The rapid yet uneven turnover of Earth's groundwater

Befus, K. M.; Jasechko, Scott; Luijendijk, Elco; Gleeson, Tom; Cardenas, M. Bayani

doi:10.1002/2017gl073322

Cited by 34 publications

(22 citation statements)

References 70 publications

(82 reference statements)

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“…Despite this potential underestimate, the 1.4 m estimate of global groundwater potential storage at the LGM most likely represents an upper bound and should be regarded as a maximum contribution for a number of other reasons. First, many areas appear to have experienced lower groundwater levels or recharge rates during the LGM not higher ones needed to sequester more groundwater at the LGM (Ferrera et al, 1999;Otto-Biesner et al, 2006;Befus et al, 2017). In addition, falling sea levels prior to the LGM exposed the shelf and likely drained now-submerged (and filled) aquifers during the LGM (Faure et al, 2002) resulting in lower groundwater storage.…”

Section: Groundwater Changes Results and Discussionmentioning

confidence: 99%

“…This volume of water is enough to raise sea levels by~63 m assuming a global ocean area of 3.619 Â 10 8 km 2 (Eakins and Sharman, 2010). A significant amount of that groundwater is known to be circulating within the hydrologic cycle with an estimated 210.5e837.6 million km 3 of water recharged since the LGM, although roughly a third of the current groundwater reservoirs are relicts from the LGM (Befus et al, 2017). Estimating the volume of groundwater at the LGM is a difficult task and direct measures of the groundwater table during the LGM are sparse.…”

Section: Introductionmentioning

confidence: 99%

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Balancing the last glacial maximum (LGM) sea-level budget

Simms

Lisiecki

Gebbie

et al. 2019

Quaternary Science Reviews

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Estimates of post-Last Glacial Maximum (LGM) sea-level rise are not balanced by the estimated amount of ice melted since the LGM. We quantify this "missing ice" by reviewing the possible contributions from each of the major ice sheets. This "missing ice" amounts to 18.1 ± 9.6 m of global sea-level rise. Ocean expansion accounts for 2.4 ± 0.3 m of this discrepancy while groundwater could contribute a maximum of another 1.4 m to this offset. After accounting for these two potential contributors to the sea-level budget, the shortfall of 15.6 ± 9.6m suggests that either a large reservoir of water (e.g. a missing LGM ice sheet) has yet to be discovered or current estimates of one or more of the known LGM ice sheets are too small. Included within this latter possibility are potential inadequacies of current models of glacial isostatic adjustment.

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Section: Groundwater Changes Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Balancing the last glacial maximum (LGM) sea-level budget

Simms

Lisiecki

Gebbie

et al. 2019

Quaternary Science Reviews

View full text Add to dashboard Cite

show abstract

“…This is consistent with observations of larger than expected groundwater gradients, given the current low recharge, that have been observed in present day arid zones 25 . While groundwater residence time and groundwater response time are fundamentally different concepts, we also note the correspondence between high GRT and significant volumes of fossil-aged groundwater storage in arid regions 2,26 . The outcome of this result is that groundwater discharge to oases, rivers or wetlands in otherwise dry landscapes will be particularly intransient in comparison to climate change, in as much as climate controls the variations in groundwater recharge.…”

Section: Textmentioning

confidence: 88%

Global patterns and dynamics of climate–groundwater interactions

et al. 2019

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Groundwater is the largest available store of global freshwater , upon which more than two billion people rely 2. It is therefore important to quantify the spatiotemporal interactions between groundwater and climate. However, current understanding of the global scale sensitivity of groundwater systems to climate change 3,4-as well as the resulting variation in feedbacks from groundwater to the climate system 5,6-is limited. Here, using groundwater model results in combination with hydrologic datasets, we examine the dynamic timescales of groundwater system responses to climate change. We show that nearly half of global groundwater fluxes could equilibrate with recharge variations due to climate change on human (~100 year) timescales, and that areas where water tables are most sensitive to changes in recharge are also those that have the longest groundwater response times. In particular, groundwater fluxes in arid regions are shown to be less responsive to climate variability than in humid regions. Adaptation strategies must therefore account for the hydraulic memory of groundwater systems which can buffer climate change impacts on water resources in many regions, but may also lead to a long, but initially hidden, legacy of anthropogenic and climatic impacts on river flows and groundwater dependent ecosystems.

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“…These characteristics can be applied to anticipate the groundwater response to present conditions and to future pressures that can be expected from anthropogenic climate change (Taylor et al, 2013a). The results from the analysis of GRACE data are reconciled to regionalscale hydrogeological conditions, which gives confidence in their validity (Beven and Germann, 2013) albeit with the caveat regarding the uncertainties inherent in all the datasets used (Wilks, 2016).…”

Section: Discussionmentioning

confidence: 98%

Climate–groundwater dynamics inferred from GRACE and the role of hydraulic memory

et al. 2020

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Abstract. Groundwater is the largest store of freshwater on Earth after the cryosphere and provides a substantial proportion of the water used for domestic, irrigation and industrial purposes. Knowledge of this essential resource remains incomplete, in part, because of observational challenges of scale and accessibility. Here we examine a 14-year period (2002–2016) of Gravity Recovery and Climate Experiment (GRACE) observations to investigate climate–groundwater dynamics of 14 tropical and sub-tropical aquifers selected from WHYMAP's (Worldwide Hydrogeological Mapping and Assessment Programme) 37 large aquifer systems of the world. GRACE-derived changes in groundwater storage resolved using GRACE Jet Propulsion Laboratory (JPL) mascons and the Community Land Model's land surface model are related to precipitation time series and regional-scale hydrogeology. We show that aquifers in dryland environments exhibit long-term hydraulic memory through a strong correlation between groundwater storage changes and annual precipitation anomalies integrated over the time series; aquifers in humid environments show short-term memory through strong correlation with monthly precipitation. This classification is consistent with estimates of groundwater response times calculated from the hydrogeological properties of each system, with long (short) hydraulic memory associated with slow (rapid) response times. The results suggest that groundwater systems in dryland environments may be less sensitive to seasonal climate variability but vulnerable to long-term trends from which they will be slow to recover. In contrast, aquifers in humid regions may be more sensitive to climate disturbances such as drought related to the El Niño–Southern Oscillation but may also be relatively quick to recover. Exceptions to this general pattern are traced to human interventions through groundwater abstraction. Hydraulic memory is an important factor in the management of groundwater resources, particularly under climate change.

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The rapid yet uneven turnover of Earth's groundwater

Cited by 34 publications

References 70 publications

Balancing the last glacial maximum (LGM) sea-level budget

Balancing the last glacial maximum (LGM) sea-level budget

Global patterns and dynamics of climate–groundwater interactions

Climate–groundwater dynamics inferred from GRACE and the role of hydraulic memory

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