Search USGS⌕ Search

SEARCH · Search USGS

Results for “Southwest Hydrology”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
USGS2007

Generalized potentiometric surface of the Arikaree aquifer, Pine Ridge Indian Reservation and Bennett County, South Dakota

INTRODUCTION The Pine Ridge Indian Reservation and Bennett County are located in southwest South Dakota. The Pine Ridge Indian Reservation includes all of Shannon County and the part of Jackson County south of the White River. Extensive Indian trust lands are in Bennett County. For purposes of this map, the Pine Ridge Indian Reservation and all of Bennett County are included in the study area (sheet 1). Ground water from wells and springs is the predominant source of public and domestic supply within the study area. The Arikaree aquifer is the largest source of ground water throughout this area. The Oglala Sioux Tribe is developing a ground-water management plan designed to “preserve, protect and maintain the quality of ground water for living and future members and non-members of the Oglala Sioux Indian Tribe within the internal and external boundaries of the Pine Ridge Reservation” (Michael Catches Enemy, Oglala Sioux Tribe Natural Resources Regulatory Agency, oral commun., 2007). Hydrologic information about the Arikaree aquifer is important to managing this resource. In 1998, the U.S. Geological Survey (USGS) began working in cooperation with the Oglala Sioux Tribe to develop a potentiometric map of the Arikaree aquifer in Jackson and Shannon Counties, with a primary component of that effort being a well inventory in those counties. In 2003, the study area was expanded to include Bennett County.

South Dakota↗
USGS1998

Evaluation of hydrologic data collected at the North Penn Area 12 Superfund Site, Montgomery County, Pennsylvania

The North Penn Area 12 Superfund Site is underlain by the Lockatong Formation, which consists of interbedded gray to black siltstone and shale. The beds of the Lockatong Formation strike northeast and dip about 10d to 20d to the northwest in the vicinity of the site. Ground water moves through fractures that are nearly vertical and horizontal in the shale and siltstone. Permeability and storage are very low. Borehole-geophysical logs were obtained from eight wells to determine the location of fractures, water-producing and water-receiving intervals, and intervals of borehole flow. The logs also were used to quantify fluid movement in the borehole, to characterize the lithology, and to obtain data on well construction. The logs indicate fractures at depths less than 100 feet are more frequent and generally are more productive than fractures at depths greater than 100 feet. The fluid resistivity of water in shallow intervals usually was greater than that in deeper intervals. The rate and direction of fluid movement under nonpumping conditions differs in the boreholes logged. In the northwest part of the site, no vertical flow was detected in three wells and very small amounts of flow were measured in two wells. In the southwest part of the site, downward flow was measured in two wells. Aquifer-isolation tests in three wells provided information on hydraulic heads and specific capacities in discrete vertical intervals and allowed collection of water samples form discrete water-bearing intervals. Natural annual fluctuations of water levels in 11 wells ranged form 11.4 to 28.3 feet. Seven of the 11 wells gave very similar water-level hydrographs. The four southernmost wells on the site show rises in water levels after precipitation much sooner than the other seven wells. Two other wells show daily fluctuations caused by pumping. A potentiometric-surface map of the site and vicinity was prepared from water-level measurements made in late July 1995. The map can be used to determine the approximate direction of ground-water flow.

Water-Resources Investigations Report↗
USGS2000

Hydrologic budget of the late Oligocene Lake Creede and the evolution of the upper Rio Grande drainage system

The filling history, hydrologic budget, and geomorphic development of ancient Lake Creede and its tributary basin are evaluated to determine the factors that controlled its character. The lake filled the Creede caldera that formed in the late Oligocene as a consequence of the eruption of the Snowshoe Mountain Tuff. The caldera's sedimentary fill accumlated to a depth of about 1.26 km and had a volume of about 89 km 3 . The highest lake level was ~3300 m (10,800 ft) present altitude before it drained eastward across a broad volcanic plateau as the ancestral Rio Grande. A tributary canyon several hundred meters deep was cut into hard rhyolite in the north wall of the caldera before the lake was more than half full; its presence demonstrates that ancient Lake Creede filled slowly and thus occupied a long-lived, closed basin. The slow filling rate is incompatible with the present water flux through the Creede caldera basin, because such a flow would fill the basin geologically instantaneously. This mismatch, together with the recognition that the Oligocene climate was similar to that of today, forces the reexamination of the hydrologic and geomorphic history of the caldera. That appraisal shows that the caldera cannot have resurged rapidly immediately after caldera collapse, and that ancient watershed must have been lass than half as large as the present upper Rio Grande basin. The ancient lake had a more or less constant surface area of about 200 km 2 that approximated a steady-state condition between inflow and evaporation. Although the lake level fluctuated with climatic variations, its surface elevation steadily climbed as sediment accumulated, accelerating as resurgance and dome growth usurped spacewithin the basin. It could have had one playa stage early in its development and another after the basin had nearly filled with sediment, but there is no direct evidence for either. At least the lower half of the sedimentary column (the part sampled by the scientific drilling) formed in an euxinic environment. This argues against a persistent early playa, although evaporative accumulation of brine was inevitable. When the rate of resurgance was rapid relative to sedimentary infilling, the lake would have been deep (i.e., bordered by bedrock rather than sedimentary fans). The geomorphic evolution of the Creede caldera and its watershed tracks a two-phase topographic history, the first the Oligocene through Miocene, and the second for Pliocene to the recent. In Oligocene time, the San Juan volcanic field was a hydrologically immature, gently undulating, and outward sloping, constructional volcanic plateau straddling the ancient Continental Divide. West of the Creede caldera, a dendritic drainage discharged northeastward into ancestral Cebolla Creek (a tributary of the ancestral Gunnison River) through an early stage of the Clear Creek graben in the vicinity of Spring Creek Pass. Miocene basalt choked, but did not reconstruct, the drainage. By the end of Miocene time a mature topography of moderate relief developed, exposing some of the higher ores in the Creede district to weathering. In the late Miocene-early Pliocene time the San Juan Mountains were uplifted and titled eastward; the ancestral Rio Grande was revitalized and cut deeply into the older terrain, excavating much of the accessible sediment from the moat of the Creede caldera and exposing successively lowe levels in the Creede district to oxidation. Simultaneously, the southeast end of the Clear Creek graben was reactivated and breached the southwest wall of the Creede caldera. The rejuvenated Rio Grande captured the formerly northeast-directed headwaters of ancestral Cebolla Creek, shifting more than 1000 km 2 from the Pacific-directed drainage to the Atlantic. The water budget for ancient Lake Creede was strictly limited by the early stages of the fist geomorphic cycle; the modern water budget is the product of the second cycle.

Colorado↗
USGS2019

Recognizing the Famine Early Warning Systems Network: Over 30 years of drought early warning science advances and partnerships promoting global food security

On a planet with more than 7 billion people, how do we identify the millions of drought-afflicted people who face a real threat of livelihood disruption or death without humanitarian assistance? Typically, these people are poor and heavily dependent on rainfed agriculture and livestock. Most live in Africa, Central America, or Southwest Asia. When the rains fail, incomes diminish while food prices increase, cutting off the poorest (most often women and children) from access to adequate nutrition. As seen in Ethiopia in 1984 and Somalia in 2011, food shortages can lead to famine. Yet these slow onset disasters also provide opportunities for effective intervention, as seen in Ethiopia in 2015 and Somalia in 2017. Since 1985, the US Agency for International Development's Famine Early Warning Systems Network (FEWS NET) has been providing evidence-based guidance for effective humanitarian relief efforts. FEWS NET depends on a Drought Early Warning System (DEWS) to help understand, monitor, model and predict food insecurity. Here we provide an overview of FEWS NET's DEWS using examples from recent climate extremes. While drought monitoring and prediction provides just one part of FEWS NET's monitoring system, it draws from many disciplines - remote sensing, climate prediction, agro-climatic monitoring, and hydrologic modeling. Here we describe FEWS NET's multi-agency multi-disciplinary DEWS and Food Security Outlooks. This DEWS uses diagnostic analyses to guide predictions. Mid-season droughts are monitored using multiple cutting-edge earth observing systems. Crop and hydrologic models can translate these observations into impacts. This information feeds into FEWS NET reports, helping to save lives by motivating and targeting timely humanitarian assistance.

Bulletin of the American Meteorological Society↗
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↗
USGS2024

Groundwater hydrology, groundwater and surface-water interactions, aquifer testing, and groundwater-flow simulations for the Fountain Creek alluvial aquifer, near Colorado Springs, Colorado, 2018–20

From 2018 through 2020, the U.S. Geological Survey, in cooperation with the Air Force Civil Engineering Center, conducted an integrated study of the Fountain Creek alluvial aquifer located near Colorado Springs, Colorado. The objective of the study was to characterize hydrologic conditions for the alluvial aquifer pertinent to the potential for transport of solutes. Specific goals of this report were to characterize the groundwater hydrology of the area, to quantify groundwater and surface-water interactions, to estimate hydraulic properties of the aquifer using aquifer testing, and to complete numerical simulations of groundwater flow. Synoptic groundwater-level elevation measurements completed throughout this study, and as part of other U.S. Geological Survey programs between 1994 and 2020, indicate groundwater-level elevations fluctuate on annual and interannual timeframes. Groundwater-level fluctuations likely were caused by temporally variable groundwater recharge and discharge components in the area, with many wells showing maximum groundwater-level elevations during the winter months (November through March). From an interannual perspective, groundwater-level fluctuations appear to have reached maximum values during 2000 to 2003, decreased during 2003 to 2006, and remained relatively constant since that time, with the exception of several wells which have displayed rising groundwater-level elevations since 2018. Spatial evaluation of groundwater-level elevations indicates groundwater flow is generally from northeast to southwest within the vicinity of several alluvial paleochannels occurring along the northeastern margin of the aquifer. Within the center of the aquifer along Fountain Creek, groundwater flow is generally from north to south, approximately paralleling surface-water flow. To quantitatively understand the potential effect of groundwater recharge and groundwater pumping on fluctuations in groundwater-level elevation, a statistical transfer-function-noise model was applied. Results of the statistical model indicate throughout most of the aquifer, fluctuations were primarily the result of recharge seasonality. In the main stem of the aquifer where groundwater pumping wells were more concentrated, however, groundwater-level elevation fluctuations were also attributable to groundwater pumping through time. Three-dimensional evaluation of the aquifer geometry near Fountain Creek was combined with synoptic streamflow measurement and accounting of stream gains and losses to evaluate groundwater and surface-water interactions in the study area. Streamflow gain or loss calculations indicate Fountain Creek both gains from and loses flow to the alluvial aquifer, and gaining or losing reaches of the stream may be partially controlled by the depth to bedrock near the stream. Reaches with streamflow gains tend to coincide with areas where the estimated depth to bedrock is decreasing, meaning the alluvial aquifer is likely thinning in these areas and groundwater-flow paths may be converging and discharging groundwater to the stream. Losing reaches tended to coincide with locally greater depth to bedrock where the alluvial aquifer is likely thicker and has greater storage potential for surface water lost from Fountain Creek. Results of aquifer testing indicate hydraulic conductivity, estimated from slug tests and single-well pumping tests, ranged from 0.32 to 1,410 feet per day (ft/d) and 4.13 to 664 ft/d, respectively. These results are similar to the range of values from previous aquifer tests in the study area. Hydraulic conductivities from aquifer testing for this study were generally greater than the estimates of previous slug tests and had a mean value less than the estimates from previous pumping tests. Spatial evaluation of aquifer testing results indicates hydraulic conductivity tends to be greater in the main stem of the alluvial aquifer and lower in paleochannels upgradient from the main stem of the aquifer. The spatial variation in hydraulic conductivity may be attributed to the geomorphologic processes that formed the alluvial aquifer. Compacted sediment in the paleochannels has not been potentially transported sufficient distance to cause grain-size sorting, resulting in a poorly sorted deposit and lower hydraulic conductivities. In the central portion of the alluvial aquifer, near Fountain Creek, the sediments have been transported farther from their source areas and are likely better sorted, removing finer grained sediments that would cause lower hydraulic conductivity. A numerical groundwater-flow model was calibrated for the Fountain Creek alluvial aquifer for 2000–19 to simulate water-budget components, groundwater-flow directions, and groundwater-flow paths. The model simulated precipitation recharge, groundwater and surface-water interactions, evapotranspiration, high-volume groundwater pumping by pumping wells, and external inflows and outflows occurring along the boundaries of the alluvial aquifer. Model calibration was completed using manual and automated approaches, the latter of which assisted in quantifying model results sensitivity to input parameters. The calibrated model corresponds well with groundwater-level elevation observations, with a mean residual (observed minus simulated groundwater-level elevation) equal to −0.60 feet. Simulated groundwater base flow to streams was typically within 10 percent of base flow estimated by independent methods. Groundwater and surface-water interactions represented the largest water-budget components of the aquifer, with the second largest groundwater discharge component coming from pumping wells. Groundwater and surface-water interactions represent both the largest gain and loss terms in the water budget, because these interactions differ spatially, meaning in some areas of the model domain groundwater is being recharged by streams, whereas in other areas, groundwater is discharged to streams. Estimates of advective groundwater-flow paths indicate pumping wells may capture groundwater recharged from losing streams and groundwater that flows into the main stem of the alluvial aquifer from paleochannels.

Colorado↗
USGS2012

Fluid geochemistry of Yucca Mountain and vicinity

Yucca Mountain, a site in southwest Nevada, has been proposed for a deep underground radioactive waste repository. An extensive database of geochemical and isotopic characteristics has been established for pore waters and gases from the unsaturated zone, perched water, and saturated zone waters in the Yucca Mountain area. The development of this database has been driven by diverse needs of the Yucca Mountain Project, especially those aspects of the project involving process modeling and performance assessment. Water and gas chemistries influence the sorption behavior of radionuclides and the solubility of the radionuclide compounds that form. The chemistry of waters that may infiltrate the proposed repository will be determined in part by that of water present in the unsaturated zone above the proposed repository horizon, whereas pore-water compositions beneath the repository horizon will influence the sorption behavior of the radionuclides transported toward the water table. However, more relevant to the discussion in this chapter, development and testing of conceptual flow and transport models for the Yucca Mountain hydrologic system are strengthened through the incorporation of natural environmental tracer data into the process. Chemical and isotopic data are used to establish bounds on key hydrologic parameters and to provide corroborative evidence for model assumptions and predictions. Examples of specific issues addressed by these data include spatial and temporal variability in net fluxes, the role of faults in controlling flow paths, fracture-matrix interactions, the age and origin of perched water, and the distribution of water traveltimes.

Nevada↗
USGS2011

Lake carbonate-δ 18 records from the Yukon Territory, Canada: Little Ice Age moisture variability and patterns

A 1000-yr history of climate change in the central Yukon Territory, Canada, is inferred from sediment composition and isotope geochemistry from small, groundwater fed, Seven Mile Lake. Recent observations of lake-water δ 18 O, lake level, river discharge, and climate variations, suggest that changes in regional effective moisture (precipitation minus evaporation) are reflected by the lake’s hydrologic balance. The observations indicate that the lake is currently 18 O-enriched by summer evaporation and that during years of increased precipitation, when groundwater inflow rates to the lake increase, lake-water δ 18 O values decrease. Past lake-water δ 18 O values are inferred from oxygen isotope ratios of fine-grained sedimentary endogenic carbonate. Variations in carbonate δ 18 O, supplemented by those in carbonate and organic δ 13 C, C/N ratios, and organic carbon, carbonate and biogenic silica accumulation rates, document changes in effective moisture at decadal time scales during the early Little Ice Age period to present. Results indicate that between ∼AD 1000 and 1600, effective moisture was higher than today. A shift to more arid climate conditions occurred after ∼AD 1650. The 19th and 20th centuries have been the driest of the past millennium. Temporal variations correspond with inferred shifts in summer evaporation from Marcella Lake δ 18 O, a similarly small, stratified, alkaline lake located ∼250 km to the southwest, suggesting that the combined reconstructions accurately document the regional paleoclimate of the east-central interior. Comparison with regional glacial activity suggests differing regional moisture patterns during early and late Little Ice Age advances.

Yukon Territory↗
USGS2020

Holocene paleoclimate change in the western US: The importance of chronology in discerning patterns and drivers

Sediment in lakes and meadows forms a powerful archive that can be used to reconstruct environmental change through time. Reconstructions of lake level, of chemical, biological, and hydrological conditions, and of surrounding vegetation provide detailed information about past climate conditions, both locally and regionally. Indeed, most of our current knowledge of centennial- to millennial-scale climate variability in the arid western United States, where information about past hydroclimate is particularly important, comes from such sediment-based reconstructions. The pressing need for robust, precise predictions of future conditions is a significant motivation for paleoclimate science, and current research questions frequently require Holocene reconstructions to be resolved at sub-centennial timescales. Increasingly, regional syntheses seek to identify synoptic-scale patterns similar to those defined from modern observations (seasonal, interannual, multi-decadal, etc.) or to compare with the output of climate model simulations. However, the age control on existing records, especially those more than about 20 years old, is often sufficient only for millennial-scale interpretation. Here we assess the age control for 84 published and unpublished records from lakes and meadows in the Great Basin, California, and desert southwest, and use Bayesian modeling to evaluate the 95% uncertainty ranges for the 42 best-dated records. In the Late Holocene, about half of the 42 records have <400-year mean uncertainty ranges; however, high-precision age control is especially critical for young records, used to develop an accurate understanding of a proxy’s response to known climate variations. In the Middle Holocene, records vary from 400 to >800-year mean uncertainty and records of the Early Holocene have 600- to >1400-year mean uncertainty ranges. We find that the largest control on modeled uncertainties is dating density, with at least 2 dates/kyr being optimal and suggest obtaining “range-finder” dates at the onset of a study to better predict the total number of dates needed for an adequate age model. Such a density avoids a commonly observed phenomenon of significant peaks in uncertainty arising in gaps between age control points. Analysis of the uncertainties associated with proxy shifts reveal that more than half are >400 years. Although such large uncertainties currently prevent sub-centennial interpretations in most cases, increased dating density, strategic use of limited funds (including budgeting for a 2 date/kyr minimum at the proposal stage), construction of age-depth models with Bayesian methods, and critical evaluation of chronological uncertainty will shed light on past climate variability at finer timescales, enhancing our understanding of global and regional drivers of western U.S. climate.

California, Idaho, Nevada, Oregon, Utah↗
USGS2010

Hydrologic Evaluation of the Jungo Area, Southern Desert Valley, Nevada

RecologyTM, the primary San Francisco waste-disposal entity, is proposing to develop a Class 1 landfill near Jungo, Nevada. The proposal calls for the landfill to receive by rail about 20,000 tons of waste per week for up to 50 years. On September 22, 2009, the Interior Appropriation (S.A. 2494) was amended to require the U.S. Geological Survey to evaluate the proposed Jungo landfill site for: (1) potential water-quality impacts on nearby surface-water resources, including Rye Patch Reservoir and the Humboldt River; (2) potential impacts on municipal water resources of Winnemucca, Nevada; (3) locations and altitudes of aquifers; (4) how long it will take waste seepage from the site to contaminate local aquifers; and (5) the direction and distance that contaminated groundwater would travel at 95 and 190 years. This evaluation was based on review of existing data and information. Desert Valley is tributary to the Black Rock Desert via the Quinn River in northern Desert Valley. The Humboldt River and Rye Patch Reservoir would not be affected by surface releases from the proposed Jungo landfill site because they are in the Humboldt basin. Winnemucca, on the Humboldt River, is 30 miles east of the Jungo landfill site and in the Humboldt basin. Groundwater-flow directions indicate that subsurface flow near the proposed Jungo landfill site is toward the south-southwest. Therefore, municipal water resources of Winnemucca would not be affected by surface or subsurface releases from the proposed Jungo landfill site. Basin-fill aquifers underlie the 680-square-mile valley floor in Desert Valley. Altitudes around the proposed Jungo landfill site range from 4,162 to 4,175 feet. Depth to groundwater is fairly shallow in southern Desert Valley and is about 60 feet below land surface at the proposed Jungo landfill site. A groundwater divide exists about 7 miles north of the proposed Jungo landfill site. Groundwater north of the divide flows north towards the Quinn River. South of the divide and near the proposed Jungo landfill site, groundwater flows in a south-southwesterly direction. Data are insufficient to determine whether groundwater eventually flows into Rye Patch Reservoir or other adjacent valleys. Estimates indicate that contaminants would travel about 0.02 mile and a maximum of 2.5 miles in 95 years and about 0.04 mile and a maximum of 5.0 miles in 190 years. The closest supply wells that could be impacted by contaminants are 5 to 6 miles downgradient and are used for industry, irrigation, and stock watering.

Open-File Report↗
USGS1976

Hydrologic interpretation of geophysical data from the southeastern Hueco Bolson, El Paso, and Hudspeth Counties, Texas

Airborne-electromagnetic and earth-resistivity surveys were used to explore for fresh ground water in the Hueco Bolson southeast of El Paso, Texas. Aerial surveys were made along about 500 miles (800 km) of flight line, and 67 resistivity soundings were made along 110 miles (180 km) of profile. The surveys did not indicate the presence of any large bodies of fresh ground water, but several areas may be underlain by small to moderate amounts of fresh to slightly saline water. The material underlying the flood plain of the Rio Grande is predominantly clay or sand of low resistivity. Along a band on the mesa next to and parallel to the flood plain, more resistive material composed partly of deposits of an ancient river channel extends to depths of about 400 to 1,700 feet (120 to 520 m). Locally, the lower part of this more resistive material is saturated with fresh to slightly saline water. The largest body of fresh to slightly saline ground water detected in this study is between Fabens and Tornillo, Texas, mostly in the sandhill area between the flood plain and the mesa. Under assumed conditions, the total amount of water in storage may be as much as 400,000 to 800,000 acre-feet (500 million to 1 billion m ). The resistivity data indicate that the deep artesian zone southwest of Fabens extends from a depth of about 1,200 feet (365 m) to about 2,800 feet (855 m).

Open-File Report↗
USGS2023

Assessment of post-wildfire geomorphic change in the North Fork Eagle Creek stream channel, New Mexico, 2017–21

The 2012 Little Bear Fire caused substantial vegetation loss in the Eagle Creek Basin of south-central New Mexico. This loss was expected to alter the localized hydrologic response to precipitation by creating conditions that amplify surface runoff, which might alter the geomorphology of North Fork Eagle Creek, a major tributary to Eagle Creek. To monitor short-term geomorphic change, annual geomorphic surveys of North Fork Eagle Creek were conducted from 2017 to 2021. The surveys measured 14 cross sections, stream gradients, woody debris accumulations, and pools found within the study reach. During the 2017–21 study period, the study reach experienced multiple high-flow events that resulted from both monsoonal rainfall and snowmelt runoff. Comparisons of the cross-section and channel profile data for the repeat geomorphic surveys indicate localized erosion and deposition occurred as a result of the high-flow events but overall study reach geomorphology shower little change through the study period. Additionally, the number of woody debris accumulations and pools increased during the study period. Evidence from the 5-year geomorphic survey indicates that the North Fork Eagle Creek’s geomorphology did not change substantially during the study period. Wildfire severity and frequency within mountainous regions of the Southwest are projected to increase and their effect on fluvial systems remains uncertain; however, continued geomorphic studies can provide informative insight on watershed post-wildfire resiliency and recovery by establishing baselines that can be used in the event of a future severe wildfire within the Eagle Creek Basin.

New Mexico↗
USGS2000

Characteristic length scale of input data in distributed models: implications for modeling grain size

The appropriate spatial scale for a distributed energy balance model was investigated by: (a) determining the scale of variability associated with the remotely sensed and GIS-generated model input data; and (b) examining the effects of input data spatial aggregation on model response. The semi-variogram and the characteristic length calculated from the spatial autocorrelation were used to determine the scale of variability of the remotely sensed and GIS-generated model input data. The data were collected from two hillsides at Upper Sheep Creek, a sub-basin of the Reynolds Creek Experimental Watershed, in southwest Idaho. The data were analyzed in terms of the semivariance and the integral of the autocorrelation. The minimum characteristic length associated with the variability of the data used in the analysis was 15 m. Simulated and observed radiometric surface temperature fields at different spatial resolutions were compared. The correlation between agreement simulated and observed fields sharply declined after a 10&times;10 m 2 modeling grid size. A modeling grid size of about 10&times;10 m 2 was deemed to be the best compromise to achieve: (a) reduction of computation time and the size of the support data; and (b) a reproduction of the observed radiometric surface temperature.

Idaho↗
USGS2012

Hydrologic conditions, groundwater quality, and analysis of sink hole formation in the Albany area of Dougherty County, Georgia, 2009

The U.S. Geological Survey, in cooperation with the Albany Water, Gas, and Light Commission has conducted water resources investigations and monitored groundwater conditions and availability in the Albany, Georgia, area since 1977. This report presents an overview of hydrologic conditions, water quality, and groundwater studies in the Albany area of Dougherty County, Georgia, during 2009. Historical data also are presented for comparison with 2009 data. During 2009, groundwater-level data were collected in 29 wells in the Albany area to monitor water-level trends in the surficial, Upper Floridan, Claiborne, Clayton, and Providence aquifers. Groundwater-level data from 21 of the 29 wells indicated an increasing trend during 2008&ndash;09. Five wells show no trend due to lack of data and three wells have decreasing trends. Period-of-record water levels (period of record ranged between 1957&ndash;2009 and 2003&ndash;2009) declined slightly in 10 wells and increased slightly in 4 wells tapping the Upper Floridan aquifer; declined in 1 well and increased in 2 wells tapping the Claiborne aquifer; declined in 4 wells and increased in 2 wells tapping the Clayton aquifer; and increased in 1 well tapping the Providence aquifer. Analyses of groundwater samples collected during 2009 from 12 wells in the Upper Floridan aquifer in the vicinity of a well field located southwest of Albany indicate that overall concentrations of nitrate plus nitrite as nitrogen increased slightly from 2008 in 8 wells. A maximum concentration of 12.9 milligrams per liter was found in a groundwater sample from a well located upgradient from the well field. The distinct difference in chemical constituents of water samples collected from the Flint River and samples collected from wells located in the well-field area southwest of Albany indicates that little water exchange occurs between the Upper Floridan aquifer and Flint River where the river flows adjacent to, but downgradient of, the well field. Water-quality data collected during 2008 from two municipal wells located in northern Albany and downgradient from a hazardous waste site indicate low-level concentrations of pesticides in one of the wells; however, no pesticides were detected in samples collected during 2009. Detailed geologic cross sections were used to create a three-dimensional, hydrogeologic diagram of the well field southwest of Albany in order to examine the occurrence of subsurface features conducive to sinkhole formation. Monitored groundwater-level data were used to assess the possible relations between sinkhole formation, precipitation, and water levels in the Upper Floridan aquifer. Although the water levels in well 12L382 oscillated above and below the top of the aquifer on a regular basis between 2007 and 2009, sinkhole development did not appear to correlate directly with either well-field pumping or water levels in the Upper Floridan aquifer. Specifically, two sinkholes formed in each of the years 2003 and 2005 when water levels were almost 20 feet above the top of the aquifer during most of the year. Water-level and sinkhole-formation data continue to be collected to allow further study and analysis.

Georgia↗
USGS2006

Evaluating uncertainty in predicting spatially variable representative elementary scales in fractured aquifers, with application to Turkey Creek Basin, Colorado

Computational limitations and sparse field data often mandate use of continuum representation for modeling hydrologic processes in large‐scale fractured aquifers. Selecting appropriate element size is of primary importance because continuum approximation is not valid for all scales. The traditional approach is to select elements by identifying a single representative elementary scale (RES) for the region of interest. Recent advances indicate RES may be spatially variable, prompting unanswered questions regarding the ability of sparse data to spatially resolve continuum equivalents in fractured aquifers. We address this uncertainty of estimating RES using two techniques. In one technique we employ data‐conditioned realizations generated by sequential Gaussian simulation. For the other we develop a new approach using conditioned random walks and nonparametric bootstrapping (CRWN). We evaluate the effectiveness of each method under three fracture densities, three data sets, and two groups of RES analysis parameters. In sum, 18 separate RES analyses are evaluated, which indicate RES magnitudes may be reasonably bounded using uncertainty analysis, even for limited data sets and complex fracture structure. In addition, we conduct a field study to estimate RES magnitudes and resulting uncertainty for Turkey Creek Basin, a crystalline fractured rock aquifer located 30 km southwest of Denver, Colorado. Analyses indicate RES does not correlate to rock type or local relief in several instances but is generally lower within incised creek valleys and higher along mountain fronts. Results of this study suggest that (1) CRWN is an effective and computationally efficient method to estimate uncertainty, (2) RES predictions are well constrained using uncertainty analysis, and (3) for aquifers such as Turkey Creek Basin, spatial variability of RES is significant and complex.

Water Resources Research↗
USGS2016

Climate-induced glacier and snow loss imperils alpine stream insects

Climate warming is causing rapid loss of glaciers and snowpack in mountainous regions worldwide. These changes are predicted to negatively impact the habitats of many range-restricted species, particularly endemic, mountaintop species dependent on the unique thermal and hydrologic conditions found only in glacier-fed and snowmelt-driven alpine streams. Though progress has been made, existing understanding of the status, distribution, and ecology of alpine aquatic species, particularly in North America, is lacking, thereby hindering conservation and management programs. Two aquatic insects – the meltwater stonefly Lednia tumana and the glacier stonefly Zapada glacier – were recently proposed for listing under the U.S. Endangered Species Act due to climate-change-induced habitat loss. Using a large dataset (272 streams, 482 total sites) with high-resolution climate and habitat information, we describe the distribution, status, and key environmental features that limit L. tumana and Z. glacier across the northern Rocky Mountains. Lednia tumana was detected in 113 streams (175 sites) within Glacier National Park (GNP) and surrounding areas. The probability of L. tumana occurrence increased with cold stream temperatures and close proximity to glaciers and permanent snowfields. Similarly, densities of L. tumana declined with increasing distance from stream source. Zapada glacier was only detected in 10 streams (20 sites), six in GNP and four in mountain ranges up to ~600 km southwest. Our results show that both L. tumana and Z. glacier inhabit an extremely narrow distribution, restricted to short sections of cold, alpine streams often below glaciers predicted to disappear over the next two decades. Climate warming-induced glacier and snow loss clearly imperils the persistence of L. tumana and Z. glacier throughout their ranges, highlighting the role of mountaintop aquatic invertebrates as sentinels of climate change in mid-latitude regions.

Global Change Biology↗
USGS2009

Water Withdrawals, Use, and Trends in Florida, 2005

In 2005, the total amount of water withdrawals in Florida was estimated at 18,359 million gallons per day (Mgal/d). Saline water accounted for 11,486 Mgal/d (63 percent), and freshwater accounted for 6,873 Mgal/d (37 percent). Groundwater accounted for 4,247 Mgal/d (62 percent) of freshwater withdrawals, and surface water accounted for the remaining 2,626 Mgal/d (38 percent). Surface water accounted for nearly all (99.9 percent) saline-water withdrawals. An additional 660 Mgal/d of reclaimed wastewater was used in Florida during 2005. The largest amount of freshwater was withdrawn from Palm Beach County, and the largest amount of saline water was withdrawn from Pasco County. Fresh groundwater provided drinking water (public supplied and self-supplied) for 16.19 million people (90 percent of Florida's population), and fresh surface water provided drinking water for 1.73 million people (10 percent). The majority of groundwater withdrawals (nearly 60 percent) in 2005 was obtained from the Floridan aquifer system which is present throughout the entire State. The majority of fresh surface-water withdrawals (59 percent) came from the southern Florida hydrologic unit subregion and is associated with Lake Okeechobee and the canals in the Everglades Agricultural Area of Glades, Hendry, and Palm Beach Counties, as well as the Caloosahatchee River and its tributaries in the agricultural areas of Collier, Glades, Hendry, and Lee Counties. Overall, agricultural irrigation accounted for 40 percent of the total freshwater withdrawals (ground and surface), followed by public supply with 37 percent. Public supply accounted for 52 percent of groundwater withdrawals, followed by agricultural self-supplied (31 percent), ommercial-industrial-mining self-supplied (8.5 percent), recreational irrigation and domestic self-supplied (4 percent each), and power generation (0.5 percent). Agricultural self-supplied accounted for 56 percent of fresh surface-water withdrawals, followed by power generation (20.5 percent), public supply (13 percent), recreational irrigation (6 percent), and commercial-industrial self-supplied (4.5 percent). Power generation accounted for nearly all (99.9 percent) saline-water withdrawals. Of the 17.92 million people who resided in Florida during 2005, 41 percent (7.36 million people) resided in the South Florida Water Management District (SFWMD), followed by the St. Johns River Water Management District (SJRWMD) and the Southwest Florida Water Management District (SWFWMD) with 25 percent each (4.46 and 4.44 million people, respectively), the Northwest Florida Water Management District (NWFWMD) with 7.5 percent (1.34 million people), and the Suwannee River Water Management District (SRWMD) with 1.5 percent (0.32 million people). The largest amount of freshwater withdrawals was from the SFWMD, which was one-half (50 percent) of the State's total freshwater withdrawals, followed by the SJRWMD (19 percent), SWFWMD (16 percent), NWFWMD (10 percent), and SRWMD (5 percent). Between 1950 and 2005, the population of Florida increased by 15.15 million (550 percent), and the total water withdrawals (fresh and saline) increased 15,700 Mgal/d (600 percent). More recently, total withdrawals decreased 1,790 Mgal/d (9 percent) between 2000 and 2005, but the total population increased by 1.94 million (12 percent). Between 1990 and 2005, saline-water withdrawals increased 1,120 Mgal/d (11 percent), whereas between 2000 and 2005, saline-water withdrawals decreased 470 Mgal/d (4 percent). Between 1990 and 2005, freshwater withdrawals decreased 710 Mgal/d (9 percent), whereas between 2000 and 2005, freshwater withdrawals decreased 1,320 Mgal/d (16 percent). The use of highly mineralized groundwater as a source of supply, primarily for public supply, also has increased in Florida. This water, referred as nonpotable water, increased from just less than 2 Mgal/d in 1970, to 142 Mgal/d in 2005. Nonpotable water is treated to meet drin

Scientific Investigations Report↗
USGS2014

Water withdrawals, use, and trends in Florida, 2010

In 2010, the total amount of water withdrawn in Florida was estimated to be 14,988 million gallons per day (Mgal/d). Saline water accounted for 8,589 Mgal/d (57 percent) and freshwater accounted for 6,399 Mgal/d (43 percent). Groundwater accounted for 4,166 Mgal/d (65 percent) of freshwater withdrawals, and surface water accounted for the remaining 2,233 Mgal/d (35 percent). Surface water accounted for nearly all (99.9 percent) saline-water withdrawals. An additional 659 Mgal/d of reclaimed wastewater was used in Florida during 2010. Freshwater withdrawals were greatest in Palm Beach County (707 Mgal/d), and saline-water withdrawals were greatest in Hillsborough County (1,715 Mgal/d). Fresh groundwater provided drinking water (public supplied and self-supplied) for 17.33 million people (92 percent of Florida’s population), and fresh surface water provided drinking water for 1.47 million people (8 percent). The statewide public-supply gross per capita use for 2010 was 134 gallons per day, whereas the statewide public-supply domestic per capita use was 85 gallons per day. The majority of groundwater withdrawals (almost 62 percent) in 2010 were obtained from the Floridan aquifer system, which is present throughout most of the State. The majority of fresh surface-water withdrawals (56 percent) came from the southern Florida hydrologic unit subregion and is associated with Lake Okeechobee and the canals in the Everglades Agricultural Area of Glades, Hendry, and Palm Beach Counties, as well as the Caloosahatchee River and its tributaries in the agricultural areas of Collier, Glades, Hendry, and Lee Counties. Overall, agricultural irrigation accounted for 40 percent of the total freshwater withdrawals (ground and surface), followed by public supply with 35 percent. Public supply accounted for 48 percent of groundwater withdrawals, followed by agricultural self-supplied (34 percent), commercial-industrial-mining self-supplied (7 percent), recreational-landscape irrigation and domestic self-supplied (5 percent each), and power generation (less than 1 percent). Agricultural self-supplied accounted for 51 percent of fresh surface-water withdrawals, followed by power generation (25 percent), public supply (11 percent), recreational-landscape irrigation (9 percent), and commercial-industrial-mining self-supplied (4 percent). Power generation accounted for nearly all (99.8 percent) saline-water withdrawals. Of the 18.80 million people who resided in Florida during 2010, 41 percent (7.68 million people) resided in the South Florida Water Management District (SFWMD), 25 percent each resided in the Southwest Florida Water Management District (SWFWMD) and the St. Johns River Water Management District (SJRWMD) (4.73 and 4.70 million people, respectively), 7 percent (1.36 million people) resided in the Northwest Florida Water Management District (NWFWMD), and 2 percent (0.33 million people) resided in the Suwannee River Water Management District (SRWMD). The largest percentage of freshwater withdrawals was from the SFWMD (47 percent), followed by the SJRWMD (21 percent), SWFWMD (18 percent), NWFWMD (9 percent), and SRWMD (5 percent). Between 1950 and 2010, the population of Florida increased by 16.03 million (580 percent), and the total water withdrawals (fresh and saline) increased by 12,334 Mgal/d (465 percent). More recently, total freshwater withdrawals decreased by more than 1,792 Mgal/d (22 percent) between 2000 and 2010, while the population increased by 2.82 million (18 percent), and total freshwater withdrawals decreased by more than 474 Mgal/d (7 percent) between 2005 and 2010, while the population increased by 0.88 million (8 percent). The recent trend of decreases in freshwater withdrawals is a result of increased rainfall during this period, the development and use of alternative water sources, water conservation efforts, more conservative regulations and mandates, changes in economic conditions, and losses of irrigated lands. Fresh-water withdrawals for public supply, agricultural self-supplied use, and commercial-industrial-mining self-supplied use all decreased between 2000 and 2010 and between 2005 and 2010, whereas freshwater withdrawals for domestic self-supplied use, recreational-landscape irrigation use, and power generation use either remained the same or changed slightly during the decade. The use of highly mineralized groundwater (referred to as nonpotable water) as a source of drinking water has increased in Florida. Nonpotable water use for public supply has increased from nearly 2 Mgal/d in 1970 to about 165 Mgal/d in 2010. Nonpotable water is either blended or treated to meet drinking-water standards and is mostly used along the east and west coasts of central and southern Florida. The use of reclaimed wastewater increased from about 206 Mgal/d in 1986 to nearly 659 Mgal/d in 2010. More than three-quarters (79 percent) of reclaimed wastewater in 2010 was used to supplement potable-quality water withdrawals for urban irrigation, agricultural irrigation, and industrial use.

Florida↗