Flash floods and Urban flooding France
The Gard region, an administrative jurisdiction located in south-eastern France, is the French region most frequently affected by flash floods (9). Over the last 25 years three exceptional rainfall events have caused considerable damage and losses:
- In 1988 the city of Nimes was completely devastated by a flood associated with rainfall accumulations in excess of 400 mm within 6 h (10), causing nine deaths.
- The extraordinary flood event of the 8th and 9th of September 2002 affected the entire Gard region, with rainfall accumulations that locally exceeded 600 mm in 12 h, causing 24 deaths in addition to economic losses estimated at € 1.2 billion (11).
- A major event was also observed on September 2005 6th–8th in the southern part of the region, with local rainfall accumulations of about 300 mm on the 6th and 250 mm on the 8th, responsible for significant inundations in Nimes, but more predominantly in the downstream plains (12).
Severe flooding in June 2010
In June storms hit the south-east of France and the large amounts of heavy rain led to localised flash flooding (5). The rainfall amounts were exceptional for the time of year. 400 mm of rain fell in less than 2 days in Provence, an amount that had not been seen over the last 50 years (6). These were the worst floods since 1827 and caused severe damage and loss of life in southern France (5). A number of towns in the department of Var were affected, with hundreds of homes flooded. According to BBC reports, at least 19 people were killed by flash floods and several others reported missing (7).
Projected changes in France in the 21st century
With respect to the impact of climate change on flash floods both projected increases and decreases have been reported. For the Cévennes region of the Massif Central a possible increase has been reported in the 10-year flood level of up to 100% by the 2050s, whereas the expected return period of what was a 10-year flood at the end of the 20th century could reduce to 2 years by the 2050s (1). In this region, by the 2050s, there might be significant increases of winter precipitation and significant decreases of summer precipitation in most of the region (2). Winter days above 10mm of precipitation may become more frequent in the northern half of France by the late 2100s (3), due to a change in the tails of the rainfall distribution and not simply a shift in mean precipitation.
In contrast, for the French Alps, the most significant climatic trends for the end of the 21st century could be a decrease in intense rainfall events, particularly during the autumn and winter (4).
For the Gard region a Road Inundation Warning System (RIWS) has been built, based on a hydro-meteorological forecasting approach, that is able to provide flash flood warnings at intersections between roads and rivers (8).
The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for France.
- Quintana-Seguí et al. (2011), in: UK Met Office (2011)
- Quintana-Seguí et al. (2010), in: UK Met Office (2011)
- Deque (2007), in: UK Met Office (2011)
- Jomelli et al. (2009); Peings et al. (2011), both in: UK Met Office (2011)
- WMO (2011), in: UK Met Office (2011)
- Méteo France (2010), in: UK Met Office (2011)
- BBC (2010), in: UK Met Office (2011)
- Naulin et al. (2013)
- Gaume et al. (2009), in: Naulin et al. (2013)
- Desbordes et al. (1989), in: Naulin et al. (2013)
- Delrieu et al. (2004), in: Naulin et al. (2013)
- Marechal et al. (2007), in: Naulin et al. (2013)