Crustal Groundwater Volumes Greater Than Previously Thought

Ferguson, Grant; McIntosh, Jennifer C.; Warr, Oliver; Lollar, Barbara Sherwood; Ballentine, C. J.; Famiglietti, J. S.; Kim, Jihyun; Michalski, J. R.; Mustard, John F.; Tarnas, J. D.; McDonnell, Jeffrey J.

doi:10.1029/2021gl093549

Cited by 36 publications

(24 citation statements)

References 71 publications

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“…Groundwater plays an important role in the global water and carbon cycles 1 – 3 . It is estimated that almost 44 million km 3 of groundwater could be stored in the upper 10 km of the continental crust 4 . This quantity exceeds the amount of water stored in ice sheets in Antarctica, Greenland, and glaciers combined (30.16 million km 3 ) 5 – 7 , and far exceeds the combined fresh water available in lakes, swamps, and rivers (0.19 million km 3 ) 8 .…”

Section: Introductionmentioning

confidence: 99%

A new conceptual framework for the transformation of groundwater dissolved organic matter

et al. 2022

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Groundwater comprises 95% of the liquid fresh water on Earth and contains a diverse mix of dissolved organic matter (DOM) molecules which play a significant role in the global carbon cycle. Currently, the storage times and degradation pathways of groundwater DOM are unclear, preventing an accurate estimate of groundwater carbon sources and sinks for global carbon budgets. Here we reveal the transformations of DOM in aging groundwater using ultra-high resolution mass spectrometry combined with radiocarbon dating. Long-term anoxia and a lack of photodegradation leads to the removal of oxidised DOM and a build-up of both reduced photodegradable formulae and aerobically biolabile formulae with a strong microbial signal. This contrasts with the degradation pathway of DOM in oxic marine, river, and lake systems. Our findings suggest that processes such as groundwater extraction and subterranean groundwater discharge to oceans could result in up to 13 Tg of highly photolabile and aerobically biolabile groundwater dissolved organic carbon released to surface environments per year, where it can be rapidly degraded. These findings highlight the importance of considering groundwater DOM in global carbon budgets.

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Section: Introductionmentioning

confidence: 99%

A new conceptual framework for the transformation of groundwater dissolved organic matter

et al. 2022

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“…This suggests that the estimated uncertainty about the global OFG volume may be underestimated due to constant porosity considered. With that in mind, our estimated global OFG volume amounts to about 5%-10% of total fresh groundwater worldwide (estimated to be between 10.5 × 10 6 km 3 (Gleeson et al 2016) and 21.8 × 10 6 km 3 (Ferguson et al 2021)) and roughly 3% of total global fresh water (Shiklomanov 1998). The OFG volumes are most likely non-renewable as they were deposited during glacial periods when sea levels were substantially lower compared to current sea level.…”

Section: Resultsmentioning

confidence: 90%

Offshore fresh groundwater in coastal unconsolidated sediment systems as a potential fresh water source in the 21st century

Zamrsky

Essink

Sutanudjaja

et al. 2021

Environ. Res. Lett.

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Coastal areas worldwide are often densely populated and host regional agricultural and industrial hubs. Strict water quality requirements for agricultural, industrial and domestic use are often not satisfied by surface waters in coastal areas and consequently lead to over-exploitation of local fresh groundwater resources. Additional pressure by both climate change and population growth further intensifies the upcoming water stress and raise the urgency to search for new fresh water sources. In recent years, offshore fresh groundwater reserves have been identified as such a potential water source. In this study, we quantify, for the first time, the global volume of offshore fresh groundwater in unconsolidated coastal aquifers and show that it is a viable option as additional fresh water source in coastal areas. Our results confirm previously reported widespread presence of offshore fresh groundwater along the global coastline. Furthermore, we find that these reserves are likely non-renewable as they were deposited during glacial periods when sea levels were substantially lower compared to current sea level. We estimate the total offshore fresh groundwater volume in unconsolidated coastal aquifers to be approximately 1.06 ± 0.2 million km³, which is roughly three times more than estimated previously and about 10% of all terrestrial fresh groundwater. With extensive active and inactive offshore oil pumping present in areas of large offshore fresh groundwater reserves, they could be considered for temporary fresh groundwater exploration as part of a transition to sustainable water use in coastal areas on the long run.

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“…Hydro-socially, groundwater provides freshwater for a wide array of human activities from drinking to agricultural irrigation to supporting recreational activities and is in many regions a resource of cultural significance (Griebler and Avramov 2015, Gleeson et al 2020a, Gleeson et al 2020b, Kreamer et al 2015, Moggridge 2020. Lastly, groundwater represents the largest store of liquid freshwater (Shiklomanov 2000, Gleeson et al 2016, Ferguson et al 2021. Fluctuations and trends in this storage have important implications on sea-level rise, riparian forest loss, land subsidence, flooding, and soil salinization.…”

Section: Key Scientific Characteristics Of Groundwater As a Resourcementioning

confidence: 99%

Applying a science-forward approach to groundwater regulatory design

Gleeson¹,

Huggins²,

Curran³

2022

Preprint

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Groundwater sustainability is challenged by the difference between legal and scientific understanding of groundwater as well as the lack of focused attention to regulatory design in the literature on groundwater institutions, governance and management. The purpose of this paper is to use groundwater science to direct the necessary elements of regulatory design for the unique characteristics of groundwater. Using plain and interdisciplinary language that could be applied in any jurisdiction or region, the article describes seven groundwater characteristics as processes, functions, qualities, physical sustainability, scale, information and data, and physical state. Using the characteristics of groundwater embeds the scientific understanding of groundwater into regulatory design and enables the expression of new values, such as Indigenous rights to water. Applying these characteristics to a case study of new groundwater regulation in a sub-national jurisdiction in the global north - British Columbia, Canada - highlights the failure of regulatory design even in a well-resourced jurisdiction where environmental regulation is the norm. Groundwater in British Columbia is extremely heterogeneous in quality and function with low observation density and undefined sustainability goals where regulations are applied on uniformly. Looking forward, three recommendations can be drawn using the characteristics of groundwater to improve regulatory design in British Columbia: defining sustainability goals and ecological thresholds; regionalizing and prioritizing; and long-term planning. This science-forward and interdisciplinary approach has implications for legally pluralistic states with customary water entitlements. It also provides practitioners with an interdisciplinary language that can be useful for assessing current and future regulatory design.

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Crustal Groundwater Volumes Greater Than Previously Thought

Cited by 36 publications

References 71 publications

A new conceptual framework for the transformation of groundwater dissolved organic matter

A new conceptual framework for the transformation of groundwater dissolved organic matter

Offshore fresh groundwater in coastal unconsolidated sediment systems as a potential fresh water source in the 21st century

Applying a science-forward approach to groundwater regulatory design

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