Nowadays, there is a certain consensus that the planet is undergoing a cycle of climate change in which human activities are the main driving force. The assessment of the recent and future impacts of this climate change and its uncertainties is a necessary step for the design and selection of future efficient and sustainable mitigation and adaptation measures. The adaptation of water resource systems to potential impacts of climate and demand changes (global change) is one of the main challenges of our society. In order to analyze adaptation strategies (including nature-based solutions, combined with non-natural ones) we need to develop methods and tools able to assess the different hydrological, technical, economic, environmental and institutional aspects. The objective of this special issue is to compile research works about recent and future impacts of global change on water source systems depending on natural storage, including aquifers, subsurface retention and stream–aquifer interaction, as well as storages in snowpacks. We also include works about the design of adaptation strategies in these systems. We intend to create a sample of studies to show singularities related to the spatial scale (river basins and aquifers), specific environment of the location (e.g., Alpine basins, coastal areas), hydrological processes (e.g., snow processes, groundwater recharge, flow and discharge and seawater intrusion) and management particularities.