LONDON - Coastal areas in the UK and Northern Europe will experience an increase in “compound flooding” in coming decades say researchers.

These events, where storm surges and heavy rainfall combine, will become more common thanks to rising global temperatures.

Devon, Cornwall and the Bristol channel may become “hotspots” with events seen more than once every six years.

Researchers say that floods on the Avon in Bristol in 2014 and in Ravenna in Italy in 2015 are both good examples of compound events that have caused significant losses to people and property.

These events are marked by a combination of storm surge and heavy rainfall, sometimes driven by the same low pressure system.

Storm surges can be made worse with heavy precipitation but they can also cause trouble by blocking or slowing down the draining of a river into the sea following a period of sustained rainfall.

Despite the fact that they often occur at the same time, risk assessment planners generally see the storm surge and rainfall as separate events.

This new study uses computer models to asses the current climate, and shows that around 3% of coastal areas experience compound flooding events more than once every six years.

At the moment, these are mainly in the Mediterranean, around the Gulf of Valencia in Spain, Algeria, the Gulf of Lyon in France and in southern Turkey.

The continent wide analysis suggests that the difficulties posed by compound events will increase in a warmer world, and will move to threaten Northern Europe far more than they do at present.

According to the modelling carried out by the team of researchers, “compound flooding is projected to robustly increase along the west coast of Great Britain, Northern France, and along the east and south coast of the North Sea”.

The report say that the fractions of coastlines expected to see return periods of lower than six years is projected to increase from the present 3% to 11% by the end of the century.

“There will be a higher probability of experiencing concurring storm surges and heavy precipitation and these might lead to increased compound flooding especially in river mouths and low lying coastal areas,” said lead author Dr EmanueleBevacqua from the University of Reading, UK.