Pioneering research on global fresh groundwater reserves

Published: 26 August 2015

Recently, NASA warned that ‘the largest underground water basins in the world are disappearing at an alarming rate’. This is bad news: drinking water supplies, food production and industry depend on fresh groundwater. Research institute Deltares and Utrecht University will be combining forces in the new, pioneering New Delta study to map out the status of the groundwater reserves in the world’s forty most important deltas. They will look at changes in the groundwater reserves caused by the combination of climate change and an expanding global population that is moving increasingly towards cities. For the first time, the complex interaction between fresh and salt groundwater (in other words, salinisation) in deltaic areas will be investigated.

Water reservoir

The study is based on the latest insights about fresh-salt modelling. For example, it is possible to make an accurate prediction of fresh groundwater reserves if you have an idea of how the landscape has developed going back thousands of years. That is a fairly specific type of knowledge that Deltares and Utrecht University have acquired. By combining it with relevant, worldwide freely availabe databases, it will now be possible for the first time to make assessments of fresh groundwater reserves in data-poor areas, such as Bangladesh and Myanmar.

Learning more about salinisation

The results of the study will teach us more about how salinisation works. It also help us on the road to establish solutions that will stop the reserves being depleted and possibly even reverse the falling trend. Some possible strategies are reducting the use of non-renewable freshwater reserves by  creating large underground water-storage facilities, or extracting submarine groundwater discharge.

Climate change

The research will be led by fresh-salt groundwater expert Gualbert Oude Essink of Deltares, who is also an associate professor at Utrecht University, and Marc Bierkens, full professor of Hydrology at the UU and senior researcher at Deltares. ‘This study is needed because the impacts of climate change and sea-level rise come to light in many low-lying coastal areas. The groundwater system is already under pressure because of large-scale groundwater extractions. As a result, the groundwater reserves are declining in absolute terms, the remaining fresh groundwater is suffering from rapid salinisation, and the land is subsiding even faster than the sea level is rising,’ explains Gualbert Oude Essink.

Marc Bierkens: ‘Our group has already been engaged in extensive research looking at changes in the availability and use of groundwater on a global scale. We are extending our scope to look at the role of the climate and socio-economic factors on those groundwater reserves. A particularly important and relevant factor is the link between fresh and salt groundwater, precisely because most population growth will be concentrated in the deltas in the decades to come’.


The study will begin on 1 September 2015 and lasts four years. The Netherlands Organisation for Scientific Research is providing funding to the amount of € 250,000; Deltares is contributing € 60,000 and the consultancy firm Witteveen+Bos will contribute a further € 10,000.

Deltares is an independent, international knowledge centre that is working globally on sustainable solutions for issues relating to water and the subsurface to make living in deltas possible, now and in the future. Utrecht University is involved in the theme of Sustainability: Water, Climate and Ecosystems, studying the global water cycle and changes resulting from human interventions and climate change.