Scope of the special issue: Aquifers are facing severe pressure from water abstraction for irrigation and other water uses, which is aggravated by land use and climate change in a non-stationary context. In many regions groundwater tables have declined considerably and aquifers have become polluted by various pollutants such as nitrates. The changes observed in groundwater quantity and quality are a threat (i) to the crucial ecosystems services groundwater provides such as drinking and irrigation water provision, natural attenuation processes, storage functions and habitats, as well as (ii) to groundwater dependent ecosystems such as springs, rivers, wetlands, and lakes and (iii) to the groundwater dependent socio-economic system (as the social and economic development in many regions is linked to the provision of safe and reliable water resources).

In order to provide sustainable solutions, new methods are needed in groundwater management in which groundwater systems are considered in a more holistic and integrated way. A new way of management is needed where groundwater hydrogeology is better integrated with hydrology and ecology. Sustainable solutions are needed that take into account socio-economic values and ecological aspects of groundwater and dependent ecosystems. In many cases successful management will involve the design of the proper institutional, legal and operational framework that ensures a long-term sustainable management of water and associated ecosystems. Decision making in groundwater quantity and quality management is often complex because of heterogeneous stakeholder interests, multiple objectives, different options, and uncertain outcomes. Conflicting stakeholder interests are often an impediment to the realization and success of any regulations, policies, and measures.

The special issue welcomes scientific papers and critical reviews on groundwater systems and their management. This includes contributions on how hydrological measurements can be linked with environmental tracer methods and numerical modeling to provide management solutions for a more integrated understanding of groundwater systems and groundwater dependent ecosystems. Further, papers are welcome addressing new hydrological and ecological indicators for vulnerability assessment and sustainable management of groundwater and dependent ecosystems. Submissions can also cover studies demonstrating how aquifers are connected to aquatic and terrestrial ecosystems, and how land use, water extraction or climate change affect groundwater and connected ecosystems. New methods to manage aquifers will be presented that take into account options for future land use as well as socio-economic and legal aspects, particularly in context of the implementation of the EU-Water Framework Directive and the Groundwater Directive. All contributions should provide knowledge on new methods or processes on how groundwater systems and their ecosystem services should be managed in the future.