A Tool to Determine Annual Ground-Water Allocations in the Tarn-et-Garonne Alluvial Aquifer (France)

Pierre Le Cointe (1) , Nuttinck, Vorlette , Jean-Daniel Rinaudo

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)

The Tarn-et-Garonne department is crossed by three main rivers (Garonne, Tarn and Aveyron) whose alluvial plain covers an area of almost 1 000 km 2. Since 1996, the "Direction Départementale des Territoires" (Gov. Administration at department level), with the technical help of the French geological survey (BRGM), initiated the development of a groundwater model and a spreadsheet tool to define annual groundwater abstraction allocations. As the field data and the computing capacities increased and the law evolved, three versions of the groundwater model were successively developed to better assess the Maximum Permissible Volumes (MPV) of groundwater abstraction on a yearly basis. The last transient state version takes into account the annual fluctuations in groundwater recharge and the water exchanges between the aquifer and the rivers. The MPVs are calculated each year in 21 management zones outside of the previously defined riverside aquifer. These zones are now managed by four agricultural users' associations, known as collective management agencies (or OUGCs). Further improvement should lead to the spreadsheet tool being available online, to encourage OUGCs and farmers to be more proactive in managing the groundwater resource.

Mots clés: Alluvial aquifer; groundwater model; riverside aquifer; management tool; annual allocation; collective management

Domaines: Hydrologie; Environnement et Société

Pierre Le Cointe, Nuttinck, Vorlette, Jean-Daniel Rinaudo. A Tool to Determine Annual Ground-Water Allocations in the Tarn-et-Garonne Alluvial Aquifer (France). Sustainable groundwater management: a comparative analysis of French and Australian policies and implications to other countries, pp.253-274, 2020, ⟨10.1007/978-3-030-32766-8_13⟩. ⟨hal-02531770⟩