Unprecedented! Why the floods in Libya are so tragic?

A man sits in front of a flooded house in the eastern Libyan city of Drna on September 15. According to the latest figures from the International Organization for Migration, more than 40,000 people have been displaced by the disaster in northeastern Libya, and the actual number may be higher. Xinhua News Agency

Hurricane Daniel made landfall on the Mediterranean coast of eastern Libya on the 10th and caused flooding. Abu Mansour and Bilad dams on the Derna River collapsed at night, causing heavy casualties in the city of Derna downstream, many people being swept away by floodwaters in their sleep, and rescue efforts are ongoing. This is the largest meteorological disaster in Libya on record, and one of the largest in Africa.

On the 17th, the United Nations Office for the Coordination of Humanitarian Affairs, citing data release report from the World Health Organization, revised the death toll caused by the floods in Libya to 3,958, and more than 9,000 people were missing. A day earlier, the U.N. Office for the Coordination of Humanitarian Affairs cited data from the Libyan Red Crescent Society as saying that at least 11,300 people died in Libya's floods, but the Libyan Red Crescent later denied the figure.

More than 40,000 people have been displaced in northeastern Libya

According to CNN, the United Nations Office for the Coordination of Humanitarian Affairs lowered the number of victims of the Libyan flood to 3,958 on the 17th, and the data source is the World Health Organization. According to the updated figures, more than 9,000 people are still missing in the floods. Citing Libyan Red Crescent Society data earlier in the day, the agency reported that at least 11,300 people had been killed and more than 10,000 missing in Derna alone.

The U.N. Office for the Coordination of Humanitarian Affairs said that according to the latest figures from the International Organization for Migration, more than 40,000 people in northeastern Libya have been displaced by the disaster, and the actual number may be higher. In addition, landmines and other munitions left over from years of conflict in Libya have been washed away from their original locations by floodwaters, posing additional risks to the affected population.

Libyan authorities say 150 people in the affected area have been poisoned by drinking contaminated water.

A quarter of the block was washed into the sea by floodwaters

On September 10, 2023, local time, Hurricane Daniel made landfall on the coast east of Benghazi, Libya. A day or two before Daniel made landfall, his wind fields and rainy clouds had begun to affect Libya, and on September 9, sandstorms turned to moderate to heavy rain in the east of the country. After the landfall of "Daniel" on September 10, the rainfall in Libya expanded, the rain intensified along the northeast coast, and the area east of Benghazi changed from moderate to heavy to heavy rain, including the upper part of the Derna River, and the mountainous northeast of Libya fell extremely heavy rainfall.

Due to rainfall, the water level of the Derna River, which is usually waterless, has soared, and since the night of September 10, the river channel in the city of Derna has been flooded. At about 2 a.m. on September 11, two reservoirs in the upper reaches of the Drna River were filled, and then the Abu Mansour Dam and Bilad Dam, which held water from the reservoir, collapsed, equivalent to two West Lakes of huge floods wrapped in sand, stones and tree branches, crossed the canyon on the south side of the city of Derna, and at about 2:30 a.m., fell from the sky with a thunderous force and swept through the city of Drna.

Judging by the water marks of the buildings in the city of Derna, after 2:30, the water level of the Derna River rose by 14-18 meters in a few minutes, and a quarter of the neighborhoods of the city of Derna were washed into the sea, and the entire plain area of the city was flooded with floods and mud. In addition to Drna, extensive areas in northeastern Libya are also flooded, with many casualties, but not as serious as Drna.

Factorial

The 24-hour water production exceeds five times the total capacity of the two upstream reservoirs

The first is natural causes. The Libyan floods were preceded by extreme weather conditions in the Mediterranean. In July-August, the Mediterranean SST exceeded 30°C, the highest value since meteorological records began. Since September, the westerly wind belt in Europe has oscillated violently, and a cold vortex in northern Europe has fallen near Greece, triggering the abnormal Mediterranean hurricane "Daniel".

Before making landfall in Libya, " Daniel " had caused extremely heavy rains in Greece , Bulgaria and Turkey , and hovered in the Mediterranean Sea for a week, spinning from semi-tropical to a real tropical cyclone before making landfall in Libya , and finally making landfall in Libya with severe tropical storm intensity, the only Mediterranean hurricane to make landfall in Libya in the summer since meteorological records began.

Because of this, Libya has received heavy rainfall this time. After "Daniel" landed in Libya, deep into the Sahara Desert, nearly half of the country's territory precipitated, the northeast coastal areas fell heavy rain to heavy rain, mountainous areas exceptionally heavy rainfall, measured maximum 24-hour rainfall of 414 mm, has exceeded the "Anemone" heavy rain in Fuzhou National Meteorological Station. Since local weather stations are scarce, the actual maximum rainfall should be much greater.

In addition, the local tropical desert climate or Mediterranean climate, the summer is extremely dry, the average precipitation in September is only 0-3 mm, so this rainfall is equivalent to 100-500 times the local precipitation in September, or even infinite times, equivalent to 2-10 times the annual precipitation, which is a heavy rain beyond the experience and imagination of the locals. Based on 200 millimetres of surface rainfall, the water production of the upper reaches of the Derna River in 24 hours exceeded the combined capacity of the two upstream reservoirs by five times.

Water conservancy facilities are in disrepair There are cracks in the dam body for a long time

The second is man-made. Due to political instability and weak government capacity in Libya, the water facilities near the city of Derna have fallen into disrepair and river management has been rendered useless. North of the city of Derna, the two reservoirs, built in the 70s, have not been maintained for more than 20 years, and the dam body has long been cracked but unattended, and finally collapsed under extreme rainstorms.

A state-run auditor said in a 2021 report that despite allocating more than $2 million for the project in 2012 and 2013, the dams remained unmaintained.

The wide upstream and narrow downstream channels of the Derna River are extremely unreasonable, but the lower channels in the urban area of Derna are still encroached upon in large quantities. This is similar to the 1999 flood in Valgaste, Venezuela. Because of this, during the extreme rainstorm, the river in the city of Derna could not effectively carry floodwater, causing the water level in the city to rise by 14-18 meters in a few minutes, which finally caused a catastrophe.

rethink

Initial heavy rainfall, local people "completely undefended" Extreme weather and climate knowledge needs to be popularized

Three days before the torrential rains, Libya's National Meteorological Centre (NMC) issued a storm warning and a red warning for heavy rain in the east, forecasting 7-8 winds and 100-240 mm of rain. But there was no warning about the dam. Although this forecast is still on the small side, it can still save many lives if prepared in time. When the torrential rains first fell in the city of Derna, and the floods first occurred, the locals were quite happy and filmed videos to commemorate the situation, which can be described as completely undefended. In this mood of complete slackening and unguardedness, a catastrophe struck a few hours later, and many people were swept into the sea by the flood in their sleep.

Libya's extreme rainstorms, floods and catastrophe tell us that in the context of climate warming, all kinds of unexpected extreme weather will occur with higher frequency, greater intensity, and more unexpected ways, and more and more extreme weather is inevitable. In terms of extreme weather defense, accurate weather forecasting and early warning is only a small aspect, developed infrastructure, strong and efficient emergency defense system, scientific education throughout the public, especially the popularization of extreme weather and climate knowledge, are essential.

Integration: Dong Shuyun

Compiler: Nandu reporter Chen Lin