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Groundwater withdrawal zones for drinking water from the Mississippi River Valley alluvial aquifer and Mississippi embayment aquifers

Metadata Updated: July 6, 2024

Of the approximately 6.6 million people living in the Mississippi embayment (MISE) region in the central United States, approximately 65 percent rely on groundwater for their drinking water (Dieter, Linsey, and others, 2017). Regional assessments of water quality in principal aquifer systems provide context for the long-term availability of these water resources for drinking-water supplies. To assess the current (2018) status of water quality in MISE in relation to drinking water supplies, groundwater withdrawal zones used for domestic and public supply were modeled using available groundwater well and hydrogeologic framework data. Three dimensional surfaces were modeled to map the depth zones at which groundwater is withdrawn for drinking water. These surfaces will be used to model groundwater quality as part of the U.S. Geological Survey National Water Quality Assessment project’s intensive principal aquifer analysis. The MISE region includes two principal aquifer systems: the surficial aquifer system, which is dominated by the Quaternary Mississippi River Valley Alluvial aquifer (MRVA), and the Mississippi embayment aquifer system, which includes deeper Tertiary aquifers and confining units. Based on the distribution of groundwater use for drinking water, the modeling effort is focused on MRVA and two hydrogeologic units from the deeper system, including the middle Claiborne aquifer (MCAQ) and lower Claiborne aquifer (LCAQ). The MRVA is a surficial, unconfined to semi-confined, highly productive aquifer used mostly for irrigation, with a lesser amount of groundwater use for public supply and domestic self-supply (Clark and others, 2011; Maupin and Barber, 2005). The median thickness of the MRVA is about 130 feet (ft) but it can be as much as 290 ft thick (Hart and others, 2008). The MCAQ is confined where overlain by the Middle Claiborne confining unit and is used dominantly for public supply. Domestic self-supply occurs along outcrop areas where the unit is shallower or crops out. The unit consists mostly of the Sparta Sand, but north of approximately the 35th parallel (near the border between Tennessee and Mississippi), the underlying lower Claiborne confining unit (LCCU) undergoes a facies change and the Memphis Sand is included in the MCAQ (Hosman and Weiss, 1991). The MCAQ has a median thickness of about 805 ft, but it can be as much as 1,890 ft thick (Hart and others, 2008). Although not as regionally important as MRVA or MCAQ, domestic and public supply wells withdraw groundwater from LCAQ, especially on the margins of the Mississippi embayment where LCAQ is relatively shallow or crops out. The aquifer does not extend north of approximately the 35th parallel because of a facies change in the LCCU. The aquifer is relatively thin, ranging from 50 to 195 ft thick with a median thickness of 125 ft (Hart and others, 2008). Continuous surfaces representing groundwater withdrawal zones used for drinking water were created for MRVA (combined domestic and public supply), MCAQ-domestic, MCAQ-public supply, LCAQ-domestic, and LCAQ-public supply, where the surfaces represent the altitude (in feet above North American Vertical Datum of 1988) of the bottom and top of the screened interval. Surfaces were created by kriging well points using Empirical Bayesian Kriging in ArcMap version 10.4 (ESRI, 2016). Well construction information for public supply (P) and domestic (D) wells and aquifer surfaces from the Mississippi Embayment hydrogeologic framework (Hart and others, 2008) were used to populate as much information as available about well use, well depth, screened interval, and aquifer as to improve the modeled surfaces. To assess error on the modeled surfaces, well datasets were separated into training (90 percent) and testing (10 percent) datasets for kriging and root mean square error was calculated. The number of wells used for kriging varied for each surface (WellsSummary.csv). A shapefile representing the density of wells within each raster cell was also produced to aid users in understanding general well locations and errors (ps_wellerrors.shp). For a full explanation of methods, see Processing Steps.

Access & Use Information

Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Dates

Metadata Created Date June 1, 2023
Metadata Updated Date July 6, 2024

Metadata Source

Harvested from DOI EDI

Additional Metadata

Resource Type Dataset
Metadata Created Date June 1, 2023
Metadata Updated Date July 6, 2024
Publisher U.S. Geological Survey
Maintainer
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Identifier USGS:5d24a20ae4b0941bde64fb46
Data Last Modified 20200910
Category geospatial
Public Access Level public
Bureau Code 010:12
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Metadata Catalog ID https://datainventory.doi.gov/data.json
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Harvest Object Id 0ae8f0b4-4f3c-434d-8b81-9abcf50d9df6
Harvest Source Id 52bfcc16-6e15-478f-809a-b1bc76f1aeda
Harvest Source Title DOI EDI
Metadata Type geospatial
Old Spatial -94.0647,31.2689,-86.8723,37.2813
Publisher Hierarchy White House > U.S. Department of the Interior > U.S. Geological Survey
Source Datajson Identifier True
Source Hash 3fb220e083331f9a4045b20cafc310ea6e2049e13f4f6fe5ae935295f697ea0c
Source Schema Version 1.1
Spatial {"type": "Polygon", "coordinates": -94.0647, 31.2689, -94.0647, 37.2813, -86.8723, 37.2813, -86.8723, 31.2689, -94.0647, 31.2689}

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