A groundwater-flow model of the Sparta aquifer was used to evaluate changes in water-level altitu... more A groundwater-flow model of the Sparta aquifer was used to evaluate changes in water-level altitudes associated with the withdrawal of groundwater at varying rates from a well field near Pine Bluff, Arkansas, in Jefferson County. Waterlevel altitudes at three different model cell locations from five different scenarios for varying withdrawal rates from the well field were compared for the period 1998 to 2048. The three model cells used for the comparison were located (1) near the center of the well field, (2) near the center of the city of Pine Bluff (about 5 miles west of the center of the well field), and (3) about 15 miles north of the well field. Pumping rates at the well field were varied from 7.2 million gallons per day to 27 million gallons per day for the five scenarios analyzed, and water-level hydrographs were constructed for each scenario for each of the three model cell locations. Water-level altitudes near the center of the well field changed the most of the three model cell locations analyzed. Water-level altitudes were approximately 90 feet higher for the 7.2 million gallon per day scenario in 2048 compared to the baseline scenario of 25.4 million gallons per day. Whereas, water-level altitudes at the same location were 9 feet lower for the 27 million gallon per day scenario in 2048 compared to the baseline scenario.
The model area (fig. ) covers 7,340 mi 2 in northwestern Arkansas, southeastern Kansas, southwest... more The model area (fig. ) covers 7,340 mi 2 in northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma. Generally, the topography in the model area is low relief prairie in the west and northwest with greater relief in the southeast. Land-surface altitude within the model area ranges from about 650 ft to about 1,320 ft, and slopes generally from the southeast toward the west in the
Simulations were done to examine the effects of ground-water withdrawals from wells J-13 and J-12... more Simulations were done to examine the effects of ground-water withdrawals from wells J-13 and J-12 near Yucca Mountain, Nevada. These simulations were done using a two-dimensional finite-element model of the subregional groundwater flow system of Yucca Mountain and vicinity. Eight different withdrawal rates ranging from 36 gallons per minute (the minimum average for well J-13) to 1,390 gallons per minute (the maximum for both J-13 and J-12 combined) were used in conjunction with specific-yield values of 0.001, 0.005, and 0.01. Drawdown was analyzed for each withdrawal rate by plotting contours of drawdown after 10 years of simulated withdrawals, and by plotting drawdown as a function of time for model locations corresponding to well J-13, well J-12, one-half mile south of well J-12, 2 miles north of the town of Amargosa Valley, and about 5 miles northwest of the Ash Meadows area. Because the range in simulated withdrawal rate was large, the range in resultant drawdown was correspondingly large. The simulated drawdowns after 10 years for the withdrawal rate of 90 gallons per minute from well J-13, based on a specific yield of 0.01 (which was considered to be a minimum value for the aquifer system) were 0.95 foot at well J-13, 0.53 foot at Amargosa Valley, and 0.16 foot northwest of Ash Meadows.
Hydrologic and other data were collected at Franklin Lake playa, one of the principal discharge a... more Hydrologic and other data were collected at Franklin Lake playa, one of the principal discharge areas of the Furnace Creek Ranch-Alkali Flat groundwater flow system, located in southern Nevada and adjacent California. This data will be used to further characterize ground-water discharge that occurs at the playa largely as bare-soil evaporation. Data presented include: (1) Hydrographs of water levels in piezometers; (2) vertical hydraulic gradients estimated from piezometer-nest data; (3) meteorological data from weather stations in the vicinity of Franklin Lake playa; and (4) estimates of moisture fluxes based on changes in soil-moisture content in the unsaturated zone.
Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NA... more Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NAVD 29). Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83). Altitude, as used in this report, refers to distance above the vertical datum.
Arkansas experienced wide extremes in climate variability during the period of 2005 to 2010, reco... more Arkansas experienced wide extremes in climate variability during the period of 2005 to 2010, recording the largest annual precipitation ever recorded in the State (100.05 inches [in.]) in 2009 (National Weather Service, 2012). Many weather stations across the State reported between 80 to 90 in. of rainfall in 2009. For comparison, the average annual precipitation in Little Rock, Arkansas, for the period 1878 to 2010 was 47.1 in. (fig. 1). In contrast, 2005 and 2010 were the 7th and 14th driest years on record in Little Rock with 34.55 and 36.52 in., respectively; both tied as the hottest years ever recorded in Arkansas (National Oceanic and Atmospheric Administration, 2011). The wettest year on record in Little Rock (2009) was interspersed within these dry years, with a total of 81.79 in. Fifteen weather stations within the State ranked 2009 as the wettest year on record (National Weather Service, 2012). Extremes in annual precipitation rates may lead to greater variability in groundwater recharge rates and water use, particularly in the agricultural areas in eastern Arkansas that rely heavily on groundwater produced from the Mississippi River Valley alluvial aquifer (hereafter referred to as the alluvial aquifer). How does this variability affect the groundwater system and water use therein? Are the effects of this variability discernable in measured water levels in wells? Czarnecki and Schrader (2012) examined these questions and provided some insights, the results of which are presented here.
A finite-element model of the ground-water flow system in the vicinity of Yucca Mountain at the N... more A finite-element model of the ground-water flow system in the vicinity of Yucca Mountain at the Nevada Test Site was developed using parameterestimation techniques. The model simulated steady-state ground-water flow occurring in tuffaceous, volcanic, and carbonate rocks, and alluvial aquifers. Hydraulic gradients in the modeled area range from 0.00001 for carbonate aquifers to 0.19 for barriers in tuffaceous rocks. Three model parameters were used in estimating transmissivities in six zones. Simulated hydraulic-head values range from about 1,200 meters near Timber Mountain to about 300 meters near Furnace Creek Ranch. Model residuals for simulated versus measured hydraulic heads range from -28.6 to 21.4 meters; most are less than ±7 meters, indicating an acceptable representation of the hydrologic system by the model. Sensitivity analyses of the model's flux boundary-condition variables were performed to assess the effect of varying boundary fluxes on the calculation of estimated model transmissivities. Varying the flux variables representing discharge at Franklin Lake and Furnace Creek Ranch has greater effect than varying other flux variables.
An existing conjunctive use optimization model of the Mississippi River Valley alluvial aquifer w... more An existing conjunctive use optimization model of the Mississippi River Valley alluvial aquifer was used to evaluate the effect of selected constraints and model variables on ground-water sustainable yield. Modifications to the optimization model were made to evaluate the effects of varying (1) the upper limit of ground-water withdrawal rates, (2) the streamflow constraint associated with the White River, and (3) the specified stage of the White River. Upper limits of ground-water withdrawal rates were reduced to 75, 50, and 25 percent of the 1997 ground-water withdrawal rates. As the upper limit is reduced, the spatial distribution of sustainable pumping increases, although the total sustainable pumping from the entire model area decreases. In addition, the number of binding constraint points decreases. In a separate analysis, the streamflow constraint associated with the White River was optimized, resulting in an estimate of the maximum sustainable streamflow at DeValls Bluff, Arkansas, the site of potential surface-water withdrawals from the White River for the Grand Prairie Area Demonstration Project. The maximum sustainable streamflow, however, is less than the amount of streamflow allocated in the spring during the paddlefish spawning period. Finally, decreasing the specified stage of the White River was done to evaluate a hypothetical river stage that might result if the White River were to breach the Melinda Head Cut Structure, one of several manmade diversions that prevents the White River from permanently joining the Arkansas River. A reduction in the stage of the White River causes reductions in the sustainable yield of ground water.
The Springfield Plateau and Ozark aquifers are important sources of ground water in the Ozark Pla... more The Springfield Plateau and Ozark aquifers are important sources of ground water in the Ozark Plateaus aquifer system. Water from these aquifers is used for agricultural, domestic, industrial, and municipal water sources. Changing water use over time in these aquifers presents a need for updated potentiometric-surface maps of the Springfield Plateau and Ozark aquifers. The Springfield Plateau aquifer consists of water-bearing Mississippian-age limestone and chert. The Ozark aquifer consists of Late Cambrian to Middle Devonian age water-bearing rocks consisting of dolostone, limestone, and sandstone. Both aquifers are complex with areally varying lithologies, discrete hydrologic units, varying permeabilities, and secondary permeabilities related to fractures and karst features. During the spring of 2006, ground-water levels were measured in 285 wells. These data, and water levels from selected lakes, rivers, and springs, were used to create potentiometric-surface maps for the Springfield Plateau and Ozark aquifers. Linear kriging was used initially to construct the water-level contours on the maps; the contours were subsequently modified using hydrologic judgment. The potentiometric-surface maps presented in this report represent groundwater conditions during the spring of 2006. During the spring of 2006, the region received less than average rainfall. Dry conditions prior to the spring of 2006 could have contributed to the observed water levels as well. The potentiometric-surface map of the Springfield Plateau aquifer shows a maximum measured water-level altitude within the study area of about 1,450 feet at a spring in Barry County, Missouri, and a minimum measured water-level altitude of 579 feet at a well in Ottawa County, Oklahoma. Cones of depression occur in Dade, Lawrence and Newton Counties in Missouri and Delaware and Ottawa Counties in Oklahoma. These cones of depression are associated with private wells. Ground water in the Springfield Plateau aquifer generally flows to the west in the study area, and to surface features (lakes, rivers, and springs) particularly in the south and east of the study area where the Springfield Plateau aquifer is closest to land surface. The potentiometric-surface map of the Ozark aquifer indicates a maximum measured water-level altitude of 1,303 feet in the study area at a well in Washington County, Arkansas, and a minimum measured water-level altitude of 390 feet in Ottawa County, Oklahoma. The water in the Ozark aquifer generally flows to the northwest in the northern part of the study area and to the west in the remaining study area. Cones of depression occur in Barry, Barton, Cedar, Jasper, Lawrence, McDonald, Newton, and Vernon Counties in Missouri, Cherokee and Crawford Counties in Kansas, and Craig and Ottawa Counties in Oklahoma. These cones of depression are associated with municipal supply wells. The flow directions, based on both potentiometric-surface maps, generally agree with flow directions indicated by previous studies.
The Mississippi River Valley alluvial aquifer is a waterbearing assemblage of gravels and sands t... more The Mississippi River Valley alluvial aquifer is a waterbearing assemblage of gravels and sands that underlies most of eastern Arkansas and several adjacent States. Ground-water withdrawals have caused cones of depression to develop in the aquifer's water-level surface, some as much as 100 feet deep. Rivers, such as the Arkansas, White, St. Francis, and Mississippi Rivers, are in hydraulic connection with the alluvial aquifer. Recharge to the alluvial aquifer from these rivers becomes induced as ground-water level declines. Long-term water-level measurements in the alluvial aquifer show an average annual decline of 1 foot per year in some areas. The expansion of the cones of depression and the consistent water-level declines indicate that ground-water withdrawals are occurring at a rate that is greater than the sustainable yield of the aquifer. Ground-water flow models of two areas of the alluvial aquifer (north alluvial and south alluvial-divided by the Arkansas River) previously were developed for eastern Arkansas and parts of northern Louisiana, southeastern Missouri, and adjacent States. The flow models showed that continued ground-water withdrawals at 1997 rates for the alluvial aquifer could not be sustained indefinitely without causing water levels to decline below half of the original saturated thickness of the alluvial aquifer. To develop estimates of withdrawal rates that could be sustained relative to the constraints of critical ground-water area designation, conjunctive-use optimization modeling previously was applied to the flow models. Optimization modeling was used to calculate the maximum sustainable yield from wells and rivers, while maintaining simulated water levels and streamflows at or above minimum specified limits. Modifications to the optimization models were made to evaluate the effects of varying ground-water level constraints and surface-water withdrawals from rivers on the model-calculated sustainable yield of the aquifer and rivers. As groundwater-level constraints are relaxed, optimized sustainable yields from rivers decrease because more ground water is available for withdrawal, which would otherwise discharge to the rivers. In addition, sustainable yield of ground water was compared for four different management scenarios involving different waterlevel constraints and river withdrawal specifications. Scenario 2 Simulation of Various Management Scenarios of the Mississippi River Valley Alluvial Aquifer in Arkansas rated thickness, although this rate was near the maximum rate of about 38.9 million gallons per day, above which model cells would go dry.
The Red River Aluminum site near Stamps, Arkansas, contains waste piles of salt cake and metal by... more The Red River Aluminum site near Stamps, Arkansas, contains waste piles of salt cake and metal byproducts from the smelting of aluminum. The waste piles are subjected to about 50 inches of rainfall a year, resulting in the dissolution of the salts and metal. To assess the potential threat to underlying ground-water resources at the site, its hydrogeology was characterized by measuring water levels and field parameters of water quality in 23 wells and at 2 surface-water sites. Seventeen of these monitor wells were constructed at various depths for this study to allow for the separate characterization of the shallow and deep ground-water systems, the calculation of vertical gradients, and the collection of water samples at different depths within the flow system. Lithologic descriptions from drill-hole cuttings and geophysical logs indicate the presence of interbedded sands, gravels, silts, and clays to depths of 65 feet. The regionally important Sparta aquifer underlies the site. Water levels in shallow wells indicate radial flow away from the salt-cake pile located near the center of the site. Flow in the deep system is to the west and southwest toward Bodcau Creek. Water-level data from eight piezometer nests indicate a downward hydraulic gradient from the shallow to deep systems across the site. Values of specific conductance (an indicator of dissolved salts) ranged from 215 to 196,200 microsiemens per centimeter and indicate that saline waters are being transported horizontally and vertically downward away from the site.
Cabot WaterWorks, located in Lonoke County, Arkansas, plans to increase ground-water withdrawals ... more Cabot WaterWorks, located in Lonoke County, Arkansas, plans to increase ground-water withdrawals from the Mississippi River Valley alluvial aquifer from a 2004 rate of approximately 2.24 million gallons per day to between 4.8 and 8 million gallons per day by the end of 2049. The effects of increased pumping from several wells were simulated using a digital model of ground-water flow. The proposed additional withdrawals by Cabot WaterWorks were specified in three 1square-mile model cells with increased pumping beginning in 2007. Increased pumping was specified at various combined rates for a period of 44 years. In addition, augmented pumping from wells owned by Grand Prairie Water Users Association, located about 2 miles from the nearest Cabot WaterWorks wells, was added to the model beginning in 2007 and continuing through to the end of 2049 in 10 of the 16 scenarios analyzed. Eight of the scenarios included reductions in pumping rates in model cells corresponding to either the Grand Prairie Water Users Association wells or to wells contained within the Grand Prairie Area Demonstration Project. Drawdown at the end of 44 years of pumping at 4.8 million gallons per day from the Cabot WaterWorks wells ranged from 15 to 25 feet in the three model cells; pumping at 8 million gallons per day resulted in water-level drawdown ranging from about 15 to 40 feet. Water levels in those cells showed no indication of leveling out at the end of the simulation period, indicating non-steady-state conditions after 44 years of pumping. From one to four new dry cells occurred in each of the scenarios by the end of 2049 when compared to a baseline scenario in which pumping was maintained at 2004 rates, even in scenarios with reduced pumping in the Grand Prairie Area Demonstration Project; however, reduced pumping produced cells that were no longer dry when compared to the baseline scenario at the end of 2049. Saturated thickness at the end of 2049 in the three Cabot WaterWorks wells ranged from about 52 to 68.5 feet for pumping rates of 4.8 million gallons per day, and from about 38 to 64 feet for pumping rates of 8 million gallons per day, the latter causing water levels to fall below half the aquifer thickness in the most heavily pumped of the three cells. analysis of the effects of withdrawals to be performed prior to the issuance of a water-withdrawal permit. To address this need and to improve the understanding of the effect of municipal users on ground-water flow in this type of aquifer, the USGS in cooperation with CWW used the north alluvial model of to simulate ground-water flow and water-level changes for the period 1918-2049 for various ground-water pumping scenarios. The purpose of this report is to compare simulated water levels derived from the north alluvial model with and without several additional ground-water withdrawal rates from several 1-square-mile model cells pumped for a period of 44 years simulated to begin in 2007 (table ). These cells include pumping from the Grand Prairie Water Users Association (GPWUA), the Grand Prairie Area Demonstration project (GPADP), as well as CWW. GPWUA plans to increase pumping and has proposed the construction of an additional well near its current well field. The GPADP is a project, under the management of the ANRC and U.S. Army Corps of Engineers, designed to route water from the White River to water users in Arkansas, Monroe, Prairie, and eastern Lonoke counties to supplement ground-water demand. By supplying this supplemental water, it is anticipated that wateruse pressure on the alluvial aquifer will decrease. Drawdown and resulting saturated thickness of the alluvial aquifer after 44 years of pumping are presented for a radial distance of about 20 miles from the pumped model cells located in eastern Lonoke County. The study area includes Lonoke, Prairie, Arkansas, White, and Jefferson Counties, all of which have been designated as Critical Ground-Water Areas by the ANRC (fig. ). Information in this report can be used by water managers to evaluate simulated effects of additional ground-water withdrawals on the ground-water resource. Because alluvial aquifers commonly provide sources of water for municipal, industrial, and agricultural use, it is important to improve the understanding of ground-water flow in this type of aquifer. Additionally, the types of scenarios analyzed using the ground-water flow model in this report demonstrate the utility of the approach for assessing complex ground-water flow systems and pumping distributions.
For more information on the USGS-the Federal source for science about the Earth, its natural and ... more For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit or call 1-888-ASK-USGS. For an overview of USGS information products, including maps, imagery, and publications, visit To order this and other USGS information products, visit Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.
of slug-test results for several wells at Franklin Lake playa 23 3. Porosity determination for co... more of slug-test results for several wells at Franklin Lake playa 23 3. Porosity determination for core samples from hole EC-2, piece 4 ..
A Program to Calculate Aquifer Transmissivity from Specific‐Capacity Data for Programmable Calculators
Groundwater, 1985
. A program that will calculate aquifer transmissivity from the specific capacity of a well has b... more . A program that will calculate aquifer transmissivity from the specific capacity of a well has been developed for handheld programmable calculators. The program extends the approach of Theis and others (1963) beyond the visual graphical interpolation of transmissivity values from type curves and solves directly a nonlinear equation for transmissivity, using a modified Regula Falsi solution algorithm. The program eliminates errors associated with visual interpolation of transmissivities obtained from type curves, especially for values of small transmissivities, and provides a quick and portable method of obtaining transmissivity values onsite.
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