Barrage de Malpasset
| Malpasset dam Barrage de Malpasset |
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| Coordinates | 43 ° 30 '44 " N , 6 ° 45' 24" E | ||||||||
| Data on the structure | |||||||||
| Construction time: | 1952-1954 | ||||||||
| Height above valley floor: | 60 m | ||||||||
| Height above foundation level : | 66 m | ||||||||
| Height above the river bed : | 100.4 m | ||||||||
| Height of the structure crown: | 102 m | ||||||||
| Building volume: | 47 857 m³ | ||||||||
| Crown length: | 222 m | ||||||||
| Crown width: | 1.5 m | ||||||||
| Base width: | 6.82 m | ||||||||
| Radius of curvature : | variable | ||||||||
| Data on the reservoir | |||||||||
| Altitude (at congestion destination ) | 98.5 m | ||||||||
| Water surface | 2 km² | ||||||||
| Storage space | 48.1 million m³ | ||||||||
| Particularities: |
Dam wall burst on December 2, 1959 |
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The Barrage de Malpasset ( French Barrage = dam ) was a dam in Provence near Fréjus in the Var department in southern France .
Completion took place in 1954 and served with the reservoir for the water supply and irrigation of the nearby Fréjus plain (fruit growing). It broke out in 1959; 423 people were killed by the resulting tidal wave .
Geographical location
The Barrage de Malpasset stood in the southern foothills of the Esterel Mountains about 9 km north-northeast of Fréjus , a town on the Côte d'Azur on the Mediterranean . The flowing water that was dammed up at that time is the Reyran mountain stream , which usually only has water in winter , and is a left tributary of the Argens . The hamlets of Malpasset and Bozon were located a little downstream below the dam . A few hundred meters east past the former location of the wall, the A 8 runs as part of today's E 80 .
Dam wall
The Barrage de Malpasset was a double-curved equal-angle arch dam with a variable radius above the foundation base, about 66 m high, about 222 m long at its crown and had a structural volume of 47,857 m³. It was built from 1952 to 1954; According to other sources, construction began in 1941. The construction cost (in 1955 prices) was 580 million francs . The French engineer André Coyne was involved in the construction; the owner was the Var department.
Reservoir
The reservoir was around 2 km² when it was fully flooded and had 48.1 million m³ of storage space. Its destination was at a height of 98.5 m.
Broken dam from 1959
tidal wave
The dam suddenly and completely collapsed on the night of December 2, 1959 at 9:13 p.m. the point in time of the break could be precisely reconstructed because it is known when the electricity due to the tidal wave failed. The wall was almost completely removed by the force of the water. Only a few parts of the wall on the right bank (seen in the direction of flow) remained. Fragments of the wall, some the size of a house, are scattered several hundred meters downstream.
The tidal wave is said to have been up to 40 m high and 70 km / h fast at the beginning. First it reached the hamlets of Malpasset and Bozon , which were completely destroyed. About 20 minutes after the wall came down, it reached Fréjus, where the wave was three meters high and buried large parts of the city in mud.
423 people died; the number of deaths is sometimes given differently, as construction workers on the A8 autoroute , which was being built at the time, were killed. In addition, not all victims were found, as the tidal wave ran into the Mediterranean and some victims were washed with it.
The damage totaled around 68 million US dollars .
root cause
The location for the structure was judged to be suitable based on geological and hydrological reports. The gneiss bedrock was waterproof. On the right-hand side (seen downstream) there was rock, on the left-hand side a concrete wing wall had to be built to connect the wall to the ground.
A few weeks before the break, cracking noises had been heard on the underwater side, but these had not been investigated further. The exact time of this cracking is not known. On the right side there should have been leakage points in November.
A tectonic fault (gap) on the left side under the wall was found to be the cause. The water that seeped under the wall accumulated underground because the rock had become impermeable due to the pressure of the dam and built up a fracture water pressure. This pressure pushed the abutment of the wall upwards at an angle, so that it slid away on the gap. This disturbance had not been discovered beforehand because it was not directly under the wall, but a little further up the air.
Shortly before the break, the water level had risen due to rainfall to a jam of 28 cm below the overflow edge. This also increased the burden. The reservoir had never been dammed so high before. The bottom outlet had been opened five hours earlier to relieve the dam. But it only had a capacity of 40 m³ / s.
After a lengthy process, a court of cassation decided in 1967 that no one could be charged with criminal conduct.
See also
literature
- J. Bellier: Le barrage de Malpasset, 1967
- Max Herzog : Elementary dam statics, 1998
- Max Herzog: Bautechnik 67 issue 12 , 1990
- Theodor Strobl, Franz Zunic: Handbook of hydraulic engineering . Springer, 2006. ISBN 3540223002
documentation
- Pictures that moved the world : The breach of the dam in Fréjus - the dam wall burst , author and presenter: Peter von Zahn , ZDF , first broadcast: September 14, 1983
Web links
- La catastrophe de malpasset en 1959 (French)
- Barrage de Malpasset. In: Structurae
- Full history of the disaster (English)
- Full history of the disaster (French)
- hazard cards: Malpasset
Individual evidence
- ↑ a b ecolo.org: La catatrophe de Malpasset en 1959
- ^ Cracking Dams ( Memento of November 2, 2005 in the Internet Archive )