Quantifying the impact of lagged hydrological responses on the effectiveness of groundwater conservation

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Authors

Thomas Jeffery Glose , Samuel C Zipper , David Hyndman, Anthony Kendall, Jillian Deines, James Butler

Abstract

Many irrigated agricultural areas seek strategies to prolong the lifespan of their groundwater resources. However, it is unclear how lagged responses, such as reduced groundwater recharge caused by more efficient irrigation, may impact the ultimate effectiveness of these initiatives. Here, we use a variably saturated groundwater model to: 1) analyze aquifer responses to pumping reductions, 2) quantify time lags between reductions and water level responses, and 3) identify the physical controls on lagged responses. We explore a range of plausible model parameters for an area of the High Plains Aquifer (USA) where stakeholder-driven conservation has slowed groundwater depletion. We identify two types of lagged responses that reduce the long-term effectiveness of groundwater conservation. When vertical hydraulic conductivity (Kz) is > 3.5 x 10-3 m d-1, more efficient irrigation reduces groundwater recharge on sub-decadal timescales (recharge-dominated response). By contrast, when Kz is < 3.5 x 10-3 m d-1, changes in recharge are negligible, but pumping reductions alter the lateral flow between the groundwater conservation area and the surrounding regions over decadal timescales (lateral-flow-dominated response). For the modeled area, we found that a pumping reduction of 30% resulted in median usable lifetime extensions of 20 or 25 years, depending on the dominant lagged response mechanism (recharge- vs. lateral-flow-dominated). These estimates are far shorter than estimates made without accounting for the lagged responses. Our results indicate that conservation-based pumping reductions can extend aquifer lifespans, but lagged responses can create a sizable difference between the initial and long-term effectiveness of those conservation measures.

DOI

https://doi.org/10.31223/X51S6X

Subjects

Earth Sciences, Hydrology, Physical Sciences and Mathematics

Keywords

numerical modeling, lagged processes, groundwater conservation, pumping reductions, irrigation practices

Dates

Published: 2021-05-27 03:16

Last Updated: 2021-05-27 10:16

License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
None

Data Availability (Reason not available):
https://github.com/tomglose/SD6_Modeling_Project.git

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