Guest editors — Niels Hartog (KWR Water Research Institute), Victor Bense (Wageningen University), Perry de Louw (Deltares), Hanneke Verweij (NJG)
Introduction — Groundwater faces complex sustainability challenges related to the combined impact of changing climate, the need for energy and land use transitions, and the continued growth of population and economy. It is a crucial resource of fresh water for domestic, agricultural and industrial uses, and for maintaining groundwater-dependent ecosystems. About 60% of the drinking water supply in the Netherlands is produced from groundwater. Groundwater conditions are also of key importance in relation to the transition towards a more sustainable energy supply, e.g. for identifying and evaluating sites for aquifer thermal energy storage, geothermal energy, and storage sites for CO2, hydrogen, nuclear waste. Climate change and foreseen sea-level rise and occurrence of extreme dry and wet events are expected to affect groundwater quality and quantity now and in the future. Sea-level rise in combination with continued land subsidence in the low-lying coastal zone of the Netherlands are expected to increase salinisation of the fresh groundwater systems in the coastal zone.
A good understanding of properties and processes of groundwater systems at different time and spatial scales are key for designing proper adaptation approaches to climate change and current and future competitive uses of the shallow subsurface in the realm of fresh groundwater resources and at greater depth, as well as environmental and social concerns related to these activities. This thematic issue provides an overview of the wide variety of recent groundwater research at universities, knowledge institutes, drinking water companies, and energy companies.
