Mapping Libya’s flood damage | Infographics

Libya suffered widespread flooding and destruction over the past week in the aftermath of a storm. We explain how it happened.

On September 10, a Mediterranean storm made landfall near the Benghazi city in northeast Libya. It brought record-breaking rainfall to the country. Between September 9 and 11, more than 100 mm rainfall was recorded. The Al Bayda station near the coast saw 414 mm of rainfall, the highest ever recorded in 24 hours. Usually, the region receives just around 1.5 mm of rain for the whole of September.

Nine areas were affected by the storm, and seven were severely affected. Derna city was among the areas severely affected. However, rainfall alone did not cause the destruction in the city.

As the storm brought record-breaking rainfall, Al-Wadia dam to the south of the city collapsed. Following this, water rushed down the Wadia valley for around 12 kilometres before reaching the second dam closer to Derna city.

The second dam, too, collapsed under the force of the fast-moving water. With this, the water surged into Derna. The floodwaters destroyed entire blocks. and five bridges along its path.

Estimated deaths have crossed 11,000. More than 38,000 people have been displaced. Around 2,176 structures have been damaged in Derna alone.

Also read |Libya’s deadly floods: what we know

Derna’s low-lying terrain made it more vulnerable to flooding. The elevation near the first dam is around 200 m, gradually dropping to around 45 m near the second dam. At Derna’s coastline, elevation is around just 10 m. Combined with this, the Wadi valley acted as an effective conduit in channelling the floodwaters straight into the city.