Les Nappes Profondes : Ressources en eau d'ultime recours en cas de crise de pollution majeure

¹ Ministère de l'Environnement, Mission Défense, Paris
² BRGM, Centre thématique Eau, Montpellier

Abstract

Within the framework of a reflection dealing with the possibility to insure sufficient drinking water supply in case of maor crisis, the Ministry of the Environment undertook an inventory of the aquiferous systems on the whole French (continental) territory. In case of a generalized surface water and groudwater contamination, these aquifers could provide substitution water, qualified as "a last resorted water" because of its temporary - fast definitive - protection statute.

A scale of value relative to the protection level was created, wich enables the researchers to identify three levels of protection and to draw up a 1/1,500,000 scale mape of France, on wich the limits of 98 phreatic water-tables, identified as protected, have been reported. The great majority of the aquifers corresponds to confined waters.

A statistical analysis on the existence of protected resources reveals that 16 departments out of 96 have got protected resources on the whole territory, and that 22 others haven't got any that are registered at national scale. Otherwise, 61 towns out of 103 which count more than 50,000 inhabitants have got protected resources, which correspond to 61% of the urban population.

In a second time, the cases of the urban centres of Paris and Lyon will be looked into more in detail, stating precisely the protected resources which could be mobilized and the existing collecting equipments which could possibly be integrated in a device used as a last resort.