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At least 829 records · Page 46Linked to original sources
USGS2021

Transport and speciation of uranium in groundwater-surface water systems impacted by legacy milling operations

Growing worldwide concern over uranium contamination of groundwater resources has placed an emphasis on understanding uranium transport dynamics and potential toxicity in groundwater-surface water systems. In this study, we utilized novel in-situ sampling methods to establish the location and magnitude of contaminated groundwater entry into a receiving surface water environment, and to investigate the speciation and potential bioavailability of uranium in groundwater and surface water. Streambed temperature mapping successfully identified the location of groundwater entry to the Little Wind River, downgradient from the former Riverton uranium mill site, Wyoming, USA. Diffusive equilibrium in thin-film (DET) samplers further constrained the groundwater plume and established sediment pore water solute concentrations and patterns. In this system, evidence is presented for attenuation of uranium-rich groundwater in the shallow sediments where surface water and groundwater interaction occurs. Surface water grab and DET sampling successfully detected an increase in river uranium concentrations where the groundwater plume enters the Little Wind River; however, concentrations remained below environmental guideline levels. Uranium speciation was investigated using diffusive gradients in thin-film (DGT) samplers and geochemical speciation modelling. Together, these investigations indicate uranium may have limited bioavailability to organisms in the Little Wind River and, possibly, in other similar sites in the western U.S.A. This could be due to ion competition effects or the presence of non- or partially labile uranium complexes. Development of methods to establish the location of contaminated (uranium) groundwater entry to surface water environments, and the potential effects on ecosystems, is crucial to develop both site-specific and general conceptual models of uranium behavior and potential toxicity in affected ground and surface water environments.

Wyoming↗
USGS1972

Records of water-level measurements in wells in the Oklahoma panhandle, 1971-72

Investigations of the ground-water resources of the Oklahoma panhandle by the U.S. Geological Survey in cooperation with the Oklahoma Water Resources Board includes collection of water-level records; the systematic collection of these records began in 1937. Records of many shallow wells were compiled in 1937 and periodic measurements were made in a few wells until 1966. Owing to the heavy development of irrigation during the 1960's (fig. 1) an expanded network of observation wells established in Texas County in 1966 and in Beaver and Cimarron Counties in 1967; measurement of water levels have been made on an annual basis since those times. This report contains water-level records for the period 1971-72 and the water-level change for the period 1966-72 in Texas County, and for the period 1967-72 in Beaver and Cimarron Counties. At the present time (1972) the annual observation-well network includes 521 wells, of which 97 are in Beaver County, 203 are in Cimarron County, and 221 are in Texas County. These data provide an index to available ground-water supplies; they will be useful in planning and studying water resources development; and they will serve as a framework of data for the detailed hydrologic investigation now in progress in the panhandle.

Oklahoma↗
USGS1994

Hydrologic data for the alluvium and terrace deposits of the Cimarron River from Freedom to Guthrie, Oklahoma

Ground water in the Quaternary alluvium and terrace deposits associated with the Cimarron River in northwestern Oklahoma is used extensively for irrigation, municipal, stock, and domestic supplies. The data in this report were collected as part of an investigation to provide State water managers with the quantitative knowledge necessary to manage the ground-water resource effectively. The investigation was conducted by the U.S. Geological Survey in cooperation with the Oklahoma Geological Survey. The information presented in this report include data collected in the field from 1985 through 1989, and unpublished data compiled from files of the U.S. Geological Survey and the Oklahoma Water Resources Board. Data include well and test-bole records, consisting of ground-water levels, depth of wells, principal aquifer, and primary use of water. Water levels include continuous, daily, monthly, and periodic measure- ments for selected wells. Concentrations of common chemical constituents, selected trace elements, organic analyses, and tritium analyses of water samples from wells completed in the Cimarron River alluvium and terrace deposits and Permian geologic units are reported. Winter and summer base-flow discharge measurements of the Cimarron River and its Tributaries are presented together with water-quality data from the measuring sites. Continuous water-level and precipitation-gage data are presented graphically. Locations of data- collection sites are shown on plates.

Open-File Report↗
USGS1961

Records of wells, water levels, and chemical quality of ground water in the French Prairie-Mission Bottom area, northern Willamette Valley, Oregon

An investigation of the ground-water resources of the northern Willamette Valley was begun in 1960 as a cooperative program between the Ground Water Branch, U.S. Geological Survey, and the Oregon State Engineer. The northern Willamette Valley area is one of the fastest growing areas of ground-water use within the state. The purpose of the investigation is to obtain an understanding of the availability, movement, and chemical quality of the ground-water resources of the area. This information is needed to attain an optimum development of the ground-water resources of the area and to aid in the prevention of problems of overdevelopment and pollution. The first phase of the program was the collection of well records, water level records, and chemical quality data in the central part of this area, which is known as the French Prairie-Mission Bottom area. The records collected in this phase of the study are essential in the preparation of an interpretive report describing the occurrence and movement of ground-water in the French Prairie-Mission Bottom area. These records, which will not be included in the interpretive report that is being prepared at this time, are being made available in this publication to aid in the location and the development of the ground-water resources of the area, and to serve as a supplement to the forthcoming interpretive report.

Oregon↗
USGS1996

Covalent binding of aniline to humic substances. 1. Kinetic studies

The reaction kinetics for the covalent binding of aniline with reconstituted IHSS humic and fulvic acids, unfractionated DOM isolated from Suwannee River water, and whole samples of Suwannee River water have been investigated. The reaction kinetics in each of these systems can be adequately described by a simple second-order rate expression. The effect of varying the initial concentration of aniline on reaction kinetics suggested that approximately 10% of the covalent binding sites associated with Suwannee River fulvic acid are highly reactive sites that are quickly saturated. Based on the kinetic parameters determined for the binding of aniline with the Suwannee River fulvic and humic acid isolates, it was estimated that 50% of the aniline concentration decrease in a Suwannee River water sample could be attributed to reaction with the fulvic and humic acid components of the whole water sample. Studies with Suwannee River fulvic acid demonstrated that the rate of binding decreased with decreasing pH, which parallels the decrease in the effective concentration of the neutral form, or reactive nucleophilic species of aniline. The covalent binding of aniline with Suwannee River fulvic acid was inhibited by prior treatment of the fulvic acid with hydrogen sulfide, sodium borohydride, or hydroxylamine. These observations are consistent with a reaction pathway involving nucleophilic addition of aniline to carbonyl moieties present in the fulvic acid.

Environmental Science & Technology↗
USGS1950

Memorandum on possibility of developing ground water for irrigation along Toc Chinlin Wash near Emmanuel Mission, Navajo Indian Reservation, Apache County, Arizona

On November 21, 1949, the writers accompanied Mr. Chester Wilson of the Navajo Service Water Supply Office to Emmanuel Mission, Arizona, to investigate the adequacy of ground-water supplies adequate for irrigation along Toc Chinlin Wash. The investigation was made as part of the ground-water studies of the Geological Survey on the Navajo Indiana Reservation.

Arizona↗
USGS2002

Epidemiological investigation of infectious hematopoietic necrosis virus in salt water net-pen reared Atlantic salmon in British Columbia, Canada

An epidemiological study of infectious hematopoietic necrosis viral disease (IHN) in farmed Atlantic salmon in British Columbia was conducted to better understand the management of this disease. The study consisted of a descriptive retrospective investigation of 18 IHN outbreaks on farms between 1992 and 1996, and a prospective surveillance program for the viral disease, after an area management plan was implemented to reduce the viral load around farms and farm-to-farm spread of the virus. The crude cumulative mortality associated with IHNV in Atlantic salmon was high (average 47%), and outbreaks lasted 5.8 months on average. On the two farms where the virus was detected during the surveillance program, IHNV was confirmed in all pens within 1 month. On two of three sites where fish were kept on farms after the initial disease outbreak subsided, IHN reoccurred within 30 weeks. The presentation of IHNV on farms, the spatial and temporal patterns of the outbreaks between 1992 and 1996, and the genetic similarity between isolates collected from nine outbreaks spanning a 5-year period, all supported the plausibility of farm-to-farm spread of the virus. Furthermore, the marked decrease in the incidence rate of IHN in farmed Atlantic salmon after the implementation of an area-based management plan aimed at reducing farm-to-farm spread of the virus also supported this hypothesis. Although the source of IHNV for the index case was not determined in this study, secondary spread of the virus between farms via management practices, such as movement of fish, co-habiting naı̈ve fish with survivors of the viral disease, and movement of equipment, likely accounted for some farm outbreaks. This suggested that many cases of IHN may be preventable using good on-farm biosecurity.

Aquaculture↗
USGS2021

Using heat to trace vertical water fluxes in sediment experiencing concurrent tidal pumping and groundwater discharge

Heat has been widely applied to trace groundwater‐surface water exchanges in inland environments, but it is infrequently applied in coastal sediment where head oscillations induce periodicity in water flux magnitude/direction and heat advection. This complicates interpretation of temperatures to estimate water fluxes. We investigate the convolution of thermal and hydraulic signals to assess the viability of using heat as a tracer in environments with tidal head oscillations superimposed on submarine groundwater discharge. We first generate sediment temperature and head time series for conditions ranging from no tide to mega‐tidal using a numerical model (SUTRA) forced with periodic temperature and tidal head signals. We then analyze these synthetic temperature time series using heat tracing software (VFLUX2 and 1DTempPro) to evaluate if conventional terrestrial approaches to infer fluxes from temperatures are applicable for coastal settings. We consider high‐frequency water flux variability within a tidal signal and averaged over tidal signals. Results show that VFLUX2 analytical methods reasonably estimated the mean discharge fluxes in most cases but could not reproduce the flux variability within tidal cycles. The model results further reveal that high‐frequency time series of water fluxes varying in magnitude and direction can be accurately estimated if paired temperature and hydraulic head are analyzed using numerical models (e.g. 1DTempPro) that consider both dynamic hydraulic gradients and thermal signals. These results point to the opportunity to incorporate pressure sensors within heat tracing instrumentation to better assess sub‐daily flux oscillations and associated reactive processes.

Water Resources Research↗
USGS2023

Nonsalmonid gas bubble trauma investigations

From 2020 to 2023, a new spill program was implemented to aid the downstream passage of juvenile salmonids at mainstem dams on the Snake and Columbia rivers. Under this program, the total dissolved gas (TDG) cap was increased to 125% and monitoring of nonsalmonids for gas bubble trauma (GBT) became a requirement. The primary objective of this work and report was to measure the incidence and severity of GBT in nonsalmonids resulting from increased juvenile salmonid passage spill and associated levels of TDG during the spring spill period in 2023. Nonsalmonids were collected downstream from Bonneville, McNary, Ice Harbor, and Lower Granite dams and examined for the incidence and severity of GBT in 2023. Fish were collected at each location weekly (3 April to 20 June) during the spring spill period by backpack electrofishing and beach seining. Washington and Oregon State water quality agencies established minimum and target sample sizes for monitoring, but the minimum sample size of 50 fish and target sample size of 100 fish were not met in all weeks at individual projects due to high water flows and resulting low fish collections. Collected fish were examined for GBT according to the criteria and protocol established for the regional smolt monitoring program (SMP). TDG levels were often high relative to the 10-year average. GBT incidence rates and severity (according to SMP criteria) were low to moderate in most weeks. We found no apparent relationship between GBT incidence and TDG due to exposure history and interspecies susceptibility to elevated TDG that could not be quantified. GBT incidence rates exceeded the 15% threshold on two occasions below Ice Harbor Dam, triggering a reduction in spill under the State water quality standards. In the weeks immediately following the spill reductions, GBT incidence was zero or relatively low at this location. Sculpin (genus Cottus ) was the main species collected at all locations. As in past years, we did find GBT in non-SMP protocol areas, particularly in sculpin. The variability in GBT incidence rates is likely due to variability in environmental conditions, fish exposure history to TDG, and species sensitivity to TDG. Many of the species encountered in shallow shoreline habitats rear for extended times and probably do not seek the water depths that would help them reduce the effects of exposure to elevated TDG through depth compensation. Limited systematic sampling of TDG in the tailraces of each project showed that TDG can vary spatially within the tailrace and with percentage of water spilled. We investigated GBT progression and mortality in sculpin and threespine stickleback ( Gasterosteus aculeatus ) in laboratory experiments (Chapter Two of this report). Fish were tested at 120%, 125%, and 130% TDG. We found that sculpin are more sensitive to TDG than stickleback and that GBT and associated mortality progress faster in sculpin than in stickleback. GBT prevalence and severity increased through time at all TDG levels tested, but relationships between severity and exposure time were weak or nonexistent. GBT and mortality progressed more rapidly as TDG increased in both species. The SMP criteria used to rank GBT did not fully capture the incidence and severity of GBT in sculpin and stickleback compared to using criteria based on all areas of the fish. The lateral line, body, dorsal fin, and pectoral fins were common locations of GBT in sculpin at 120 and 125% TDG, but signs were more prevalent in all areas at 130% TDG. In stickleback, GBT was most common on the head and body at all TDG levels tested. Positive buoyancy of fish with severe GBT was observed in both species and may have consequences for similarly impaired fish in the wild. The proximate cause of GBT-related death in sculpin and stickleback was bubbles in the gills and heart, but unlike in other species, bubbles appeared rapidly just before the point of death. Our results help fill the information void GBT progression and mortality for sculpin and stickleback.

Oregon, Washington↗
USGS2003

Relation of age-0 largemouth bass abundance to hydrilla coverage and water level at Lochloosa and Orange Lakes, Florida

Changes in electrofishing catch per hour (CPH) of age-0 largemouth bass Micropterus salmoides were examined in relation to aquatic macrophytes and seasonal water elevation at Lochloosa and Orange lakes, Florida, during the 1990s. At Lochloosa Lake, stepwise multiple regression revealed a significant positive relationship between the mean CPH of age-0 largemouth bass and the percentage of areal coverage by hydrilla Hydrilla verticallata. At Orange Lake, mean CPH was directly associated with the percentage of areal coverage by hydrilla and inversely related to summer water levels. Thus, the influence of vegetation on age-0 largemouth bass abundance was similar at both lakes, but the effects of water levels were not. Further investigations into the effects of fluctuations in water levels on age-0 largemouth bass in natural lakes are needed.

North American Journal of Fisheries Management↗
USGS1965

Ground-water levels in observation wells in Oklahoma, 1963-64

The investigation of the ground-water resources of Oklahoma by the U.S. Geological Survey in cooperation with the Oklahoma Water Resources Board includes a continuing program to collect records of water levels in selected observation wells on a systematic basis. These water-level records: (1) provide an index to available ground-water supplies; (2) facilitate the prediction of trends in water levels that will indicate likely changes in storage; (3) aid in the prediction of the base flow of streams; (4) provide information for use in basic research; (5) provide long-time continuous records of fluctuations of water levels in representative wells; and (6) serve as a framework to which other types of hydrologic data my be related. Prior to 1956, measurements of water levels in observation wells in Oklahoma were included in water-supply papers published annually by the U.S. Geological Survey. Beginning with the 1956 calendar year, however, Geological Survey water-level reports will contain only records of a selected network of observation wells, and will be published at 5-year intervals. The first of this series, for the 1956-59 period was published in 1962. This report has been prepared primarily to present water-level records of wells not included in the Federal network. However, for the sake of completeness it includes water-level records of Federal wells that either have been or will be published in water-supply papers since 1955. This report, which contains water-level records for the 2-year period (1963-64), is the third of a series presenting water-level records for all permanent observations wells in Oklahoma. The first report, published in 1963, contains water-level records for the 5-year period of (1956-60). The second report, published in 1964, contains water-level records for the 2-year period (1961-62.) (available as photostat copy only)

Open-File Report↗
USGS1967

Ground-water levels in observation wells in Oklahoma, 1965-66

The investigation of the ground-water resources of Oklahoma by the U.S. Geological Survey in cooperation with the Oklahoma Water Resources Board includes a continuing program to collect records of water levels in selected observation wells on a systematic basis. These water-level records: (1) provide an index to available ground-water supplies; (2) facilitate the prediction of trends in water levels that will indicate likely changes in storage; (3) aid in the prediction of the base flow of streams; (4) provide information for use in basic research; (5) provide long-time continuous records of fluctuations of water levels in representative wells; and (6) serve as a framework to which other types of hydrologic data my be related. Prior to 1956, measurements of water levels in observation wells in Oklahoma were included in water-supply papers published annually by the U.S. Geological Survey. Beginning with the 1956 calendar year, however, Geological Survey water-level reports will contain only records of a selected network of observation wells, and will be published at 5-year intervals. The first of this series, for the 1956-59 period was published in 1962. This report has been prepared primarily to present water-level records of wells not included in the Federal network. However, for the sake of completeness it includes water-level records of Federal wells that either have been or will be published in water-supply papers since 1955. This report, which contains water-level records for the 2-year period (1965-66), is the fourth in a series presenting water-level records for all permanent observations wells in Oklahoma. The first report, published in 1963, contains water-level records for the 2-year period of (1961-62); the second report, published in 1964, contains water-level records for the 2-year period (1961-62); and the third report, published in 1965, contains water-level records for the 2-year period (1963-64). (available as photostat copy only)

Open-File Report↗
USGS2009

Distribution of major anions and trace elements in the unsaturated zone at Franklin Lake Playa, California, USA

The composition of surficial salts formed near dry and drying saline lakes are partly the product of processes active in the unsaturated zone between the ground surface and the water table. These processes were investigated by determining the abundance of water-extractable solutes in sediment from the ground surface to the water table (~2.8 m) beneath Franklin Lake playa, California. Accumulation of solutes in the sediment is attributed to evaporation of aqueous solutions transported upward from the water table through the capillary fringe to an evaporation font that is currently 20-30 cm below the ground surface. Salts in the sediment from 0 to 20 cm depth are depleted in chloride and enriched in carbonate relative to deeper samples. Chloride depletion is most likely a product of selective dissolution by vertical recharge. The entire unsaturated zone contains greater amounts of carbonate than expected for evaporation of ground water and is best explained by preferential dissolution of more soluble salts in recharging precipitation but may also reflect the assimilation of CO2 as carbonate minerals precipitate. Variations in the concentrations of arsenic, molybdenum, tungsten, and uranium in the water-soluble fraction of the sediment are complex and suggest unique geochemical controls on the abundance of each element. The distribution of these trace element abundances indicates the arsenic is the element most likely to accumulate in near-surface salts.

California↗
USGS1985

Data on surface-water quality and quantity, Truckee River system, Nevada and California, 1979-81

Selected hydrologic data were collected between May 1979 and October 1981 at 59 sites on the Truckee River, 10 sites on selected tributaries and smaller diversions, and 9 sites on the Truckee Canal. The data were collected in support of the water-quality and hydrologic investigation components of the Truckee-Carson River-Quality Assessment by the U.S. Geological Survey. This report contains data from: (1) diel and antecedent measurements made in conjunction with four synoptic water-quality studies, (2) analyses of phytoplankton samples to supplement other biological data collected during the synoptic studies, (3) an investigation of surface and intragravel water quality to determine the suitability of the river as a spawning habitat for Lahontan cutthroat trout, (4) 10 water-temperature recorders, (5) 11 dye-tracer studies, (6) 5 gas-tracer reaeration studies, (7) summaries of dye-tracer travel times derived from the dye and reaeration studies, and (8) discharge measurements with associated channel-geometry descriptions at 46 miscellaneous sites on the river, selected tributaries, and the canal. (USGS)

Open-File Report↗
USGS1998

Factors affecting Escherichia coli concentrations at Lake Erie public bathing beaches

The environmental and water-quality factors that affect concentrations of Escherichia coli (E. coli) in water and sediment were investigated at three public bathing beachesEdgewater Park, Villa Angela, and Sims Parkin the Cleveland, Ohio metropolitan area. This study was done to aid in the determination of safe recreational use and to help water- resource managers assess more quickly and accurately the degradation of recreational water quality. Water and lake-bottom sediments were collected and ancillary environmental data were compiled for 41 days from May through September 1997. Water samples were analyzed for E. coli concentrations, suspended sediment concentrations, and turbidity. Lake- bottom sediment samples from the beach area were analyzed for E. coli concentrations and percent dry weight. Concentrations of E. coli were higher and more variable at Sims Park than at Villa Angela or Edgewater Park; concentrations were lowest at Edgewater Park. Time-series plots showed that short-term storage (less than one week) of E. coli in lake-bottom sediments may have occurred, although no evidence for long-term storage was found during the sampling period. E. coli concentrations in water were found to increase with increasing wave height, but the resuspension of E. coli from lake-bottom sediments by wave action could not be adequately assessed; higherwave heights were often associated with the discharge of sewage containing E. coli during or after a rainfall and wastewater-treatment plant overflow. Multiple linear regression (MLR) was used to develop models to predict recreational water quality at the in water. The related variables included turbidity, antecedent rainfall, antecedent weighted rainfall, volumes of wastewater-treatment plant overflows and metered outfalls (composed of storm-water runoff and combined-sewer overflows), a resuspension index, and wave heights. For the beaches in this study, wind speed, wind direction, water temperature, and the prswimmers were not included in the model because they were shown to be statistically unrelated to E. coli concentrations. From the several models developed, one model was chosen that accounted for 58 percent of the variability in E. coli concentrations. The chosen MLR model contained weighted categorical rainfall, beach-specific turbidity, wave height, and terms to correct for the different magnitudes of E. coli concentrations among the three beaches. For 1997, the MLR model predicted the recreational water quality as well as, and in some cases better than, antecedent E. coli concentrations (the current method). The MLR model improved the sensitivity of the prediction and the percentage of correct predictions over the current method; however, the MLR model predictions still erred to a similar degree as the current method with regard to false negatives. A false negative would allow swimming when, in fact, the bathing water standard was exceeded. More work needs to be done to validate the MLR model with data collected during other recreational seasons, especially during a season with a greater frequency and intensity of summer rains. Studies could focus on adding to the MLR model other environmental and water-quality variables that improve the predictive ability of the model. These variables might include concentrations of E. coli in deeper sediments outside the bathing area, the direction of lake currents, site-specific-rainfall amounts, time-of-day information on overflows and metered outfalls, concentrations of E. coli in treated wastewater-treatment plant effluents, and occurrences of sewage-line breaks. Rapid biological or chemical methods for determination of recreational water quality could also be used as variables in model refinements. Possible methods include the use of experimental rapid assay methods for determination of E. coli concentrations or other fecal indicators and the use of chemical tracers for fecal contamination, such as coprostanol (a degradation

Water-Resources Investigations Report↗
USGS1969

Reconnaissance of the ground-water resources of the upper Fremont River valley, Wayne County, Utah

This report presents the results of an investigation of the ground-water resources of the upper Fremont River valley, Utah, which was carried out during the period July 1966-June 1967, by the U.S. Geological Survey in cooperation with the Utah Department of Natural Resources, Division of Water Rights. The purpose of the investigation was to determine: the source, occurrence, availability, approximate quantity, movement, and chemical quality of ground water in the valley; the recharge to and discharge from the ground-water reservoir; the extent and effects of use and development on the ground-water resources; the relation of ground water to streamflow; and if and where additional studies are needed. The report is concerned primarily with ground water in the valley fill and adjacent volcanic rocks and secondarily with the general hydrology of the upper Fremont River valley drainage basin. The field investigation was made mostly during the summer and fall of 1966. Data were collected for 63 wells and 16 springs in the valley. Records for wells and springs are given in table 4; drillers' logs of selected wells are given in table 5, and well locations are shown in figure 5. All the wells (except a few small-discharge wells) and all major springs were visited. The specific conductance of water was determined at most wells and springs; chemical analyses were made of water from selected wells and springs. Conductance data are included in table 4 and chemical analyses are given in table 6. The yield of water from wells and the water levels or artesian pressures were measured or estimated. Water-level measurements were made at monthly intervals 6 at 10 selected wells. Altitudes of the land surface at wells and springs were estimated from topographic maps or by hand leveling or determined by altimeter. Aerial photographs were used in the field to locate wells, boundaries of meadows or cultivated areas, edge of valley fill, and other features.

Utah↗
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↗
USGS2020

Operational global actual evapotranspiration: Development, evaluation, and dissemination

Satellite-based actual evapotranspiration (ETa) is becoming increasingly reliable and available for various water management and agricultural applications from water budget studies to crop performance monitoring. The Operational Simplified Surface Energy Balance (SSEBop) model is currently used by the US Geological Survey (USGS) Famine Early Warning System Network (FEWS NET) to routinely produce and post multitemporal ETa and ETa anomalies online for drought monitoring and early warning purposes. Implementation of the global SSEBop using the Aqua satellite’s Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature and global gridded weather datasets is presented. Evaluation of the SSEBop ETa data using 12 eddy covariance (EC) flux tower sites over six continents indicated reasonable performance in capturing seasonality with a correlation coefficient up to 0.87. However, the modeled ETa seemed to show regional biases whose natures and magnitudes require a comprehensive investigation using complete water budgets and more quality-controlled EC station datasets. While the absolute magnitude of SSEBop ETa would require a one-time bias correction for use in water budget studies to address local or regional conditions, the ETa anomalies can be used without further modifications for drought monitoring. All ETa products are freely available for download from the USGS FEWS NET website.

Article↗