Groundwater Depletion

Groundwater constitutes the primary source of drinking water for more than two billion people across the globe. Moreover, groundwater contributes to food and energy security, as well as human health and ecosystem preservation. However, groundwater depletion is a common phenomenon worldwide. This phenomenon appears when extraction surpasses the recharge of the aquifer, and it is triggered by the socioeconomic framework and controlled by the aquifer regime. Groundwater depletion can lead to seawater intrusion in coastal aquifers, a reduction in river base flow, upconing of deep geothermal water, and increased pumping costs. Groundwater depletion has been reported on both a global and regional scale. This Reprint, entitled "Groundwater Depletion: Current Trends and Future Challenges to Mitigate the Phenomenon", attempts to highlight the efficiency and adequacy of global and regional strategies in mitigating the phenomenon, and to promote the transition from the regional to aquifer scale. Additionally, it is critically important to appraise the role of climate variability, management practices, and the monitoring of groundwater reserves. The Special Issue also provides the state-of-the-art of tools and methods to map, model, and forecast the phenomenon.