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This data release contains input data used in model development and TIF raster files used to predict the probability of high arsenic (As) and high manganese (Mn) in groundwater within the glacial aquifer system in the northern United States. Input data include measured As and Mn concentrations at groundwater wells, and associated predictor variable data. The probability of high As and high Mn was predicted using boosted regression tree methods using the gbm package in R version 4.0.0. The response variables for individual models were the occurrence of: (1) As >10 µg/L, and (2) Mn >300 µg/L. Water-quality data were compiled from three sources, as described in Wilson and others (2019): a compilation of data from numerous...
This data release contains input data used in model development and TIF raster files used to predict the probability of low dissolved oxygen (DO) and high dissolved iron (Fe) in groundwater within the glacial aquifer system in the northern continental United States. Input data include measured DO and Fe concentrations at groundwater wells, and associated predictor variable data. The probability of low DO and high Fe was predicted using boosted regression tree methods using the gbm package in R (v. 4.0.0) in RStudio (v. 1.2.5042). The response variables for individual models were the occurrence of: (1) DO ≤0.5 mg/L, (2) DO ≤2 mg/L, and (3) Fe >100 µg/L. Water-quality data were compiled from three sources, as described...
Categories: Data;
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: Connecticut,
Geochemistry,
Hydrology,
Idaho,
Illinois,
A boosted regression tree (BRT) model was developed to predict pH conditions in three-dimensions throughout the glacial aquifer system (GLAC) of the contiguous United States using pH measurements in samples from 18,258 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 flow paths, 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...
Categories: Data;
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: Boosted regression trees,
Calcite saturation index,
Connecticut,
Geochemistry,
Geochemistry,
The Lithologic Logs dataset includes state well records, and the well logs were standardized so that the lithologic information used a consistent terminology by Bayless and others (2017). The dataset contains 1,565,051 records, of which 746,568 are for wells that are used for withdrawing water.
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. With the data and computer codes in this data release users can (1) reconstruct and run 115 General Simulation Models (GSMs) of groundwater flow, (2) calculate groundwater age metrics at selected GSM cells, (3) train a boosted regression tree model using the provided data, (4) predict...
The Sediment and Aquifer Characteristics dataset includes two, grid-based polygon feature classes. The first class uses a five-kilometer grid to show the density of lithologic logs available for analysis. The second class contains attributes that characterize either Quaternary sediment in the glaciated conterminous United States or aquifer material within it. The attributes are derived from lithologic logs obtained from boreholes and wells. The polygons were delineated by a constrained, kriging-based interpolation based on the distribution of map units in the source Surficial Geologic Units dataset using a grid-based algorithm to interpolate between the point data, as defined in the processing steps.
The bedrock geology for the Glacial Environments and Surficial Sediments (GESS) geodatabase is an amalgamation of several “Integrated Geologic Map Databases for the United States” (Dicken and others, 2008; Ludington and others, 2007; Nicholson and others, 2007-1,-2,-3; Stoeser and others, 2007). Using the LITH62 and LITH62MINO attribute values from that series of maps and the associated lithclass 6.2 code text descriptions from the geodatabase, spatial elements of that geodatabase were grouped. A new GESS attribute was created, “Litho_class,” and each spatial element was given a Litho_class value of non-carbonate sedimentary rock, carbonate rock, non-carbonate metamorphic rock, volcanic rock, plutonic rock, or unconsolidataed...
The Groundwater Usage for Public Supply dataset contains attributes pertaining to groundwater use in the glaciated conterminous United States summarized by county. The attributes were computed from total groundwater usage by county compiled by Maupin and others (2010), and from inventories of water-use records for 71,267 public water-supply systems by Buchwald and others (in press). Source aquifers (Quaternary sediments or bedrock) were assigned for the public water-supply systems based on reported data (e.g., well construction records, aquifer delineation maps), or based on well depth and the Quaternary sediment thickness. Water usage rates are reported on an average annual, areal basis in units of millimeters...
This data release is a compilation of the digital products from a hydrogeologic framework of the glaciated conterminous United States that were constructed to portray sediment and aquifer characteristics within this area. These digital products are described in Yager, R.M., Kauffman, L.J., Soller, D.R., Haj, A.E., Heisig, P.M., Buchwald, C.A., Westenbroek, S.M., and Reddy, J.E., 2018, Characterization and occurrence of confined and unconfined aquifers in Quaternary sediments in the glaciated conterminous United States: U.S. Geological Survey Scientific Investigations Report 2018–5091, 90 p., https://doi.org/10.3133/sir20185091.
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