The role of a floodplain in regulating aquifer recharge during a flood event of the River Adour in southwest France

Abstract

Abstract This study forms part of a French Government initiative supporting research into the function of wetlands as regulators of water regimes and supporters of a rich biodiversity. Aquifer recharge has been studied in a section of the floodplain of the River Adour, between Saubusse and Le Vimport, one of the major wetland areas in southwest France. The study has focused primarily on a major flood event observed during 6 to 19 March 1999. The March flood allows 2.1 × 106 m3 of water to be stored in the sub-surface as the water-table rises to the surface of the floodplain giving complete saturation. After the passage of the flood wave, the water table declines to a level that restores the original volume of water stored in the sub-surface. The 7 km2 floodplain has an estimated total sub-surface storage capacity of ∼ 6.3 × 106 m3 down to a layer of impermeable clay. During summer low water periods, the sub-surface storage is estimated to be ∼ 4.2 × 106 m3 (i.e., 67% of the total available sub-surface sto...