Geology topics

Research about Mississippi River Valley alluvial aquifer

Source-linked reports with geographic coverage including Mississippi River Valley alluvial aquifer.

9 recordsLinked to original sources

USGS2026

Altitude of the potentiometric surface and depth to water in the Mississippi River Valley alluvial aquifer, spring 2024

Potentiometric-surface and depth-to-water maps for spring 2024 were created for the Mississippi River Valley alluvial aquifer using groundwater-altitude data from 1,151 wells completed in the Mississippi River Valley alluvial aquifer and from the altitude of the top of the water surface in area rivers from 160 U.S. Geological Survey and U.S. Army Corps of Engineers streamgages. The potentiometric-surface and depth-to-water maps for 2024 were created to support investigations to characterize the Mississippi River Valley alluvial aquifer as part of the U.S. Geological Survey Water Availability and Use Science Program. Sufficient data were available to map the potentiometric surface and depth to water of the Mississippi River Valley alluvial aquifer for spring 2024 for about 83 percent of the aquifer area. The potentiometric contours ranged from 0 to 330 feet (ft) above the North American Vertical Datum of 1988. The regional direction of the groundwater gradient was generally to the south-southwest, except in areas of groundwater-altitude depressions, where the groundwater gradient direction was into the depression, and near rivers, where the groundwater gradient direction was either from the aquifer to the river or from the river into the aquifer. Groundwater depressions in the potentiometric-surface map are in the lower one-half of the Cache region and in most of the Grand Prairie and Delta regions. Depth to water by well in the Mississippi River Valley alluvial aquifer in spring 2024 ranged from 0.27 ft above land surface to 145.65 ft below land surface.

Arkansas, Illinois, Kentucky, Louisiana, Mississip↗

USGS2026

Multiple machine-learning estimation of groundwater levels and trends for the regional Mississippi River Valley alluvial aquifer

The Mississippi River Valley alluvial aquifer provides irrigation, public, and domestic water supplies across the south-central United States. Declining groundwater levels require improved characterization of changing conditions. Traditional potentiometric-surface mapping does not use all available water-level data or quantify uncertainty. To address these limitations, we developed a data-driven multiple machine-learning (MML) framework delivered through two open-source R packages. The covMRVAgen1 software assembles covariates to 155,960 monthly groundwater levels from 57,695 wells; the mmlMRVAgen1 software trains Cubist and Random Forest models, blends them, and makes 1-kilometer gridded predictions of monthly potentiometric surfaces for the period January 1980–December 2022. The MML approach provides a methodological foundation for region-scale spatiotemporal groundwater prediction and uncertainty quantification, generating 90-percent prediction limits with appropriate empirical coverage. Model performance is acceptable, with a root-mean-square error of about 4.2 feet, standard deviation of 24.82 feet, and a normalized Nash–Sutcliffe efficiency of 0.973.

Arkansas, Illinois, Louisiana, Mississippi, Missou↗

USGS2025

Quantitative subsurface characterization illuminates the origin of the Quaternary Mississippi River Valley alluvial aquifer

The Mississippi River Valley alluvial aquifer (MRVA) is vital to U.S. food security and global agricultural supply. However, quantitative understanding of its Quaternary origin, architecture, and hydrologic function remains incomplete. Here we develop a three-dimensional hydrostratigraphic model to characterize the deposition of clay and silt, fine-medium sands, and graveliferous sands using lithologic data from 75,000 boreholes compiled across the Lower Mississippi Valley and a geostatistical method—interval kriging. We find that cyclic glacial entrenchments, evidenced by remnants of pre-Wisconsinan postglacial sediments, alongside geodynamic activities shaped the MRVA basal configuration. Stratal weakening from faulting and salt diapirism enhanced glacial incision and thereby produced abrupt aquifer thickening. We demarcate the top of graveliferous sands as the regional marker of the Pleistocene-Holocene transition. The MRVA hydrostratigraphy reveals hydrologic function and geologic controls on groundwater storage and quality, advancing the assessment of aquifer sustainability under a changing climate, with implications for alluvial aquifers globally.

Arkansas, Illinois, Kentucky, Louisiana, Mississip↗

USGS2025

Altitude of the potentiometric surface and depth to water in the Mississippi River Valley alluvial aquifer, spring 2022

Potentiometric-surface and depth-to-water maps for spring 2022 were created for the Mississippi River Valley alluvial aquifer (MRVA) using groundwater-altitude data from 1,136 wells completed in the MRVA and from the altitude of the top of the water surface in area rivers from 160 streamgages. The potentiometric-surface and depth-to-water maps for 2022 were created to support investigations to characterize the MRVA as part of the U.S. Geological Survey Water Availability and Use Science Program. Sufficient data were available to map the potentiometric surface and depth to water of the MRVA for spring 2022 for about 83 percent of the aquifer area. The potentiometric contours ranged from 0 to 340 feet (ft) above the North American Vertical Datum of 1988. The regional direction of groundwater gradient was generally to the south-southwest, except in areas of groundwater-altitude depressions, where the groundwater gradient was into the depression, and near rivers, where the groundwater gradient can be from aquifer to the river or from the river into the aquifer. There are large depressions in the potentiometric-surface map in the lower one-half of the Cache region and in much of the Grand Prairie and Delta regions. Depth to water in the MRVA, spring 2022, by well ranged from 5.00 ft above land surface to 145.66 ft below land surface.

Mississippi River Valley alluvial aquifer↗

USGS2020

Altitude of the potentiometric surface in the Mississippi River Valley alluvial aquifer, spring 2018

A potentiometric-surface map for spring 2018 was created for the Mississippi River Valley alluvial (MRVA) aquifer using available groundwater-altitude data from 1,126 wells completed in the MRVA aquifer and from the altitude of the top of the water surface in area rivers from 66 streamgages. Personnel from Arkansas Natural Resources Commission, Arkansas Department of Health, Arkansas Geological Survey, Illinois Department of Agriculture, Illinois State Water Survey, Louisiana Department of Natural Resources, Louisiana Department of Transportation and Development, Mississippi Department of Environmental Quality, Missouri Department of Natural Resources, Yazoo Mississippi Delta Joint Water Management District, U.S. Department of Agriculture-Natural Resources Conservation Service, and U.S. Geological Survey (USGS) routinely collect groundwater-level data from wells screened in the MRVA aquifer. The USGS and the U.S. Army Corps of Engineers routinely collect data on river stage and streamflow for the rivers overlying the MRVA aquifer area. The potentiometric-surface map for 2018 was created utilizing existing groundwater and surface-water altitudes to support investigations to characterize the MRVA aquifer as part of the USGS Water Availability and Use Science Program. Sufficient data were available to map the potentiometric surface of the MRVA aquifer for spring 2018 for about 87 percent of the aquifer area. The potentiometric contours ranged from 10 to 340 feet above North American Vertical Datum of 1988. The regional direction of groundwater flow was generally to the south-southwest, except in areas of groundwater-altitude depressions, where groundwater flowed into the depression, and near rivers, where flow can be from aquifer to the river or from the river into the aquifer. There are large depressions in the potentiometric-surface map in the lower one-half of the Cache region and in most of the Grand Prairie and Delta regions.

Mississippi River Valley alluvial aquifer↗

USGS2015

Water levels and water quality in the Mississippi River Valley alluvial aquifer in eastern Arkansas, 2012

During the spring of 2012, the U.S. Geological Survey, in cooperation with the Arkansas Natural Resources Commission and the Arkansas Geological Survey, measured water levels in 342 wells completed in the Mississippi River Valley alluvial aquifer in eastern Arkansas. The Arkansas Natural Resources Commission measured water levels in 11 wells, and the U.S. Department of Agriculture-Natural Resources Conservation Service measured water levels in 239 wells completed in the alluvial aquifer and provided these data to the Arkansas Natural Resources Commission. In 2010, estimated water withdrawals from the alluvial aquifer in Arkansas totaled about 7,592 million gallons per day. Withdrawals more than doubled between 1985 and 2010, about a 115-percent increase. The regional direction of groundwater flow is generally to the south and east except where flow is affected by groundwater withdrawals. East of Crowleys Ridge, water flows from north to south along Crowleys Ridge and northeast to southwest along the Mississippi River. West of Crowleys Ridge, water flows from northeast to southwest along Crowleys Ridge from Clay County to Craighead County. From Craighead County to Monroe County, a depression redirects groundwater flow from all directions. A depression in Arkansas, Lonoke, and Prairie Counties alters groundwater flow from all directions. South of the Arkansas River, the flow is towards the southeast, except near depressions in Lincoln and Desha Counties and Desha and Chicot Counties where flow is towards the depression. In 2012, the lowest water-level altitude was 73 feet (ft) in Arkansas County. The highest water-level altitude was 288 ft in northeastern Clay County on the western side of Crowleys Ridge. The 2012 potentiomentric-surface map shows eight depressions, two large depressions and six small depressions. One large depression begins in southeastern Arkansas County, at the Arkansas and Desha County line, extends north into Prairie County, west into Lonoke County, and east into the westernmost part of Monroe County. The area in Lonoke, Prairie, and White Counties in the northwestern half of the depression has a water-level altitude measurement of 90 ft and has expanded into the northern third of Prairie County. The 2012 potentiometric-surface map shows a general north-south depression with the southern end in central Monroe County through western Lee, St. Francis, Cross, Poinsett, and Craighead Counties and eastern Woodruff and Jackson Counties. There are two deeper areas in this depression, one at the Monroe and Lee County line, with a low water-level altitude measurement of 123 ft, and the second in Poinsett County, with a low water-level altitude measurement of 113 ft. The six small depressions are located in northern Ashley County, in southern Desha and northern Chicot Counties, in eastern Lincoln and western Chicot Counties, at the Arkansas and Desha County line, in northern Phillips County, and in southeastern Greene County. A map showing the difference in water levels was constructed using 541 differences in water levels measured during 2008 and 2012. The difference in measured water levels from 2008 to 2012 ranged from -27.4 ft to 18.7 ft, with a mean of -1.0 ft. The largest decline of -27.4 ft occurred in Lonoke County, and the largest rise of 18.7 ft occurred in Prairie County. Four areas were predominated by declines—west of Crowleys Ridge from Greene County south to Lee County, including Lawrence and southern Woodruff Counties; east of Crowleys Ridge from Clay County south to Poinsett County and Mississippi County; Lonoke and Jefferson Counties; and Ashley, Chicot, Desha, and Drew Counties. Three areas are predominated by rises in measured water levels—east of Crowleys Ridge in Crittenden, Cross, Lee, and St. Francis Counties; Jackson and northern Woodruff Counties; and Arkansas, Monroe, Phillips, Prairie, and White Counties. Long-term water-level changes were evaluated using hydrographs from 319 wells in the alluvial aquifer for the period from 1988 to 2012. The annual rise or decline in water level for the entire study area was -0.45 feet per year (ft/yr) with a range from -2.08 to 0.84 ft/yr. Arkansas County had two different rates of annual decline for the two hydrographs shown, about 0.97 ft/yr and about 0.26 ft/yr. In Craighead, Cross, Lee, Poinsett, and St. Francis Counties, water levels are declining at a greater rate in areas west of Crowleys Ridge than in areas east of Crowleys Ridge. Two hydrographs are shown in each of Craighead, Cross, Lee, Poinsett, and St. Francis Counties, one on the west side of Crowleys Ridge and one on the east side of Crowleys Ridge. The hydrographs west of Crowleys Ridge have annual water-level declines from -0.91 to -1.24 ft/yr. The hydrographs east of Crowleys Ridge have annual water-level declines from -0.07 to -0.40 ft/yr. The mean county annual water-level declines for these counties range from -0.55 to -0.87 ft/yr. Water samples were collected in the summer of 2012 from142 wells completed in the alluvial aquifer and measured onsite for specific conductance, temperature, and pH. Samples were collected from 94 wells for dissolved chloride analysis. Specific conductance ranged from 91 microsiemens per centimeter at 25 degrees Celsius (μS/cm at 25 °C) in Drew County to 984 μS/cm at 25 °C in Monroe County. The mean specific conductance was 547 μS/cm at 25 °C. Temperature ranged from 18.1 degrees Celsius (°C) in Crittenden County to 22.4 °C in Prairie County. The mean temperature was 22.1 °C. The pH ranged from 8.3 in Randolph County to 6.2 in Drew County and had a median of 7.3. Dissolved chloride concentrations ranged from 3.34 milligrams per liter (mg/L) in Randolph County to 182 mg/L in Lincoln County. The mean chloride concentration was 27.6 mg/L.

Arkansas↗

USGS2003

Conjunctive-use optimization model of the Mississippi River Valley alluvial aquifer of northeastern Arkansas

The Mississippi River Valley alluvial aquifer is a water-bearing assemblage of gravels and sands that underlies about 32,000 square miles of Missouri, Kentucky, Tennessee, Mississippi, Louisiana, and Arkansas. Because of the heavy demands placed on the aquifer, several large cones of depression over 100 feet deep have formed in the potentiometric surface, resulting in lower well yields and degraded water quality in some areas. A ground-water flow model of the alluvial aquifer was previously developed for an area covering 14,104 square miles, extending northeast from the Arkansas River into the northeast corner of Arkansas and parts of southeastern Missouri. The flow model showed that continued ground-water withdrawals at rates commensurate with those of 1997 could not be sustained indefinitely without causing water levels to decline below half the original saturated thickness of the aquifer. To develop estimates of withdrawal rates that could be sustained in compliance with the constraints of critical ground-water area designation, conjunctive-use optimization modeling was applied to the flow model of the alluvial aquifer in northeastern Arkansas. Ground-water withdrawal rates form the basis for estimates of sustainable yield from the alluvial aquifer and from rivers specified within the alluvial aquifer model. A management problem was formulated as one of maximizing the sustainable yield from all ground-water and surface-water withdrawal cells within limits imposed by plausible withdrawal rates, and within specified constraints involving hydraulic head and streamflow. Steady-state flow conditions were selected because the maximized withdrawals are intended to represent sustainable yield of the system (a rate that can be maintained indefinitely). Within the optimization model, 11 rivers are specified. Surface-water diversion rates that occurred in 2000 were subtracted from specified overland flow at the appropriate river cells. Included in these diversions were the planned diversions of 63,339,248 ft3/d for the Bayou Meto project area and 55,078,367 ft3/d for the Grand Prairie project area, which factor in an additional 30 and 40 percent transmission loss, respectively. Streamflow constraints were specified at all 1,165 river cells based on average 7-day minimum flows for 10 years. Sustainable yield for all rivers ranged from 0 (Current, Little Red, and Bayou Meto Rivers) to almost 5 billion cubic feet per day for the Arkansas River. Total sustainable yield from all rivers combined was 12.8 billion cubic feet per day, which represents a substantial source for supplementing ground water to meet the total water demand. Sustainable-yield estimates are affected by the allowable upper limit on withdrawals from wells specified in the optimization model. Ground-water withdrawal rates were allowed to vary as much as 200 percent of the withdrawal rate in 1997. As the overall upper limit on withdrawals is increased, the sustainable yield generally increases. Tests with the optimization model show that without limits on pumping, wells adjacent to sources of water would have optimized withdrawal rates that were orders of magnitude larger than rates corresponding to those of 1997. The sustainable yield from ground water for the entire study area while setting the maximum upper limit as the amount withdrawn in 1997 is 360 million cubic feet per day, which is only about 57 percent of the amount withdrawn in 1997 (635.6 million cubic feet per day). Optimal sustainable yields from within the Bayou Meto irrigation project area and within the Grand Prairie irrigation project area are 18.1 and 9.1 million cubic feet per day, respectively, assuming a maximum allowable withdrawal rate equal to 1997 rates. These values of sustainable yield represent 35 and 30 percent respectively of the amount pumped from these project areas in 1997. Unmet demand (defined as the difference between the optimized withdrawal rate or sustainable yield, and the anticipated demand) was calculated using different demand rates based on multiples of the 1997 withdrawal rate. Assuming that demand is the 1997 withdrawal rate, and that sustainable-yield estimates are those obtained using upper limits of withdrawal rates of 100-, 150-, and 200-percent of 1997 withdrawal rates, then the resulting unmet demand for the entire model area is 275.5, 190.9, and 110 million cubic feet per day, respectively. Whereas, if the demand is specified as 100-, 150-, and 200-percent of the 1997 withdrawal rate, and the sustainable-yield estimates remain the same, then the resulting unmet demand for the entire model area is 275.5, 508.8, and 745.8 million cubic feet per day, respectively. These unmet demands for ground water could be obtained from large sustainable surface-water withdrawals.

Arkansas↗

USGS2003

Recalibration of a ground-water flow model of the Mississippi River Valley alluvial aquifer in southeastern Arkansas, 1918-1998, with simulations of hydraulic heads caused by projected ground-water withdrawals through 2049

To evaluate the effects of projected ground water withdrawals, three scenarios were used to simulate a range of possible withdrawals. Five additional stress periods of 10 years each were added to the model to facilitate predictive scenario generation. The predictive scenarios control pumpage by either continuing 1997 pumpage into the future (scenario 1) or by increasing water-use trends into the future (scenario 2 and 3). The ASWCC Critical Ground Water area designation includes a requirement that a 50-percent saturated formation thickness be maintained. For this reason, the level of 50-percent saturated formation thickness is used as a reference surface in the scenario output presented. Animations of simulated heads changing through time are included on the compact disc in the "Animations" folder. In the animations, the level of 50 percent saturated formation thickness is indicated by a mesh surface and the dry cells appear as voids in the model surface.

Arkansas↗

USGS1989

Hydrology of the Mississippi River Valley alluvial aquifer, south- central United States — A preliminary assessment of the regional flow system

Data describing the aquifer framework and steady-state regional flow were assembled for the Mississippi River Valley alluvial aquifer north of Vicksburg, Mississippi. The aquifer is part of the Mississippi embayment aquifer system. The 60 to 140 ft thick alluvial aquifer grades from gravel at the bottom to fine sand near the top. It is overlain by the Mississippi River Valley confining unit, which consists of 10 to 50 ft of silts, clays, and fine-grained sands. Underlying units consist of alternating sands and clays corresponding to regional hydrogeologic units of the Mississippi embayment aquifer system. The three-layer finite difference model was used to simulate two-dimensional confined or unconfined steady-state flow for predevelopment and 1972. Preliminary analysis of predevelopment flow indicates that recharge to the alluvial aquifer was from underlying aquifers and the confining unit. Rivers accounted for almost all discharge. Pumpage from the alluvial aquifer for irrigation substantially changed regional flow direction toward depressions in the potentiometric surface. Recharge from rivers and the confining unit increased and recharge from underlying aquifers decreased. Discharge to underlying aquifers increased and discharge to rivers decreased. Recharge from the confining unit reached a maximum of 1.3 inch/year for large parts of the aquifer. Nearly all drawdown exceeding 20 ft was at two locations in Arkansas--the Grande Prairie region, and west of Crowleys Ridge. Model results indicate the importance of leakage from rivers and the confining unite to providing recharge to sustain large amounts of pumpage from the alluvial aquifer.

Mississippi River Valley alluvial aquifer↗