The current stress on global freshwater supplies, particularly in densely populated coastal regions, will be exacerbated significantly by ongoing climate change, associated seawater rise and population increase (Figure 1).  A future sustainable water supply for coastal regions will depend on our understanding of ground- and seawater interaction in amphibious coastal aquifer systems.

In many coastal regions the salt/freshwater interface is moving landward, signifying a potential threat to water security through saltwater intrusion. However, in some regions of the world, the saline/fresh water interface in the subsurface may also be located 10s of kilometres seaward, on the shelf, indicating the presence of offshore freshened groundwater (OFG) and signifying a reduced threat to coastal fresh water supplies.

Within this collaborative high-risk AI project between GEOMAR, Helmholtz Centre for Marine Research Kiel and UFZ Helmholtz Centre for Environmental Research, we aim to use globally available geospatial data on surface features (e.g. Digital Elevation Model, Land Surface Models, shelf bathymetry and the GRACE datasets), in conjunction with climatic data and hydrogeological modelling, to predict the globally the largely unknown location of the saltwater/freshwater interface in the subsurface. We expect to provide a tool that allows us to produce global probability maps of the location of the coastal fresh/saline water interface (a proxy for the presence of OFG), that can be adjusted to future climate scenarios.

The gain from developing an inexpensive, computationally efficient method to predict the existence and extent of offshore groundwater is undeniably a major advancement for all stakeholders on sustainable coastal water management. It will significantly impact how sampling/drilling strategies are devised in future reconnaissance studies.

For more information about offshore freshened groundwater see also:

Collaboration Partners

Dr. Christian Siebert

UFZ Helmholtz Centre for Environmental Research
Dept. Catchment Hydrology

Dr. Laura Haffert

GEOMAR, Helmholtz Centre for Marine Research Kiel
Data Science Unit

Dr. Marion Jegen

GEOMAR, Helmholtz Centre for Marine Research Kiel
Research Division 4, Dynamics of the Ocean Floor.

Prof. Dr. Christian Berndt

GEOMAR, Helmholtz Centre for Marine Research Kiel
Research Division 4, Dynamics of the Ocean Floor.



Micallef, A., Person, M., Berndt, C., Bertoni, C., Cohen, D., Dugan, B., et al. (2020). Offshore freshened groundwater in continental margins. Reviews of Geophysics, 58, e2020RG000706.