Libya floods: Why damage to Derna was so catastrophic

Record rainfall

The water was brought by Storm Daniel which hit Libya on Sunday.

The storm – a Mediterranean hurricane-like system known as a medicane – brought more than 400mm of rain to parts of the north-east coast within a 24-hour period.

That is an extraordinary deluge of water for a region which usually sees about 1.5mm throughout the whole of September.

Libya’s National Meteorological Centre says it is a new rainfall record.

Satellite data shows the extent of some of the rainfall across the region – although in many places the amount recorded on the ground was higher.

Residents of the city, who had been ordered by the local authorities to stay in their homes, reported hearing a loud blast before the city was engulfed in water.

“The dams would have held back the water initially, with their failure potentially releasing all the water in one go.

“The debris caught up in the floodwaters would have added to the destructive power,” says Prof Stephens.