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Inferring hillslope groundwater recharge ratios from the storage-discharge relation
  • David N Dralle,
  • W. Jesse Hahm,
  • Daniella Rempe
David N Dralle
Pacific Southwest Research Station, United States Forest Service

Corresponding Author:david.dralle@usda.gov

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W. Jesse Hahm
Simon Fraser University
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Daniella Rempe
University of Texas at Austinn
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Accurate observation of hillslope groundwater storage and instantaneous recharge remains difficult due to limited monitoring and the complexity of mountainous landscapes. We introduce a novel storage-discharge method to estimate hillslope recharge and the recharge ratio---the fraction of precipitation that recharges groundwater. The method, which relies on streamflow data, is corroborated by independent measurements of water storage dynamics inside the Rivendell experimental hillslope at the Eel River Critical Zone Observatory, California USA. We find that along-hillslope patterns in bedrock weathering and plant-driven storage dynamics govern the seasonal evolution of recharge ratios. Thinner weathering profiles and smaller root-zone storage deficits near-channel are replenished before larger ridge-top deficits. Consequently, precipitation progressively activates groundwater from channel to divide, with an attendant increase in recharge ratios throughout the wet season. Our novel approach and process observations offer valuable insights into controls on groundwater recharge, enhancing our understanding of a critical flux in the hydrologic cycle.
26 Apr 2023Submitted to ESS Open Archive
28 Apr 2023Published in ESS Open Archive