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At least 829 records · Page 46Linked to original sources
USGS1998

Yields and trends of nutrients and total suspended solids in nontidal areas of the Chesapeake Bay basin, 1985-96

Excessive concentrations of nutrients and suspended solids in water adversely affect water quality in the Chesapeake Bay. High levels of nutrients in the Bay result in algal blooms and suspended solids reduce water clarity, both of which decrease the amount of light reaching submerged aquatic vegetation (SAV). The die off and decomposition of algae and SAV deplete oxygen supplies in the water. Low dissolved oxygen (DO) levels (less than 5.0 milligrams per liter for aquatic life, U.S. Environmental Protection Agency, 1986) can lead to fish kills and stress other living resources in the Bay. In 1987, the Chesapeake Bay Agreement called for a 40-percent reduction in the amount of controllable nutrients reaching the Chesapeake Bay by the year 2000. This goal was based on results of computer simulations that predicted that periods of low DO would be reduced or eliminated if nutrient inputs to the Bay were reduced by that amount. In an effort to achieve that goal, nutrient-reduction strategies, including banning phosphate detergents, upgrading sewagetreatment plants, controlling runoff from agricultural and urban areas, and preserving forest and wetland areas (Zynjuk, 1995), were implemented in many areas of the basin to help reduce nutrient inputs to the Bay. In 1997, a basinwide reevaluation of the 40-percent reduction goal was initiated to determine if that goal is achievable and to identify and document any changes in water quality and living resources in response to nutrient-reduction strategies. In support of this reevaluation, the U.S. Geological Survey (USGS) designed a database and retrieved water-quality data from approximately 1,300 nontidal stream sites in the Chesapeake Bay Basin (Langland and others, 1995). At 84 of the 1,300 sites, where sufficient data were available, trends, yields, and annual loads of nutrients and suspended solids were estimated for 1985 through 1996. This report presents: (1) spatial distribution of available nutrient and suspended-solids data for the 84 sites, (2) yields of nutrients and total suspended solids, and (3) trends in concentrations of nutrients and total suspended solids. Results presented here are limited to analyses for total nitrogen (TN), nitrate nitrogen (NO3), total phosphorus (TP), and total suspended solids (TSS).

Water-Resources Investigations Report↗
USGS2006

Continuous hydrologic simulation and flood-frequency, hydraulic, and flood-hazard analysis of the Blackberry Creek watershed, Kane County, Illinois

Results of hydrologic model, flood-frequency, hydraulic model, and flood-hazard analysis of the Blackberry Creek watershed in Kane County, Illinois, indicate that the 100-year and 500-year flood plains range from approximately 25 acres in the tributary F watershed (a headwater subbasin at the northeastern corner of the watershed) to almost 1,800 acres in Blackberry Creek main stem. Based on 1996 land-cover data, most of the land in the 100-year and 500-year flood plains was cropland, forested and wooded land, and grassland. A relatively small percentage of urban land was in the flood plains. The Blackberry Creek watershed has undergone rapid urbanization in recent decades. The population and urbanized lands in the watershed are projected to double from the 1990 condition by 2020. Recently, flood-induced damage has occurred more frequently in urbanized areas of the watershed. There are concerns about the effect of urbanization on flood peaks and volumes, future flood-mitigation plans, and potential effects on the water quality and stream habitats. This report describes the procedures used in developing the hydrologic models, estimating the flood-peak discharge magnitudes and recurrence intervals for flood-hazard analysis, developing the hydraulic model, and the results of the analysis in graphical and tabular form. The hydrologic model, Hydrological Simulation Program-FORTRAN (HSPF), was used to perform the simulation of continuous water movements through various patterns of land uses in the watershed. Flood-frequency analysis was applied to an annual maximum series to determine flood quantiles in subbasins for flood-hazard analysis. The Hydrologic Engineering Center-River Analysis System (HEC-RAS) hydraulic model was used to determine the 100-year and 500-year flood elevations, and to determine the 100-year floodway. The hydraulic model was calibrated and verified using high water marks and observed inundation maps for the July 17-18, 1996, flood event. Digital maps of the 100-year and 500-year flood plains and the 100-year floodway for each tributary and the main stem of Blackberry Creek were compiled.

Scientific Investigations Report↗
USGS2015

Not putting all their eggs in one basket: bet-hedging despite extraordinary annual reproductive output of desert tortoises

Bet-hedging theory makes the counter-intuitive prediction that, if juvenile survival is low and unpredictable, organisms should consistently reduce short-term reproductive output to minimize the risk of reproductive failure in the long-term. We investigated the long-term reproductive output of an Agassiz's desert tortoise ( Gopherus agassizii ) population and conformance to a bet-hedging strategy of reproduction in an unpredictable but comparatively productive environment. Most females reproduced every year, even during periods of low precipitation and poor germination of food plants, and the mean percentage of reproducing females did not differ significantly on an annual basis. Although mean annual egg production (clutch size × clutch frequency) differed significantly among years, mean clutch size and mean clutch frequency remained relatively constant. During an El Niño year, mean annual egg production and mean annual clutch frequency were the highest ever reported for this species. Annual egg production was positively influenced by maternal body size but clutch size and clutch frequency were not. Our long-term results confirm earlier conclusions based on short-term research that desert tortoises have a bet-hedging strategy of producing small clutches almost every year. The risk of long-term reproductive failure is minimized in unpredictable environments, both through time by annually producing multiple small clutches over a long reproductive lifespan, even in years of low resource availability, and through space by depositing multiple annual clutches in different locations. The extraordinary annual reproductive output of this population appears to be the result of a typically high but unpredictable biomass of annual food plants at the site relative to tortoise habitat in dryer regions. Under the comparatively productive but unpredictable conditions, tortoises conform to predictions of a bet-hedging strategy of reproduction with relatively small but consistent clutch sizes.

Biological Journal of the Linnean Society↗
USGS2006

Surface-Water Quality and Nutrient Loads in the Nepaug Reservoir Watershed, Northwestern Connecticut, 1999-2001

Water quality was characterized at three tributary watersheds to the Nepaug Reservoir-Nepaug River, Phelps Brook, and Clear Brook-from October 1998 through September 2001 to document existing water-quality conditions and evaluate potential future effects of the removal of sand and gravel from areas of the watershed. Some removal operations may include removal of vegetation and top soil and steepening of slopes. Routine water samples collected monthly in all three watersheds were analyzed for nutrients, organic carbon, major ions, and fecal indicator bacteria. Results of the analyses indicate that, in general, the water quality in all three tributary watersheds is good and meets standards established for drinking-water supplies for nitrate, but does not always meet contact-recreation standards for bacteria. Median concentrations of total nitrogen, total phosphorus, and total organic carbon were highest in the routine monthly samples from Phelps Brook and lowest from Clear Brook. Samples also were collected during selected storms to examine changes in concentrations of nutrients during periods of high streamflow. The maximum values measured for total nitrogen, total phosphorus, and total organic carbon were in storm samples from Clear Brook. The Nepaug River watershed delivered the largest loads of total nitrogen, total phosphorus, and total organic carbon to the reservoir. Yields of nutrients and organic carbon differed significantly from year to year and among the three watersheds. Yields of total nitrogen and total organic carbon were largest from Phelps Brook and smallest from Clear Brook. The yields of total phosphorus were largest from Nepaug River and smallest from Phelps Brook. In comparison to other watersheds in Connecticut, annual loads and yields from the three streams were lower than those of developed urban areas and comparable to those of other rural and forested basins. Delivery of nutrients and organic carbon to the reservoir took place mostly during the spring with the exception of those constituents delivered during Tropical Storm Floyd, a large fall storm.

Scientific Investigations Report↗
USGS2010

Development and Application of Regression Models for Estimating Nutrient Concentrations in Streams of the Conterminous United States, 1992-2001

Data collected for the U.S. Geological Survey National Water-Quality Assessment program from 1992-2001 were used to investigate the relations between nutrient concentrations and nutrient sources, hydrology, and basin characteristics. Regression models were developed to estimate annual flow-weighted concentrations of total nitrogen and total phosphorus using explanatory variables derived from currently available national ancillary data. Different total-nitrogen regression models were used for agricultural (25 percent or more of basin area classified as agricultural land use) and nonagricultural basins. Atmospheric, fertilizer, and manure inputs of nitrogen, percent sand in soil, subsurface drainage, overland flow, mean annual precipitation, and percent undeveloped area were significant variables in the agricultural basin total nitrogen model. Significant explanatory variables in the nonagricultural total nitrogen model were total nonpoint-source nitrogen input (sum of nitrogen from manure, fertilizer, and atmospheric deposition), population density, mean annual runoff, and percent base flow. The concentrations of nutrients derived from regression (CONDOR) models were applied to drainage basins associated with the U.S. Environmental Protection Agency (USEPA) River Reach File (RF1) to predict flow-weighted mean annual total nitrogen concentrations for the conterminous United States. The majority of stream miles in the Nation have predicted concentrations less than 5 milligrams per liter. Concentrations greater than 5 milligrams per liter were predicted for a broad area extending from Ohio to eastern Nebraska, areas spatially associated with greater application of fertilizer and manure. Probabilities that mean annual total-nitrogen concentrations exceed the USEPA regional nutrient criteria were determined by incorporating model prediction uncertainty. In all nutrient regions where criteria have been established, there is at least a 50 percent probability of exceeding the criteria in more than half of the stream miles. Dividing calibration sites into agricultural and nonagricultural groups did not improve the explanatory capability for total phosphorus models. The group of explanatory variables that yielded the lowest model error for mean annual total phosphorus concentrations includes phosphorus input from manure, population density, amounts of range land and forest land, percent sand in soil, and percent base flow. However, the large unexplained variability and associated model error precluded the use of the total phosphorus model for nationwide extrapolations.

Scientific Investigations Report↗
USGS2013

Suspended-sediment loads and reservoir sediment trap efficiency for Clinton Lake, Kansas, 2010-12

Continuous streamflow and turbidity data collected from October 1, 2010, to September 30, 2012, at a site upstream and downstream from Clinton Lake, Kansas, were used to compute the total suspended-sediment load delivered to and released from the reservoir as well as the sediment trap efficiency for the reservoir. Ongoing sedimentation is inhibiting the ability of Clinton Lake to serve several purposes including flood control, water supply, and recreation. The inflow suspended-sediment load was substantially larger than the outflow load and most of the suspended-sediment load was delivered during short-term, high-discharge periods. Respectively, the total 2-year inflow and outflow suspended-sediment loads were computed to be 44.4 and 1.49 million pounds. Sediment trap efficiency for the reservoir was estimated to be 97 percent. The mean annual suspended-sediment yield from the upstream basin was estimated to be 60,500 pounds per square mile. Because this study was completed during a drought, the estimated inflow suspended-sediment load and suspended-sediment yield likely are substantially less than what would occur during a period of average or above average precipitation and runoff.

Kansas↗
USGS2018

Shoreline erosion at selected areas along Lake Sharpe on the Lower Brule Reservation in South Dakota, 1966–2015

The Lower Brule Reservation in central South Dakota is losing land because of shoreline erosion along Lake Sharpe, a reservoir on the Missouri River, which has caused detrimental effects for the Lower Brule Sioux Tribe including losses of cultural sites, recreation access points, wildlife habitat, irrigated cropland, and landmass. To better understand and quantify shoreline erosion, the Lower Brule Sioux Tribe and the U.S. Geological Survey cooperated on a series of data-collection efforts and study of shoreline erosion along Lake Sharpe. Data collected or compiled for 1966–2015 were used to describe and quantify shoreline erosion along Lake Sharpe. The progression of shoreline erosion near the community of Lower Brule, South Dakota, was tracked by comparing current or recent aerial imagery with existing historical maps. At 33 evaluation lines along a 7-mile reach of Lake Sharpe shoreline near Lower Brule, cumulative change of shoreline from 1966 to 2010 ranged from about −224 feet of deposition to 770 feet of erosion. Photographic and location data were collected for this study to understand the processes affecting erosion and estimate erosion rates. Photographs were collected only in the 7-mile reach near Lower Brule, but locations of the bank over time were collected at the 7-mile reach and two additional reaches within the Lower Brule Reservation. Global navigation satellite system equipment was used in real-time kinematic mode to collect bank locations along three reaches of interest. Reach-length data were collected four times between November 2011 and November 2012. A small, unmanned aerial system (drone) was used to capture digital video along the shoreline of the 7-mile reach. Water-level fluctuations contribute to the number of wet-dry cycles experienced by the soils at the shoreline or bank. The soils present under the current (2017) location of the reservoir are predominantly terrace alluvium, consisting of sand and silt. Detailed soils data for Lyman County indicate that the dominant soil type along the southern part of the shoreline in the 7-mile reach is Bullcreek clay. Weather within the study area can affect the erosion rate. Air temperature can potentially affect erosion rates by freezing and thawing water and soils. Mean hourly wind speeds vary somewhat throughout the year but averaged 13.3 miles per hour. The direction of prevailing winds near Lower Brule indicates that there are several miles of fetch to build large waves. Annual erosion rates calculated or measured throughout this study varied by location. Long-term annual average erosion rates of the 7-mile reach, as calculated by image analysis, ranged from −5.1 feet per year (deposition) to 17.5 feet per year (erosion). Short-term annual erosion rates measured using global navigation satellite system equipment during 2010–12 ranged from about 0 to 31.7 feet per year for the 7-mile reach. Existing scour countermeasures have been effective variably. Fieldstone rip-rap seems to have stabilized the shoreline, whereas tree strips paralleling the shoreline seem to have slowed erosion.

South Dakota↗
USGS1995

Precipitation depth-duration and frequency characteristics for Antelope Valley, Mojave Desert, California

Methods to evaluate changes in the volume of storm runoff from drainage basins that are likely to be urbanized are needed by land-use planning agencies to establish criteria for the design of flood-control systems. To document the changes in runoff volume of basins that may be urbanized, nine small basins that are considered representative of varying hydrologic conditions in Antelope Valley, California, were selected for detailed study. Precipitation and stream-gaging stations were established and data were collected for the period 1990-93. The data collected at these U.S. Geological Survey stations were supplemented by data collected at 35 Long-term precipitation stations operated by the National Oceanic and Atmospheric Administration and the Los Angeles County Department of Public Works. These data will be used to calibrate and verify rainfall-runoff models for the nine basins. Results of the model runs will then be used as a guide for estimating basin runoff characteristics throughout Antelope Valley. Annual precipitation in Antelope Valley ranges from more than 20 inches in the mountains to less than 4 inches on the valley floor. Most precipitation in the valley falls during the months of December through March, but cyclonic storms in the fall and convectional storms in the summer sometimes occur. The duration of most storms ranges from 1 to 8 days, but most of the precipitation usually occurs within the first 2 days. Many parts of the valley have been affected by storms with precipitation depths that equal or exceed 0.60 inch per hour. The storms of January 1943 and March 1983 were the most intense storms of record, with recurrence intervals greater than 100 years in some parts of the valley. Depth-duration ratios were calculated by disaggregating daily total precipitation data for intervals of 1, 2, 3, 4, 6, 12, and 18 hours for storms that occurred during 1990-93. The hourly total precipitation data were then disaggregated at 5-minute intervals. A comparison of the depth-duration data collected during 1990-93 at the Geological Survey stations with the data collected at the other stations indicated that the 1990-93 data are not representative of historical storms. Therefore, depth-duration ratios developed using these data should be considered preliminary for use in disaggregating the historical hourly data for Antelope Valley. Annual maximum 24-hour precipitation records were used to calculate precipitation depth-frequency relations for 23 stations in the valley using the log Pearson type III distribution. These calculations indicate that the storms of January 1943 and March 1983 were the most intense of record in the valley with recurrence intervals greater than 100 years.

Water-Resources Investigations Report↗
USGS1997

Water Budget for the Iao Area, Island of Maui, Hawaii

Ground-water recharge is estimated as the residual component of a monthly water budget calculated using soil characteristics and long-term average rainfall, streamflow, irrigation, and pan-evaporation data. The water-budget components of rainfall, direct runoff, evapotranspiration, and ground-water recharge are defined seasonally, through the use of monthly data, and spatially by land-use and geohydrologic areas, through the use of a geographic information system model. The long-term average ground-water recharge for the Iao area was estimated for four scenarios using natural land-use, and using 1926-79, 1980-85, and 1986-95 land-use and irrigation data. The recharge rate for natural conditions is 34 million gallons per day, which is 34 percent of rainfall. The average annual ground-water recharge rate for 1926-79 conditions is 51 million gallons per day, which is 41 percent of the sum of rainfall and irrigation. The recharge rates for 1980-85 and 1986-95 conditions are 40 and 36 million gallons per day, which are 37 and 35 percent of rainfall plus irrigation, respectively.

Water-Resources Investigations Report↗
USGS1995

Simulation of streamflow and sediment transport in two surface-coal-mined basins in Fayette County, Pennsylvania

The Hydrological Simulation Program - Fortran (HSPF) was used to simulate streamflow and sediment transport in two surface-mined basins of Fayette County, Pa. Hydrologic data from the Stony Fork Basin (0.93 square miles) was used to calibrate HSPF parameters. The calibrated parameters were applied to an HSPF model of the Poplar Run Basin (8.83 square miles) to evaluate the transfer value of model parameters. The results of this investigation provide information to the Pennsylvania Department of Environmental Resources, Bureau of Mining and Reclamation, regarding the value of the simulated hydrologic data for use in cumulative hydrologic-impact assessments of surface-mined basins. The calibration period was October 1, 1985, through September 30, 1988 (water years 1986-88). The simulated data were representative of the observed data from the Stony Fork Basin. Mean simulated streamflow was 1.64 cubic feet per second compared to measured streamflow of 1.58 cubic feet per second for the 3-year period. The difference between the observed and simulated peak stormflow ranged from 4.0 to 59.7 percent for 12 storms. The simulated sediment load for the 1987 water year was 127.14 tons (0.21 ton per acre), which compares to a measured sediment load of 147.09 tons (0.25 ton per acre). The total simulated suspended-sediment load for the 3-year period was 538.2 tons (0.30 ton per acre per year), which compares to a measured sediment load of 467.61 tons (0.26 ton per acre per year). The model was verified by comparing observed and simulated data from October 1, 1988, through September 30, 1989. The results obtained were comparable to those from the calibration period. The simulated mean daily discharge was representative of the range of data observed from the basin and of the frequency with which specific discharges were equalled or exceeded. The calibrated and verified parameters from the Stony Fork model were applied to an HSPF model of the Poplar Run Basin. The two basins are in a similar physical setting. Data from October 1, 1987, through September 30, 1989, were used to evaluate the Poplar Run model. In general, the results from the Poplar Run model were comparable to those obtained from the Stony Fork model. The difference between observed and simulated total streamflow was 1.1 percent for the 2-year period. The mean annual streamflow simulated by the Poplar Run model was 18.3 cubic feet per second. This compares to an observed streamflow of 18.15 cubic feet per second. For the 2-year period, the simulated sediment load was 2,754 tons (0.24 ton per acre per year), which compares to a measured sediment load of 3,051.2 tons (0.27 ton per acre per year) for the Poplar Run Basin. Cumulative frequency-distribution curves of the observed and simulated streamflow compared well. The comparison between observed and simulated data improved as the time span increased. Simulated annual means and totals were more representative of the observed data than hourly data used in comparing storm events. The structure and organization of the HSPF model facilitated the simulation of a wide range of hydrologic processes. The simulation results from this investigation indicate that model parameters may be transferred to ungaged basins to generate representative hydrologic data through modeling techniques.

Pennsylvania↗
USGS2014

Estimates of groundwater recharge rates and sources in the East Mountain area, Eastern Bernalillo County, New Mexico, 2005-12

The U.S. Geological Survey, in cooperation with the Bernalillo County Public Works Division, has conducted a monitoring program in the East Mountain area of eastern Bernalillo County, New Mexico, since 2000 to better define the hydrogeologic characteristics of the East Mountain area and to provide scientific information that will assist in the sustainable management of water resources. This report presents estimates of groundwater recharge to the aquifers that supply water to a network of springs that discharged within the East Mountain area of eastern Bernalillo County during 2005–12. Chloride concentration, the mass ratio of chloride to bromide, and the stable isotope ratios of hydrogen and oxygen were used to estimate annual groundwater recharge rates and to identify the sources and timing of recharge to the aquifers in the East Mountain area. Groundwater recharge rates were estimated by using a chloride mass-balance (CMB) method applied to data from selected springs located in the study area. Eleven springs and four downgradient monitoring wells were sampled for this study. On the basis of chloride concentrations and the mass ratio of chloride to bromide, eight of the eleven sampled springs are considered representative of dilute groundwater recharged by meteoric water in the Sandia Mountains. Eight of the eleven springs sampled as part of this investigation are considered representative of dilute groundwater not influenced by nonmeteoric chloride sources on the basis of analysis of chloride concentrations and the mass ratio of chloride to bromide. Chloride concentrations at three of the sampled springs were likely affected by nonmeteoric chloride sources. Results of CMB calculations for the eight springs with Cl:Br ratios and chloride concentrations within the range of dilute groundwater (not influenced by nonmeteoric chloride sources) indicated that between about 5.5 and 23 percent of annual precipitation recharges the groundwater system. The variation in estimated recharge rates indicated that the mechanisms for recharge and groundwater movement in the East Mountain area are complex and that factors such as climate variability, the extent and interconnection of structural features such as faults and fractures, and potential solution enhancement of the aquifers all play important roles in the rates and timing of recharge. Stable isotope data from springs and snowpacks sampled in the East Mountain area were compared with local, regional, and global meteoric water lines and were analyzed along with values representing the stable isotope composition of winter precipitation and summer monsoonal rains. Results of the stable isotope analysis from springs in this study suggested that winter precipitation is the primary source of groundwater recharge to the aquifers supplying the springs, but there is a component of more isotopically enriched precipitation being recharged as well, likely from summer monsoonal rains. Specific conductance, groundwater-level hydrographs, snowpack chemistry, and snow-water equivalent data were used to inform the analyses and corroborate the findings of the CMB and stable isotope results.

New Mexico↗
USGS2019

Evaluation of recommended revisions to Bulletin 17B

For the past 36 years, Bulletin 17B, published by the Interagency Committee on Water Data in 1982, has guided flood-frequency analyses in the United States. During this period, much has been learned about both hydrology and statistical methods. In keeping with the tradition of periodically updating the Bulletin 17B guidelines in light of advances in our understanding and methods, the Hydrologic Frequency Analysis Work Group (HFAWG) was charged by the Subcommittee on Hydrology (SOH) of the Advisory Committee on Water Information (ACWI) to consider possible updates to Bulletin 17B. The purpose of this report is to consider the statistical performance of possible revisions to Bulletin 17B procedures. Of particular interest are procedures designed to accommodate more general forms of flood information. The concern is how the proposed procedures would affect the precision, accuracy and robustness of flood-frequency estimates. The investigations reported here focus on techniques for the following: incorporating information related to historical flooding that occurred outside the period of systematic streamgaging; and identification of potentially influential low floods (PILFs). The proposed changes, which mostly involve generalizing Bulletin 17B’s method-of-moments procedures by using the Expected Moments Algorithm (EMA), are relatively modest, at least in the sense that they would not affect the main features of Bulletin 17B. The proposed methods include the following: continued use of the log-Pearson Type 3 (LP3) distribution; continued use of the Method-of-Moments fitting method applied to the logarithms of annual-peak-flow data; and a generalization of the Grubbs-Beck test used in Bulletin 17B to identify low outliers. The new multiple Grubbs-Beck test is sensitive to multiple PILFs. The hydrological literature already provides extensive support for the theory behind the proposed changes. The remaining question is practical: How well do the proposed methods perform under typical and realistic conditions and, specifically, with difficult records occasionally encountered in practice? In order to answer these questions, the HFAWG commissioned the work reported here. The following four major sets of results are provided: Monte Carlo simulations of fitting procedures employing data drawn from simulated LP3 populations; Monte Carlo simulations of fitting procedures employing data drawn from non-LP3 populations that were selected to reflect likely deviations of flood series from LP3 distributions, based on the experience of HFAWG members; a direct comparison of the fitted LP3 distributions for 82 real “test sites” identified by an independent data group as both “typical” and “challenging” for flood-frequency estimation; and simulations of fitting procedures using records obtained by resampling with replacement from the longest of the 82 test-site records. Collectively, these studies provide a reasonably comprehensive, valid, and robust assessment of the properties of the Bulletin 17B methods and proposed alternatives. The experiments and analysis indicate that the flood quantile estimators, proposed as a revision of Bulletin 17B, do the following: perform generally as well as, and in some cases much better than, Bulletin 17B estimators in terms of the mean square error of flood quantiles estimates; allow for incorporation and efficient statistical treatment of broader classes of flood-frequency data and information, including historical information, binomial data and interval data; and generally confirm studies and the theoretical findings reported in the hydrological literature that would support use of updated estimation procedures that have been developed since Bulletin 17B was published.

Open-File Report↗
USGS1981

Sediment transport and effective discharge of the North Platte, South Platte, and Platte Rivers in Nebraska

Sediment discharge was computed for four locations along the North Platte, South Platte, and the Platte Rivers between North Platte and Grand Island, Nebraska in order to determine the effective discharge. The total-sediment discharge was computed by the Colby method and modified Einstein method so that comparisons could be made with the measured total-sediment discharge. The results agreed closely. The Colby method is the simplest and most convenient to use. The mean annual total-sediment discharge for the four sites investigated ranged from 150 tons per day for the South Platte River at North Platte to 1,260 tons per day for the Platte River near Grand Island. The effective discharge at the sites ranged from 41 to 158 cubic meters per second. The probability of the effective discharge being equaled or exceeded ranged from 1 to 30 percent for the four sites. (USGS)

Open-File Report↗
USGS1999

Estimates of ground-water discharge as determined from measurements of evapotranspiration, Ash Meadows area, Nye County, Nevada

Ash Meadows is one of the major discharge areas within the regional Death Valley ground-water flow system of southern Nevada and adjacent California. Ground water discharging at Ash Meadows is replenished from inflow derived from an extensive recharge area that includes the eastern part of the Nevada Test Site (NTS). Currently, contaminants introduced into the subsurface by past nuclear testing at NTS are the subject of study by the U.S. Department of Energy's Environmental Restoration Program. The transport of any contaminant in contact with ground water is controlled in part by the rate and direction of ground-water flow, which itself depends on the location and quantity of ground water discharging from the flow system. To best evaluate any potential risk associated with these test-generated contaminants, studies were undertaken to accurately quantify discharge from areas downgradient from the NTS. This report presents results of a study to refine the estimate of ground-water discharge at Ash Meadows. The study estimates ground-water discharge from the Ash Meadows area through a rigorous quantification of evapotranspiration (ET). To accomplish this objective, the study identifies areas of ongoing ground-water ET, delineates unique areas of ET defined on the basis of similarities in vegetation and soil-moisture conditions, and computes ET rates for each of the delineated areas. A classification technique using spectral-reflectance characteristics determined from satellite images recorded in 1992 identified seven unique units representing areas of ground-water ET. The total area classified encompasses about 10,350 acres dominated primarily by lush desert vegetation. Each unique area, referred to as an ET unit, generally consists of one or more assemblages of local phreatophytes. The ET units identified range from sparse grasslands to open water. Annual ET rates are computed by energy-budget methods from micrometeorological measurements made at 10 sites within six of the seven identified ET units. Micrometeorological data were collected for a minimum of 1 year at each site during 1994 through 1997. Evapotranspiration ranged from 0.6 foot per year in a sparse, dry saltgrass environment to 8.6 feet per year over open water. Ancillary data, including water levels, were collected during this same period to gain additional insight into the evapotranspiration process. Water levels measured in shallow wells showed annual declines of more than 10 feet and daily declines as high as 0.3 foot attributed to water losses associated with evapotranspiration. Mean annual ET from the Ash Meadows area is estimated at 21,000 acre-feet. An estimate of ground-water discharge, based on this ET estimate, is presented as a range to account for uncertainties in the contribution of local precipitation. The estimates given for mean annual ground-water discharge range from 18,000 to 21,000 acre-feet. The low estimate assumes a large contribution from local precipitation in computed ET rates; whereas, the high estimate assumes no contribution from local precipitation. The range presented is only slightly higher than previous estimates of ground-water discharge from the Ash Meadows area based primarily on springflow measurements.

Nevada↗
USGS2005

Vulnerability of production wells in the Potomac-Raritan-Magothy aquifer system to saltwater intrusion from the Delaware River in Camden, Gloucester, and Salem Counties, New Jersey

The Potomac-Raritan-Magothy aquifer system is hydraulically connected to the Delaware River in parts of Camden and Gloucester Counties, New Jersey, and has more limited contact with the river in Salem County, New Jersey. The aquifer system is used widely for water supply, and 122 production wells that are permitted by the New Jersey Department of Environmental Protection to pump more than 100,000 gallons per year in the three counties are within 2 miles of the river. During drought, saltwater may encroach upstream from the Atlantic Ocean and Delaware Bay to areas where the aquifer system is recharged by induced infiltration through the Delaware River streambed. During the drought of the mid-1960's, water with a chloride concentration in excess of potability standards (250 mg/L (milligrams per liter)) encroached into the reach of the river that recharges the aquifer system. The vulnerability of the major production wells in the area to similar saltwater encroachment in the future is a concern to water managers. This vulnerability was evaluated by investigating two scenarios: (1) a one-time recurrence of the conditions approximating those that occurred in the1960's, and (2) the recurrence of those same conditions on an annual basis. Results of ground-water-flow simulation in conjunction with particle tracking and one-dimensional transport analysis indicate that the wells that are most vulnerable to saltwater intrusion are those in the Morris and Delair well fields in Camden County. A single 30-day event during which the concentration of dissolved chloride or sodium exceeds 2,098 mg/L or 407 mg/L, respectively, in the Delaware River would threaten the potability of water from these wells, given New Jersey drinking-water standards of 250 mg/L for dissolved chloride and 50 mg/L for dissolved sodium. This chloride concentration is about six times that observed in the river during the 1960's drought. An annually occurring 1-month event during which the concentrations of dissolved chloride or sodium in the river exceeds 1,818 mg/L or 358 mg/L, respectively, would threaten the potability of water from these wells. Wells outside the Morris and Delair well fields are substantially less vulnerable to the intermittent saltwater intrusion that was simulated.

New Jersey↗
USGS2009

Hydrologic characterization for Spring Creek and hydrologic budget and model scenarios for Sheridan Lake, South Dakota, 1962-2007

The U.S. Geological Survey cooperated with South Dakota Game, Fish and Parks to characterize hydrologic information relevant to management of water resources associated with Sheridan Lake, which is formed by a dam on Spring Creek. This effort consisted primarily of characterization of hydrologic data for a base period of 1962 through 2006, development of a hydrologic budget for Sheridan Lake for this timeframe, and development of an associated model for simulation of storage deficits and drawdown in Sheridan Lake for hypothetical release scenarios from the lake. Historically, the dam has been operated primarily as a 'pass-through' system, in which unregulated outflows pass over the spillway; however, the dam recently was retrofitted with an improved control valve system that would allow controlled releases of about 7 cubic feet per second (ft3/s) or less from a fixed depth of about 60 feet (ft). Development of a hydrologic budget for Sheridan Lake involved compilation, estimation, and characterization of data sets for streamflow, precipitation, and evaporation. The most critical data need was for extrapolation of available short-term streamflow records for Spring Creek to be used as the long-term inflow to Sheridan Lake. Available short-term records for water years (WY) 1991-2004 for a gaging station upstream from Sheridan Lake were extrapolated to WY 1962-2006 on the basis of correlations with streamflow records for a downstream station and for stations located along two adjacent streams. Comparisons of data for the two streamflow-gaging stations along Spring Creek indicated that tributary inflow is approximately proportional to the intervening drainage area, which was used as a means of estimating tributary inflow for the hydrologic budget. Analysis of evaporation data shows that sustained daily rates may exceed maximum monthly rates by a factor of about two. A long-term (1962-2006) hydrologic budget was developed for computation of reservoir outflow from Sheridan Lake for the historical pass-through operating system. Two inflow components (stream inflow and precipitation) and one outflow component (evaporation) were considered. The hydrologic budget uses monthly time steps within a computational year that includes two 6-month periods - May through October, for which evaporation is accounted for, and November through April, when evaporation is considered negligible. Results indicate that monthly evaporation rates can substantially exceed inflow during low-flow periods, and potential exists for outflows to begin approaching zero-flow conditions substantially prior to the onset of zero-inflow conditions, especially when daily inflow and evaporation are considered. Results also indicate that September may be the month for greatest potential benefit for enhancing fish habitat and other ecosystem values in downstream reaches of Spring Creek with managed releases of cool water. Computed monthly outflows from Sheridan Lake for September are less than 1.0 ft3/s for 8 of the 44 years (18 percent) and are less than 2.0 ft3/s for 14 of the 44 years (32 percent). Conversely, none of the computed outflows for May are less than 2.0 ft3/s. A short-term (July through September 2007) data set was used to calculate daily evaporation from Sheridan Lake and to evaluate the applicability of published pan coefficients. Computed values of pan coefficients of approximately 1.0 and 1.1 for two low-flow periods are larger than the mean annual pan coefficient of 0.74 for the area that is reported in the literature; however, the computed values are consistent with pan coefficients reported elsewhere for similar late summer and early fall periods. Thus, these results supported the use of variable monthly pan coefficients for the long-term hydrologic budget. A hydrologic model was developed using the primary components of the hydrologic budget and was used to simulate monthly storage deficits and drawdown for Sheridan Lake using hypothetical

South Dakota↗
USGS2019

Assessing potential effects of highway and urban runoff on receiving streams in total maximum daily load watersheds in Oregon using the stochastic empirical loading and dilution model

The Stochastic Empirical Loading and Dilution Model (SELDM) was developed by the U.S. Geological Survey (USGS) in cooperation with the Federal Highway Administration to simulate stormwater quality. To assess the effects of runoff, SELDM uses a stochastic mass-balance approach to estimate combinations of pre-storm streamflow, stormflow, highway runoff, event mean concentrations (EMCs) and stormwater constituent loads from a site of interest. In addition, SELDM can be used to assess the effects of stormwater Best Management Practices (BMPs), which are designed to mitigate the adverse effects of runoff into a waterbody. Adverse effects of stormwater on receiving waters are one of the greatest unsolved water-quality problems Nationwide. State DOTs, municipalities, Federal facilities, and private property owners who manage impervious surfaces need information about the potential magnitude of their contributions and the potential effectiveness of methods to mitigate the adverse effects of runoff. Because the efficacy of at-site controls are limited, information about the potential effectiveness of alternative strategies is needed. The USGS, in cooperation with the Oregon Department of Transportation (ODOT), conducted a study to research methods in which SELDM can be used to enhance the efficiency of ODOT’s stormwater program, support the development of a stormwater banking program, and meet environmental goals. Results can be used to develop a strategic, systems-level approach to stormwater management by considering entire watersheds instead of individual road crossings. Two watersheds, Bear Creek and Mill Creek, in western Oregon were selected for analysis. Within each watershed, seven road crossings were selected for demonstrating the utility of SELDM in nested basins. Precipitation statistics, pre-storm streamflow, runoff coefficients, and hydrograph recession factors were calculated for each location and used in SELDM to simulate flow, water-quality concentrations, and constituent loads in the upstream basin, from the highway (or developed area), and downstream from the road crossing. Three water-quality constituents were selected for modeling: suspended-sediment concentration (SSC), total phosphorus (TP), and total copper (TCu). Using water-quality transport curves, the relations between streamflow and SSC and between streamflow and TP were simulated. Concentrations of TCu were simulated by configuring a linear relation between SSC and TCu. A generic BMP was simulated using the median treatment statistics for flow reductions, hydrograph extensions, concentration reductions, and minimum irreducible concentrations from nine BMP categories with data from the 2012 International BMP database. Five simulation scenarios were modeled for demonstrative purposes. These simulations were used to evaluate potential effects of different watershed properties, water-quality inputs, and stormwater mitigation measures. Instream EMCs were compared to hypothetical water-quality criteria for suspended sediment, total phosphorus, and total copper to demonstrate the concept of water-quality risk analysis. For all five scenarios, it was assumed that highway runoff concentrations were independent of location or average annual daily traffic. These five scenarios are as follows: • Simulation Scenario 1—Natural Conditions (hereafter Simulation Scenario 1) represents conditions in an undeveloped watershed. This scenario demonstrates that the strategic placement of a hypothetical road crossing within a watershed could be used to avoid exceeding water-quality standards of TP and SSC, but that no location choice results in meeting TCu standards. Implementation of BMP had the most pronounced effects on downstream water-quality constituent EMCs at road crossings with the highest ratio of highway catchment area to upstream drainage area, but the largest effect of BMP treatment on mean annual load is based on highway catchment area alone. • Simulation Scenario 2—Current Conditions (hereafter Simulation Scenario 2) represents current watershed conditions, where all developed area upstream from the road crossing was modeled as a highway and combined with the undeveloped part of the upstream drainage area (scenario 2A) and where the output from scenario 2A is used for the upstream area (developed area and the undeveloped area), and where the road crossing is added as usual (scenario 2B). Scenario 2 results indicate that attaining water-quality standards is more difficult with upstream developed areas. Specific road-crossing sites can be selected to achieve the fewest water-quality exceedances per year, but water-quality targets are not met without BMP implementation, and in some instances are not achievable even with BMP implementation. Results from this scenario also serve to quantify the upper limit of constituent reduction if funding were available to implement BMPs to large areas of development, and to quantify how much area would need BMP implementation to achieve water-quality targets. • Simulation Scenario 3—Alternative Road Layouts (hereafter Simulation Scenario 3) was designed to assess the sensitivity of SELDM to various road layouts. In this scenario, different highway configurations were superimposed at one road crossing. Results indicate that downstream waterquality constituent EMCs did not exhibit much variation, but annual water-quality constituent loads varied considerably. • Simulation Scenario 4—Varying Road Width (hereafter Simulation Scenario 4) was designed to assess the sensitivity of SELDM to road width. Similar to scenario 3, the results indicate little variation in downstream water-quality constituent EMCs, but annual water-quality constituent loads increased in proportion to road width. • Simulation scenario 5—Changes to Impervious Area (hereafter Simulation Scenario 5) was designed to investigate the effects of changing amounts of imperviousness upstream from the road crossing. Results indicate that the downstream water-quality constituent EMCs are highly correlated with the percentage of impervious area upstream.

Oregon↗
USGS2001

Channel-bed elevation changes downstream from large reservoirs in Kansas

Channel-bed elevation changes were assessed downstream from 24 large Federal reservoirs in Kansas using information from U.S. Geological Survey streamflow-gaging stations. Changes in river/stream stage associated with mean annual discharge indicated that channel-bed lowering had occurred downstream from most of the reservoirs. The net decrease in channel-bed elevation ranged from less than 1 foot to slightly more than 9 feet. The magnitude of channel-bed lowering downstream from the reservoirs likely was related to the composition of the channel bed.

Kansas↗