Evaluation and modelling of drought impacts on groundwater reserves in Wallonia (Belgium) in the context of climate change

The severity of the 2017 summer drought in Wallonia (Belgium) and the perspective suggesting an increase in extreme events with climate change, introduced the need for tools and indicators able to quantify the resilience and the vulnerability of aquifer systems to such stresses.
In this context, the methodology developed in Wallonia is described hereafter. A dual approach has been adopted relying on numerical groundwater flow models able to simulate both the piezometric evolution and the flow budget changes caused by recharge scenarios. Based on groundwater regional models, the first approach consists of producing maps of maximal piezometric drawdowns and recovery time to assess the spatial variability of groundwater system dynamics. The second approach adopts a global flow budget perspective to quantify, through chosen indicators, relative shifts in water transfers between aquifer recharge, rivers, adjacent aquifers, and exploited groundwater water resources.
The methodology is applied to different strategic regional aquifers to illustrate the complementarity of the two approaches and to assess the impact and resilience of groundwater resources throughout Wallonia using various drought scenarios.