Broken dams: murderous precedents, including in France

2023-06-06 12:09:58

The Kachovka hydroelectric dam, located in an area of ​​the Kherson region (south of l’Ukraine) occupied by Russia, was partially destroyed on Tuesday. Moscow and kyiv accuse each other of having damaged the work of art, retaining a reservoir of more than 18,000 million m3.

The International Commission on Large Dams currently lists more than 55,000 large structures, that is to say whose height is between 5 and 15 meters and which retain more than 3 million cubic meters of water. Accidents have happenedfor centuries, during the construction, the impoundment or later. Most of them did not cause any human losses, the populations being generally evacuated before the tragedy. Other ruptures, on the other hand, are perfectly voluntary, especially in times of war. The stakes are such that dams are protected by the Geneva Convention. Update on the most significant precedents.

The most devastating: Banqiao, in China. In August 1975, Typhoon Nina hit Henan Province. 83 cm of rain fell in just six hours. A first dam gives way, and by domino effect, leads to the rupture of 61 others. The human toll was only made public in 2005: the provincial department of hydrology estimates that 85,600 people died in the flood, to which must be added the 145,000 victims who perished afterwards, from famine and epidemics. The dam was rebuilt in 1986.

Other murderous precedents. On May 31, 1889, the artificial dike in South Fork, Pennsylvania (USA), broke at altitude. A huge wave breaks in the valley, to the town of Johnstown, located 23 km downstream, and covers it with 18 m of water. 2209 people die.

In 1963, in Italy, construction defects and successive landslides led to a breach in the Vajont dam in the Italian Alps. The emptying of the lake is decided to reduce the pressure. On October 8, a partial evacuation of the population was ordered. The next day, October 9, a slope of Mount Toc collapsed, carrying millions of m3 of rock and earth into the reservoir. Three successive waves hit inhabited areas, killing 2,600 people.

On August 11, 1979, the rupture of the Macchu-2 dam in India, due to bad weather, caused a wave of 5 to 10 meters high in the town of Morvi, 5 km downstream. The number of victims is estimated between 2,000 and 15,000.

In France, two fatal accidents. In April 1895, the rupture of the Bouzey dam (Vosges) caused 87 deaths. Cracks had appeared on the structure, which had begun to deform before suddenly yielding. The study of the accident subsequently made it possible to modify certain construction data. On December 2, 1959, the Malpasset dam (Var), built five years earlier, broke during its first filling. Two weeks of heavy rains caused the water level to rise and part of the foundations creaked. 50 million cubic meters of water and mud swept over the town of Fréjus. The damage was considerable: 423 dead, including 135 children, 155 buildings, 1,000 ha of damaged agricultural land. The bill amounts to two billion francs, the equivalent today of 4 billion euros.

Rare sabotage. In 1943, the Royal Air Force (RAF) developed an aerial bombardment operation of German roadblocks in the Ruhr area. This is Operation Chastise. On May 17, the concrete dam of the Möhne river gives way, those of concrete of the Eder and earth of Sope are simply damaged. 330 million m3 of water flow, flooding roads, factories, railways, mines, homes up to 80 km downstream of the dams. The number of dead is estimated at 1,294 people, including 749 French and Ukrainian prisoners of war. 53 of the 133 aircrew of RAF aircraft were also killed. To prepare for Operation Chastise, and develop the right explosives, the Nant-y-Gro dam in Wales was destroyed without causing any casualties.

More recently, in 1993, in the midst of the Croatian war, retreating Serbian forces attempted to blow up Brana Peruća’s restraint. UN peacekeepers had been there since the previous summer and discovered that Serb militiamen had planted 35 tons of explosives on the dam, installed in such a way as to prevent any defusing. Before leaving, on January 28, 1993, the Serbs detonated 5 tons of explosives in the foundations. But, we will learn two years later, a UN observer, the British Mark Nicholas Gray, had lowered the water level in the reservoir before the dam was destroyed. Without his intervention, 20,000 people could have died.

In Ukraine, a double historical precedent. After the destruction of the Kachovka dam, kyiv quickly accused Moscow of doing it again. And in fact. In 1941, Ukraine was invaded by Nazi Germany and subjected to a very strict occupation regime. The Soviet troops multiply the destruction, and in particular, on August 18, 1941, of the hydroelectric power station and the dam of the Dnieper, baptized DniproHES, 170 km from Kachovka. Many villages are swept away by the flood around Zaporijjia, causing the death of 20,000 to 100,000 people, civilians and soldiers. During the fierce Battle of the Dnieper in 1943, one of the most important of the world conflict, German troops in turn blew up the power station, damaging the dam.