Biodiversity and Functions of Alluvial Systems Facing Severe Droughts Induced by Global Change

Abstract

The goal of the study is to obtain realistic forecasts at 60 years of the relative vulnerability of different types of wetlands for dewatering and drought. The work will lead successively to the production of (1) a hydroclimatic scenario for the impact of global change on river recharge and (2) a hydrogeological model of the river and its aquifer, which will in turn result in a model for the dewatering regime wetlands at the 50 m scale. The case study is an alluvial aquifer located on the sedimentary plain of the Ain River, France. The aquifer is essentially fed by rainwater and drained water by the Ain River. The groundwater flow model used is a modular three-dimensional finite-difference groundwater flow model (MODFLOW) developed by the United States Geological Survey. The model is based on a numerical solution of the Boussinesq equation that governs groundwater flow through porous media. MODFLOW works with a block-centered grid in which it is assumed that hydraulic and hydrogeologic properties are uniform over the extent of a cell. There are about 249,000 cells in the irregular cells. The model is calibrated in the transient state with piezometric water levels in wet and dry seasons. © 2024 Taylor & Francis Group, LLC.