Quantifying Groundwater Flow and Solute Transport Processes through Modelling and Experiments

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Hydrogeology".

Deadline for manuscript submissions: closed (15 April 2024) | Viewed by 9580

Special Issue Editors


E-Mail Website
Guest Editor
Faculty of Environmental Sciences and Natural Resource Management (MINA), Norwegian University of Life Sciences (NMBU), 1430 Ås, Norway
Interests: contaminant transport; unsaturated zone; groundwater, modelling; hydrogeophysics; spatial heterogeneity
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Geoscience, Aarhus University, Aarhus, Denmark
Interests: hydrogeology; groundwater modelling; natural tracers; isotopes; heat transport; coastal aquifers; saltwater intrusion; groundwater–surface-water interaction
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Groundwater is an important source of water for drinking, irrigation, industrial purposes and maintaining ecosystems, both quantity and quality determines its use. Groundwater quality is affected by natural conditions and human activities at multiple scales. Sources of diffuse pollution can be agriculture or atmospheric deposition, while landfills, airports, mining, and industry are potential point sources. The study of contamination and solute transport is frequently linked to the development of models to reproduce flow and aquifer conditions. Chemicals and contaminants can react, be degraded, or transformed during their transit through aquifers. In the context of global change, the knowledge on processes and modelling techniques is highly relevant. The exponential growth in computer power combined with increased user friendliness of groundwater models has facilitated the use of models to estimate potential effects on groundwater quality.

The last decades have also provided new methods for characterizing and monitoring subsurface properties and processes, such as hydrogeophysics, improved well logging techniques and field and lab tests. Hence, subsurface heterogeneity can more easily be implemented in standard groundwater modelling software, that together with parameter estimation tools provide more realistic pictures of transport in groundwater systems.

With all these improvements are we able to give better advice to practitioners on how to deal with contaminant issues? Water and solute travel times from a few months to hundreds of thousands of years reflects different climate conditions and impact of human activities in a complex way. Identifying the origin and fate of contaminants requires extensive field campaigns that later can be simulated with numerical models. The choice of conceptual model is still one of the most important steps of modelling, how do we know the simplifications done in this step are the best? Despite technical advancements in groundwater flow modelling capabilities, the complexity of bio-geochemical reactions often leads to a simplification of flow to steady state situation. However transient boundary conditions, e.g. recharge including contaminants from the unsaturated zone, combined with highly heterogeneous subsurface may be of paramount importance to solute transport and the pattern of contaminant transport, reactions, storage and the final composition of the water released at the discharge zone.

Prof. Dr. Helen K. French
Dr. Carlos Duque
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • groundwater modelling
  • contamination
  • groundwater quality
  • field experiments
  • lab experiments

Published Papers (6 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

17 pages, 5390 KiB  
Article
Comparative Study of Microbial Diversity in Different Coastal Aquifers: Determining Factors
by María del Carmen Vargas-García, Fernando Sola and Ángela Vallejos
Water 2023, 15(7), 1337; https://doi.org/10.3390/w15071337 - 28 Mar 2023
Cited by 5 | Viewed by 1901
Abstract
Coastal aquifers have been extensively studied from the hydrodynamic and geochemical points of view, but there is still a significant gap in the knowledge of their microbial diversity. The bacterial communities of four coastal aquifers at different depths and salinities were studied in [...] Read more.
Coastal aquifers have been extensively studied from the hydrodynamic and geochemical points of view, but there is still a significant gap in the knowledge of their microbial diversity. The bacterial communities of four coastal aquifers at different depths and salinities were studied in order to infer the anthropogenic and physico-chemical influences on groundwater microbiota. At the physico-chemical level, samples from different aquifers, but with similar salinities, are more similar than those taken within the same aquifer. The microbial community at the phylum level shows the dominance of Proteobacteria, Firmicutes, and Actinobacteria. Samples from the same aquifer, although having very different salinities, are more similar than samples with similar physico-chemical characteristics. Therefore, the taxa present in these media are resilient to environmental variations. The aquifer preserving the most pristine conditions harbors the lowest values of biodiversity, compared to those affected by anthropic activities. The incorporation of pollutants into the aquifer favors the development of a so-called “rare biosphere”, consisting of a high number of taxa which represent a low percentage (<1%) of the total microbial community. The analysis of microbial biodiversity in a coastal aquifer could be used as an indicator of the degree of anthropic alteration. Full article
Show Figures

Figure 1

22 pages, 3150 KiB  
Article
Post Audit of Groundwater Model Predictions under Changing Conditions
by Jacob Kidmose, Lars Troldborg and Jens Christian Refsgaard
Water 2023, 15(6), 1144; https://doi.org/10.3390/w15061144 - 15 Mar 2023
Viewed by 1097
Abstract
Post audits of hydrological or groundwater models are the last part of the modelling protocol, where the original model predictions are tested using new data obtained after a certain period. The evaluation of model predictions and associated predictive uncertainty was performed by comparing [...] Read more.
Post audits of hydrological or groundwater models are the last part of the modelling protocol, where the original model predictions are tested using new data obtained after a certain period. The evaluation of model predictions and associated predictive uncertainty was performed by comparing an original hydrological model, a model with post audited geology, and a model with post audited geology and calibrated against new types of observation data. The post audit showed original model predictions close to what was observed (in terms of abstracted volumes necessary to lower a shallow groundwater table). In contrast to the robust original model predictions, the original model underestimated the predictive uncertainty compared to the assessments of uncertainty using the new and updated post audit model. To ensure a robust model evaluation, we propose a four-step post audit protocol, including (1) testing the validity of the original model predictions with new data, (2) estimating the predictive uncertainty of the original model, (3) producing a new post audit model(s) based on revising the conceptual model and calibration, and (4) assessing the predictive uncertainty of the new post audit models. The work presented here was motivated by the lack of studies that, after a certain time, have re-evaluated model predictions (post audit) with new data. Full article
Show Figures

Figure 1

17 pages, 4592 KiB  
Article
Quantification of Groundwater Vertical Flow from Temperature Profiles: Application to Agua Amarga Coastal Aquifer (SE Spain) Submitted to Artificial Recharge
by José Antonio Jiménez-Valera, Iván Alhama and Emilio Trigueros
Water 2023, 15(6), 1093; https://doi.org/10.3390/w15061093 - 13 Mar 2023
Viewed by 1255
Abstract
The Agua Amarga coastal aquifer has experienced different anthropic interventions over the last 100 years. Since 2008, groundwater abstractions along the coastline to supply the Alicante I and II desalination plants have been combined with artificial recharge. This measure, consisting of seawater irrigation [...] Read more.
The Agua Amarga coastal aquifer has experienced different anthropic interventions over the last 100 years. Since 2008, groundwater abstractions along the coastline to supply the Alicante I and II desalination plants have been combined with artificial recharge. This measure, consisting of seawater irrigation over the salt marsh, has reduced the impact on the piezometry and surface ecosystems. The study of the effect of this measure on groundwater flow is addressed by applying an inverse problem protocol to temperature profiles monitored in a piezometer located inside the recharge area. Information on monthly seawater irrigation volumes, rainfall, and average air and seawater temperatures have also been gathered as input data to quantify vertical flow. An upward flow component for the period 2010–2022 that varies between 2 × 10−9 and 7.5 × 10−7 m/s has been found. These values decrease near the surface, where the flow is mainly horizontal. Full article
Show Figures

Figure 1

16 pages, 5065 KiB  
Article
Modelling Plume Development with Annual Pulses of Contaminants Released from an Airport Runway to a Layered Aquifer, Evaluation of an In Situ Monitoring System
by Helen K. French, Mona C. Hansen, Kamilla G. Moe and Julie Stene
Water 2023, 15(5), 985; https://doi.org/10.3390/w15050985 - 4 Mar 2023
Cited by 3 | Viewed by 1584
Abstract
In cold climates, the use of de-icing chemicals in the winter can lead to groundwater contamination, especially when used in large quantities, such as at airports. Oslo Airport, Gardermoen, is situated on Norway’s largest rain-fed aquifer. Potassium formate is used to remove ice [...] Read more.
In cold climates, the use of de-icing chemicals in the winter can lead to groundwater contamination, especially when used in large quantities, such as at airports. Oslo Airport, Gardermoen, is situated on Norway’s largest rain-fed aquifer. Potassium formate is used to remove ice from runways and propylene glycol from airplanes; the organic parts are degradable. Most of the wells to monitor the spread of de-icing chemicals in the underlying aquifer have well screens near the groundwater level, while the runways and the source of de-icing chemicals are near the groundwater divides, where vertical flow is expected. The objective of this study is to demonstrate the importance of layers and time-varying recharge on the spreading of contaminant plumes in an aquifer near a groundwater divide. This is done with numerical modelling. The model results show increased vertical transport of the added tracer in the presence of horizontal layers, both continuous and discontinuous, in the aquifer. With certain distributions of hydraulic conductivity, Ks, we demonstrate that deeper monitoring wells are required. With the scenarios modelled here, time-varying recharge has a weaker effect on plume distribution. Measured concentrations of potassium and total organic carbon show the cyclic effect of seasonally varying recharge of contaminants, and an asymptotic accumulation of concentration over time, that is consistent with the model runs. In conclusion, groundwater monitoring systems near a groundwater divide should include multi-level samplers to ensure control of the vertical plume movement. Full article
Show Figures

Figure 1

13 pages, 2304 KiB  
Article
A Method for Calibrating the Transient Storage Model from the Early and Late-Time Behavior of Breakthrough Curves
by Eleonora Dallan, Andrea Bottacin-Busolin, Mattia Zaramella and Andrea Marion
Water 2023, 15(5), 979; https://doi.org/10.3390/w15050979 - 3 Mar 2023
Viewed by 1430
Abstract
Solute transport in rivers is controlled by mixing processes that occur over a wide spectrum of spatial and temporal scales. Deviations from the classic advection–dispersion model observed in tracer test studies are known to be generated by the temporary trapping of solutes in [...] Read more.
Solute transport in rivers is controlled by mixing processes that occur over a wide spectrum of spatial and temporal scales. Deviations from the classic advection–dispersion model observed in tracer test studies are known to be generated by the temporary trapping of solutes in storage zones where velocities and mixing rates are relatively small. In this work, the relation between the early and late-time behavior of solute breakthrough curves (BTCs) and the key parameters of the Transient Storage Model (TSM) is analyzed using non-asymptotic approximations of the model equations. Two main slopes are identified corresponding to the rising and decreasing limbs of the BTCs which are linked by specific relationships to transport and storage parameters. The validity of the proposed approximations is demonstrated with both synthetic and experimental data. Consistent with the TSM assumptions, the range of validity of the proposed approximations represents the limit of separability between surface dispersion and transient storage and can be expressed as a function of a nondimensional parameter. The results of this work can help environmental scientists identify solute transport and transient storage parameters and support the design of enhanced field tracer experiments. Full article
Show Figures

Figure 1

15 pages, 2663 KiB  
Article
Combined Column Test for Characterization of Leaching and Transport of Trace Elements in Contaminated Soils
by Karen Ane Skjennum, Helen K. French, Pasquale Carotenuto and Gudny Okkenhaug
Water 2023, 15(5), 874; https://doi.org/10.3390/w15050874 - 24 Feb 2023
Cited by 2 | Viewed by 1708
Abstract
Environmental assessments are required prior to remediation and redevelopment of contaminated sites. To date, regulatory guidelines are commonly based on total concentrations. Occasionally, simple leaching procedures are included in environmental assessment. Despite being essential for quantification of contaminant transport, analysis of hydraulic conductivity [...] Read more.
Environmental assessments are required prior to remediation and redevelopment of contaminated sites. To date, regulatory guidelines are commonly based on total concentrations. Occasionally, simple leaching procedures are included in environmental assessment. Despite being essential for quantification of contaminant transport, analysis of hydraulic conductivity is rarely considered. Cost-effective methods that reflect both contaminant leaching and hydrogeological properties of contaminated soils are needed to ensure proper soil management. The aim of this study was to simultaneously evaluate contaminant leaching and hydraulic conductivity in soil using a combined column test (CCT) and compare this to the leaching results from batch tests (BT) and transport estimates derived from the empirical Hazen equation. Two soils of different origin were characterized using the CCT. By including physical and chemical factors affecting the release and retention of contaminants, the CCT provides an integrated assessment of leaching and transport of trace elements from soils. Additionally, the effect of soil compaction was investigated as a physical treatment to reduce leaching and transport in contaminated soils. Soil compaction did not demonstrate reduced leaching, but a less extensive contaminant transport was observed due to reduced hydraulic conductivity in the soil. Full article
Show Figures

Figure 1

Back to TopTop