Synthèse des études sur le système multicouche des nappes tertiaires du nords de l'Aquitaine

¹ B.R.G.M.
² Centre d'hydrogéologie de Bordeaux.
³ Arrondissement minéralogique de Bordeaux.
⁴ Géohydraulique.
⁵ Centre d'Information géologique de l'E.N.S.M.P.

Résumé

The province of Aquitaine contains very abundant water supplies which are only being tapped very locally. More over, as it is bounded by the shores of the Gironde estuary and the Atlantic coast, salt water encroaches inland right up to the vicinity of the tapping points. This synthesis is the result of teamwork which, by geological, geophysical and hydrodynamics research and the use of natural radioactive tracers has shown that in tapping these ground water resources, one cannot consider each aquifer separately even where the local formations between them are relatively impervious. It was necessary to consider that whole sedimentary mass if one was to reliably estimate the effects of pumping on the aquifers and the accomanying risks of salt water contamination of the ground water. And lastly, the separation between surface and ground water no longer has any physical meaning at that scale. In its concrete form, the synthesis is provided by mathematical and multi-layer analogue models representing all the Tertiary aquifers and impervious formations between them north of the Western Aquitaine region, covering a total area of some 15,000 sq.kms.