Distinct Hydrologic Pathways Regulate Perennial Surface Water Dynamics in a Hyperarid Basin

McKnight, Sarah; Boutt, D. F.; Munk, LeeAnn; Moran, B.

doi:10.1029/2022wr034046

Cited by 4 publications

(4 citation statements)

References 58 publications

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“…In arid, remote regions, limited precipitation and the importance of basin-scale groundwater flow systems together with a lack of long-term, high-quality instrumental records make responsibly allocating water resources challenging [13,14]. These conditions also mean that surface water is scarce and groundwater discharge is primarily sourced from relic water (defined herein as water originating 100s to 1000s of years ago, including waters termed "Premodern" or "Fossil") often underpins the hydrological cycle, acting as critical buffers from large inter-annual fluctuations [2,15,16]. Fundamental questions remain regarding key aspects of the hydrological functioning in these environments which perpetuate persistent uncertainties around water sources and transport.…”

Section: Introductionmentioning

confidence: 99%

Contemporary and relic waters strongly decoupled in arid alpine environments

Moran,

Boutt,

Munk

et al. 2024

PLOS Water

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Deciphering the dominant controls on the connections between groundwater, surface water, and climate is critical to understanding water cycles in arid environments. Yet, persistent uncertainties in the fundamental hydrology of these systems remain. The growing demand for critical minerals such as lithium and associated water demands in the arid environments in which they often occur has amplified the urgency to address these uncertainties. We present an integrated hydrological analysis of the Dry Andes region utilizing a uniquely comprehensive set of tracer data (3H, 18O/2H) for these environments, paired directly with physical hydrological observations. We find two strongly decoupled hydrological systems that interact only under specific hydrogeological conditions where preferential conduits exist. The primary conditions creating these conduits are laterally extensive fine-grained evaporite and/or lacustrine units and perennial flowing streams connected with regional groundwater discharge sites. The efficient capture and transport of modern or “contemporary” water (weeks to years old) within these conduits is the primary control of the interplay between modern hydroclimate variations and groundwater aquifers in these environments. Modern waters account for a small portion of basin budgets but are critical to sustaining surface waters due to the existence of these conduits. As a result, surface waters near basin floors are disproportionally sensitive to short-term climate and anthropogenic perturbations. The framework we present describes a new understanding of the dominant controls on natural water cycles intrinsic to these arid high-elevation systems that will improve our ability to manage critical water resources.

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Section: Introductionmentioning

confidence: 99%

Contemporary and relic waters strongly decoupled in arid alpine environments

Moran,

Boutt,

Munk

et al. 2024

PLOS Water

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“…Moreover, the existence of FA wells in the structural plain adjacent to the basins would indicate that wetlands and shallow lakes may also receive groundwater discharge from deeper aquifers. Although groundwater flow is controlled by water table configurations, it can also be controlled by the density difference (Hamann et al, 2015; McKnight et al, 2023). In this sense, less saline water flowing from the structural plain (DP) and from deep upwelling wells (FA) may present an upward flow in the shallow lake zone where a saline‐fresh water interface occurs (McKnight et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

“…Although groundwater flow is controlled by water table configurations, it can also be controlled by the density difference (Hamann et al, 2015;McKnight et al, 2023). In this sense, less saline water flowing from the structural plain (DP) and from deep upwelling wells (FA) may present an upward flow in the shallow lake zone where a saline-fresh water interface occurs (McKnight et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

Factors and processes controlling hydrochemistry and evaporitic deposits in hypersaline wetland‐shallow lake systems

Acosta,

Carol,

Borzi

et al. 2023

Hydrological Processes

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Three wetland‐shallow lakes were studied with the aim of analysing the processes and factors that control hydrochemistry and evaporite deposits in them in basins of the Pampean Plain, Argentina. In this sense, water balances and analysis of the water content of the lakes with normalized water difference index were made, and geologic‐geomorphological characteristics and groundwater flows were defined. Groundwater, surface water and evaporite samples were taken, along with sediment samples from wetland‐shallow lakes and surroundings. In situ pH, electrical conductivity and temperature, and laboratory chemical determinations of major ions of the water were measured. x‐ray diffraction (XRD) and scanning electron microscope (SEM)‐energy dispersive spectroscopy (EDS) analyses of evaporite and sediment samples were carried out. The results obtained allow the identification of two different systems. One of them is represented by Leubucó wetland‐lake basin, which is topographically higher and smaller than the other system, with Na‐HCO3 and Na‐Cl/SO4 groundwater inflows, with high concentrations of Ca2+ and Mg2+. In periods of high evaporation, the regional water table drops, and due to its topographic position, the lake dries. These determine the formation of thick layers of halite associated with magnesium salts on surface, and gypsum layers interbedded with clastic sediments. The other system involves de la Sal and Chasilauquen wetland‐lake basins, which have larger extensions. They receive Na‐HCO3 and Na‐Cl/SO4 groundwater inflow, but with low Mg2+ and Ca2+. Their lower topographic position determines that even during deficit periods, the water table intercepts the lakes surface and therefore, lakes have a shallow surface water level almost all the year, which is hypersaline, Na‐Cl type. These systems only have thin evaporite crusts, composed of halite and thenardite at the edges of the lakes, and the formation of Ca‐Mg sulfates is not observed. It is concluded that topographic position, basins size, geology, groundwater inflow and evaporation are the main processes and factors controlling hydrochemistry and evaporitic deposits.

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“…Water is a scarce but essential resource for human societies and ecosystems in Earth's driest regions (Gleeson et al, 2020). Due to the nature of water cycles and hydrogeological systems in and groundwater discharge sourced from relic water (100s to 1000s of years old) often underpins the hydrological cycle, acting as critical buffers to hydrological systems from large inter-annual fluctuations (Fan et al, 2013;Bierkens & Wada, 2019;Mcknight et al, 2023). Fundamental questions remain to be answered about the hydrological functioning of these systems perpetuating persistent uncertainties around water sources and transport in these environments.…”

Section: Introductionmentioning

confidence: 99%

Contemporary and Relic Waters Strongly Decoupled in Arid Alpine Environments

Moran,

Boutt,

Munk

et al. 2023

Preprint

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Deciphering the dominant controls on interconnections between groundwater, surface water, and climate is critical to understanding water cycles in arid environments, yet persistent uncertainties in the fundamental hydrology of these systems remain. The growing demand for critical minerals such as lithium and associated water demands in these arid environments has amplified the urgency to address these uncertainties. We present an integrated hydrological analysis of the Dry Andes region utilizing a uniquely comprehensive set of tracer data (3H, 18O/2H) for this type of environment, paired directly with physical hydrological observations. We find two strongly decoupled hydrological systems that interact only under specific hydrogeological conditions where preferential conduits have developed. The primary conditions in these conduits form are when laterally extensive fine-grained evaporite and/or lacustrine units or perennial flowing streams exist in connection with groundwater discharge sites. These conduits which efficiently capture and transport modern or “contemporary” water (weeks to years old) within the system control the interplay between modern hydroclimate variations and groundwater aquifers. Modern waters account for a small portion of basin budgets but are critical to sustaining surface waters due to the existence of these conduits. As a result, surface waters near basin floors are disproportionally sensitive to short-term climate and anthropogenic perturbations. This framework describes a new understanding of the dominant controls on natural water cycles intrinsic to these arid high-elevation systems which improves our ability to manage critical water resources.

show abstract

Distinct Hydrologic Pathways Regulate Perennial Surface Water Dynamics in a Hyperarid Basin

Cited by 4 publications

References 58 publications

Contemporary and relic waters strongly decoupled in arid alpine environments

Contemporary and relic waters strongly decoupled in arid alpine environments

Factors and processes controlling hydrochemistry and evaporitic deposits in hypersaline wetland‐shallow lake systems

Contemporary and Relic Waters Strongly Decoupled in Arid Alpine Environments

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