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At least 667 records · Page 37Linked to original sources
USGS1992

Geohydrologic systems in Kansas: Physical framework of the upper aquifer unit in the western interior plains aquifer system

The purpose of this Hydrologic Investigations Atlas is to provide a description of the principal geohydrologic systems in Upper Cambrian through Lower Cretaceous rocks in Kansas. This investigation was made as part of the Central Midwest Regional Aquifer-System Analysis (CMRASA). The CMRASA is one of several major investigations by the U.S. Geological Survey of regional aquifer systems in the United States. These regional investigations are designed to increase knowledge of the flow regime and hydrologic properties of major aquifer systems and to provide quantitative information for the assessment, development, and management water supplies. The CMRASA study area includes all or parts of 10 Central Midwestern States (Jorgensen and Signor, 1981), as shown on the envelope cover. This Hydrologic Investigations Atlas, which consists of a series of nine chapters, presents a description of the physical framework and the geohydrology of principal aquifers and confining systems in Kansas. Chapter D presents maps that show the areal extent, altitude and configuration of the top, and thickness of Mississippian rocks that compose the upper aquifer unit of the Western Interior Plains aquifer system in Kansas, The chapter is limited to the presentation of the physical framework of the upper aquifer unit. The interpretation of the physical framework of the upper aquifer unit is based on selected geophysical and lithologic logs and published maps of stratigraphically equivalent units. Maps indicating the thickness and the altitude and configuration of the top of the upper aquifer unit in the Western Interior Plains aquifer system have been prepared as part of a series of interrelated maps that describe the stratigraphic interval from the Precambrian basement through Lower Cretaceous rocks. A concerted effort was made to ensure that maps of each geohydrologic unit are consistent with the maps of underlying and overlying units. Chapter A of this atlas series (Wolf and others, 1990) describes the relation of principal geohydrologic systems in Kansas and presents a more detailed discussion of the methods and data used to prepare and ensure consistency among the sets of maps.

Kansas↗
USGS2010

Changes in groundwater flow and volatile organic compound concentrations at the Fischer and Porter Superfund Site, Warminster Township, Bucks County, Pennsylvania, 1993-2009

The 38-acre Fischer and Porter Company Superfund Site is in Warminster Township, Bucks County, Pa. Historically, as part of the manufacturing process, trichloroethylene (TCE) degreasers were used for parts cleaning. In 1979, the Bucks County Health Department detected TCE and other volatile organic compounds (VOCs) in water from the Fischer and Porter on-site supply wells and nearby public-supply wells. The Fischer and Porter Site was designated as a Superfund Site and placed on the National Priorities List in September 1983. A 1984 Record of Decision for the site required the Fischer and Porter Company to pump and treat groundwater contaminated by VOCs from three on-site wells at a combined rate of 75 gallons per minute to contain groundwater contamination on the property. Additionally, the Record of Decision recognized the need for treatment of the water from two nearby privately owned supply wells operated by the Warminster Heights Home Ownership Association. In 2004, the Warminster Heights Home Ownership Association sold its water distribution system, and both wells were taken out of service. The report describes changes in groundwater levels and contaminant concentrations and migration caused by the shutdown of the Warminster Heights supply wells and presents a delineation of the off-site groundwater-contamination plume. The U.S. Geological Survey (USGS) conducted this study (2006-09) in cooperation with the U.S. Environmental Protection Agency (USEPA). The Fischer and Porter Site and surrounding area are underlain by sedimentary rocks of the Stockton Formation of Late Triassic age. The rocks are chiefly interbedded arkosic sandstone and siltstone. The Stockton aquifer system is comprised of a series of gently dipping lithologic units with different hydraulic properties. A three-dimensional lithostratigraphic model was developed for the site on the basis of rock cores and borehole geophysical logs. The model was simplified by combining individual lithologic units into generalized units representing upward fining sedimentary cycles capped by a siltstone bed. These cycles were labeled units 1 through 8 and are called stratigraphic units in this report. Groundwater in the unweathered zone mainly moves through a network of interconnecting secondary openings--bedding-plane fractures and joints. Groundwater generally is unconfined in the shallower part of the aquifer and confined or semiconfined in the deeper part of the aquifer. The migration of VOCs from the Fischer and Porter Site source area is influenced by geologic and hydrologic controls. The hydrologic controls have changed with time. Stratigraphic units 2 and 3 crop out beneath the former Fischer and Porter plant. VOCs originating at the plant source area entered these stratigraphic units and moved downdip to the northwest. When the wells at and in the vicinity of the site were initially sampled in 1979-80, three public-supply wells (BK-366, BK-367, MG-946) and three industrial-supply wells (BK-368, BK-370, and BK-371) were pumping. Groundwater contaminated with VOCs flowed downdip and then northeast along strike toward well BK-366, downdip toward well BK-368, and downdip and then west along strike toward well MG-946. The long axis of the TCE plume is oriented about N. 18° W. in the direction of dip. In 1979-80, the leading edge of the plume was about 3,500 feet wide. With the cessation of pumping of the supply wells in 2004, the size of the plume has decreased. In 2007-09, the plume was approximately 2,000 feet long and 2,000 feet wide at the leading edge. On the western side of the site, TCE and tetrachloroethylene (PCE) appear to be moving downdip though stratigraphic unit 3. The downdip extent of TCE and PCE migration extended approximately 550 feet off-site to the northwest and 750 feet off-site to the north. TCE concentrations in water samples from wells at the western site boundary increased from 1996 to 2007. On the northern side of the site, TCE and PCE appeared to be moving downward and laterally though stratigraphic units 2, 3, and 4. Groundwater-flow directions shifted to the northwest in the intermediate and deep zones after cessation of pumping of well BK-366 in 2004. The shutdown of the Warminster Heights wells had little effect on the direction of groundwater flow in the shallow zone. In 2007, TCE concentrations measured in water samples from the three remediation wells by the USGS ranged from less than 340 to 3,000 µg/L, and PCE concentrations ranged from less than 8.4 to 51 µg/L. TCE concentrations in water samples from the source-area remediation wells have decreased with time but remain highly variable. From 2001 to 2008, the TCE and PCE concentrations in water samples from wells BK-370 and BK-371 showed a linear decreasing trend. TCE and PCE concentrations in water samples from well BK-1324 showed an exponentially decreasing trend. In 2007, TCE concentrations measured in water samples from shallow wells ranged from less than 0.1 to 14,000 µg/L, and PCE concentrations ranged from less than 0.1 to 340 µg/L. The TCE and PCE plumes followed the hydraulic gradient in the shallow zone. In 2007, TCE concentrations measured in water samples from on-site intermediate-depth monitor wells ranged from less than 0.1 to 500 µg/L, and PCE concentrations ranged from 1.3 to 28 µg/L. The TCE and PCE plumes followed the hydraulic gradient in the intermediate zone and extended off-site to the north and northwest of the source area. Concentrations of TCE in water samples north and west of the source area increased from 1996 to 2007. In 2007, the TCE concentrations measured in water samples from on-site monitor wells in the deep zone ranged from 1.1 to 86 µg/L, and PCE concentrations ranged from less than 0.1 to 8.4 µg/L. The TCE and PCE plumes generally followed the hydraulic gradient in the deep zone and extended off-site to the northwest of the source area. In general, concentrations of TCE in water samples from monitor wells outside the source area increased between 1996 and 2005 and decreased between 2005 and 2007; concentrations were less in 2007 than in 1996.

Pennsylvania↗
USGS2020

Runoff sensitivity to snow depletion curve representation within a continental scale hydrologic model

The spatial variability of snow water equivalent (SWE) can exert a strong influence on the timing and magnitude of snowmelt delivery to a watershed. Therefore, the representation of subgrid or subwatershed snow variability in hydrologic models is important for accurately simulating snowmelt dynamics and runoff response. The U.S. Geological Survey National Hydrologic Model infrastructure with the Precipitation-Runoff Modeling System (NHM-PRMS) represents the subgrid variability of SWE with snow depletion curves (SDCs), which relate snow-covered area to watershed-average SWE during the snowmelt period. The main objective of this research was to evaluate the sensitivity of simulated runoff to SDC representation within the NHM-PRMS across the continental United States (CONUS). SDCs for the model experiment were derived assuming a range of SWE coefficient of variation (CV) values and a lognormal probability distribution function. The NHM-PRMS was simulated at a daily time step for each SDC over a 14-year period. Results highlight that increasing the subgrid snow variability (by changing the SDC) resulted in a consistently slower snowmelt rate and longer snowmelt duration when averaged across the hydrologic response unit scale. Simulated runoff was also found to be sensitive to SDC representation, as increases in the subgrid SWE CV by 1.0 resulted in decreases in runoff ratio by as much as 12 percent in snow-dominated regions of the CONUS. Simulated decreases in runoff associated with slower snowmelt rates were approximately inversely proportional to increases in simulated evapotranspiration. High snow persistence and peak SWE:annual precipitation combined with a water limited dryness index were associated with the greatest runoff sensitivity to changing snowmelt. Results from this study highlight the importance of carefully parameterizing SDCs for hydrologic modeling. Furthermore, improving model representation of snowmelt input variability and its relation to runoff generation processes is shown to be an important consideration for future modeling applications.

Hydrological Processes↗
USGS1968

Water data for metropolitan areas: A summary of data from 222 areas in the United States

Expansion of metropolitan areas poses persistent problems in management of the hydrologic environment. Adequate hydrologic data are prerequisite to proper planning and engineering design of urban environments. Some such data are available and are tabulated for each Standard Metropolitan Statistical Area in the United States. Information for each area consists of (1) data on size and population, (2) a short statement of the hydrology of the area, (3) a summary of current data-collection activities in the area, (4) a listing of current U.S. Geological Survey investigational projects in the area, and (5) a short listing of reports relating to the hydrology of the area.

Water Supply Paper↗
USGS2018

Findings and lessons learned from the assessment of the Mexico-United States transboundary San Pedro and Santa Cruz aquifers: The utility of social science in applied hydrologic research

Study Region This study region encompasses the Transboundary San Pedro and Santa Cruz aquifers which are shared between the states of Sonora (Mexico) and Arizona (US). Special regional considerations include a semi-arid climate, basin-fill aquifers with predominantly montane recharge areas, economic drivers in the mining, trade, and military sectors, groundwater-dependent cities with expanding cones of depression, interbasin groundwater transfers, ground- and surface-water contamination, and protected aquatic and riparian habitats that act as significant migration corridors for hundreds of species, including some that are threatened and endangered. Study Focus We focus on lessons learned from the hydrologic assessment of the Transboundary San Pedro and Santa Cruz aquifers. We conducted the work, in two phases: (1) laying the groundwork and (2) implementation. The “laying the groundwork” phase consisted of binational meetings with stakeholders and key actors (agencies and individuals), and the development of an understanding of the physical, institutional, historical, and socio-political context. This led to signing of the binational Transboundary Aquifer Assessment Program (TAAP) agreement in 2009 and detailed the process for cooperation and coordination in the assessment of shared aquifers. The implementation phase began with an agreement to proceed with the study of four “focus” aquifers (Santa Cruz, San Pedro, Mesilla (Conejos-Médanos in Mexico), and Hueco Bolson (Bolsón del Hueco in Mexico)) and development of associated technical teams. Though we do include a brief discussion of the lessons learned from the physical science portion of the study, the results have been described and published elsewhere. The bulk of the paper instead focuses on the findings and lessons learned from the integration of social-science perspectives into a largely physical-science based program, since there is a growing recognition of the need for this type of approach especially in the management and assessment of transboundary aquifers. New Hydrological Insights for the Region The Sonora-Arizona effort succeeded because both countries were adequately represented, and because of flexibility of skills and ability of teams comprising both university and government scientists. Teams included social and earth scientists. Including the social sciences was critical to research design and implementation, and to addressing the cultural, institutional, and socio-political contexts of transboundary aquifer assessment. Significant components of the continuing implementation phase include strategic planning, data compilation and analysis, cross-border integration of datasets, geophysical and geochemical surveys, and internal, peer, and stakeholder engagement.

Arizona, Sonora↗
USGS1973

Fluvial-sediment discharge to the oceans from the conterminous United States

This report is a contribution to the UNESCO-sponsored project of the International Hydrological Decade called the World Water Balance. Annual fluvial-sediment discharge from the conterminous United States averages 491,449,600 short tons, of which 14,204,000 is discharged to the Atlantic Ocean, 378,179,000 to the Gulf of Mexico, and 99,066,600 to the Pacific Ocean. Data from 27 drainage areas were used to estimate the average annual discharge, yield, and concentration of fluvial sediment. The data may be used to extrapolate part of the total world sediment yield to the marine environment.

Circular↗
USGS2019

Simulation of water availability in the Southeastern United States for historical and potential future climate and land-cover conditions

A study was conducted by the U.S. Geological Survey (USGS), in cooperation with the Gulf Coastal Plains and Ozarks Landscape Conservation Cooperative (GCPO LCC) and the Department of the Interior Southeast Climate Adaptation Science Center, to evaluate the hydrologic response of a daily time step hydrologic model to historical observations and projections of potential climate and land-cover change for the period 1952–2099. The model simulations were used to compute the potential changes in hydrologic response and streamflow statistics across the Southeastern United States, using historical observations of climate and streamflow. Thirteen downscaled general circulation models with four representative concentration pathways were used to represent a range of potential future changes in climate (a total of 45 future simulations) from the Coupled Model Intercomparison Project Phase 5. The streamflow statistics were selected to describe streamflow conditions that may be most useful in defining the suitability for each river or stream to support sustaining populations of priority aquatic species across the GCPO LCC. An application of the Precipitation-Runoff Modeling System (included as part of the USGS National Hydrologic Model) was used to develop the hydrologic simulations. The results showed increases in air temperature across the study area, with the highest increases occurring in the northern part of the study area during July to September. The results showed a mix of increases and decreases in precipitation accumulation across the study area and across seasons, with decreases in precipitation accumulation across all seasons for the southwestern part of the study area. Actual evapotranspiration decreased for the southeastern part of the study area and increased for the northwestern part of the study area. The results showed general decreases in runoff across the study area, with increases in runoff in areas surrounding large metropolitan regions where potential future increases in impervious area occur. Results from a statistical analysis (Kolmogorov-Smirnov test) showed that the downscaled general circulation models generally have more skill in producing historical streamflow statistics in the duration and magnitude categories and less skill in producing historical streamflow statistics in the frequency, rate of change, and timing categories for this study area. The potential changes in the streamflow statistics and the results of the Kolmogorov-Smirnov test are available through the GCPO LCC Conservation Planning Atlas, an online science-based mapping platform built specifically for land managers and planners.

Alabama, Arkansas, Florida, Georgia, Illinois, Kan↗
USGS1992

Geohydrologic systems in Kansas; physical framework of the confining unit in the Western Interior Plains aquifer system

The purpose of this Hydrologic Investigations Atlas is to provide a description of the geohydrologic systems in Upper Cambrian through Lower Cretaceous rocks in Kansas. This investigation was made as part of the Central Midwest Regional Aquifer-System Analysis (CMRASA). The CMRASA is one of several major investigations by the U.S. Geological Survey of regional aquifer systems in the United States. These regional investigations are designed to increase knowledge of the flow regime and hydrologic properties of major aquifer systems and to provide quantitative information for the assessment, development, and management of water supplies. The CMRASA study area includes all or parts of 10 Central Midwestern States (Jorgensen and Signor, 1981), as shown on the envelope cover.

Hydrologic Atlas↗
USGS2017

Description of chronostratigraphic units preserved as channel deposits and geomorphic processes following a basin-scale disturbance by a wildfire in Colorado

The consequence of a 1996 wildfire disturbance and a subsequent high-intensity summer convective rain storm (about 110 millimeters per hour) was the deposition of a sediment superslug in the Spring Creek basin (26.8 square kilometers) of the Front Range Mountains in Colorado. Spring Creek is a tributary to the South Platte River upstream from Strontia Springs Reservoir, which supplies domestic water for the cities of Denver and Aurora. Changes in a superslug were monitored over the course of 18 years (1996–2014) by repeat surveys at 18 channel cross sections spaced at nearly equal intervals along a 1,500-meter study reach and by a time series of photographs of each cross section. Surveys were not repeated at regular time intervals but after major changes caused by different geomorphic processes. The focus of this long-term study was to understand the evolution and internal alluvial architecture of chronostratigraphic units (defined as the volume of sediment deposited between two successive surveys), and the preservation or storage of these units in the superslug. The data are presented as a series of 18 narratives (one for each cross section) that summarize the changes, illustrate these changes with photographs, and provide a preservation plot showing the amount of each chronostratigraphic unit still remaining in June 2014. The most significant hydrologic change after the wildfire was an exponential decrease in peak discharge of flash floods caused by summer convective rain storms. In response to these hydrologic changes, all 18 locations went through an aggradation phase, an incision phase, and finally a stabilization phase. However, the architecture of the chronostratigraphic units differs from cross section to cross section, and units are characterized by either a laminar, fragmented, or hybrid alluvial architecture. In response to the decrease in peak-flood discharge and the increase in hillslope and riparian vegetation, Spring Creek abandoned many of the nearly horizontal erosional and depositional surfaces and left a landscape consisting of a series of cut-and-fill terraces as a legacy of this wildfire disturbance.

Colorado↗
USGS2007

Relation between stream-water quality and geohydrology during base-flow conditions, Roberts creek watershed, Clayton County, Iowa

An investigation to determine the relation between stream water quality and geohydrology in the Roberts Creek watershed, Clayton County, Iowa, was conducted during selected base-flow periods in 1988-90. Discharge measurements were made and water samples collected for analyses of nutrients and selected herbicides in 19 subbasins along the main stem and tributaries of Roberts Creek. The areal extent of unconsolidated and bedrock units subcropping in each subbasin was quantified. The hydrologic data were correlated statistically with the geologic data to determine relations. Roberts Creek generally gained water and had larger nitrogen concentrations in subbasins in which loess and alluvial material were underlain primarily by low-permeability till and shale units. Roberts Creek generally lost water and had lower nitrate concentrations in subbasins with subcropping karstic units. Nitrogen concentrations decreased in streams underlain by the karstic units because the nitrogen removed by biological processes was not replaced by ground-water inflow. Seepage from Roberts Creek to ground water in areas of subcropping karstic carbonate rocks reduced the flow, which reduced the velocity, causing increased residence time of water in the stream. The additional residence time may allow additional time for biological processes to remove nitrogen from solution. There was no significant relation between dissolved orthophosphate or atrazine and the underlying geology.

Iowa↗
USGS1974

Streamflow measurement network review for hydroelectric power applications in Brazil

This review of selected segments of the stream-gaging network of Brazil was undertaken by the writer in March and April, 1973, pursuant to an agreement between Companhia de Pesquisa de Recursos Minerais (CPRM) and Centrais Eletricas Brasileiras S.A. (ELETROBRAS) as a part of the cooperative program of the U.S. Geological Survey (USGS) and CPRM under the auspices of the Ministerio das Minas e Energia (MME) and the U.S. Agency for International Development (USAID). Its primary purpose is to provide an evaluation of the adequacy of streamflow data on streams which are being considered for or are already being utilized for hydroelectric power sources. Some comments are included pertaining to the general coverage hydrologic network. These comments were generated by the examination of the streamflow data useful for power purposes because all gaging stations form a part of the total network for hydrologic investigations. Present plans are that the entire network will eventually be operated by or under the jurisdiction of the MME through the Departamento National de Aguas e Energia Eletrica (DNAEE). Brazil is a large country, larger than the conterminous United States, and it has been engaged in hydrologic investigations for more than 50 years. The network has been maintained by Federal agencies, State agencies, power companies, and consulting firms and until recently no organizational mechanism existed to coordinate the various activities or to establish uniform standards of data collection, computation, and publication. It is estimated that stage and/or discharge data have been collected at 2,500 or more sites in Brazil. Because there has been no centralized publication system, it has not been possible to locate with assurance all measurement sites or to ascertain precisely the types and quality of the data collected or available. For these reasons the suggestions outlined in this report are expected to be modified on the basis of local need and site information, which may not have been evident at the time of the review. For example, specific suggestions have been made to discontinue some stations which appear superfluous or which essentially duplicate other stations. In other instances additions to the network have been proposed. There may be reasons for the continued operation of a given station which cannot be discerned from the available literature. Also coverage may have been established in an area but the evidence has not yet appeared in print. DEAEE is currently (1973) working diligently to overcome a backlog of data computation and publication. Brazil is currently developing at a rapid rate with electric power demands increasing at a 12% annually, a reflection of the tremendous growth of the economy. With this rate of increase likely to continue for the foreseable future, it goes without saying that hydrologic information needed tomorrow must be collected today.

Open-File Report↗
USGS2011

Digital hydrologic networks supporting applications related to spatially referenced regression modeling

Digital hydrologic networks depicting surface-water pathways and their associated drainage catchments provide a key component to hydrologic analysis and modeling. Collectively, they form common spatial units that can be used to frame the descriptions of aquatic and watershed processes. In addition, they provide the ability to simulate and route the movement of water and associated constituents throughout the landscape. Digital hydrologic networks have evolved from derivatives of mapping products to detailed, interconnected, spatially referenced networks of water pathways, drainage areas, and stream and watershed characteristics. These properties are important because they enhance the ability to spatially evaluate factors that affect the sources and transport of water-quality constituents at various scales. SPAtially Referenced Regressions On Watershed attributes (SPARROW), a process-based ⁄ statistical model, relies on a digital hydrologic network in order to establish relations between quantities of monitored contaminant flux, contaminant sources, and the associated physical characteristics affecting contaminant transport. Digital hydrologic networks modified from the River Reach File (RF1) and National Hydrography Dataset (NHD) geospatial datasets provided frameworks for SPARROW in six regions of the conterminous United States. In addition, characteristics of the modified RF1 were used to update estimates of mean-annual streamflow. This produced more current flow estimates for use in SPARROW modeling.

Journal of the American Water Resources Associatio↗
USGS1974

Hydrology of the Dismal Swamp, Virginia-North Carolina

The Dismal Swamp, on the border between eastern Virginia and North Carolina is one of the few remaining large (approximately 210,000 acres) areas of wet wilderness in the eastern United States. There has been much speculation concerning the hydrologic conditions that led to the formation of the swamp. Oaks and Coch (1973) recently completed a detailed investigation of the geology and morphology of the area. An analysis of their geology and the pollen work of Whitehead (1972) has lead the authors to the following hypothesis concerning the hydrologic conditions that led to the formation of the peat in the swamp. A permeable sand facies of the Norfolk Formation underlies Dismal Swamp. This facies was originally completely covered by the Sand Bridge Formation, which is a confining layer, and underlain by the impermeable Yorktown Formation. Movement of water eastward within the Norfolk Formation from the outcrop area on the top of the Suffolk Scarp was further restricted by a less permeable facies of the Norfolk east of the swamp; thereby creating an artesian head within the permeable sand facies of the Norfolk Formation. Erosion during the Pleistocene age breached the Sand Bridge confining layer and allowed upward seepage of water along the shallow stream valleys. This seepage, combined with the abundant rainfall and naturally sluggish surface drainage, may have been sufficient to trigger the formation of peat along stream valleys about 9,000 years ago. The peat further inhibited surface drainage, which in turn, accelerated the accumulation of peat until the interfluve areas were covered. The present role of the Norfolk Formation in the hydrology of the swamp is not clear, but it is considered to be one of the most important aspects of the hydrology to be studied in future investigations. Surface inflow is from small streams draining from the west. The flow of these streams varies widely, being generally less in the summer than in winter. Outflow is primarily through the Feeder Ditch-Dismal Swamp Canal system, which discharges at South Mills and Deep Creek locks. Rates and direction of surface flow within the swamp are partly controlled by gates on many of the ditches. Inadequately controlled ditches penetrating the Norfolk Formation plus withdrawal of water from wells along Suffolk Scarp have altered the flow of ground water under the swamp. These modifications and the loss of water through the Dismal Swamp Canal have probably resulted in a generally drier swamp as indicated by changes in the vegetation. It is feasible to preserve Dismal Swamp, but more detailed studies of the hydrology are needed to aid in future management.

North Carolina, Virginia↗
USGS2014

Coupled hydrological and biogeochemical processes controlling variability of nitrogen species in streamflow during autumn in an upland forest

Autumn is a season of dynamic change in forest streams of the northeastern United States due to effects of leaf fall on both hydrology and biogeochemistry. Few studies have explored how interactions of biogeochemical transformations, various nitrogen sources, and catchment flow paths affect stream nitrogen variation during autumn. To provide more information on this critical period, we studied (1) the timing, duration, and magnitude of changes to stream nitrate, dissolved organic nitrogen (DON), and ammonium concentrations; (2) changes in nitrate sources and cycling; and (3) source areas of the landscape that most influence stream nitrogen. We collected samples at higher temporal resolution for a longer duration than typical studies of stream nitrogen during autumn. This sampling scheme encompassed the patterns and extremes that occurred during base flow and stormflow events of autumn. Base flow nitrate concentrations decreased by an order of magnitude from 5.4 to 0.7 µmol L −1 during the week when most leaves fell from deciduous trees. Changes to rates of biogeochemical transformations during autumn base flow explained the low nitrate concentrations; in-stream transformations retained up to 72% of the nitrate that entered a stream reach. A decrease of in-stream nitrification coupled with heterotrophic nitrate cycling were primary factors in the seasonal nitrate decline. The period of low nitrate concentrations ended with a storm event in which stream nitrate concentrations increased by 25-fold. In the ensuing weeks, peak stormflow nitrate concentrations progressively decreased over closely spaced, yet similarly sized events. Most stormflow nitrate originated from nitrification in near-stream areas with occasional, large inputs of unprocessed atmospheric nitrate, which has rarely been reported for nonsnowmelt events. A maximum input of 33% unprocessed atmospheric nitrate to the stream occurred during one event. Large inputs of unprocessed atmospheric nitrate show direct and rapid effects on forest streams that may be widespread, although undocumented, throughout nitrogen-polluted temperate forests. In contrast to a week-long nitrate decline during peak autumn litterfall, base flow DON concentrations increased after leaf fall and remained high for 2 months. Dissolved organic nitrogen was hydrologically flushed to the stream from riparian soils during stormflow. In contrast to distinct seasonal changes in base flow nitrate and DON concentrations, ammonium concentrations were typically at or below the detection limit, similar to the rest of the year. Our findings reveal couplings among catchment flow paths, nutrient sources, and transformations that control seasonal extremes of stream nitrogen in forested landscapes.

Vermont↗
USGS2024

Climate change will impact surface water extents and dynamics across the central United States

Climate change is projected to impact river, lake, and wetland hydrology, with global implications for the condition and productivity of aquatic ecosystems. We integrated Sentinel-1 and Sentinel-2 based algorithms to track monthly surface water extent (2017–2021) for 32 sites across the central United States (U.S.). Median surface water extent was highly variable across sites, ranging from 3.9% to 45.1% of a site. To account for landscape-based differences (e.g., water storage capacity, land use) in the response of surface water extents to meteorological conditions, individual statistical models were developed for each site. Future changes to climate were defined as the difference between 2006–2025 and 2061–2080 using MACA-CMIP5 (MACAv2-METDATA) Global Circulation Models. Time series of climate change adjusted surface water extents were projected. Annually, 19 of the 32 sites under RCP4.5 and 22 of the 32 sites under RCP8.5 were projected to show an average decline in surface water extent, with drying most consistent across the southeast central, southwest central, and midwest central U.S. Projected declines under surface water dry conditions at these sites suggest greater impacts of drought events are likely in the future. Projected changes were seasonally variable, with the greatest decline in surface water extent expected in summer and fall seasons. In contrast, many north central sites showed a projected increase in surface water in most seasons, relative to the 2017–2021 period, likely attributable to projected increases in winter and spring precipitation exceeding increases in projected temperature.

Earth's Future↗
USGS2021

Runoff response to directional land cover change across reference basins in the conterminous United States

Land cover change plays a critical role in influencing hydrological responses. Change in land cover has impacted runoff across basins with substantial human interference; however, the impacts in basins with minimal human interference have been studied less. In this study, we investigated the impacts of directional land cover changes (forest to/from combined grassland and shrubland) in runoff coefficient (RC; ratio of runoff to precipitation) and runoff volume across 603 low human interference reference basins in the conterminous United States (CONUS). The results indicate basins with significant ( p <0.05) increasing trends in runoff and RC were across the northeast and northwest regions of CONUS, and basins with decreasing trends were in the southern CONUS region. A unit percent increase in basin area from grassland and shrubland to forest was associated with a ∼4% decrease in RC across basins with decreasing RC trends. Similarly, a unit percent increase in basin area from forest to a combined grassland and shrubland was associated with a ∼1% increase in RC across increasing RC trend basins. Runoff volume was decreased (increased) by ∼25 × 10 6 m 3 yr −1 (∼9 × 10 6 m 3 yr −1 ) across basins with decreasing (increasing) trends in runoff and RC. When relating runoff volume with the area of directional land cover changes, each 1 km 2 increase in area from grassland and shrubland to forest resulted in a decrease of ∼530,000 m 3 runoff volume across basins with decreasing trends. In contrast, each 1 km 2 increase in area from forest to grassland and shrubland increased runoff volume by ∼200,000 m 3 across increasing trend basins. Basins in the southern region of CONUS were more impacted by runoff parameters (RC and runoff volume) from directional land cover changes than basins in the northern region. The findings of this study are useful for planning and managing water availability for sustainable and adaptive water resources management at regional scales.

Advances in Water Resources↗
USGS2005

Use of relational databases to evaluate regional petroleum accumulation, groundwater flow, and CO2 sequestration in Kansas

Large-scale relational databases and geographic information system tools are used to integrate temperature, pressure, and water geo-chemistry data from numerous wells to better understand regional-scale geothermal and hydrogeological regimes of the lower Paleozoic aquifer systems in the mid-continent and to evaluate their potential for geologic CO2 sequestration. The lower Paleozoic (Cambrian to Mississippian) aquifer systems in Kansas, Missouri, and Oklahoma comprise one of the largest regional-scale saline aquifer systems in North America. Understanding hydrologic conditions and processes of these regional-scale aquifer systems provides insight to the evolution of the various sedimentary basins, migration of hydrocarbons out of the Anadarko and Arkoma basins, and the distribution of Arbuckle petroleum reservoirs across Kansas and provides a basis to evaluate CO2 sequestration potential. The Cambrian and Ordovician stratigraphic units form a saline aquifer that is in hydrologic continuity with the freshwater recharge from the Ozark plateau and along the Nemaha anticline. The hydrologic continuity with areas of freshwater recharge provides an explanation for the apparent underpressure in the Arbuckle Group. Copyright ?? 2005. The American Association of Petroleum Geologists. All rights reserved.

American Association of Petroleum Geologists Bulle↗
USGS2011

Water year 2004: Western water managers feel the heat

This spring, a rare combination of exceptionally warm temperatures and near-record lack of precipitation in the western United States caused a rapid change in hydrologic conditions and an unexpectedly early onset of spring conditions. With much of the western U.S. already in its fifth year of drought, an above-average western snowpack on 1 March 2004 provided hope for much-needed abundant runoff. Unfortunately snowmelt began far earlier than anticipated, resulting in dramatic declines in seasonal spring-summer streamflow forecasts as the month proceeded, declines more rapid by some measures than ever before in the past 75 years. With reservoirs near historic lows, many water users have been hard pressed to deal with the continuing drought.

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