Characterization and occurrence of confined and unconfined aquifers in Quaternary sediments in the glaciated conterminous United States

Yager, Richard M.; Kauffman, Leon J.; Soller, David R.; Haj, Adel E.; Heisig, Paul M.; Buchwald, Cheryl A.; Westenbroek, Stephen M.; Reddy, James E.

doi:10.3133/sir20185091

Cited by 18 publications

(28 citation statements)

References 12 publications

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“…Based on metamodels created in this study, the volume of young groundwater can be calculated. In this study, the mean saturated thickness was 26 m (the median saturated thickness across terranes ranges from 6 to 45 m (Yager et al., 2019)), and the mean fraction of young water was 0.80 (80% young). The mean transport porosity from the local‐scale model matches to tritium data was 0.15, which is used here as a lower bound for the purpose of estimating the volume of young groundwater.…”

Section: Discussionmentioning

confidence: 53%

“…Recharge was not an adjustable parameter; it was calculated independently by Reitz et al (2017). Total recharge for each GSM was summed and assigned to each K zone such that recharge to coarse sediment was 2.7 times that to fine sediment, based on approximate ratios of recharge to coarse and fine materials (Yager et al, 2019). Streams were simulated using hydrography from the NHDPlus by implementing a nonlinear head-dependent boundary that allows water to flow into the stream (proportional to the head difference) but not out of it.…”

Section: General Simulation Modelsmentioning

confidence: 99%

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Three‐Dimensional Distribution of Groundwater Residence Time Metrics in the Glaciated United States Using Metamodels Trained on General Numerical Simulation Models

Starn

Kauffman

Carlson

et al. 2021

Water Resources Research

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Residence time distribution (RTD) is a critically important characteristic of groundwater flow systems; however, it cannot be measured directly. RTD can be inferred from tracer data with analytical models (few parameters) or with numerical models (many parameters). The second approach permits more variation in system properties but is used less frequently than the first because large‐scale numerical models can be resource intensive. Using a novel automated approach, a set of 115 inexpensive general simulation models (GSMs) was used to create RTD metrics (fraction of young groundwater, defined as <65 years old; mean travel time of young fraction; median travel time of old fraction; and mean path length). GSMs captured the general trends in measured tritium concentrations in 431 wells. Boosted Regression Tree metamodels were trained to predict these RTD metrics using available wall‐to‐wall hydrogeographic digital sets as explanatory features. The metamodels produced a three‐dimensional distribution of predictions throughout the glacial system that generally matched with the numerical model RTD metrics. In addition to the expected importance of aquifer thickness and recharge rate in predicting RTD metrics, two new data sets, Multi‐Order Hydrologic Position (MOHP) and hydrogeologic terrane were important predictors. These variables by themselves produced metamodels with Nash‐Sutcliffe efficiency close to the full metamodel. Metamodel predictions showed that the volume of young groundwater stored in the glaciated United States is about 6,000 km3, or about 0.5% of globally stored young groundwater.

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Section: Discussionmentioning

confidence: 53%

Section: General Simulation Modelsmentioning

confidence: 99%

Three‐Dimensional Distribution of Groundwater Residence Time Metrics in the Glaciated United States Using Metamodels Trained on General Numerical Simulation Models

Starn

Kauffman

Carlson

et al. 2021

Water Resources Research

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“…The median reported well depth was 33 m (108 ft). Few groundwater wells are completed in unconsolidated sediments, as the mapped stratified drift aquifer in the domain is limited to the valley encompassing the Susquehanna River (Haj et al, 2018; Yager et al, 2019). Instead, groundwater wells in the study area primarily tap the fractured bedrock aquifer, which was extensively weathered by glacial and orogenic processes in the region (Williams et al, 1998).…”

Section: Methodsmentioning

confidence: 99%

Evaluating Domestic Well Vulnerability to Contamination From Unconventional Oil and Gas Development Sites

Soriano

Siegel

Gutchess

et al. 2020

Water Resources Research

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The rapid expansion of unconventional oil and gas development (UD), made possible by horizontal drilling and hydraulic fracturing, has triggered concerns over groundwater contamination and public health risks. To improve our understanding of the risks posed by UD, we develop a physically based, spatially explicit framework for evaluating groundwater well vulnerability to aqueous phase contaminants released from surface spills and leaks at UD well pad locations. The proposed framework utilizes the concept of capture probability and incorporates decision-relevant planning horizons and acceptable risks to support goal-oriented modeling for groundwater protection. We illustrate the approach in northeastern Pennsylvania, where a high intensity of UD activity overlaps with local dependence on domestic groundwater wells. Using two alternative models of the bedrock aquifer and a precautionary paradigm to integrate their results, we found that most domestic wells in the domain had low vulnerability as the extent of their modeled probabilistic capture zones were smaller than distances to the nearest existing UD well pad. We also found that simulated capture probability and vulnerability were most sensitive to the model parameters of matrix hydraulic conductivity, porosity, pumping rate, and the ratio of fracture to matrix conductivity. Our analysis demonstrated the potential inadequacy of current state-mandated setback distances that allow UD within the boundaries of delineated capture zones. The proposed framework, while limited to aqueous phase contamination, emphasizes the need to incorporate information on flow paths and transport timescales into policies aiming to protect groundwater from contamination by UD.

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“…As previously described, terranes represent regions with Quaternary sediments that have a common age and mode of deposition and are of similar texture and thickness (Yager et al 2018) (Table S1). The mineral composition of sediments in these terranes is governed by the bedrock type over which glacial ice lobes traveled (Rodgers 1989, Grasby et al 2010 or from which residuum formed in the mountainous areas of terrane 1G (Yager et al 2018). Together these factors control the stratigraphic complexity and composition of sediments in each terrane, which in turn affects the movement and quality of groundwater.…”

Section: Hydrogeologic Terranes and Hydrologic Position On The Land Smentioning

confidence: 99%

“…Location of A) hydrogeologic terranes(Yager et al 2018) and B) well sites. Well sites are color coded by pH value categories.…”

mentioning

confidence: 99%

Machine Learning Predictions of pH in the Glacial Aquifer System, Northern USA

et al. 2020

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A boosted regression tree model was developed to predict pH conditions in three dimensions throughout the glacial aquifer system of the contiguous United States using pH measurements in samples from 18,386 wells and predictor variables that represent aspects of the hydrogeologic setting. Model results indicate that the carbonate content of soils and aquifer materials strongly controls pH and, when coupled with long flowpaths, results in the most alkaline conditions. Conversely, in areas where glacial sediments are thin and carbonate-poor, pH conditions remain acidic. At depths typical of drinking-water supplies, predicted pH >7.5-which is associated with arsenic mobilization-occurs more frequently than predicted pH <6-which is associated with water corrosivity and the mobilization of other trace elements. A novel aspect of this model was the inclusion of numerically based estimates of groundwater flow characteristics (age and flowpath length) as predictor variables. The sensitivity of pH predictions to these variables was consistent with hydrologic understanding of groundwater flow systems and the geochemical evolution of groundwater quality. The model was not developed to provide precise estimates of pH at any given location. Rather, it can be used to more generally identify areas where contaminants may be mobilized into groundwater and where corrosivity issues may be of concern to prioritize areas for future groundwater monitoring.

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Characterization and occurrence of confined and unconfined aquifers in Quaternary sediments in the glaciated conterminous United States

Cited by 18 publications

References 12 publications

Three‐Dimensional Distribution of Groundwater Residence Time Metrics in the Glaciated United States Using Metamodels Trained on General Numerical Simulation Models

Three‐Dimensional Distribution of Groundwater Residence Time Metrics in the Glaciated United States Using Metamodels Trained on General Numerical Simulation Models

Evaluating Domestic Well Vulnerability to Contamination From Unconventional Oil and Gas Development Sites

Machine Learning Predictions of pH in the Glacial Aquifer System, Northern USA

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