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

Published on by in Academic

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

SEE FULL ARTICLE ATTACHED

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

Communications Earth & Environment   volume 7 , Article number: 45 (2026) Cite this article Abstract

Groundwater is the largest accessible freshwater on Earth, yet its quantity and distribution remain unknown. Here, we develop a high-resolution (approximately 30 m) estimate of water table depth over the continental United States using machine learning that includes uncertainty. We estimate that there is 306,500 km³ (uncertainty range: 291,850–316,720 km³) of groundwater over North America. This represents our highest resolution estimate of accessible freshwater to date, supported by robust statistical performance. 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.

Similar content being viewed by others

Efficacy of mitigation strategies for aquifer sustainability under climate change

Article Open access06 December 2024

Global groundwater warming due to climate change

Article Open access04 June 2024

Offshore freshened groundwater in the Pearl River estuary and shelf as a significant water resource

Article Open access24 June 2023

Introduction

Groundwater has large spatial variability, which poses challenges for management

The vast majority of Earth’s freshwater lies underground1, yet its accessibility remains poorly defined. Water table depths, or how far water is from the surface, can vary greatly over short distances. Observations are helpful to detect local to global water table trends2, and to estimate the total quantity of groundwater3. Prior studies have made great strides in simulating groundwater flow at a large scale4,5 or using remote sensing to infer extraction6,7. However, national to global scale hydrological simulations that include pumping8,9,10 are computationally and data expensive, typically at coarse resolution (greater than one square kilometer) and lacking uncertainty estimates. At the same time, remote sensing approaches cover only recent decades and have low resolution. Estimating actual water table depths (i.e., including anthropogenic impacts) at high resolution remains a challenge11.

Groundwater systems are not a uniform reservoir and have significant spatial variability across multiple scales12. Water table depth is often portrayed as a subdued replica of topography13, however, groundwater recharging at higher elevations can travel great distances laterally underground to topographic lows, also known as groundwater convergence. Groundwater can maintain shallow water table depth in areas of local convergence during dry conditions, the same way that baseflow supports streamflow4,8. These groundwater-land surface connections are of great importance to both watershed dynamics and ecosystem function14 often helping to sustain vegetation through drought15,16,17.

Shallow groundwater supports more than just ecosystems and streamflow. Local variability in water table depth can also challenge local users who rely on groundwater. For example, a center-pivot irrigation system in which a sprinkler is attached to a single groundwater well to water crops covers approximately 500 m2 (Fig. 1). There are more than 14 million center pivots over a large agricultural region like the Ogallala18 which covers an area of almost 500,000 km2 (Fig. 1). Farmers make individual irrigation decisions at these local (500 m2) scales but collectively their actions impact major aquifers regionally that span several US states.

Media

Taxonomy