6 October 2020
Saint-Martin-Vesubie: Planet Labs images of the aftermath of the extraordinary flooding from Storm Alex
Posted by Dave Petley
Saint-Martin-Vesubie: Planet Labs images of the aftermath of the extraordinary flooding from Storm Alex
As I noted yesterday, Storm Alex generated extreme levels of rainfall across much of Europe at the weekend, causing extensive damage. One of the locations that suffered the greatest impact was the village of Saint-Martin-Vesubie, located in the Alpes-Maritimes department to the north of Nice, and close to the border with Italy. Planet Labs have very kindly captured some high resolution SkySat imagery of the impacts of the storm, and have made the images available to me.
This is a an image of the area around the village prior to the storm – the image was collected in September 2018:
Planet Labs SkySat image of Saint-Martin-Vesubie before the flooding. Planet Labs SkySat image collected in September 2018, Copyright Planet Labs, used with permission.
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This is the same area of Saint-Martin-Vesubie, after the flood:
Planet Labs SkySat image of Saint-Martin-Vesubie before the flooding. Planet Labs SkySat image collected on 5 October 2020, Copyright Planet Labs, used with permission.
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Note the very extensive damage along the channel to the west of the village. Comparison of the two images suggests that several structures have been lost. To me the level of change in the channel suggests more than simple flood damage, especially when compared to the channel to the east of the village. I wonder if the channel upstream became blocked and then breached to generate this level of catastrophic flooding.
It is worth taking a look at the image in more detail. This is the area in the immediate vicinity of the historic centre of Saint-Martin-Vesubie before the flood:-
Planet Labs SkySat image of Saint-Martin-Vesubie before the flooding. Planet Labs SkySat image collected in September 2018, Copyright Planet Labs, used with permission.
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This is the same area after the flood:
Planet Labs SkySat image of Saint-Martin-Vesubie before the flooding. Planet Labs SkySat image collected on 5 October 2020, Copyright Planet Labs, used with permission.
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Quickslide 1: Imagery of the Barry Arm rockslide in Alaska
NASA has posted a very nice article, with some excellent images, of the Barry Arm rockslide in Alaska. It is easy to see from these images why this site is such a concern.
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Quickslide 2: Gender and natural disasters
The ever excellent Nepali Times has a good article on why natural disasters in Nepal kill more women than men. The conclusion is that “Women bear the brunt of most disasters like floods, earthquakes and landslides in Nepal because the countryside has been ‘feminised’ by the outmigration of men. And it is the women who tend to be inside the house more often than men”. In addition, “women have less access to information and seldom participate in disaster learning skills. Socio-cultural perceptions of sexuality and traditional beliefs about gender responsibility also put women at greater risk in disasters.”
These are really important issues; addressing them needs to be a part of the ways in which communities build resilience to natural disasters.
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Reference and acknowledgement
Planet Team (2020). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/
Thanks to my friends at Planet Labs for collecting the images and making them available to me.
Dave Petley is the Vice-Chancellor of the University of Hull in the United Kingdom. His blog provides commentary and analysis of landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings.
Lot of steep unvegetalized slopes just few kilometers above the city, mountains can reach 3000 m high. With such rainfall (500 mm/24h), pretty sure some landslides occured and channelised, given the massive destruction.
I believe Fabien comments in Le Monde. Like him I am amazed, but not really surprised, as to the lack of curiosity from the media about the real causes of this catastrophe, As well as the reasons why the impact on roads (interestingly, not so much railroad) is so large. Then I watched videos of the area, criss-crossed by asphalted roads precariously squeezed between river bed/gorge and cliffs. The whole road+building infrastructure was built outside of proper risk parameters (but it was the same in Banda Aceh, Japan, South and SOuth-East coastal USA).
If you would like to investigate the landslides, debris flows, and river flooding from this event in the new HazMapper Google Earth Engine app here is the link that will take you to the Saint-Martin-Vesubie area where one can begin exploring the impacts of Storm Alex on the Maritime Alps.
https://cmscheip.users.earthengine.app/view/hazmapper#lon=7.257083894338896;lat=44.07358043630321;zoom=13;dataset=0;prewindow=0.5;postwindow=0.5;maxCloudCover=30;slopeThreshold=0;eventDate=20201002;