Collapse of two dams upstream of the coastal Derna city in NE of Libya, the North African Mediterranean country in the night of Sept 10, 2023, leads to deaths of 5200 and over 10000 missing. This is the worst ever flood disaster of Northern Africa in last 130 years of recorded history. The storm had a climate change footprint, but the city of Darna suffered this fate largely due to dam collapses. This underlines the threat that the dams pose in changing climate. (Feature image above: Remains of a damaged dam upstream of the Derna city in Libya, N Africa in Sept 2023 disaster.)
No Warning, no storm monitoring The disaster got worsened as there was no warning for the people, nor any preparedness for facing such a situation. The only hospital in the city of about 90 000 population was overwhelmed with the hundreds of dead bodies arriving on its doorstep. A storm like Daniel, which can be forecast hours or days ahead. The storm displayed its destructive power the previous week in Greece, Turkey and Bulgaria, killing more than a dozen people, Libyan authorities seemed to have no serious plan to monitor the dams, warn residents or evacuate them.
People were swept away in the middle of night. Hospitals were unable to operate, morgues were full. Emergency services were not available. The rain, which swept across several cities in Libya’s north-east, is the result of a very strong low-pressure system that brought catastrophic flooding to Greece the previous week and moved into the Mediterranean before developing into a tropical-like cyclone known as a medicane.
“The weather conditions were not studied well, the seawater levels and rainfall were not studied, nor were the wind speeds, there was no evacuation of families that could be in the path of the storm and in valleys,” Aly, the emergency authority spokesman said. This is likely to be the deadliest flood disaster of the North Africa region, the casualities in Derna alone outstripping the 3000 deaths in 1927 Algeria floods, the earlier deadliest disaster.[i]
Little information about the dams Water engineering experts said it is likely the upper dam, around 12km from the city, had failed first, sending its water sweeping down the Wadi river valley towards the second dam, which lies closer to Derna – where neighbourhoods were inundated. “At first we just thought it was heavy rain but at midnight we heard a huge explosion and it was the dam bursting,” Raja Sassi, who survived along with his wife and small daughter, said.[ii]
The two dams near Derna, each around 230 feet in height, weren’t fortified enough to handle the storm’s might. When the first dam was overwhelmed, the water collected behind the second dam, causing it to rupture, amplifying the flood’s magnitude.[iii] It is not clear if the dam gates were open or closed and what was their capacity. Derna, situated near the coast, was particularly susceptible. The surrounding mountains funneled rainwater towards the city, creating a disastrous setup when combined with the dam failures.
Engineers had previously issued generalised warnings about the risk of the dams bursting and the urgent need to strengthen their defences. A 2022 report in an academic journal had warned that if a flood equivalent to one in 1959 was repeated, it would be “likely to cause one of the two dams to collapse, making the residents of the valley and the city of Derna vulnerable due to a high risk of flooding”.[iv]
A Cell phone video shows the damaged dam, possibly the one closer to Derna.[v]
Another dam at risk? On Tuesday (Sept 12), a local official speaking to al-Masar said that another dam in the eastern region was filled with water and on the brink of collapse. The Jaza dam — located between Derna and the city of Benghazi — needed maintenance to prevent another disaster, the mayor of the municipality of Tocra, Mahmoud Al Sharaima, said.
The disaster Sondos Shuwaib, a local blogger, said she was in her home when suddenly she found herself torn away by the flood waters. She described seeing children and babies caught in the current. “There were corpses next to me, and corpses above me, and corpses beneath me,” she wrote.
In the city of Derna alone, at least 5,200 people died, said Tarek al-Kharraz, a spokesman for the interior ministry of the government that oversees eastern Libya, according to the Libyan television station al-Masar. But the floodwaters also swept through other eastern settlements, including Shahhat, Al-Bayda and Marj, and at least 20,000 people were displaced.[vi]
Derna lies along the coast of the Mediterranean Sea, at the end of a long, narrow natural valley, called a wadi, which is dry for much of the year. As the port city was inundated by Storm Daniel, which made landfall in Libya on Sunday, the wadi worked as a funnel, forcing the rushing water into the center of the city. Riverbanks swelled, bridges were washed out and two dams farther up the wadi burst, adding their waters to the deluge.[vii]
Analysts said the country’s woes — political division, economic instability, corruption, environmental degradation and dilapidated infrastructure — seemed to coalesce in one catastrophe when the dams south of the city collapsed.
The country is also especially vulnerable to climate change and severe storms. Warming causes the waters of the Mediterranean to expand and its sea levels to rise, eroding shorelines and contributing to flooding, with low-lying coastal areas of Libya at particular risk, according to the United Nations. The dry riverbeds that dot the Arabian Peninsula and North Africa can flood rapidly when it rains heavily, as the parched earth struggles to absorb the downpour.
This is yet another wake up call for all vulnerable regions with multiple large dams, unaccountable dams governance, fragile ecology and poor disaster governance, including India.
SANDRP (ht.sandrp@gmail.com)
POST SCRIPT: Sept 14 2023: In the 1960s studies indicated that the dams should be constructed to protect the city. The dams were constructed in the 1970s by a Yugoslavian company. The upper dam was called the Al-Bilad Dam, with a storage capacity of 1.5 million cubic metres of water, whilst the lower dam, the Abu Mansour Dam, had a storage capacity of 22.5 million cubic metres. The dams had a core of compacted clay with a carapace of stone.
Clearly the rainfall associated with Storm Daniel was extreme – over 200 mm has been reported. This might have exceeded the design capacity of the structures. To what extent can this be attributed to climate change? Derna suffered floods in 1986, but the dams succeeded in managing the water to avoid serious damage to the city. It will be useful to compare the 2023 event to previous storms.
The failed dams in Wadi Derna in Libya
2. SEPT 15 2023: On Thursday (Sept 14), a United Nations World Meteorological Organisation official said that the scale of the crisis was also in part the result of the lack of a functional meteorological authority in Libya. Similarly crisis management was non existent in Libya. Late on Wednesday, a top Libyan official demanded an investigation into both the collapse of the dams and the response to the floods that followed. “We asked the attorney general to open a comprehensive investigation into the events of the disaster,” Mohamed al-Menfi, the head of the Libyan Presidential Council — which is based in the west — said in a social media post. He said that “everyone who made a mistake or neglected either in abstaining or taking actions that resulted in the collapse of the dams in the city of Derna” should be held accountable.
– On Thursday, the health minister for the eastern government said the official, documented count had risen to 3,065 dead, with 4,227 formally reported missing. The Libyan authorities have previously said that the death toll could be more than 5,000 and that more than 10,000 people were missing.
– While the Libyan meteorological service did issue early warnings about heavy rain and floods, it did not address the risk posed by “the aging dams,” the World Meteorological Organization said in a later statement on Thursday. The Libyan weather service’s abilities were limited, the U.N. agency said, by “major gaps in its observing systems,” as well as its information technology.
https://www.nytimes.com/2023/09/14/world/middleeast/libya-floods.html
3. Perhaps the most important source of information is on a site called Hidrotehnika, it provides data on the two dams. The site reports that the upper dam was 45 m high with a storage capacity of 1.5 million cubic metres. The lower dam was 75 m high with a storage capacity of 18 million cubic metres. Both were constructed by Hidroprojekt from Beograd in the former Yugoslavia on behalf of the Ministry of Agriculture in Libya. Construction was from 1973 to 1977.
– There are obvious signs of poor maintenance – for example, shrubs growing on the dam crest. The most likely cause of failure would seem to be that the spillway was simply too small to cope with the volumes of water falling into the catchment, leading to overtopping.
https://eos.org/thelandslideblog/further-information-about-the-wadi-derna-dams
4. The death toll in Libya‘s coastal city of Derna has risen to 11,300, as questions were raised about the maintenance of two dams which burst after heavy rain, unleashing massive floods. A further 10,100 people are reported missing in the Mediterranean city, Marie el-Drese, secretary-general of the Libyan Red Crescent aid group, said. A report by a state-run audit agency in 2021 said the dams had not been maintained despite the allocation of more than £170m for that purpose in 2012 and 2013.
https://inews.co.uk/news/world/death-toll-floods-libyan-coast-city-derna-11300-questions-dam-maintenance-2618838
5. “This disaster was violent and brutal,” said Yann Fridez, head of the Federation’s Libya delegation, in a statement. “A wave 7 meters high wiped out buildings and washed infrastructure into the sea. Now family members are missing, dead bodies are washing back up on shore, and homes are destroyed. The city faces immense emotional trauma.”
– “Poor maintenance and management over the intervening years may have contributed to the problem, but the most likely scenario is that the inflow over the last weekend due to Storm Daniel exceeded the spillway capacity at the upstream Al-Bilad Dam, whether due to the spillway capacity being inadequate, or a blockage of some sort in the spillway,” said Quentin Shaw, a director at ARQ Consulting Engineers and a vice president of the International Commission on Dams, in an email. This excess water led to the breaching of both dams and their eventual collapse, he added.
https://www.enr.com/articles/57112-causes-weighed-of-catastrophic-libya-dam-failure-that-killed-6-000
6. Following images help understand the disaster better.
https://www.reuters.com/graphics/LIBYA-STORM/EXPLAINER/klvyzqebzpg/
7. It started with a bang at 3 a.m. Monday as the residents of Derna were sleeping. One dam burst, then a second, sending a huge wave of water gushing down through the mountains towards the coastal Libyan city, killing thousands as entire neighborhoods were swept into the sea. Those dams haven’t undergone maintenance since 2002, the city’s deputy mayor Ahmed Madroud told Al Jazeera. But the problems with the dams were known. The Sebha University paper warned that the dams in Derna had a “high potential for flood risk” and that periodic maintenance is needed to avoid “catastrophic” flooding.
– Dam failures can be very hard to forecast, and are fast and ferocious, she told CNN. “You have this monstrous volume of water just taking out the city entirely,” Cloke said. “It’s one of the worst types of floods that ever happens.”
https://edition.cnn.com/2023/09/14/middleeast/lethal-factors-leading-to-libya-floods-intl/index.html
8. Libya’s top prosecutor will investigate the collapse of two dams in the eastern port of Derna that launched a fast-moving wall of water that killed thousands of people and largely destroyed the city. General Prosecutor al-Sediq al-Sour told reporters that local authorities, previous governments, and the allocation of the dams’ maintenance funds will be scrutinised.
https://www.aljazeera.com/news/2023/9/16/disaster-of-epic-proportions-libya-prosecutor-probes-deadly-dam-collapse
REFERENCES:
[i] https://edition.cnn.com/2023/09/11/africa/libya-flooding-storm-daniel-climate-intl/index.html
[ii] https://www.bbc.com/news/world-africa-66785466
[iii] https://coopwb.in/info/what-caused-the-flooding-in-libya/
[iv] https://www.theguardian.com/world/2023/sep/12/libya-floods-death-toll-dams-burst
[v] https://www.nbcnews.com/video/video-shows-destroyed-dam-that-led-to-deadly-flooding-of-derna-libya-192764997690
[vi] https://www.nytimes.com/2023/09/12/world/middleeast/libya-floods-dams-collapse.html
[vii] https://www.nytimes.com/interactive/2023/09/12/world/africa/libya-flooding-map.html
SANDRP 