Catchment Name and Location: The Var Catchment that includes the Vesubie sub- catchment affected in 2020 by the ALEX storm is located in southeast France, in the French Riviera. The catchment covers the most important area of Alpes-Maritimes department as well as a small part of Alpes-de-Haute-Provence department. The catchment has a total area of 2.800 km2 and is characterized by a variation of altitude from 0 m at the Mediterranean Sea, to 3.132m at the mountain peaks of the Southern Alps.
Recent flash flood events have affected the French Rivera (Côte d´Azur: Nice Metropolitan territory, Cannes,) as well as Corsica Island. Among the most significant flash flood events that occured in this region stand out:
• 2015 Oct.03 (Nice Metropolitan territory & Cannes)
• 2016 Nov.24 (Corsica Island, Bigugliga catchment)
• 2020 Oct.02 Alex storm (Nice Metropolitan Area – Vésubie valley)
• 2023 Oct.20 Aline storm (Nice Metropolitan Area – Vésubie valley)
In 2020, ALEX storm blew in from the Atlantic to impact France’s western coastline with wind gusts reaching as high as 180 km/h with rainfall of more than 500 mm registered over 24 hours in Saint-Martin- Vésubie. The rainfall was induced by 3 stationary convective cells that where never observed before in France. Damages in the Alpes Maritime region of southern France and the Nice area were estimated at more than US $1.75 billion, on an economic basis and with 9 victims. Extreme flood events like this have occurred in 1994 and 2015 as well. In these events, due to the fast-occurring flash floods, field measurements were often unavailable as measurement instrument were destroyed by the floods. Also, water pollution from the combined sewer overflow (CSO) systems and other industrial facilities added more challenges to the management and recovery from the flood. These types of flood event are typical representations in the Mediterranean coastal cities in France and Italy. The climate evolution analysis produced by Meteo France assume that this type of event could be more frequent in the coming years.
Damage in Saint Martin Vésubie
