263 Exploring Groundwater Recharge and Management: Managed Aquifer Recharge and Other Innovative Tools for Water Supply Development and Operations (Posters)

Growing demand for water has highlighted the need to understand aquifer recharge to improve groundwater management and production methods. This session explores groundwater recharge and innovative water supplies and infrastructure. Topics include evapotranspiration, vadose zone processes, brackish groundwater desalination, managed aquifer recharge, stormwater management, and others.

Wednesday, 22 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Quantifying the Influence of Spin-Up on Vadose Zone Water Travel Time and Recharge

Paper number: 263-0
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Groundwater recharge estimates hinge on accurately simulating percolation through the vadose zone — an unsaturated layer that has expanded in many drought‑stressed basins as water tables decline, such as California’s Central Valley. Although numerical tools such as HYDRUS‑1D are indispensable for this task, their predictive accuracy is routinely compromised by an often-overlooked detail: the spin‑up (warm-up) period used to equilibrate antecedent moisture conditions. A poorly chosen spin‑up can embed moisture deficits or surpluses that persist tens of meters downward, biasing critical water flux and travel time predictions that underpin managed‑aquifer‑recharge (MAR) planning, tracer interpretation, and regional water budgeting.

This study investigates the influence of spin-up period strategies on vadose zone water flow and recharge travel times, using soil columns representative of Central Valley’s Modesto and Turlock subbasins as a case study. By systematically evaluating how different spin-up durations and initial condition approaches impact water movement in the vadose zone, we aim to: (1) quantify how spin-up choices propagate uncertainties in deep percolation rates and travel times; (2) clarify their interplay with soil texture and layering; and (3) develop guidelines for optimal spin-up protocols that stabilize model output and enhance vadose-zone model reliability. These insights are expected to advance robust vadose zone modeling, provide practical guidance for improved recharge estimates, and support more reliable groundwater‑management decisions in water‑scarce regions.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412834

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