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. Further, 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. In GEOWAT, I propose to take 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. We 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. We 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 most pressing challenges that mankind will face: how to sustainably manage the freshwater resources needed to survive on this planet?
The key objectives of GEOWAT are:
1. Determine the physical limits of groundwater use by estimating the volume of total and fresh groundwater, estimating how much of that volume is physically extractable, and projecting the time to physical depletion of groundwater reserves under future climate and socioeconomic scenarios.
2. Determine the economic limits of groundwater use by estimating the maximum depth at which groundwater withdrawal is still profitable under current land use and future scenarios, and by finding withdrawal trajectories that are economically sustainable over time.
3. Determine the ecological limits of groundwater use by estimating how groundwater withdrawal affects groundwater-dependent ecosystems globally and valuating resulting ecosystem deterioration economically.
