| Safety
Dam disaster highlights climate and safety concerns
The recent Libyan dam failures have highlighted how climate change continues to intensify the severity of weather-related disasters, and why dam safety should be pushed to the top of the agenda worldwide. Report by Suzanne Pritchard
ALMOST A QUARTER OF Africa’s deadliest weather- related disasters since 1900 are reported to have occurred in the past two years. And the most recent catastrophe in Libya, where devasting floods amassed a death tally of thousands, was the seventh to have killed at least 500 Africans since 2022. According to meteorologists, climate change is, and will continue to increase, the severity of African weather disasters. On 10 September 2023, a medicane (a
Mediterranean hurricane-like system) reached its peak in northeastern Libya with strong winds of 70-80km/h. Called Storm Daniel, it also brought 150-240mm of torrential rains that caused flash flooding in several cities. The port city of Derna was one of the hardest hit and received more than 100mm which far exceeded its average monthly rainfall of less than 1.5mm for September. Such record-breaking rainfall trigged the collapse of the Abu Mansur and Derna dams along a usually dry riverbed (wadi) and as this floodwater, sometimes up to 7m in height and 100m wide, tore through the city of Derna, it led to the collapse of many roads and buildings, even sweeping them out to sea. Both dams were built in the 1970s. Situated about 14km away from the city, Abu Mansour was over 70m high and could hold up to 22.5Mm3
of water, while the
Derna dam, also known as Belad, was much closer to the city and could hold 1.5Mm3
. Estimates suggest that up to 100Mm3 of water filled
the valley prior to the collapse of the Abu Mansur dam, while it’s been claimed that in order to discharge the water entering the valley, the dam would have required a discharge capacity of 1200m3 designed capacity was 170m3
/sec, whereas its /sec.
In the aftermath of the disaster it’s still unclear how many people were killed as many bodies are believed to have been washed out to sea. Derna, with a population of 90,000 was the hardest hit town and estimated loss of life could be in the region of 20,000. At least 4000 people have been confirmed dead, with another 10,000 reported missing, while the Office for the Coordination of Humanitarian Affairs estimated that more than 880,000 people lived in areas impacted by the floods. Tensions have flared in the wake of these tragic events with conflicting reports about how the emergency procedures were handled. Libya’s National Meteorological Centre claims it issued early warnings for the extreme weather event 72 hours before its
www.waterpowermagazine.com | November 2023 | 25
occurrence, and notified all government authorities by emails and through media urging them to take more care and preventive measures. Other reports have highlighted how local residents
were indeed evacuated away from the riverbed and seafront in Derna, as there were fears about rising sea levels, but many people were then reportedly moved into the centre of the city, and killed by later flooding. Although the Mayor of Derna (who later resigned) says he personally ordered evacuation three to four days before the disaster, other reports claim that officials told residents to stay put with no warnings of possible flooding. A Reuters report even mentions a Facebook post from the Water Resources Ministry that told residents not to worry, that the dams were in good condition, and everything was under control.
Challenges Hydrologist Abdul Wanis Ashour disputes the claim
that the two Libyan dams were in good condition. Only last year he warned in an academic paper published in the Sebha University Journal of Pure and Applied Sciences, that if the dams were not maintained there could be a disaster in the Derna Valley basin. Ashour has been researching the Derna dam system for 17 years and unearthed data that revealed the presence of numerous cracks in the dam, along with other worries about rainfall and repeated flooding. In his paper he asserted that the dams were unable to withstand a storm like Daniel and were at risk of collapse if faced with such large amounts of rainfall.
Below: Deadly floods occurred in Libya during September 2023 Editorial credit: seraj elhouni /
Shutterstock.com
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