Apport des traçages isotopiques à la compréhension des inondations : le cas de la Somme

Isotopic constraints for flooding processes comprehension: the Somme case

BRGM, Service EAU, Avenue C. Guillemin, BP 6009, 45060 Orleans cedex 02, France.

Abstract

Floods in the Somme district during 2001 were studied with regard to the water chemistry (major and trace elements) and isotopic tracing (oxygène, hydrogene, tritium and strontium). The chemical and isotopic composition of river and ground-waters are constrained by the weathering of the surrounding lithologies and the anthropogenic influences. The coupled using of water chemistry and isotopic tracing allows deciphering the nature of the water fluxes, e.g. runoff and groundwater inputs, during the period of maximum flooding (april 2001) and during another period of lower river discharge (october 2001). The use of isotopic systematics strengthens and gives new insight to the hydrodynamic analysis of groundwater induced flood processes.