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Velocity bias induced by flow patterns around ADCPs and associated deployment platforms

Velocity measurements near the Acoustic Doppler Current Profiler (ADCP) are important for mapping surface currents, measuring velocity and discharge in shallow streams, and providing accurate estimates of discharge in the top unmeasured portion of the water column. Improvements to ADCP performance permit measurement of velocities much closer (5 cm) to the transducer than has been possible in the past (25 cm). Velocity profiles collected by the U.S. Geological Survey (USGS) with a 1200 kHz Rio Grande Zedhead ADCP in 2002 showed a negative bias in measured velocities near the transducers. On the basis of these results, the USGS initiated a study combining field, laboratory, and numerical modeling data to assess the effect of flow patterns caused by flow around the ADCP and deployment platforms on velocities measured near the transducers. This ongoing study has shown that the negative bias observed in the field is due to the flow pattern around the ADCP. The flow pattern around an ADCP violates the basic assumption of flow homogeneity required for an accurate three-dimensional velocity solution. Results, to date (2014), have indicated velocity biases within the measurable profile, due to flow disturbance, for the TRDI 1200 kHz Rio Grande Zedhead and the SonTek RiverSurveyor M9 ADCPs. The flow speed past the ADCP, the mount and the deployment platform have also been shown to play an important role in the magnitude and extent of the velocity bias.

Conference Paper↗

Water quality and landscape processes of four watersheds in eastern Puerto Rico

Humid tropical regions occupy about a quarter of Earth's land surface, yet they contribute a substantially higher fraction of the water, solutes, and sediment discharged to the world's oceans. Nearly half of Earth's population lives in the tropics, and development stresses can potentially harm soil resources, water quality, and water supply and in addition increase landslide and flood hazards. Owing to Puerto Rico's steep topography, low water storage capacity, and dependence on trade-wind precipitation, the island's people, ecosystems, and water supply are vulnerable to extreme weather such as hurricanes, floods, and droughts. Eastern Puerto Rico offers a natural laboratory for separating geologic and land-cover influences from regional- and global-scale influences because of its various bedrock types and the changing land cover surrounding intact, mature forest of the Luquillo Experimental Forest. Accordingly, a multiyear assessment of hydrological and biogeochemical processes was designed to develop an understanding of the effects of these differences on local climate, streamflow, water quality, and ecosystems, and to form the basis for a long-term and event-based program of climate and hydrologic monitoring. Because infrequent, large storms play a major role in this landscape, we focused on high-runoff events, sampling 263 storms, including all major hurricanes from 1991 through 2005. The largest storms have profound geomorphic consequences, such as landslides, debris flows, deep gullying on deforested lands, excavation and suspension of sediment in stream channels, and delivery of a substantial fraction of annual stream sediment load. Large storms sometimes entrain ocean foam and spray causing high concentrations of seasalt-derived constituents in stream waters during the storm. Past deforestation and agricultural activities in the Cayaguás and Canóvanas watersheds accelerated erosion and soil loss, and this material continues to be remobilized during large storms. Nearly 5,000 routine and event samples were analyzed for parameters that allow determination of denudation rates based on suspended and dissolved loads; 860 of these samples were analyzed for a comprehensive suite of chemical constituents. The rivers studied are generally similar in water-quality characteristics, and windward or leeward aspect appears to exert a stronger influence on water quality than geology or land cover. Of samples analyzed for comprehensive chemistry and for sediment, 543 were collected at runoff rates greater than 1 millimeter per hour, 256 at rates exceeding 10 millimeters per hour, and 3 at rates exceeding 90 millimeters per hour. Streams have rarely been sampled during events with such high runoff rates. Rates of physical and chemical weathering are especially high, and physical denudation rates, forested watersheds included, are considerably greater than is expected for a steady-state system. The elevated physical erosion drives an increased particulate organic carbon flux, one that is large, important to the carbon cycle, and sustainable, because soil-carbon regeneration is rapid. The 15-year Water, Energy, and Biogeochemical Budget dataset, which includes discharge, field parameters, suspended sediment, major cations and anions, and nutrients, is available from the U.S. Geological Survey's National Water Information System (http://waterdata.usgs.gov/nwis). The dataset provides a baseline for characterizing future environmental change and will improve our understanding of the interdependencies of land, water, and biological resources and their responses to changes in climate and land use. Because eastern Puerto Rico resembles many tropical regions in terms of geology and patterns of development, implications from this study are transferable to other tropical regions facing deforestation, rapid land-use change, and climate change.

Professional Paper↗

Assessment of hydrogeologic terrains, well-construction characteristics, groundwater hydraulics, and water-quality and microbial data for determination of surface-water-influenced groundwater supplies in West Virginia

In January 2014, a storage tank leaked, spilling a large quantity of 4-methylcyclohexane methanol into the Elk River in West Virginia and contaminating the water supply for more than 300,000 people. In response, the West Virginia Legislature passed Senate Bill 373, which requires the West Virginia Department of Health and Human Resources (WVDHHR) to assess the susceptibility and vulnerability of public surface-water-influenced groundwater supply sources (SWIGS) and surface-water intakes statewide. In response to this mandate for reassessing SWIGS statewide, the U.S. Geological Survey (USGS), in cooperation with the WVDHHR, Bureau of Public Health, Office of Environmental Health Services, compiled available data and summarized the results of previous groundwater studies to provide the WVDHHR with data that could be used as part of the process for assessing and determining SWIGS. Existing geologic, hydrologic, well-construction, water-quality, and other related data and information from previous U.S. Geological Survey (USGS) hydrogeologic studies and the USGS National Water Information System (NWIS) database, in conjunction with data from the West Virginia Bureau for Public Health (WVBPH) Department of Health and Human Resources (WVDHHR) and the West Virginia Department of Environmental Protection database and files, were collected, compiled, and analyzed to help the WVDHHR to better assess public groundwater supply wells that may meet the definition of a surface-water-influenced- groundwater supply (SWIGS). In this study, measures of intrinsic susceptibility, which are characterized by the physical properties that affect the ease with which water moves through the unsaturated zone and, subsequently, into the saturated zone within an aquifer, showed that karst limestone aquifers are the aquifers most intrinsically susceptible to contamination within the State of West Virginia. Karst limestone aquifers are present within Cambrian- and Ordovician-age formations within West Virginia’s eastern panhandle and in Mississippian-age limestones within the Greenbrier River valley. Solution development within these limestone aquifers allows rapid recharge and flow of groundwater within the aquifer, both of which allow surface contaminants to easily enter the aquifer and travel long distances in a short period of time. Alluvial aquifers bordering the Ohio River in western West Virginia are also potentially highly susceptible to contamination because these alluvial aquifers can receive significant recharge from the adjacent Ohio River. Any potential contaminants that may be present in the river have the potential to enter the aquifer and contaminate wells completed within the sand and gravel alluvial sediments within which the wells are completed. These same alluvial sediments, however, help to retard the movement of bacteria and other potentially pathogenic organisms, such as Cryptosporidia and Giardia lamblia , into the aquifer. As a result, samples from alluvial aquifers bordering the Ohio River and elsewhere within the State do not commonly test positive for indicator bacteria, such as total coliform, fecal coliform, or Escherichia coli ( E. coli ). The alluvial sediments do not, however, provide assimilative capacity with respect to water soluble compounds such as nitrate and certain volatile and semi-volatile organic compounds. Therefore, the Ohio River alluvial aquifers are highly susceptible to organic compounds present in the river or on the land surface near a well. These aquifers are also susceptible to nitrate contamination from fertilizers, pesticides, and manure, which are commonly used on the fertile agricultural soils present on terraces along the Ohio River. Abandoned-coal-mine aquifers, which are typically used as a source of groundwater in southern West Virginia, are moderately susceptible to contamination. The vast network of voids from mine entries provide vast storage for groundwater in abandoned mine aquifers, and fracturing of overburden strata, which is common in areas of past or current mining, can allow rapid infiltration of contaminants to the aquifer. Where streams cross over below-drainage underground coal mines, there is an increased potential for contamination of coal-mine aquifers. As a result, above-drainage underground coal mines, those mines that are present at an elevation above local tributary drainage, are probably less susceptible to contamination than are below-drainage underground coal mines. Public groundwater supplies in abandoned coal mines need to be evaluated on a case-by-case basis to assess the potential for recharge of contaminated surface water to enter below-drainage underground coal-mine aquifers and to assess potential hydraulic conductivity to nearby surface-water bodies, such as lakes, ponds, rivers, or streams. Fractured-rock aquifers compose an additional major type of aquifer within the State of West Virginia. Owing to their low permeability and their typically small groundwater capture areas, fractured-rock aquifers within the State of West Virginia typically have low susceptibility to contamination. However, there are exceptions, and wells completed in fractured-rock aquifers that are in close proximity to streams may be adversely affected by induced recharge from the stream. Where such systems are present, frequent bacterial testing of the source water can be used to ascertain the potential for microbial contamination of the aquifer. Intrinsic susceptibility alone does not fully predict whether or not a well is vulnerable to contamination, only that the hydrogeologic terrain is suitable for rapid transport of pathogenic organisms or chemical compounds to and within the aquifer. However, contaminants may or may not be present in the recharge water to an individual well or well field. Therefore, an assessment of potential contaminant sources, such as nearby gas wells, landfills, underground storage tanks, above ground storage tanks, major transportation corridors, surface or underground coal mines, and flood plains, is needed to assess vulnerability. The assessments need to be conducted on a case-by-case basis or, as has been done in this study, by collecting and compiling the number of potential contaminant sources that may be present in the source-water-protection area for an individual public groundwater supply source. Groundwater public-supply systems in areas of high intrinsic susceptibility and with a large number of potential contaminant sources within the recharge or source-water-protection area of individual wells or well fields are potentially vulnerable to contamination and probably warrant further evaluation as potential SWIGS. However, measures can be taken to educate the local population and initiate safety protocols and protective strategies to appropriately manage contaminant sources to prevent release of contaminants to the aquifer, therefore, reducing vulnerability of these systems to contamination. However, each public groundwater supply source needs to be assessed on an individual basis. Data presented in this report can be used to categorize and prioritize wells and springs that have a high potential for intrinsic susceptibility or vulnerability to contamination.

West Virginia↗

Central Colorado Assessment Project (CCAP)-Geochemical data for rock, sediment, soil, and concentrate sample media

This database was initiated, designed, and populated to collect and integrate geochemical data from central Colorado in order to facilitate geologic mapping, petrologic studies, mineral resource assessment, definition of geochemical baseline values and statistics, environmental impact assessment, and medical geology. The Microsoft Access database serves as a geochemical data warehouse in support of the Central Colorado Assessment Project (CCAP) and contains data tables describing historical and new quantitative and qualitative geochemical analyses determined by 70 analytical laboratory and field methods for 47,478 rock, sediment, soil, and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey (USGS) personnel and analyzed either in the analytical laboratories of the USGS or by contract with commercial analytical laboratories. These data represent analyses of samples collected as part of various USGS programs and projects. In addition, geochemical data from 7,470 sediment and soil samples collected and analyzed under the Atomic Energy Commission National Uranium Resource Evaluation (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) program (henceforth called NURE) have been included in this database. In addition to data from 2,377 samples collected and analyzed under CCAP, this dataset includes archived geochemical data originally entered into the in-house Rock Analysis Storage System (RASS) database (used by the USGS from the mid-1960s through the late 1980s) and the in-house PLUTO database (used by the USGS from the mid-1970s through the mid-1990s). All of these data are maintained in the Oracle-based National Geochemical Database (NGDB). Retrievals from the NGDB and from the NURE database were used to generate most of this dataset. In addition, USGS data that have been excluded previously from the NGDB because the data predate earliest USGS geochemical databases, or were once excluded for programmatic reasons, have been included in the CCAP Geochemical Database and are planned to be added to the NGDB.

Colorado↗

Using OTIS to model solute transport in streams and rivers

Solute transport in streams and rivers is governed by a suite of hydrologic and geochemical processes. Knowledge of these processes is needed when assessing the fate of contaminants that are released into surface waters. The study of solute fate and transport often is aided by solute transport models that mathematically describe the underlying processes. This fact sheet describes a model that considers One-Dimensional Transport with Inflow and Storage (OTIS). As shown by several example applications, OTIS may be used in conjunction with field-scale data to quantify hydrologic processes (advection, dispersion, and transient storage) and certain chemical reactions (sorption and first-order decay).

Fact Sheet↗

Hydroacoustic Current Meters for the Measurement of Discharge in Shallow Rivers and Streams

The U.S. Geological Survey (USGS) is evaluating the use of hydroacoustic current meters for making discharge measurements in shallow rivers and streams. The USGS historically has made discharge measurements in shallow rivers using mechanical, impellor-type current meters attached to a wading rod. The evaluation project has focused on three categories of hydroacoustic meters: an acoustic Doppler velocimeter (ADV) called a Flowtracker3, an acoustic Doppler velocity profiler (BoogieDopp), and bottom-tracking acoustic Doppler current profilers (ADCPs). The USGS role in this project includes providing USGS discharge-computation methods and algorithms to instrument manufacturers and evaluating instruments in the laboratory and field. An ADV (Flowtracker) designed for making discharge measurements in shallow rivers, has been tested in a USGS tow tank and was found to meet USGS calibration standards for mechanical, impellor-type current meters. The Flowtracker was field tested by USGS offices in five states; the tests were conducted by comparing discharge measurements made with the ADV to discharge measurements made with mechanical, impellor-type current meters. In general, the comparisons of Flowtracker performance to mechanical-meter results were favorable. An acoustic Doppler velocity profiler (BoogieDopp) is being evaluated for making discharge measurements in shallow rivers. The Boogiedopp will measure vertical velocity profiles at stationary positions across a channel, and the velocity profiles will be used to compute discharge. Discharge-computation software based on USGS methods and algorithms is under development for the acoustic Doppler velocity profiler. The USGS will evaluate bottom-tracking ADCPs from two manufacturers for making discharge measurements in shallow water. The bottom-tracking feature allows ADCPs to compute discharge from a moving platform as the platform moves across the channel.

Conference Paper↗

Hydrogeology, simulation of regional ground-water flow, and saltwater intrusion, Potomac-Raritan-Magothy Aquifer System, Northern Coastal Plain of New Jersey

The Potomac-Raritan-Magothy aquifer system in Middlesex and Monmouth Counties in the northern Coastal Plain of New Jersey consists primarily of unconsolidated Cretaceous sediments, which are divided into the upper and middle aquifers and confining units. These units, which strike northeastsouthwest along the Fall Line, dip and thicken to the southeast. The upper aquifer consists primarily of the Old Bridge Sand Member of the Magothy Formation, which is composed of coarse-grained sands, localized thin clay beds, and younger surficial sands and gravels in and near the outcrop. Transmissivity ranges from 1,760 to 19,400 ft 2 /d (feet squared per day) and tends to be higher in updip areas. Estimated withdrawals from the upper aquifer in the northern Coastal Plain were approximately 42 Mgal/d (million gallons per day) in 1986. Cones of depression whose centers range from 36 to 42 ft (feet) below sea level have developed as a result of these withdrawals. The upper aquifer is confined throughout most of the northern New Jersey Coastal Plain by clays and silts of the Cretaceous Woodbury Clay and Merchantville Formation and younger sediments of the Magothy Formation. This confining unit generally is greater than 200 ft thick. The simulated vertical hydraulic conductivity for the confining unit ranges from 8.4 x 10 -5 to 5.6 x 10 -3 feet per day; interpreted vertical hydraulic conductivities generally are lower except in southwestern Middlesex County, where the vertical hydraulic conductivities of the confining unit are higher. The middle aquifer consists primarily of the Farrington Sand Member of the Cretaceous Raritan Formation and surficial Holocene and Miocene sands and gravels in its outcrop area. It also can include the uppermost sands of the Cretaceous Potomac Group in parts of Monmouth County. The middle aquifer is composed of fine to coarse sand that contains some lignite and pyrite, and, locally, some clay beds. It pinches out in the northern part of Sayreville Township, near Raritan River. The transmissivity of the aquifer ranges from 2,140 to 13,800 ft 2/ d and tends to decrease in the northern part of the northern Coastal Plain of New Jersey where the aquifer thins. A poorly permeable confining unit composed mostly of clays and silts of the Woodbridge Clay Member of the Raritan Formation overlies the aquifer in most of this area. The confining unit generally is greater than 100 ft thick, although it thins and is sandy in the southwestern part of Middlesex County, where a good hydraulic connection exists between the middle and upper aquifers. Estimated withdrawals from the middle aquifer in the northern Coastal Plain were about 22 Mgal/d in 1986. These withdrawals have caused cones of depression whose centers range from 77 to 93 ft below sea level. A finite-difference, quasi-three-dimensional ground-water flow model was developed to simulate ground-water flow in the aquifer system. The confined and unconfined areas of the upper and middle aquifers were modeled as separate layers. The model was calibrated primarily by adjusting vertical hydraulic conductivity in the confining units and horizontal hydraulic conductivity in the aquifers, then matching simulated and measured groundwater levels for the period 1896-1986 and simulated and interpreted potentiometric surfaces under predevelopment conditions and in 1984. For the predevelopment period, the total flow into and out of the upper and middle aquifers is 35 and 21 Mgal/d, respectively. Recharge to the aquifer system is from direct recharge in the unconfined areas and from vertical leakage through overlying confining units. The main recharge areas are the topographically high areas in southwestern Middlesex County for both aquifers, in the eastern Sayreville area for the upper aquifer, and north of the Raritan River for the middle aquifer. Most ground water discharges to low-lying regional surface-water drains (streams), which flow into the South River. For 1984 transient conditions, the total ground-water flow into and out of the upper and middle aquifers is 61 and 34 Mgal/d, respectively. The largest amount of recharge is from direct recharge in the unconfined areas, but some recharge also is derived from vertical leakage through the Merchantville-Woodbury confining unit, captured ground-water discharge to streams, and induced inflow at artificial-recharge facilities. Regional flow is from recharge areas toward major cones of depression. Sensitivity analysis showed that the model was useful for representing flow in the system, especially in the confined-aquifer areas. Model representation of lateral and vertical boundary conditions was judged acceptable. Simulation results were less sensitive to changes in aquifer properties in the unconfined areas of the aquifers and to changes in storage in the confining units. Sensitivity analysis and calibration of hydraulic parameters and conditions showed that the distribution of hydraulic head was sensitive to changes in horizontal hydraulic conductivity in the aquifers, vertical hydraulic conductivity in the confining units, magnitudes of ground-water withdrawals, and initial hydraulic head in aquifer outcrop areas. Two scenarios were simulated to determine the effects of ground-water withdrawals from 1986 through 2019. For the scenario in which ground-water withdrawals increase to about 69 Mgal/d in the upper aquifer and 37 Mgal/d in the middle aquifer, centers of cones of depression are as deep as 100 ft below sea level in the upper aquifer and 170 ft below sea level in the middle aquifer. For this scenario, most of the additional water comes from captured surface-water discharge, induced cross-formational flow from overlying aquifers, and increases in induced flow from artificial-recharge areas. Induced flow from Raritan Bay also increases. For the scenario in which ground water withdrawals are reduced to 42.5 Mgal/d in the upper aquifer and 15 Mgal/d in the middle aquifer, water levels recover to above sea level nearly everywhere. In each aquifer, ground-water discharge to streams increases and induced flow through the confining units and from the overlying sediments decreases, and discharge of ground water to Raritan Bay in the upper aquifer exceeds the induced recharge from Raritan Bay. Reversal of ground-water gradients has caused saltwater intrusion in the two aquifers. Chloride concentrations in water from the upper aquifer in Keyport and Union Beach Boroughs were as high as 2,100 mg/L (milligrams per liter) in 1986. The intrusion has not increased significantly since well fields in the area were closed in the late 1970's. Elevated chloride concentrations also were measured in Keanesburg Borough in 1986. In both of these areas, saltwater has entered the upper aquifer from the Bay because of movement of the freshwater-saltwater interface in response to increasing ground-water withdrawals. Chloride concentrations in well-water samples from the middle aquifer were as high as 6,000 mg/L in Sayreville Borough in 1987; concentrations in samples from drive-point wells from the same aquifer near the Washington Canal, the main source of saltwater, were as high as 7,100 mg/L. The migration of the saltwater front at about 470 feet per year to the southeast is influenced mainly by a thinning of the middle aquifer, which constrains flow, and by the locations of regional cones of depression caused by groundwater withdrawals.

New Jersey↗

Summary and interpretation of geochemical maps for stream sediment and heavy mineral concentrate samples, Mount Hayes Quadrangle, eastern Alaska Range, Alaska

This report and accompanying maps summarize the results of geochemical exploration studies in the Mount Hayes quadrangle, Alaska. This is one of a series of maps and reports on the geological, geochemical, and geophysical studies of the quadrangle prepared as part of the Alaskan Mineral Resource Assessment Program (AMRAP) of the U.S. Geological Survey. These maps are part of the Mount Hayes l:250,000-scale folio. The geochemical studies were made in order to identify and define mineralized areas in the quadrangle and to aid in characterizing the nature of the mineral occurrences within these areas. The studies included the collection of composite samples of stream sediment or glacial debris and preparation of these samples, as described by O'Leary and others (1982), to yield a minus-80-mesh (0.2-mm) fraction and nonmagnetic heavy-mineral-concentrate fraction consisting of mineral grains having a specific gravity greater than 2.85. Samples were collected at 911 sites either from tributary streams or tributary glaciers with drainage basins ranging from 1 to 5 sq mi in area. The samples were analyzed for 30 elements by semiquantitative emission spectrography (O'Leary and others, 1982). The stream-sediment and glacial-debris samples also were analyzed for zinc by an atomic absorption method (Ward and others, 1969), and those results were used in preparing map A. The maps in this report show drainage basins in which the stream sediment or glacial debris contained anomalously high amounts of selected metals. The geologic base map aids in showing the geologic terranes of the quadrangle. The accompanying tables give frequencies and cumulative percents of the selected metals for all major geologic terranes within the quadrangle.

Alaska↗

Persistence and extirpation in invaded landscapes: patch characteristics and connectivity determine effects of non-native predatory fish on native salamanders

Studies have demonstrated negative effects of non-native, predatory fishes on native amphibians, yet it is still unclear why some amphibian populations persist, while others are extirpated, following fish invasion. We examined this question by developing habitat-based occupancy models for the long-toed salamander (Ambystoma macrodactylum) and nonnative fish using survey data from 1,749 water bodies across 470 catchments in the Northern Rocky Mountains, USA. We first modeled the habitat associations of salamanders at 468 fishless water bodies in 154 catchments where non-native fish were historically, and are currently, absent from the entire catchment. Wethen applied this habitat model to the complete data set to predict the probability of salamander occupancy in each water body, removing any effect of fish presence. Finally, we compared field-observed occurrences of salamanders and fish to modeled probability of salamander occupancy. Suitability models indicated that fish and salamanders had similar habitat preferences, possibly resulting in extirpations of salamander populations from entire catchments where suitable habitats were limiting. Salamanders coexisted with non-native fish in some catchments by using marginal quality, isolated (no inlet or outlet) habitats that remained fishless. They rarely coexisted with fish within individual water bodies and only where habitat quality was highest. Connectivity of water bodies via streams resulted in increased probability of fish invasion and consequently reduced probability of salamander occupancy.These results could be used to identify and prioritize catchments and water bodies where control measures would be most effective at restoring amphibian populations. Our approach could be useful as a framework for improved investigations into questions of persistence and extirpation of native species when non-native species have already become established.

Rocky Mountains↗

Level II scour analysis for Bridge 1 (CANATH00010001) on Town Highway 1, crossing Halls Stream, Canaan, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure CANATH00010001 on town highway 1 crossing Halls Stream, Canaan, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). A Level I study is included in Appendix E of this report. A Level I study provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and can be found in Appendix D. The site is in the White Mountain section of the New England physiographic province of northeastern Vermont in the town of Canaan. The 89.5-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the banks have tree, shrub and brush, and grass vegetation coverage. In the study area, Halls Stream has a sinuous channel with a slope of approx-imately 0.0012 ft/ft, an average channel top width of 109 ft and an average channel depth of 4 ft. The predominant channel bed materials are sand and gravel (D50 is 5.03 mm or 0.0165 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 27, 1994, indicated that the reach was laterally unstable. The lateral instability was evident due to a wide point-bar and cut-banks with undermining of bank material, slumping, fallen bank vegetation evident in the upstream channel. The town highway 1 crossing of Halls Stream is a 99-ft-long, two-lane bridge consisting of one 33-foot and two 31-foot concrete T-beam spans (Vermont Agency of Transportation, written communication, August 5, 1994). The bridge is supported by vertical, concrete abutments with spill-through embankments in front of each abutment wall. The channel is skewed approximately 10 degrees to the opening while the opening-skew-to-roadway is zero degrees. There are two piers in the channel at this site. Field notes and the channel survey at the bridge indicate that the streambed elevation is higher on the downstream right sides of each pier and lower on the downstream left sides. This asymmetrical streambed condition suggests a flow attack angle may influence scour on each pier. Furthermore, field observations suggest that the flow attack angle is higher for the right pier (pier 2) than the left pier (pier 1). The scour protection measures at the site were type-2 stone fill (less than 36 inches diameter) on both upstream banks and both downstream road embankments. Type-3 stone fill (less than 48 inches diameter) was found on the spill-through slopes of each abutment and both downstream banks. The stone fill protection on the spill-through embankment of the right abutment was noted as slumped with some of the fill material evident in the channel immediately downstream of the bridge. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows ranged from 8.0 to 8.8 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 8.9 to 17.3 ft. The worst-case abutment scour occurred at the 500-year discharge. For the two piers, scour ranged from 11.1 to 15.8. The worst-case pier scour occurred for pier2 at the incipient overtopping discharge. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particle-size distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Vermont↗

Urban growth and the water regimen

The continuing growth and concentration of population and industry in urban and suburban areas in recent decades has caused a complex merging of social, economic, and physical problems, The interrelationships of man and his use and development of the land and water resources is a particularly significant aspect of urbanization, but there has been relatively little study to date of the effect of urban man upon natural hydrologic conditions. As urban man changes an area from one of field and forest to one of buildings and streets, he covers land where water once entered the soil, and thus creates or aggravates problems of drainage, including storm-water runoff. As he requires increasing amounts of water for home and factory, he drills deeper wells, and builds longer aqueducts and larger dams and reservoirs. As he disposes of un- wanted waste materials, he either treats them by using water or pollutes the receiving body of water. As he dredges and deepens coastal streams carrying salt water, and he pumps greater quantities of water from wells in coastal areas, he increases the likelihood of salt-water contamination. These and many other urban effects upon hydrology deserve increasing study if we are to provide for the best use of the water and land resources available to the Nation's urban centers.

Water Supply Paper↗

Water quality of streams in the Red River of the North Basin, Minnesota, North Dakota, and South Dakota, 1970-2001

Data for the Red River of the North (Red River) Basin in Minnesota, North Dakota, and South Dakota were analyzed to determine whether the water quality of streams in the basin is adequate to meet future needs. For the Red River at Emerson, Manitoba, site, pH values, water temperatures, and dissolved-oxygen concentrations generally were within the criteria established for the protection of aquatic life. Dissolved-solids concentrations ranged from 245 to 1,100 milligrams per liter. Maximum sulfate and chloride concentrations were near, but did not exceed, the established secondary maximum contaminant level. The trace elements considered potentially harmful generally were at concentrations that were less than the established guidelines, standards, and criteria. The concentrations of lead that were detected may have occurred as a result of sample contamination. For the Red River upstream from Emerson, Manitoba, sites, pH and other field values rarely exceeded the criteria established for the protection of aquatic life. Many constituent concentrations for the Red River below Fargo, N. site exceeded water-quality guidelines, standards, and criteria. However, the trace-element exceedances could be natural or could be related to pollution or sample contamination. Many of the tributaries in the western part of the Red River Basin had median specific-conductance values that were greater than 1,000 microsiemens per centimeter. Sulfate concentrations occasionally exceeded the established drinking-water standard. Median arsenic concentrations were 6 micrograms per liter or less, and maximum concentrations rarely exceeded the 10-microgram-per-liter drinking-water standard that is scheduled to take effect in 2006. The small concentrations of lead, mercury, and selenium that occasionally were detected may have been a result of sample contamination or other factors. The tributaries in the eastern part of the Red River Basin had median specific-conductance values that were less than 1,000 microsiemens per centimeter. Concentrations of pesticides that were detected and that had regulatory limits were less than the cited water-quality guidelines, standards, and criteria. Concentrations of compounds that were detected generally were less than the sediment- quality standards and criteria. The data considered in this report generally provide a good baseline from which to evaluate changes in water-quality conditions. However, because many of the trace elements detected, including lead and mercury, may have been the result of sample contamination, additional data are needed to confirm that trace-element concentrations generally are low. Concentrations of major ions, including sulfate, and specific conductance may continue to approach drinking-water standards during periods of low flow because the streams, particularly those in the western part of the basin, are sustained mostly by ground-water discharge that generally has large dissolved-solids concentrations.

Scientific Investigations Report↗

An Assessment of Hydrology, Fluvial Geomorphology, and Stream Ecology in the Cardwell Branch Watershed, Nebraska, 2003-04

An assessment of the 16.3-square-mile Cardwell Branch watershed characterized the hydrology, fluvial geomorphology, and stream ecology in 2003-04. The study - performed by the U.S. Geological Survey in cooperation with the City of Lincoln, Nebraska, and the Lower Platte South Natural Resources District - focused on the 7.7-square-mile drainage downstream from Yankee Hill Reservoir. Hydrologic and hydraulic models were developed using the Hydrologic Modeling System (HEC-HMS) and River Analysis System (HEC-RAS) of the U.S. Army Corps of Engineers Hydraulic Engineering Center. Estimates of streamflow and water-surface elevation were simulated for 24-hour-duration design rainstorms ranging from a 50-percent frequency to a 0.2-percent frequency. An initial HEC-HMS model was developed using the standardized parameter estimation techniques associated with the Soil Conservation Service curve number technique. An adjusted HEC-HMS model also was developed in which parameters were adjusted in order for the model output to better correspond to peak streamflows estimated from regional regression equations. Comparisons of peak streamflow from the two HEC-HMS models indicate that the initial HEC-HMS model may better agree with the regional regression equations for higher frequency storms, and the adjusted HEC-HMS model may perform more closely to regional regression equations for larger, rarer events. However, a lack of observed streamflow data, coupled with conflicting results from regional regression equations and local high-water marks, introduced considerable uncertainty into the model simulations. Using the HEC-RAS model to estimate water-surface elevations associated with the peak streamflow, the adjusted HEC-HMS model produced average increases in water-surface elevation of 0.2, 1.1, and 1.4 feet for the 50-, 1-, and 0.2-percent-frequency rainstorms, respectively, when compared to the initial HEC-HMS model. Cross-sectional surveys and field assessments conducted between November 2003 and March 2004 indicated that Cardwell Branch and its unnamed tributary appear to be undergoing incision (the process of downcutting) (with three locations showing 2 or more feet of streambed incision since 1978) that is somewhat moderated by the presence of grade controls and vegetation along the channel profile. Although streambank failures were commonly observed, 96 percent of the surveyed cross sections were classified as stable by planar and rotational failure analysis-a disconnect that may have been the result of assumed soil properties. Two process-based classification systems each indicated that the reaches within the study area were incising and widening, and the Rosgen classification system characterized the streams as either type E6 or B6c. E6 channels are hydraulically efficient with low width-depth ratios, low to moderate sinuosity, and gentle to moderately steep slopes. B6c channels typically are incised with low width-depth ratios maintained by riparian vegetation, low bedload transport, and high washload transport. No obvious nickpoints (interruption or break in slope) were observed in the thalweg profile (line of maximum streambed descent), and the most acute incision occurred immediately downstream from bridges and culverts. Nine water-quality samples were collected between August 2003 and November 2004 near the mouth of the watershed. Sediment-laden rainfall-runoff substantially affected the water quality in Cardwell Branch, leading to greater biochemical and chemical oxygen demands as well as increased concentrations of several nutrient, bacteriological, sediment, and pesticide constituents. The storage of rainfall runoff in Yankee Hill Reservoir may prolong the presence of runoff-related constituents downstream. Across the study area, there was a lack of habitat availability for aquatic biota because of low dissolved oxygen levels and low streamflows or dry channels. In August 2003, the aquatic community near the mouth of

Scientific Investigations Report↗

Streamflow depletion by wells--Understanding and managing the effects of groundwater pumping on streamflow

Groundwater is an important source of water for many human needs, including public supply, agriculture, and industry. With the development of any natural resource, however, adverse consequences may be associated with its use. One of the primary concerns related to the development of groundwater resources is the effect of groundwater pumping on streamflow. Groundwater and surface-water systems are connected, and groundwater discharge is often a substantial component of the total flow of a stream. Groundwater pumping reduces the amount of groundwater that flows to streams and, in some cases, can draw streamflow into the underlying groundwater system. Streamflow reductions (or depletions) caused by pumping have become an important water-resource management issue because of the negative impacts that reduced flows can have on aquatic ecosystems, the availability of surface water, and the quality and aesthetic value of streams and rivers. Scientific research over the past seven decades has made important contributions to the basic understanding of the processes and factors that affect streamflow depletion by wells. Moreover, advances in methods for simulating groundwater systems with computer models provide powerful tools for estimating the rates, locations, and timing of streamflow depletion in response to groundwater pumping and for evaluating alternative approaches for managing streamflow depletion. The primary objective of this report is to summarize these scientific insights and to describe the various field methods and modeling approaches that can be used to understand and manage streamflow depletion. A secondary objective is to highlight several misconceptions concerning streamflow depletion and to explain why these misconceptions are incorrect.

Circular↗

Methods for Monitoring Fish Communities of Buffalo National River and Ozark National Scenic Riverways in the Ozark Plateaus of Arkansas and Missouri: Version 1.0

Buffalo National River located in north-central Arkansas, and Ozark National Scenic Riverways, located in southeastern Missouri, are the two largest units of the National Park Service in the Ozark Plateaus physiographic province. The purpose of this report is to provide a protocol that will be used by the National Park Service to sample fish communities and collect related water-quality, habitat, and stream discharge data of Buffalo National River and Ozark National Scenic Riverways to meet inventory and long-term monitoring objectives. The protocol includes (1) a protocol narrative, (2) several standard operating procedures, and (3) supplemental information helpful for implementation of the protocol. The protocol narrative provides background information about the protocol such as the rationale of why a particular resource or resource issue was selected for monitoring, information concerning the resource or resource issue of interest, a description of how monitoring results will inform management decisions, and a discussion of the linkages between this and other monitoring projects. The standard operating procedures cover preparation, training, reach selection, water-quality sampling, fish community sampling, physical habitat collection, measuring stream discharge, equipment maintenance and storage, data management and analysis, reporting, and protocol revision procedures. Much of the information in the standard operating procedures was gathered from existing protocols of the U.S. Geological Survey National Water Quality Assessment program or other sources. Supplemental information that would be helpful for implementing the protocol is included. This information includes information on fish species known or suspected to occur in the parks, sample sites, sample design, fish species traits, index of biotic integrity metrics, sampling equipment, and field forms.

Open-File Report↗

Map showing flood of June 1972 resulting from tropical storm Agnes, Cayuga Inlet and Cayuga Lake at Ithaca, New York

In June 1972, tropical storm Agnes caused severe flooding in Pennsylvania and southern New York. The floods on many major streams were the highest known since the river valleys were settled. Maximum discharges were as much as twice the discharge of a 50-year flood. In southern New York, large areas in Corning, Elmira, Wellsville, Salamanca, and in many smaller communities were inundated to depths of several feet. Levels of all of the Finger Lakes were higher than any previously recorded, and extensive flooding of lakeside properties resulted. The extent of flooding shown on the map was delineated by the U.S. Geological Survey from field surveys made immediately after the flood.

New York↗

Map showing flood of June 1972 resulting from tropical storm Agnes, Owasco Inlet at Moravia, New York

In June 1972, tropical storm Agnes caused severe flooding in Pennsylvania and southern New York. The floods on many major streams were the highest known since the river valleys were settled. Maximum discharges were as much as twice the discharge of a 50-year flood. In southern New York, large areas in Corning, Elmira, Wellsville, Salamanca, and in many smaller communities were inundated to depths of several feet. Levels of all of the Finger Lakes were higher than any previously recorded, and extensive flooding of lakeside properties resulted. The extent of flooding shown on the map was delineated by the U.S. Geological Survey by field surveys.

New York↗