Remembering The Malpasset Dam (1959)
An area almost a kilometer wide was swept away by the water
In December 1959, France faced one of the worst disasters in its history:
The Bursting of the Malpasset Dam.
The failure of this dam is a major event in modern history.
It may seem less significant when compared to the failure of the Banqiao Dam in China in 1975, with estimates of between 85,000 and 240,000 deaths.
Indeed, the Malpasset Dam failure shed light on a problem in dam construction, likely preventing the failure of many others.
December 2nd, 1959
1,030 hectares completely destroyed
Its design aimed to retain the waters of the Reyran River for irrigation and water supply to the region.
The region had experienced heavy rains for several weeks, unexpectedly filling the reservoir at a rapid rate.
In the days leading up to the tragedy, several warning signs were observed, including leaks and deformations in the dam.
At 21:13, the dam gave way. A massive wave, estimated at around 50 million cubic meters of water, surged down the valley with devastating force.
The wave reached Fréjus in less than an hour (10km away), sweeping away everything in its path.
Over 400 people lost their lives in the disaster.
Roads, bridges, houses, farms, and other infrastructure were destroyed or severely damaged. The landscape of the valley was radically altered.
The Underrated Cause
The wave broke at a speed of 70km/h
An investigation confirmed the non-responsibility of the dam’s design engineer.
Indeed, the dimensions were sufficient to withstand the water levels in the reservoir.
The cause of the failure stemmed from geology.
The flanks on which the dam rested gave way due to excessive interstitial pressure (water within the rock).
Water can infiltrate everywhere, including the flanks, and more easily when they are fractured.
Furthermore, some parts of the foundation rock (gneiss) were brittle and less resistant than preliminary studies had suggested.
During the design and construction, these geological conditions were not fully taken into account, leading to weaknesses in the structure and its anchoring.
Lessons For Today’s Constructions
The wave reached a height of around 40–50 meters
The infrastructure of such scale must harmonize with its environment.
The Malpasset catastrophe underscored how crucial it is to have a profound understanding of the environment in which one intends to build such structures.
It highlighted the disastrous consequences that can arise from a lack of knowledge or underestimation of the geological and environmental characteristics of the site.
Today, before undertaking a large-scale project such as a dam, in-depth geological and environmental studies are imperative.
These investigations not only ensure the safety of the structure itself but also the protection of the surrounding populations and environment.
Final Words (For Quick Glancers)
On December 2nd, 1959, France’s Malpasset Dam failed after persistent rains, releasing a devastating wave that claimed over 400 lives and drastically altered the Fréjus valley.
While the dam’s design was sound, its geological foundation was flawed, leading to its collapse. This disaster underlined the critical importance of thorough geological assessments before major infrastructural projects, shaping modern construction standards.
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