Three powerful rainy episodes caused flooding in the Vallouise valley this year 2024. Some aerial images and HD virtual tours of the last episode which occurred at the end of September.
Damage in the upper Onde valley
The Entraigues car park to get to the Bans refuge is inaccessible from Les Fauries
Huge rock masses collapsed from the Riou du Gerpa under the Rascrouset pass and the former glacier of the same name. This event, which occurred during the night of Thursday 25 to Friday 26 September 2024, spread to the Vallouise plain, further down to Vigneaux and Argentière la Bessée, causing flooding and the destruction of sections of road.
The old Fauries footbridge, providing access to the meadows on the right bank, was completely engulfed by this torrential lava phenomenon, an expression used during the Bérarde rock avalanche that same year. 
Several large sections of road, all along the Onde torrent, were swallowed up by the waters. A few hundred meters before Entre les Aigues, large rock flows cut the road leading to the parking lot, where hikers going to the Bans refuge or the Jas la Croix cabin park.
Herds of sheep and cattle had difficulty crossing the landslides and going down the right bank to Les Fauries to leave their summer pastures.
Two vehicles were blocked before being airlifted by "Helena", a powerful Super Puma helicopter registered "HB-ZKN" in Switzerland (1700 hp, 4.5 tons of payload) from the French Air Rescue (SAF)...
Aerial videos of the rock avalanche and the heliport
Many locals came to see the extent of the damage with their own eyes. A small lake (Gerpa or Entraigues lake?) formed at the bottom of the valley, at Entre les Aigues, because of the accumulation of rocks coming from the Riou du Gerpa.
It should be noted that this small expanse of water did not seem to have an apparent outlet, unlike the Gerpa alluvial fan releasing a stream towards the Onde. The flow of the torrent reappeared just after the old Fauries footbridge. Suggesting underground infiltration. Some were worried about a possible pocket of underground water that would end up releasing with the imaginable risks at the bottom of the valley... All this deserves to be analyzed by hydrologists, let's bet that the services concerned were worried about this...
A digression to point out that the IGN maps indicate "Entre les Aigues" whose etymology we imagine means "between the waters". The Vallouisiens use the neighboring term Entraigues.
Millennial phenomena and global warming
The mountain has been a place of erosion and transformation since the dawn of time. This is evidenced by the archive photos of the Gerpa alluvial fan fed by successive landslides. The topographic origin of the collapse raises some debates in the valley, with some believing that most of the materials came from the bottom of the Riou du Gerpa below the 2200 m altitude mark. Others imagining a possible water retention system in the form of an ephemeral high-altitude lake fed by the slope coming from the Col des Beaufs rouges and the Colt du Rascrouset, perhaps just above the 2300 m altitude which would have given way creating a torrential lava. Note that, towards this 2200 m mark, a marked constriction in the form of a canyon, with several bends, delimits the upper and lower part of the Gerpa… as can be seen in the aerial images on this page.
Archive images 1928 and 1933: Onde, Entre les Aigues and Gerpa
Archive images of the 1928 flood: the photographic plates from the Departmental Archives (from the Mountain Land Restoration Service) offer us beautiful images from the years 1928 and 1933 in Entraigues, combe du Gerpa, in the Onde under the current Pont des Places and Grésonnières sector.
We recommend that you visit the website of the Hautes-Alpes departmental archives https://archives.hautes-alpes.fr/ from which the period images come.
High definition aerial virtual tours between Vallouise and Entre Les Aigues as well as the Riou du Gerpa
Global warming in the Alps
These ten-year and hundred-year floods are increasing, with three massive episodes in one year in 2024. The village made national headlines during the flood of June 21, when continuous news channels broadcast images of a parked car sinking into the Gyr torrent, at the place called the gravel pit at the entrance to the municipal campsite.
In August 2023, the Pelvoux and Sélé refuges were closed to access following powerful landslides (evoking permafrost melting).
During the same rainy episode that saw the Gyr rage, La Berarde, a small hamlet on the western slope of the Écrins massif, was completely devastated in June 2024.
Human-caused global warming, scientifically and unanimously recognized by the international scientific community, is occurring at a rate never before documented in the history of the globe.
The concept of the Anthropocene describes the human impact on geology.
In terms of climate and meteorology, it is enough to understand that air masses are like sponges that can accommodate all the more water (in gaseous or liquid form) the warmer they are. A few extra degrees potentially generate and multiply stronger rainy episodes. A meteorologist from Météo France, in August 2023, presenting a prospective study of the snow cover of the ski resorts of Pelvoux and Puy Saint Vincent PSV, explained that the precipitation will not necessarily be higher annually but distributed in a more concentrated manner with more violent episodes. These climatic upheavals also increase the frequency of fires in the Alps, such as in Vigneaux in 2003.
Aerial photos Onde and Gerpa/Entraigues
Hydrology: minor and major bed and land use planning
The minor bed describes the usual location of the torrent, the major bed occupies the banks during floods and intense rainfall events. Note that the damage of September 2024 only concerns a tiny surface of the valley. The wave about 7 km long between Vallouise and Entre les Aigues only deviated from its minor bed by a few meters (5 or 10 maximum).
Some developments attempt to channel the major bed in order to avoid overflows, such as at the beginning of the Vallouise plain before the Gérendoine bridge, on the left bank or just after on the right bank. One of our former neighbors, former mayor of the village, told us that the plain was largely flooded at the beginning of the twentieth century with a meter of water in places.
The question inevitably arises of the sustainability of these developments over time, of their costs for the community while these climatic upheavals do not seem ready to diminish… All this against a backdrop of lasting financial scarcity for the State and local authorities, demographic, land, tourist pressure, etc.
Without mentioning, according to informed analysts like Jean-Marc Jancovici (read the comic strip “A world without end”), the coming energy and mining shortage. Europe hardly has this, today indispensable, magical and powerful fossil energy, generating CO2… allowing to try to tame nature…
All this is a question of balances to be found, of various particular interests versus collective interests, of mentalities… Those with a little political and sociological culture will remember P Bourdieu’s interpellation: “Where are you speaking from”, to say the subjectivity of our opinions, beliefs, chin strokes.
Easier to have definitive certainties than to confront physical realities and human consequences, in all their complexities and meanderings. The excellent Boris Cyrulnik in “The Labourer and the Wind Eaters” deals in this book with the relationship to reality and the mirage of simplistic solutions… but let’s stop, momentarily, these few digressions…
Panoramic photos
The human consequences in the Vallouise valley
Will the Entraigues car park to access the Bans refuge, a very popular family walk frequented by holidaymakers, be easily accessible again?
We can doubt it at least in the near future. Indeed the works seem titanic to open access to the large parking lot of Entre les Aigues (about two hundred spaces). Not to mention the impossible purge of the Gerpa valley where many blocks seem to be precariously balanced 300 to 500 meters above the road.
There remains the small location at the level of the chapel of Béassac (remember the maquis of Béassac and Celestin Freinet in Vallouise) but it only has about twenty spaces. The hypothetical solution of a shuttle, during the summer holidays, from Vallouise, as in Névache in the North of the Hautes-Alpes, diffuses in the discussions. Starting the walk from the chapel of Béassac, it would therefore take about half an hour to reach Entraigues (about 2 km and 140m of positive elevation gain), provided that you can cross to the right bank (at the level of Fauries), then cross back to the left bank at the level of Entraigues. Which would require building two footbridges or bridges...? The situation remains on the rest of the path that goes up to the Bans refuge and which is apparently also damaged...?
The bottom of the Onde valley at Vallouise is also home to cross-country ski trails that had to be completely redesigned to adapt to the damage, with an associated local economy (instructors, rental companies, accommodation providers, shopkeepers, restaurateurs, etc.). This section of the Onde between the Pont des Places and Gérendoine is home to the Pissette waterfall as well as many walkers, runners, horse riders, mountain bikers, etc., as the place is heavenly in all seasons...
The risk, difficult to assess, of flooding the village of Vallouise and its useful access points for tourist activity must also be taken into account. The main road leading to Pelvoux and Ailefroide was cut off at the entrance to the village during the Gyr flood last June. What would happen if the bridges were blown up, cutting the village off from the rest of the world or at least from its continuous flow of tourists during the holidays?
These phenomena encourage us all to be very humble in the face of the power of nature. Without falling into a catastrophic, unproductive and paralyzing spiral (the “what’s the point” effect) but without lacking lucidity (the opposite of an “ostrich” effect), adaptability and resilience in the face of these upheavals that are only just beginning…
