Critical Aquifer Overdraft Accelerates Degradation of Groundwater Quality in California's Central Valley During Drought

Levy, Zeno F.; Jurgens, Bryant C.; Burow, Karen R.; Voss, S.; Faulkner, Kirsten E.; Arroyo-Lopez, Jose Alfredo; Fram, Miranda S.

doi:10.1029/2021gl094398

Cited by 40 publications

(27 citation statements)

References 37 publications

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“…Our pan-US statistical analyses are consistent with local-scale research in California’s Central Valley 26 , 27 , where groundwater pumping draws young and shallow groundwater deeper into the aquifer system; our results suggest that pumping-induced downwelling is not unique to California’s Central Valley and is likely occurring in other heavily pumped US aquifer systems. Though we find that modern groundwater tends to reach deeper depths in heavily pumped aquifer systems (Fig.…”

Section: Resultssupporting

confidence: 84%

Modern groundwater reaches deeper depths in heavily pumped aquifer systems

et al. 2022

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Deep groundwater is an important source of drinking water, and can be preferable to shallower groundwaters where they are polluted by surface-borne contaminants. Surface-borne contaminants are disproportionately common in ‘modern’ groundwaters that are made up of precipitation that fell since the ~1950s. Some local-scale studies have suggested that groundwater pumping can draw modern groundwater downward and potentially pollute deep aquifers, but the prevalence of such pumping-induced downwelling at continental scale is not known. Here we analyse thousands of US groundwater tritium measurements to show that modern groundwater tends to reach deeper depths in heavily pumped aquifer systems. These findings imply that groundwater pumping can draw mobile surface-borne pollutants to deeper depths than they would reach in the absence of pumping. We conclude that intensive groundwater pumping can draw recently recharged groundwater deeper into aquifer systems, potentially endangering deep groundwater quality.

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Section: Resultssupporting

confidence: 84%

Modern groundwater reaches deeper depths in heavily pumped aquifer systems

et al. 2022

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“…For example, increasing ambient temperatures cause faster chlorine decay, subsequently requiring a higher chlorine dosage to achieve free chlorine residual targets and potentially increasing DBP formation . Similarly, prolonged droughts may accelerate degradation of groundwater quality by nitrate and increase arsenic and GWR violations (Figure ). Recent studies have highlighted the importance of other climate hazards that threaten water quality including post-wildfire increases in hexavalent chromium concentrations in soils, and volatile and semivolatile organic compounds (VOCs and SVOCs), and arsenic, nitrate, and DBPs in public drinking water systems …”

Section: Resultsmentioning

confidence: 99%

Drivers of Spatiotemporal Variability in Drinking Water Quality in the United States

Scanlon

Fakhreddine

Reedy

et al. 2022

Environ. Sci. Technol.

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Approximately 10% of community water systems in the United States experience a health-based violation of drinking water quality; however, recently allocated funds for improving United States water infrastructure ($50 billion) provide an opportunity to address these issues. The objective of this study was to examine environmental, operational, and sociodemographic drivers of spatiotemporal variability in drinking water quality violations using geospatial analysis and data analytics. Random forest modeling was used to evaluate drivers of these violations, including environmental (e.g., landcover, climate, geology), operational (e.g., water source, system size), and sociodemographic (social vulnerability, rurality) drivers. Results of random forest modeling show that drivers of violations vary by violation type. For example, arsenic and radionuclide violations are found mostly in the Southwest and Southcentral United States related to semiarid climate, whereas disinfection byproduct rule violations are found primarily in Southcentral United States related to system operations. Health-based violations are found primarily in small systems in rural and suburban settings. Understanding the drivers of water quality violations can help develop optimal approaches for addressing these issues to increase compliance in community water systems, particularly small systems in rural areas across the United States.

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“…Specifically, since the latter half of the 20th century, demands for non‐renewable groundwater reserves have tripled, providing about 20% of global irrigation water (Wada et al, 2012 ). Due to these large demands/dependence on groundwater, several key agricultural regions around the world are encountering the negative impacts of groundwater overuse, which include permanent aquifer depletion (Butler et al, 2018 ; Cao et al, 2013 ; Faunt et al, 2016 ; Rodell et al, 2009 ; Scanlon et al, 2012 ; Shekhar et al, 2020 ; Smith et al, 2017 ; Tiwari et al, 2009 ), land subsidence (Galloway & Burbey, 2011 ; Herrera‐García et al, 2021 ; Smith & Li, 2021 ; Smith & Majumdar, 2020 ), and water contamination (Costall et al, 2020 ; Erban et al, 2013 ; Goebel et al, 2017 ; Gottschalk et al, 2020 ; Levy et al, 2021 ; Smith et al, 2018 ). Despite such pressing challenges, groundwater withdrawals (also known as extraction or pumping) are not monitored in most areas at a scale suitable for implementing sustainable groundwater management practices (Foster et al, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

Advancing remote sensing and machine learning‐driven frameworks for groundwater withdrawal estimation in Arizona: Linking land subsidence to groundwater withdrawals

Majumdar

Smith

Conway³

et al. 2022

Hydrological Processes

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Groundwater plays a crucial role in sustaining global food security but is being over‐exploited in many basins of the world. Despite its importance and finite availability, local‐scale monitoring of groundwater withdrawals required for sustainable water management practices is not carried out in most countries, including the United States. In this study, we combine publicly available datasets into a machine learning framework for estimating groundwater withdrawals over the state of Arizona. Here we include evapotranspiration, precipitation, crop coefficients, land use, annual discharge, well density, and watershed stress metrics for our predictions. We employ random forests to predict groundwater withdrawals from 2002 to 2020 at a 2 km spatial resolution using in situ groundwater withdrawal data available for Arizona Active Management Areas (AMA) and Irrigation Non‐Expansion Areas (INA) from 2002 to 2009 for training and 2010–2020 for validating the model respectively. The results show high training (R2≈0.9$$ {R}^2\approx 0.9 $$) and good testing (R2≈0.7$$ {R}^2\approx 0.7 $$) scores with normalized mean absolute error (NMAE) ≈ 0.62 and normalized root mean square error (NRMSE) ≈ 2.34 for the AMA/INA region. Using this method, we spatially extrapolate the existing groundwater withdrawal estimates to the entire state and observe the co‐occurrence of both groundwater withdrawals and land subsidence in South‐Central and Southern Arizona. Our model predicts groundwater withdrawals in regions where production wells are present on agricultural lands and subsidence is observed from Interferometric Synthetic Aperture Radar (InSAR), but withdrawals are not monitored. By performing a comparative analysis over these regions using the predicted groundwater withdrawals and InSAR‐based land subsidence estimates, we observe a varying degree of subsidence for similar volumes of withdrawals in different basins. The performance of our model on validation datasets and its favourable comparison with independent water use proxies such as InSAR demonstrate the effectiveness and extensibility of our combined remote sensing and machine learning‐based approach.

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Critical Aquifer Overdraft Accelerates Degradation of Groundwater Quality in California's Central Valley During Drought

Cited by 40 publications

References 37 publications

Modern groundwater reaches deeper depths in heavily pumped aquifer systems

Modern groundwater reaches deeper depths in heavily pumped aquifer systems

Drivers of Spatiotemporal Variability in Drinking Water Quality in the United States

Advancing remote sensing and machine learning‐driven frameworks for groundwater withdrawal estimation in Arizona: Linking land subsidence to groundwater withdrawals

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