Evolution of the vulnerability of people and property to flooding in three cities of the Gard department (south of France)

Abstract : The bottom of valleys, like the seaside, represents privileged places for the setting-up and extension of human population. The last decades have seen a very fast urbanization there, including in low zones renowned for being easily flooded. When they combine an accentuated topography and intense and brutal precipitation, these zones can have extremely sudden and devastating floods. The department of the Gard, the French metropolitan territory the most exposed to these fast floods, provides one such example. In living memory, these catastrophic floods mark out the history of the region despite numerous actions having been undertaken with more or less success to deal with the problem. Regulations have also evolved in order to channel urbanization and reduce the vulnerability of people and their property. However, if at the legal level, the mayors and the prefects have had the possibility of forbidding urbanization in high-risk areas since the end of the 19th century, we can remark a limited recourse to these plans (plan of submersible surface 1935, plan of risk exposure 1982, the perimeter R111-3 of the planning laws 1959) to control the urbanization in flood-risk areas before the implementation of the plans of risk prevention (PPR). One of the stakes in the program " Mobiclimex ", financed by the ANR, is to highlight the consideration of flood risks and the regulations in the delivery of the recent building permits. According to the Ministry of Ecology, sustainable development and energy, in 2009, 44 % of housing and 41 % of the population were exposed to the risk of flooding in 2009 in the Gard; figures among the highest in France. However, this order of magnitude says nothing of the evolutions of construction observed in flood-risk areas. That is why, looking at three symbolic municipalities of the Gard (Nîmes, Alès and Sommières), we can analyze simultaneously the level of flood risk, the evolution of buildings and the evolution of the legislation on the subject. Having dated the set of buildings recognized by a precise scale (BDTopo source of the IGN), we can lead a thorough statistical analysis of the phenomena of urbanization coupled with the levels of hazards. This approach allows us on one hand, to underline the strong relations between types of constructions, zones of hazards and periods of urbanization, and to highlight different strategies according to the different municipalities, these strategies evolving over time.
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https://hal-mines-paristech.archives-ouvertes.fr/hal-01295710
Contributeur : Magalie Prudon <>
Soumis le : jeudi 31 mars 2016 - 15:05:28
Dernière modification le : jeudi 18 juillet 2019 - 01:32:19

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  • HAL Id : hal-01295710, version 1

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Edwige Dubos-Paillard, Joël Boulier, Antonin Pavard, Valérie Sanseverino-Godfrin. Evolution of the vulnerability of people and property to flooding in three cities of the Gard department (south of France). 9th HyMeX Workshop - Hydrological cycle in the MEditerranean EXperiment, Sep 2015, Mykonos, Greece. ⟨hal-01295710⟩

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