people living in these flooded locations increased by 58-86 million.

Further findings from the research include:

  • By 2030 the model estimates that climate and demographic change will add 25 new countries to the 32 already experiencing increasing floods.
  • Despite representing less than 2 percent of floods, dam breaks had the highest increased incidence (177%) in proportion of population exposed.
  • Population growth in flooded areas is driven by people moving into flood-prone areas, and economic development in those regions. Vulnerable populations often have no choice but to settle in flood zones.
  • Nearly 90% of flood events occurred in South and Southeast Asia, with the large basins (Indus, Ganges-Brahmaputra, and Mekong) having the largest absolute numbers of people exposed and increased proportions of population exposed to inundation.
  • The satellite data also uncovered previously unidentified increases in flood exposure in Southern Asia, Southern Latin America, and the Middle East.

It is hoped that the database will provide a credible benchmark for the insurance industry to assess flood risks, both from an aggregated annual average loss perspective, as well as single extreme loss-making floods.

A collaboration between Cloud to Street and the Willis Research Network aims to better understand flood risk and mitigate the economic impact of flooding, while also creating parametric risk transfer solutions.

As flood risk is expected to increase through population changes and urbanisation, overlaid onto a background trend driven by climate change, the dataset will provide an ongoing and essential view of risk to support humanitarian and risk management efforts.