PhD on the Physical Limits to Global Groundwater Use (1.0 FTE)

A better future for everyone. This ambition motivates our scientists in executing their leading research and inspiring teaching. At Utrecht University , the various disciplines collaborate intensively towards major societal themes. Our focus is on Dynamics of Youth, Institutions for Open Societies, Life Sciences and Sustainability.

Utrecht University's Faculty of Geosciences studies the Earth: from the Earth's core to its surface, including man's spatial and material utilisation of the Earth - always with a focus on sustainability and innovation. With 3,400 students (BSc and MSc) and 720 staff, the faculty is a strong and challenging organisation. The Faculty of Geosciences is organised in four Departments: Earth Sciences, Human Geography & Spatial Planning, Physical Geography, and Sustainable Development.

The Department of Physical Geography excels in research and education on BSc, MSc and PhD level. Our research focuses on processes, patterns and dynamics of the Earth’s continental and coastal systems, and on the interaction between these processes. This knowledge is essential for the sustainable management of our planet and to guarantee the availability of resources for the next generations. 

About the GEOWAT project
The ERC AdG project GEOWAT stands for 'The Global Assessment of the Limits of Groundwater Use'. It is a €2.5 million 5-year research project funded by the European Research Council under the Advanced Grant scheme. 

Summary: Population growth and economic development have dramatically increased the demand for food and water. The resulting expansion of agriculture into areas with limited precipitation and surface water has greatly increased the reliance on groundwater irrigation. Furthermore, urban groundwater use has risen exponentially to meet the ever-increasing population growth of mega-cities. These trends have resulted in a dramatic rise in groundwater pumping and associated high rates of aquifer depletion around the globe. The depletion of our world’s aquifers is unsustainable and will eventually impact the food security of future generations. Also, groundwater depletion results in severe environmental impacts such as land subsidence, groundwater salinisation, and damage to groundwater-dependent ecosystems. Despite decades of research on groundwater overuse, knowledge on attainable groundwater reserves and the critical time horizons of their depletion is completely lacking.

GEOWAT takes the giant leap to extractable volumes and depletion horizons by answering the obvious question that has been avoided thus far: How much groundwater is there and how long will it last? To this end, GEOWAT will build the first high-resolution global groundwater model supported with a 3D-mapping of the world’s aquifers. GEOWAT will use these unique modelling tools, in combination with dedicated case studies, to assess, for the first time, the global volume of physically and economically extractable fresh groundwater, and determine the time to physical and economic depletion under future pumping. It will also provide the first global assessment of the effects of groundwater pumping on groundwater-dependent ecosystems and explore pathways to sustainable groundwater use. As such, GEOWAT will provide critically-needed new knowledge to address one of the most pressing challenges that mankind will face: how to sustainably manage the freshwater resources needed to survive on this planet?

Research design: GEOWAT is organised into six inter-related work packages (WPs) executed by six scientists (including the PI), a research assistant and one model engineer. The backbone of the research approach (WP1 – This Postdoc 1) is the creation of a high-resolution 30 arc-second (~1 km) physically-based, global-scale surface water - groundwater model (GLAM). To support this model, we will develop a 30 arc-second hydrogeological schematisation (HYGS) of the world’s aquifers that consists of aquifer and aquitard thicknesses and their hydraulic properties. The HYGS will use a novel combination of new and existing global datasets, machine learning and data-assimilation (WP2 – Postdoc 2). The GLAM and HYGS will then be used to address the key scientific objectives: to estimate past, current, and future volumes of fresh groundwater globally (physical limits, WP4; PhD 1); to assess the volume of groundwater that can be extracted, including costs and benefits and assess pathways to sustainable use (economic limits, WP5; PhD 2); and to assess how extraction strategies impact the extent and biodiversity of groundwater-dependent ecosystems (ecological limits, WP6; PhD3). The results of all WPs will be synthesized into one multi-faceted assessment of the limits of groundwater use. To assess the accuracy of these results, we will use a three-pillar strategy:

a) global analyses will be grounded on regional case studies in four depletion hotspots (WP3); b) results will be evaluated against hydrogeological datasets, including regional groundwater models; c) uncertainty assessment will be integral to our approach, including all relevant sources of uncertainty.