High resolution US water table depth estimates reveal quantity of accessible groundwater

Groundwater is the largest accessible freshwater on Earth, yet its quantity and distribution remains unknown. Here we develop a high resolution (approximately 30m) estimate of water table depth over the continental United States using machine learning that includes groundwater pumping and uncertainty. This represents our most accurate estimate of accessible freshwater to date. We calculate total and accessible groundwater storage and results show that coarse resolution products are systematically biased in their estimates locally, where decisions are made, as well as at large scales. Our approaches are spatially extensive and locally relevant and thereby bridge a gap between remote sensing and point observations.