Water Isotopes as Environmental Tracers for Conceptual Understanding of Groundwater Flow: An Application for Fractured Aquifer Systems in the “Scansano-Magliano in Toscana” Area (Southern Tuscany, Italy)

Abstract. Computational experiments are performed to evaluate the effects of locally heterogeneous conductivity fields on regional exchanges of water between stream and aquifer systems in the Middle Heihe River basin (MHRB) of northwestern China. The effects are found to be nonlinear in the sense that simulated discharges from aquifers to streams are systematically lower than discharges produced by a base model parameterized with relatively coarse effective conductivity. A similar, but weaker, effect is observed for stream leakage. The study is organized around three hypotheses: (H1) small-scale spatial variations of conductivity significantly affect regional exchanges of water between streams and aquifers in river basins, (H2) aggregating small-scale heterogeneities into regional effective parameters systematically biases estimates of stream–aquifer exchanges, and (H3) the biases result from slow paths in groundwater flow that emerge due to small-scale heterogeneities. The hypotheses are evaluated by comparing stream–aquifer fluxes produced by the base model to fluxes simulated using realizations of the MHRB characterized by local (grid-scale) heterogeneity. Levels of local heterogeneity are manipulated as control variables by adjusting coefficients of variation. All models are implemented using the MODFLOW (Modular Three-dimensional Finite-difference Groundwater Flow Model) simulation environment, and the PEST (parameter estimation) tool is used to calibrate effective conductivities defined over 16 zones within the MHRB. The effective parameters are also used as expected values to develop lognormally distributed conductivity (K) fields on local grid scales. Stream–aquifer exchanges are simulated with K fields at both scales and then compared. Results show that the effects of small-scale heterogeneities significantly influence exchanges with simulations based on local-scale heterogeneities always producing discharges that are less than those produced by the base model. Although aquifer heterogeneities are uncorrelated at local scales, they appear to induce coherent slow paths in groundwater fluxes that in turn reduce aquifer–stream exchanges. Since surface water–groundwater exchanges are critical hydrologic processes in basin-scale water budgets, these results also have implications for water resources management.

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Separation of groundwater-flow components in a karstified aquifer using environmental tracers

Tracer Hydrology 97 ◽

10.1201/9781003078142-45 ◽

2020 ◽

pp. 269-272

Author(s):

R. Nativ ◽

G. Günay ◽

L. Tezcan ◽

H. Hötzl ◽

B. Reichert ◽

...

Keyword(s):

Groundwater Flow ◽

Environmental Tracers ◽

Flow Components

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A glimpse of the Anthropocene captured by environmental tracers in the groundwater of a fractured aquifer

10.7185/gold2021.6897 ◽

2021 ◽

Author(s):

Eliot Chatton ◽

Thierry Labasque ◽

Werner Aeschbach ◽

Virginie Vergnaud ◽

Luc Aquilina

Keyword(s):

Environmental Tracers ◽

Fractured Aquifer

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The use of simulation and multiple environmental tracers to quantify groundwater flow in a shallow aquifer

Water Resources Research ◽

10.1029/93wr02655 ◽

1994 ◽

Vol 30 (2) ◽

pp. 421-433 ◽

Cited By ~ 128

Author(s):

Thomas E. Reilly ◽

L. Niel Plummer ◽

Patrick J. Phillips ◽

Eurybiades Busenberg

Keyword(s):

Groundwater Flow ◽

Shallow Aquifer ◽

Environmental Tracers

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A multi-environmental tracer study to determine groundwater residence times and recharge in a structurally complex multi-aquifer system

Hydrology and Earth System Sciences ◽

10.5194/hess-24-249-2020 ◽

2020 ◽

Vol 24 (1) ◽

pp. 249-267 ◽

Cited By ~ 1

Author(s):

Cornelia Wilske ◽

Axel Suckow ◽

Ulf Mallast ◽

Christiane Meier ◽

Silke Merchel ◽

...

Keyword(s):

Groundwater Flow ◽

Groundwater Recharge ◽

Groundwater Age ◽

Age Distribution ◽

Dead Sea ◽

Artificial Sweetener ◽

Environmental Tracers ◽

Jordan Valley ◽

Aquifer System ◽

Lumped Parameter

Abstract. Despite being the main drinking water resource for over 5 million people, the water balance of the Eastern Mountain Aquifer system on the western side of the Dead Sea is poorly understood. The regional aquifer consists of fractured and karstified limestone – aquifers of Cretaceous age, and it can be separated into a Cenomanian aquifer (upper aquifer) and Albian aquifer (lower aquifer). Both aquifers are exposed along the mountain ridge around Jerusalem, which is the main recharge area. From here, the recharged groundwater flows in a highly karstified aquifer system towards the east and discharges in springs in the lower Jordan Valley and Dead Sea region. We investigated the Eastern Mountain Aquifer system for groundwater flow, groundwater age and potential mixtures, and groundwater recharge. We combined 36Cl ∕ Cl, tritium, and the anthropogenic gases SF6, CFC-12 (chlorofluorocarbon) and CFC-11, while using CFC-113 as “dating” tracers to estimate the young water components inside the Eastern Mountain Aquifer system. By application of lumped parameter models, we verified young groundwater components from the last 10 to 30 years and an admixture of a groundwater component older than about 70 years. Concentrations of nitrate, simazine (pesticide), acesulfame K (ACE-K; artificial sweetener) and naproxen (NAP; drug) in the groundwater were further indications of infiltration during the last 30 years. The combination of multiple environmental tracers and lumped parameter modelling helped to understand the groundwater age distribution and to estimate recharge despite scarce data in this very complex hydrogeological setting. Our groundwater recharge rates support groundwater management of this politically difficult area and can be used to inform and calibrate ongoing groundwater flow models.

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