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Abstract

The Grand Canyon provides a deeply dissected view of the aquifers of the Colorado Plateau and its public and tribal lands. Stacked sandstone and karst aquifers are vertically connected by a network of faults and breccia pipes creating a complex groundwater network. Hydrochemical variations define structurally controlled groundwater sub-basins, each with main discharging springs. North Rim (N-Rim), South Rim (S-Rim), and far-west springs have different stable isotope fingerprints, reflecting different mean recharge elevations. Variation within each region reflects proportions of fast/slow aquifer pathways. Often considered perched, the upper Coconino (C) aquifer has a similar compositional range as the regional Redwall-Muav (R-M) karst aquifer, indicating connectivity. Natural and anthropogenic tracers show that recharge can travel 2 km vertically and tens of kilometers laterally in days to months via fracture conduits to mix with older karst baseflow. Six decades of piping N-Rim water to S-Rim Village and infiltration of effluent along the Bright Angel fault have sustained S-Rim groundwaters and likely induced S-Rim microseismicity. Sustainable groundwater management and uranium mining threats require better monitoring and application of hydrotectonic concepts.

  • ▪  Hydrotectonic concepts include distinct structural sub-basins, fault fast conduits, confined aquifers, karst aquifers, upwelling geothermal fluids, and induced seismicity.
  • ▪  N-Rim, S-Rim, and far-west springs have different stable isotope fingerprints reflecting different mean recharge elevations and residence times.
  • ▪  The upper C and lower R-M aquifers have overlapping stable isotope fingerprints in a given region, indicating vertical connectively between aquifers.
  • ▪  S-Rim springs and groundwater wells are being sustained by ∼60 years of piping of N-Rim water to S-Rim, also inducing seismicity.

Expected final online publication date for the , Volume 52 is May 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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/content/journals/10.1146/annurev-earth-080723-083513
2024-02-21
2024-04-15
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  • Article Type: Review Article
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