PNNL

Abstract

Future rates of global groundwater depletion will depend on the economic and sociopolitical viability of extracting water from increasingly stressed aquifers. Here we analyze global groundwater depletion by considering exploitability limits explicitly. Global gridded groundwater availability and extraction cost data are aggregated to produce non-renewable resource supply curves for 235 water basins with global coverage. These resources are then exposed to dynamically-generated demands for water in a fully-coupled, multi-sectoral, global simulation. As groundwater head levels drop, imposing greater capital and operating costs to bring water to the surface, the model initiates a range of supply- and demand-driven adaptive responses. Results demonstrate large sensitivity in global groundwater depletion rates to adjustments in resource exploitability. The imposition of extraction costs moderates demands for groundwater substantially, resulting in the onset of a decline in global groundwater depletion rates within the 21st century. The spatial distribution of global groundwater depletion shifts as crop producers abandon over-exploited basins and expand croplands in regions with cheaper, more plentiful water resources.