1. Context

Groundwater accounts for over 97% of the planet's freshwater resources (excluding glaciers and ice caps). The remaining 3% is made up mainly of surface water (lakes, rivers, wetlands) and soil moisture. Until recently, groundwater was considered primarily as a source of drinking water (around 2/3 of the European Union's inhabitants depend on groundwater to meet their domestic needs). This resource is also important for industry (e.g. cooling water) and agriculture (irrigation). However, it has become clear that groundwater should not only be considered as a reservoir of drinking water, but also as a fragile aquatic ecosystem