Use of multiple tracers and groundwater flow modelling for the estimation of groundwater travel times to water supply wells, vulnerability assessments and improved management of well fields

2020 ◽  
Author(s):  
Klaus Hinsby ◽  
Roland Purtschert ◽  
Stéphanie Musy ◽  
Jürgen Sültenfuss ◽  
David Wachs ◽  
...  
Keyword(s):  
Water Supply ◽  
Travel Time ◽  
Emerging Contaminants ◽  
Groundwater Modeling ◽  
Groundwater Resources ◽  
Environmental Tracers ◽  
Monitoring Wells ◽  
Groundwater Flow Modelling ◽  
Groundwater Dating ◽  
Water Companies

<p>Groundwater dating and travel time distributions are important tools and data for assessment of the vulnerability of water supply wells towards pollution from the surface. Here we present selected results from more than 30 water supply and monitoring wells from major Danish water companies. The wells were recently sampled and investigated using multiple environmental tracers including <sup>85</sup>Kr, <sup>39</sup>Ar, <sup>3</sup>H/<sup>3</sup>He, <sup>14</sup>C, SF<sub>6</sub>, CFCs and noble gases and different groundwater modeling techniques. The results demonstrate the value of groundwater dating and travel time estimations for the assessment of the history and fate of contaminants in the subsurface. This information is crucial for the assessment of the efficiency of measures to mitigate pollution of groundwater by harmful substances such as pesticides, nitrate and a large range of emerging contaminants. We demonstrate how groundwater ages and travel time distributions can be used to assess the vulnerability or susceptibility of water supply wells towards pollution, and how level specific sampling in long well screens can provide additional important information for assessment of the vulnerability of deep and shallow parts of a water supply well. Potential applications of the estimated travel time distributions include 1) improved management of well fields 2) development of pumping strategies and well screens minimizing the risk of pollution of drinking water wells, and 3) assessment of the adequacy of regulations established by authorities to protect valuable groundwater resources against pollution.   </p>

scholarly journals Assessment of Halon-1301 as a groundwater age tracer

2015 ◽  
Vol 19 (6) ◽  
pp. 2775-2789 ◽  
Author(s):  
M. Beyer ◽  
R. van der Raaij ◽  
U. Morgenstern ◽  
B. Jackson
Keyword(s):  
Groundwater Age ◽  
Groundwater Resources ◽  
Water Soluble ◽  
Elevated Concentration ◽  
Environmental Tracers ◽  
Halon 1301 ◽  
Gaseous Substance ◽  
Groundwater Samples ◽  
Groundwater Dating ◽  
Age Estimates

Abstract. Groundwater dating is an important tool to assess groundwater resources in regards to their dynamics, i.e. direction and timescale of groundwater flow and recharge, contamination risks and manage remediation. To infer groundwater age information, a combination of different environmental tracers, such as tritium and SF6, are commonly used. However, ambiguous age interpretations are often faced, due to a limited set of available tracers and their individual restricted application ranges. For more robust groundwater dating multiple tracers need to be applied complementarily (or other characterisation methods need to be used to complement tracer information). It is important that additional, groundwater age tracers are found to ensure robust groundwater dating in future. We have recently suggested that Halon-1301, a water soluble and entirely anthropogenic gaseous substance, may be a promising candidate, but its behaviour in water and suitability as a groundwater age tracer had not yet been assessed in detail. In this study, we determined Halon-1301 and inferred age information in 17 New Zealand groundwater samples and various modern (river) water samples. The samples were simultaneously analysed for Halon-1301 and SF6, which allowed for identification of issues such as contamination of the water with modern air during sampling. All analysed groundwater sites had also been previously dated with tritium, CFC-12, CFC-11 and SF6, and exhibited mean residence times ranging from modern (close to 0 years) to over 100 years. The investigated groundwater samples ranged from oxic to highly anoxic. All samples with available CFC data were degraded and/or contaminated in one or both of CFC-11 and CFC-12. This allowed us to make a first attempt of assessing the conservativeness of Halon-1301 in water, in terms of presence of local sources and its sensitivity towards degradation, which could affect the suitability of Halon-1301 as groundwater age tracer. Overall we found Halon-1301 reliably inferred the mean residence time of groundwater recharged between 1980 and 2014. Where direct age comparison could be made 71% of mean age estimates for the studied groundwater sites were in agreement with ages inferred from tritium and SF6 (within an uncertainty of 1 standard deviation). The remaining (anoxic) sites showed reduced concentrations of Halon-1301 along with even further reduced concentrations of CFCs. The reason(s) for this need to be further assessed, but are likely to be caused by sorption or degradation of the compounds. Despite some groundwater samples showing evidence of contamination from industrial or agricultural sources (inferred by elevated CFC concentrations), no sample showed a significantly elevated concentration of Halon-1301, which suggests no local anthropogenic or geologic sources of Halon-1301 contamination.

scholarly journals Assessment of Halon-1301 as a groundwater age tracer

2015 ◽  
Vol 12 (1) ◽  
pp. 1397-1436
Author(s):  
M. Beyer ◽  
R. van der Raaij ◽  
U. Morgenstern ◽  
B. Jackson
Keyword(s):  
Groundwater Age ◽  
Groundwater Resources ◽  
Water Soluble ◽  
Elevated Concentration ◽  
Environmental Tracers ◽  
Halon 1301 ◽  
Gaseous Substance ◽  
Groundwater Samples ◽  
Groundwater Dating ◽  
Age Estimates

Abstract. Groundwater dating is an important tool to assess groundwater resources in regards to their dynamics, i.e. direction and time scale of groundwater flow and recharge, to assess contamination risks and manage remediation. To infer groundwater age information, a combination of different environmental tracers, such as tritium and SF6, are commonly used. However, ambiguous age interpretations are often faced, due to a limited set of available tracers and their individual restricted application ranges. For more robust groundwater dating multiple tracers need to be applied complementarily and it is vital that additional, groundwater age tracers are found to ensure robust groundwater dating in future. We recently suggested that Halon-1301, a water soluble and entirely anthropogenic gaseous substance, may be a promising candidate, but its behaviour in water and suitability as a groundwater age tracer had not yet been assessed in detail. In this study, we determine Halon-1301 and infer age information in 17 New Zealand groundwaters and various modern (river) water samples. The samples are simultaneously analysed for Halon-1301 and SF6, which allows identification of issues such as contamination of the water with modern air during sampling. Water at all analysed groundwater sites have also been previously dated with tritium, CFC-12, CFC-11 and SF6, and exhibit mean residence times ranging from modern (close to 0 years) to over 100 years. The investigated groundwater ranged from oxic to highly anoxic, and some showed evidence of CFC contamination or degradation. This allowed us to make a first attempt of assessing the conservativeness of Halon-1301 in water, in terms of presence of local sources and its sensitivity towards degradation etc., which could affect the suitability of Halon-1301 as groundwater age tracer. Overall we found Halon-1301 reliably inferred the mean residence time of groundwater recharged between 1980 and 2014. Where direct age comparison could be made 71% of mean age estimates for the studied groundwater sites were in agreement with ages inferred from tritium and SF6 (within ± 2 years). The remaining (anoxic) sites showed reduced concentrations of Halon-1301 along with even further reduced concentrations of CFCs. The reason(s) for this need to be further assessed, but are likely to be caused by sorption or degradation of the compounds. Despite some groundwater samples showing evidence of contamination from industrial or agricultural sources via elevated CFC concentrations, no sample indicated significantly elevated concentration of Halon-1301, which may indicate a lack of local anthropogenic or geologic sources of Halon-1301 contamination.

scholarly journals Characterization of Groundwater with Complementary Age Tracers

2021 ◽  
Author(s):  
◽  
Monique Beyer
Keyword(s):  
Major Ions ◽  
Groundwater Age ◽  
Groundwater Resources ◽  
Cost Effective ◽  
Environmental Tracers ◽  
Application Range ◽  
Groundwater Dating ◽  
Model Components ◽  
The Many

<p>Groundwater age or residence time is the time water has resided in the subsurface since recharge. Depending on the application, this definition may or may not include travel through the unsaturated zone. The determination of groundwater age can aid understanding and characterization of groundwater resources, because it can provide information on e.g. groundwater mixing and flow, and volumes of groundwater and recharge. Groundwater age can be inferred from environmental tracers, such as SF₆ and tritium, that have a known input to groundwater and/or undergo known alteration processes in groundwater. The currently used age tracers face limitations regarding their application range and reliability. For example, some age tracers have local sources that can lead to contamination of groundwater. This contamination can result in misleading estimates of age. Other tracers have ambiguous inputs to groundwater, which can result in ambiguous age estimations. To reduce these limitations, it is now recognized that multiple tracers should be applied complementarily. There is also a need for new groundwater age tracers and/or new groundwater dating techniques to supplement the existing ones. Cost-effective and easily applicable tracers/techniques are preferred, since most established groundwater dating techniques are very costly and/or complex. Commonly measured hydrochemistry parameters , such as the concentrations of major ions and pH, have been suggested as cost-effective and easily determinable potential age tracers. To date, the use of commonly measured hydrochemistry parameters as independent age tracer has only been demonstrated for water recharged weeks to months ago relying on seasonal changes. Other studies applied commonly measured hydrochemistry complementarily to established age tracers to better constrain groundwater age and/or better understand and predict anthropogenic effects on groundwater quality. Further study is needed to assess the extent to which commonly measured hydrochemistry can be used to reduce uncertainty in tracer-inferred age as well as the extent to which commonly measured hydrochemistry can be used to extrapolate tracer-inferred age.  In addition to tracer specific limitations, quantification of uncertainty and ambiguity is not standard in age modelling. Although a few studies have attempted to quantify uncertainty in age modelling with the aid of probabilistic approaches, their methods are often relatively complex and not transferrable to the many cases with little available data. Uncertainties in the tracer’s recharge estimate and identification of appropriate model components, such as the objective function, have not been considered. Studies in other areas of hydrological modelling, where probabilistic approaches are more commonly used, have highlighted the need for careful identification of model components.</p>

scholarly journals Characterization of Groundwater with Complementary Age Tracers

2021 ◽  
Author(s):  
◽  
Monique Beyer
Keyword(s):  
Major Ions ◽  
Groundwater Age ◽  
Groundwater Resources ◽  
Cost Effective ◽  
Environmental Tracers ◽  
Application Range ◽  
Groundwater Dating ◽  
Model Components ◽  
The Many

<p>Groundwater age or residence time is the time water has resided in the subsurface since recharge. Depending on the application, this definition may or may not include travel through the unsaturated zone. The determination of groundwater age can aid understanding and characterization of groundwater resources, because it can provide information on e.g. groundwater mixing and flow, and volumes of groundwater and recharge. Groundwater age can be inferred from environmental tracers, such as SF₆ and tritium, that have a known input to groundwater and/or undergo known alteration processes in groundwater. The currently used age tracers face limitations regarding their application range and reliability. For example, some age tracers have local sources that can lead to contamination of groundwater. This contamination can result in misleading estimates of age. Other tracers have ambiguous inputs to groundwater, which can result in ambiguous age estimations. To reduce these limitations, it is now recognized that multiple tracers should be applied complementarily. There is also a need for new groundwater age tracers and/or new groundwater dating techniques to supplement the existing ones. Cost-effective and easily applicable tracers/techniques are preferred, since most established groundwater dating techniques are very costly and/or complex. Commonly measured hydrochemistry parameters , such as the concentrations of major ions and pH, have been suggested as cost-effective and easily determinable potential age tracers. To date, the use of commonly measured hydrochemistry parameters as independent age tracer has only been demonstrated for water recharged weeks to months ago relying on seasonal changes. Other studies applied commonly measured hydrochemistry complementarily to established age tracers to better constrain groundwater age and/or better understand and predict anthropogenic effects on groundwater quality. Further study is needed to assess the extent to which commonly measured hydrochemistry can be used to reduce uncertainty in tracer-inferred age as well as the extent to which commonly measured hydrochemistry can be used to extrapolate tracer-inferred age.  In addition to tracer specific limitations, quantification of uncertainty and ambiguity is not standard in age modelling. Although a few studies have attempted to quantify uncertainty in age modelling with the aid of probabilistic approaches, their methods are often relatively complex and not transferrable to the many cases with little available data. Uncertainties in the tracer’s recharge estimate and identification of appropriate model components, such as the objective function, have not been considered. Studies in other areas of hydrological modelling, where probabilistic approaches are more commonly used, have highlighted the need for careful identification of model components.</p>

scholarly journals Seismically induced changes in groundwater levels and temperatures following the ML5.8 (ML5.1) Gyeongju earthquake in South Korea

2021 ◽  
Author(s):  
Soo-Hyoung Lee ◽  
Jae Min Lee ◽  
Sang-Ho Moon ◽  
Kyoochul Ha ◽  
Yongcheol Kim ◽  
...  
Keyword(s):  
South Korea ◽  
Groundwater Level ◽  
Seismic Waves ◽  
Groundwater Resources ◽  
Fluid Pressure ◽  
Water Levels ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Monitoring Wells ◽  
Gyeongju Earthquake

AbstractHydrogeological responses to earthquakes such as changes in groundwater level, temperature, and chemistry, have been observed for several decades. This study examines behavior associated with ML 5.8 and ML 5.1 earthquakes that occurred on 12 September 2016 near Gyeongju, a city located on the southeast coast of the Korean peninsula. The ML 5.8 event stands as the largest recorded earthquake in South Korea since the advent of modern recording systems. There was considerable damage associated with the earthquakes and many aftershocks. Records from monitoring wells located about 135 km west of the epicenter displayed various patterns of change in both water level and temperature. There were transient-type, step-like-type (up and down), and persistent-type (rise and fall) changes in water levels. The water temperature changes were of transient, shift-change, and tendency-change types. Transient changes in the groundwater level and temperature were particularly well developed in monitoring wells installed along a major boundary fault that bisected the study area. These changes were interpreted as representing an aquifer system deformed by seismic waves. The various patterns in groundwater level and temperature, therefore, suggested that seismic waves impacted the fractured units through the reactivation of fractures, joints, and microcracks, which resulted from a pulse in fluid pressure. This study points to the value of long-term monitoring efforts, which in this case were able to provide detailed information needed to manage the groundwater resources in areas potentially affected by further earthquakes.

scholarly journals Groundwater management based on monitoring of land subsidence and groundwater levels in the Kanto Groundwater Basin, Central Japan

2015 ◽  
Vol 372 ◽  
pp. 53-57 ◽  
Author(s):  
K. Furuno ◽  
A. Kagawa ◽  
O. Kazaoka ◽  
T. Kusuda ◽  
H. Nirei
Keyword(s):  
Sea Level ◽  
Groundwater Resources ◽  
Sustainable Use ◽  
Ground Subsidence ◽  
Groundwater Levels ◽  
Monitoring Wells ◽  
Chiba Prefecture ◽  
Groundwater Basin ◽  
Term Monitoring

Abstract. Over 40 million people live on and exploit the groundwater resources of the Kanto Plain. The Plain encompasses metropolitan Tokyo and much of Chiba Prefecture. Useable groundwater extends to the base of the Kanto Plain, some 2500 to 3000 m below sea level. Much of the Kanto Plain surface is at sea level. By the early 1970s, with increasing urbanization and industrial expansion, local overdraft of groundwater resources caused major ground subsidence and damage to commercial and residential structures as well as to local and regional infrastructure. Parts of the lowlands around Tokyo subsided to 4.0 m below sea level; particularly affected were the suburbs of Funabashi and Gyotoku in western Chiba. In the southern Kanto Plain, regulations, mainly by local government and later by regional agencies, led to installation of about 500 monitoring wells and almost 5000 bench marks by the 1990's. Many of them are still working with new monitoring system. Long-term monitoring is important. The monitoring systems are costly, but the resulting data provide continuous measurement of the "health" of the Kanto Groundwater Basin, and thus permit sustainable use of the groundwater resource.

scholarly journals Causes and consequences of long-term groundwater overabstraction in Jordan

2021 ◽  
Author(s):  
Florian Brückner ◽  
Rebecca Bahls ◽  
Mohammad Alqadi ◽  
Falk Lindenmaier ◽  
Ibraheem Hamdan ◽  
...  
Keyword(s):  
Water Supply ◽  
Large Scale ◽  
Flow Direction ◽  
Groundwater Resources ◽  
Regional Scale ◽  
Irrigated Agriculture ◽  
Groundwater Levels ◽  
Contour Lines ◽  
Hydraulic Conditions ◽  
Groundwater Basins

AbstractIn 2017, a comprehensive review of groundwater resources in Jordan was carried out for the first time since 1995. The change in groundwater levels between 1995 and 2017 was found to be dramatic: large declines have been recorded all over the country, reaching more than 100 m in some areas. The most affected areas are those with large-scale groundwater-irrigated agriculture, but areas that are only used for public water supply are also affected. The decrease of groundwater levels and saturated thickness poses a growing threat for drinking water supply and the demand has to be met from increasingly deeper and more remote sources, causing higher costs for drilling and extraction. Groundwater-level contour lines show that groundwater flow direction has completely reversed in some parts of the main aquifer. Consequently, previously established conceptual models, such as the concept of 12 “groundwater basins” often used in Jordan should be revised or replaced. Additionally, hydraulic conditions are changing from confined to unconfined; this is most likely a major driver for geogenic pollution with heavy metals through leakage from the overlying bituminous aquitard. Three exemplary case studies are presented to illustrate and discuss the main causes for the decline of the water tables (agriculture and population growth) and to show how the results of this assessment can be used on a regional scale.

Pilot Study of Methods to Support Stakeholder Prioritization of Transboundary Aquifers for Investigation along the US-Mexico Border

2021 ◽  
Author(s):  
James Callegary ◽  
Anne-Marie Matherne ◽  
Sandra Owen-Joyce ◽  
Elia Tapia Villaseñor ◽  
Amy Rosebrough ◽  
...  
Keyword(s):  
Groundwater Modeling ◽  
Groundwater Resources ◽  
Aquifer Vulnerability ◽  
Border Region ◽  
Institutional Setting ◽  
Border States ◽  
The Us ◽  
Mexico Border ◽  
Transboundary Aquifers ◽  
Us Mexico Border

&lt;p&gt;Four US and six Mexican border states share significant interconnections in terms of trade, jobs, energy production, manufacturing, and natural resources such as water. The border states have a mutual interest in characterizing groundwater resources shared between the US and Mexico, a task made difficult by scarcity of information. To address this challenge, a number of US and Mexican federal agencies and universities via the Transboundary Aquifer Assessment Program (TAAP) have come together to jointly study the shared groundwater resources of the border region, and to develop the information needed by cities, states, industries and local communities to support decision making and land management.&lt;/p&gt;&lt;p&gt;Investigations of four binational aquifers selected in the first phase of TAAP are in progress. Carrying out these investigations has created a cohesive binational multi-institutional team of social and physical scientists and established relationships with a broad network of stakeholders. Completed products relevant to the present work include: (1) analysis of the availability and integration potential of binational data sets, (2) aquifer assessments including a review of US-Mexico aquifer classifications (3) development of water-balance models, (4) analysis of aquifer vulnerability to contamination, and (5) a set of protocols and agreements that address the specific physical, legal, cultural, and institutional setting of the US-Mexico border.&lt;/p&gt;&lt;p&gt;Additional aquifers along the border (estimates of the total range from of 8 to 38) could be investigated, but there are questions as to how to define them, which to choose, and what types of studies are needed. To help answer these questions, we developed a pilot project to investigate and develop methods and tools to assist decision makers and land managers in prioritizing additional aquifers for investigation along the US-Mexico border. First is an approach for rapid assessment of additional aquifers using existing data, published literature, and simple analytical tools including conceptual hydrogeologic model development and precipitation-groundwater lag-correlation analysis. Second, a groundwater modeling platform was developed for use by stakeholders for both learning and planning. Third, in preparation for stakeholder ranking of aquifers for investigation, we conducted a review of multicriteria decision analysis (MCDA) as applied to coupled human-natural resource systems and a review of real-world examples of aquifer prioritization schemes used by governmental entities. Finally, an assessment of uncertainty with respect to knowledge about and trajectory of the coupled human-biophysical system was carried out to aid in stakeholder discussions of prioritization criteria and weighting schemes. These results and tools can be used to support prioritization of any set of aquifers. However, some are specifically designed to address transboundary aquifers and will be used to inform binational discussions regarding prioritization of future aquifer investigations along the US-Mexico border.&lt;/p&gt;

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