Barrage de Malpasset

At the end of the 1939-45 war, one of the many problems that the general council of the Var department had to solve concerned hydraulic equipment. The greatest needs were in the south of the department, a region in full tourist and agricultural development, the fruits and early vegetables of Fréjus already had a great international reputation.

The Ministry of Agriculture gave its approval, by decision of August 3, 1950, to establish a dam on the Reyran, at the Malpasset site.

Malpasset, means a bad passage, where travelers and merchants were attacked by highwaymen. Reyran in Provençal comes from: "Riaio" (torrent) and "Ran" (in abundance). The valley is dry three quarters of the year, but during the rainy season it can cause serious flooding in the plain of Fréjus.

Taming the Reyran is therefore important. The water reserve thus created will provide essential water to ever-growing populations, supply thirsty lands, contribute to the development of tourism and protect our Esterel forests from fires. The dam will be the work of the Var General Council. Professor Corroy of the Faculty of Sciences of Marseille, consulted, gives a preliminary geological opinion favorable to the place called: Malpasset.

For the study of the preliminary design of the dam, the General Council turned to the office of André Coyne, president of the International Association of Large Dams. He is the most renowned engineer in the field of arch dams. His finest achievements are Tignes and Bort-les-Orgues in France and the Lake Kariba dam in Zambia, one of the largest dams in the world.

The type of dam chosen is the arch dam. The arch-shaped dam design means that the water pressure tightens the wall and the arch transmits the colossal forces it receives to the banks. This type of structure requires that the banks receiving the bulk of the pressure be extremely robust. On the left bank, the absence of a shoulder capable of serving as a stop required the construction of an artificial abutment, made of reinforced concrete.

The construction site began on April 1, 1952 and was completed in 1954. Characteristics of the dam:

Maximum height – 59 m

Coronation – 225 m

Total retention capacity – 49300000 m3

Wall thickness: base 6,78m, crest 1,50m. This low thickness made it the thinnest dam in Europe.

In the fall of 1959, torrential rains fell on the region for three weeks.

The first filling, the most critical phase in the life of a dam, is carried out without any possible control. Filling had begun at the end of 1954, but due to delays in expropriations, the reservoir had not exceeded level 95.

At 18:00 p.m. on December 2, 1959, the order was given to open the drain valve.

21:13 p.m. …

The consequences were dramatic. Officially, 423 people were killed, 7000 were homeless, and 79 were orphaned. The damage in 1970 was estimated at more than 100 million francs.

Malpasset, built for the glory and wealth of the region, unfortunately caused only disaster and despair in its path. The "Pink Valley is gone forever."

It took 8 years for the causes of the disaster to be clearly established and recognised:

Judgment rendered by the Court of Cassation on December 7, 1967:

"No fault was committed at any stage"

The expulsion of the rocky dihedral on which the foundations of the left bank support of the arch rested appears to be the cause of the dam failure. The Malpasset accident led to a strengthening of technical regulations with the establishment in 1967 of the Permanent Technical Committee for Dams.