The percentage of global population at risk from flooding has risen by almost a quarter since the year 2000, a new study has found.
The analysis shows that migration and a growing number of flood events are behind the rapid increase, reports the BBC.
By 2030, millions more will experience increased flooding due to climate and demographic change, the authors say.Flooding is the environmental disaster that impacts more people than any other, said researchers.
That view has echoed around the world in recent weeks, with huge inundations destroying lives and property.
In Germany and China, record downpours overwhelmed defences, amid arguments about levels of preparation.
One of the challenges with flooding, according to researchers, is that most maps of where the waters will likely penetrate are based on models.
These simulate floods based on information such as elevation, rainfall and data from ground sensors.
But they have significant limitations: they fail to consider population or infrastructure changes and are unable to predict random events such as dam breaches.
In this new study, 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. This represents an increase of 20-24% in the proportion of the world population exposed to floods, some 10 times higher than previous estimates.
The increase was not evenly spread throughout the world. Countries with increased flood exposure were mainly in Asia and sub-Saharan Africa. In European and North American nations, the risk was stable or decreasing.