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Edward J. Doheny

Publications and source records attributed to Edward J. Doheny.

18 recordsLinked to original sources
USGS2022

Peak-flow and low-flow magnitude estimates at defined frequencies and durations for nontidal streams in Delaware

Reliable estimates of the magnitude of peak flows in streams are required for the economical and safe design of transportation and water conveyance structures. In addition, reliable estimates of the magnitude of low flows at defined frequencies and durations are needed for meeting regulatory requirements, quantifying base flows in streams and rivers, and evaluating time of travel and dilution of toxic spills. This report, in cooperation with the Delaware Department of Transportation and the Delaware Geological Survey, presents methods for estimating the magnitude of peak flows and low flows at defined frequencies and durations on nontidal streams in Delaware, at locations both monitored by streamflow-gage sites and ungaged. Methods are presented for estimating (1) the magnitude of peak flows for return periods ranging from 2 to 500 years (50-percent to 0.2-percent annual-exceedance probability), and (2) the magnitude of low flows as applied to 7-, 14-, and 30-consecutive day low-flow periods with recurrence intervals of 2, 10, and 20 years (50-, 10-, and 5-percent annual non-exceedance probabilities). These methods are applicable to watersheds that exhibit a full range of development conditions in Delaware. The report also describes StreamStats, a web application that allows users to easily obtain peak-flow and low-flow magnitude estimates for user-selected locations in Delaware. Peak-flow and low-flow magnitude estimates for ungaged sites are obtained using statistical regression analysis through a process known as regionalization, where information from a group of streamflow-gage sites within a region forms the basis for estimates for ungaged sites within the same region. Ninety-four streamflow-gage sites in and near Delaware with at least 10 years of nonregulated annual peak-flow data were used for the peak-flow regression analysis, a subset of the 121 sites for which peak-flow estimates were computed. These sites included both continuous-record streamflow-gage sites as well as partial record sites. Forty-five streamflow-gage sites with at least 10 years of nonregulated low-flow data available were used for the low-flow regression analyses, a subset of the 68 sites for which low-flow estimates were computed. Estimates for gaged sites are obtained by combining (1) the station peak-flow statistics (mean, standard deviation, and skew) and peak-flow estimates using the recent Bulletin 17C guidelines that incorporate the Expected Moments Algorithm with (2) regional estimates of peak-flow magnitude derived from regional regression equations and regional skew derived from sites with records greater than or equal to 35 years. Example peak-flow estimate calculations using the methods presented in the report are given for (1) ungaged sites, (2) gaged sites, (3) sites upstream or downstream from a gaged location, and (4) sites between gaged locations. Estimates for low-flow gaged sites are obtained by combining (1) the station low-flow statistics (mean, standard deviation, and skew) and low-flow estimates with (2) regional estimates of low-flow magnitude derived from regional regression equations. Example low-flow estimate calculations using the methods presented in the report are given for (1) ungaged sites, (2) gaged sites, (3) sites upstream or downstream from a gaged location, and (4) sites between gaged locations. A total of 54 sites in the Coastal Plain region were used to develop peak-flow regressions for the region and 40 sites were used for the Piedmont region. Similarly, 24 sites were used for low-flow regression equation development in the Coastal Plain, with 21 in the Piedmont. Peak and low-flow site inclusion in the Coastal Plain tended to be more restricted with tidal influence and ranges of basin characteristics, including drainage area, limiting regression equation development and application. Regional regression equations for peak flows and low flows, as applicable to ungaged sites in the Piedmont and Coastal Plain Physiographic Provinces in Delaware, are presented. Peak-flow regression equations used variables that quantified drainage area, basin slope, percent area with well-drained soils, percent area with poorly drained soils, impervious area, and percent area of surface water storage in estimating peak-flow estimates, whereas low-flow regression equations used only drainage area and percent poorly drained soils in the estimation of low flows. Average standard errors for peak-flow regressions tended to be lower than those for low- flow regressions, with lower errors in the Piedmont region for both peak- and low-flow regressions. For peak-flow estimates, a sensitivity analysis of Piedmont regression equation estimates to changes in impervious area is also presented. Additional topics associated with the analyses performed during the study are discussed, including (1) the availability and description of 32 basin and climatic characteristics considered during the development of the regional regression equations; (2) the treatment of increasing trends in the annual peak-flow series identified at 18 gaged sites and inclusion in or exclusion from the regional analysis; (3) regional skew analysis and determination of regression regions; (4) sample adjustments and removal of sites owing to regulation and redundancy; and (5) a brief comparison of peak- and low-flow estimates at gages used in previous studies.

Delaware↗
USGS2021

Storms and floods of July 30, 2016, and May 27, 2018, in Ellicott City, Howard County, Maryland

Introduction On July 30, 2016, and May 27, 2018, the downtown area of Ellicott City, Maryland (fig. 1), was severely flooded by intense, short-duration rainfall that resulted in loss of life; significant damage to buildings, roads, infrastructure; and hundreds of vehicles washed away. Precipitation from the 2016 event totaled 6.60 inches in 3 hours (National Oceanic and Atmospheric Administration, 2016). Precipitation from the 2018 storm totaled 6.56 inches in 3 hours (National Oceanic and Atmospheric Administration, 2018). In the aftermath of both storms, personnel from the U.S. Geological Survey (USGS) performed indirect discharge measurements to determine peak flow on the three streams that drain through the downtown area of Ellicott City and empty into the Patapsco River. High-water marks were flagged on selected reaches of three streams, Hudson Branch (station 01589017), Tiber Branch (station 01589019), and New Cut Branch (station 01589021) (fig. 2). Peak flows were computed using flow-through-culvert techniques with road overflow for Hudson Branch and slope-area techniques for Tiber Branch and New Cut Branch. This fact sheet describes the basin characteristics, hydrologic characteristics, and flood history of the Ellicott City, Maryland, area. The storms and flood characteristics for July 30, 2016, and May 27, 2018, are described. Peak discharges computed from the indirect discharge measurements for Hudson Branch, Tiber Branch, and New Cut Branch are presented for the storms and floods of July 30, 2016, and May 27, 2018. To provide historical perspective on these floods in Ellicott City, results from the indirect discharge measurement computations were compared to peak flows from 75 USGS streamgages and 6 miscellaneous sites in Maryland and Delaware that resulted from intense storms in August and September 1971 (Carpenter, 1974). The findings indicate that although the Ellicott City storms and floods from July 30, 2016, and May 27, 2018, are considered very rare in terms of their probability of occurrence, other storms have occurred in the Maryland and Delaware regions in the past that have produced comparable runoff characteristics relative to drainage-area magnitude.

Maryland↗
USGS2021

Precipitation, peak streamflow, and inundation in the Bynum Run and Winters Run watersheds in Harford County, Maryland

The Harford County Department of Public Works and the U.S. Geological Survey have been working cooperatively to monitor continuous streamflow at several streamgages in Harford County, Maryland, including Bynum Run and Winters Run. A perceived recent uptick in the number of flooding events in the Bynum Run and Winters Run watersheds have led to questions about the relative frequency and magnitude of floods experienced by county residents. Precipitation, stage (water elevation), and peak flow analyses and trends were evaluated. Although there was no one contributor to point to for the perceived increase in flooding, it is most likely attributable to a combination of precipitation, stage, and peak flow. There have been numerous rainfall events with exceedingly long return intervals, but none were statistically out of the ordinary. The stages of the streams at higher flows are slightly higher (less than 0.5 feet) than historical stages, but likely are not great enough to cause a significant increase in flooding. The ratings (stage discharge relationship) for the streams have changed slightly. The latest ratings indicate erosion and deposition in the streambed over the years of observation, but again these alone do not result in more flooding. These factors taken together may point to an observational bias for incidental flooding. With the increase in land development, there may simply be more observations of flooding in the county.

Maryland↗
USGS2018

Geomorphic characteristics of Tenmile Creek, Montgomery County, Maryland, 2014–16

Data collected from April 2014 through September 2016 were used to assess geomorphic characteristics and geomorphic changes over time in a selected reach of Tenmile Creek, a small rural watershed near Clarksburg, Maryland. Longitudinal profiles of the channel bed, water surface, and bank features were developed from field surveys. Changes in cross-section geometry between field surveys were documented. Grain-size distributions for the channel bed were developed from pebble counts. Continuous-record streamflow and precipitation data were also collected in the Tenmile Creek watershed and used to supplement the geomorphic analyses. The Rosgen system of stream classification was used to classify the stream channel according to morphological measurements of slope, entrenchment ratio, width-to-depth ratio, sinuosity, and median particle diameter of the channel materials. Boundary shear stress near the U.S. Geological Survey (USGS) streamflow-gaging station was assessed by using hydraulic variables computed from the cross-section surveys and slope measurements derived from crest-stage gages and temporary data loggers installed along the study reach. Analysis of the longitudinal profiles indicated relatively small changes in the percentage and distribution of riffles, pools, and runs in the study reach between April 2014 and March 2015. More noticeable changes were observed during surveys conducted in March 2016 and September 2016. The channel-bed slope showed a net reduction over time from 0.0072 to 0.0040 feet per foot (ft/ft). The low-flow water-surface slope also showed a net reduction over time from 0.0065 to 0.0045 ft/ft. Net aggradation in the lower section of the study reach combined with net degradation in the upper section of the study reach contributed to the net reduction in channel-bed and water-surface slope. The large storm and resulting flood on July 30, 2016 was a major factor in observed changes in the longitudinal profiles between the March 2016 and September 2016 surveys. Comparison of data from the cross-sectional surveys indicated vertical changes in all cross sections, with more extreme changes observed between surveys in the lower section of the study reach due in part to alternating periods of net storage and transport of sand. Lateral erosion was not a major factor in the study reach, with the exception of cross section Dd, where considerable lateral erosion was documented during the study period. The flood that resulted from the large storm on July 30, 2016 was a major factor in some of the vertical changes observed in the channel bed of the study reach cross sections. Particle-size analyses of the channel bed from pebble counts indicated median particle diameters ranging from 15.5 millimeters (mm) to 23.1 mm, which is characterized as medium to coarse gravel. Sand percentages ranging from 3.4 percent to 16.4 percent of the total counts were observed over time. Net increases in storage of fine sediment in the reach were observed between April 2014 and March 2016, and a considerable reduction in storage was observed between March 2016 and September 2016. The Tenmile Creek stream channel was classified as a C4 channel, based on morphological descriptions from the Rosgen system of stream classification. The C4 classification describes a single-thread channel with a slight entrenchment ratio; a moderate to high width-to-depth ratio; moderate to high sinuosity; a water-surface slope of less than 2 percent; and a median particle diameter in the gravel range of 2 to 64 mm. The analysis of boundary shear stress indicated a range of 0.35 to 1.18 pounds per square foot for instantaneous streamflow ranging from 79 to 2,860 cubic feet per second during the study period. The relation between discharge and boundary shear stress for Tenmile Creek was compared to similar relations that were previously developed for Minebank Run, a small, urban watershed in the eastern section of the Piedmont Physiographic Province in Baltimore County, Md. that was physically restored during 2004–05. The comparison indicated a much flatter slope in the relation for Minebank Run in both its unrestored and restored conditions. This difference in the relations indicates that the erosive power in the urban watershed of Minebank Run is much more sensitive to increases in discharge magnitude than in the non-urban watershed of Tenmile Creek.

Maryland↗
USGS2010

Selected low-flow frequency statistics for continuous-record streamgage locations in Maryland, 2010

According to a 2008 report by the Governor's Advisory Committee on the Management and Protection of the State's Water Resources, Maryland's population grew by 35 percent between 1970 and 2000, and is expected to increase by an additional 27 percent between 2000 and 2030. Because domestic water demand generally increases in proportion to population growth, Maryland will be facing increased pressure on water resources over the next 20 years. Water-resources decisions should be based on sound, comprehensive, long-term data and low-flow frequency statistics from all available streamgage locations with unregulated streamflow and adequate record lengths. To provide the Maryland Department of the Environment with tools for making future water-resources decisions, the U.S. Geological Survey initiated a study in October 2009 to compute low-flow frequency statistics for selected streamgage locations in Maryland with 10 or more years of continuous streamflow records. This report presents low-flow frequency statistics for 114 continuous-record streamgage locations in Maryland. The computed statistics presented for each streamgage location include the mean 7-, 14-, and 30-consecutive day minimum daily low-flow dischages for recurrence intervals of 2, 10, and 20 years, and are based on approved streamflow records that include a minimum of 10 complete climatic years of record as of June 2010. Descriptive information for each of these streamgage locations, including the station number, station name, latitude, longitude, county, physiographic province, and drainage area, also is presented. The statistics are planned for incorporation into StreamStats, which is a U.S. Geological Survey Web application for obtaining stream information, and is being used by water-resource managers and decision makers in Maryland to address water-supply planning and management, water-use appropriation and permitting, wastewater and industrial discharge permitting, and setting minimum required streamflows to protect freshwater biota and ecosystems.

Open-File Report↗
USGS2007

Hydraulic Geometry Characteristics of Continuous-Record Streamflow-Gaging Stations on Four Urban Watersheds Along the Main Stem of Gwynns Falls, Baltimore County and Baltimore City, Maryland

Four continuous-record streamflow-gaging stations are currently being operated by the U.S. Geological Survey on the main stem of Gwynns Falls in western Baltimore County and Baltimore City, Maryland. The four streamflow-gaging stations drain urban or suburban watersheds with significantly different drainage areas. In addition to providing continuous- record discharge data at these four locations, operation of these stations also provides a long-term record of channel geometry variables such as cross-sectional area, channel width, mean channel depth, and mean velocity that are obtained from physical measurement of the discharge at a variety of flow conditions. Hydraulic geometry analyses were performed using discharge-measurement data from four continuous-record streamflow-gaging stations on the main stem of Gwynns Falls. Simple linear regression was used to develop relations that (1) quantify changes in cross-sectional area, channel width, mean channel depth, and mean velocity with changes in discharge at each station, and (2) quantify changes in these variables in the Gwynns Falls watershed with changes in drainage area and annual mean discharge. Results of the hydraulic geometry analyses indicated that mean velocity is more responsive to changes in discharge than channel width and mean channel depth for all four streamflow-gaging stations on the main stem of Gwynns Falls. For the two largest and most developed watersheds, on Gwynns Falls at Villa Nova, and Gwynns Falls at Washington Boulevard at Baltimore, the slope of the regression lines, or hydraulic exponents, indicated that mean velocity was more responsive to changes in discharge than any of the other hydraulic variables that were analyzed. This was true even when considering changes in cross-sectional area with discharge, which incorporates the combined effects of channel width and mean channel depth. A comparison of hydraulic exponents for Gwynns Falls to average values from previous work indicated that the velocity exponents for all four stations on the Gwynns Falls are larger than the average value of 0.34. For stations 01589300 and 01589352, the exponents for mean velocity are about twice as large as the average value. Analyses of cross-sectional area, channel width, mean channel depth, and mean velocity in conjunction with changes in drainage area and annual mean discharge indicated that channel width is much more responsive to changes in drainage area and annual mean discharge than are mean channel depth or mean velocity. Cross-sectional area, which combines the effects of channel width and mean channel depth, was also found to be highly responsive to changes in drainage area and annual mean discharge.

Scientific Investigations Report↗
USGS2007

Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04

Data collected from 2002 through 2004 were used to assess geomorphic characteristics and geomorphic changes over time in a selected reach of Minebank Run, a small urban watershed near Towson, Maryland, prior to its physical restoration in 2004 and 2005. Longitudinal profiles of the channel bed, water surface, and bank features were developed from field surveys. Changes in cross-section geometry between field surveys were documented. Grain-size distributions for the channel bed and banks were developed from pebble counts and laboratory analyses. Net changes in the elevation of the channel bed over time were documented at selected locations. Rosgen Stream Classification was used to classify the stream channel according to morphological measurements of slope, entrenchment ratio, width-to-depth ratio, sinuosity, and median-particle diameter of the channel materials. An analysis of boundary shear stress in the vicinity of the streamflow-gaging station was conducted by use of hydraulic variables computed from cross-section surveys and slope measurements derived from crest-stage gages in the study reach. Analysis of the longitudinal profiles indicated noticeable changes in the percentage and distribution of riffles, pools, and runs through the study reach between 2002 and 2004. Despite major changes to the channel profile as a result of storm runoff events, the overall slope of the channel bed, water surface, and bank features remained constant at about 1 percent. The cross-sectional surveys showed net increases in cross-sectional area, mean depth, and channel width at several locations between 2002 and 2004, which indicate channel degradation and widening. Two locations were identified where significant amounts of sediment were being stored in the study reach. Data from scour chains identified several locations where maximum scour ranged from 1.0-1.4 feet during storm events. Bank retreat varied widely throughout the study reach and ranged from 0.2 feet to as much as 7.9 feet. Sequential measurements of bed elevation in selected locations indicated as much as 2 feet of channel degradation in one location during a storm event in May 2004 and identified pulses of sediment that were gradually transported through the study reach during the monitoring period. Particle-size analyses of channel bed materials indicated a median particle diameter of 20.5 millimeters (coarse gravel) for the study reach, with more than 24 percent being sand particles (greater than 0.062 millimeters). Analyses of bank samples showed finer-grained material composing the channel banks, predominantly silt/clay or a mixture of silt/clay (less than 0.062 millimeters) and very fine to coarse sand. The Minebank Run stream channel was classified as a B4c channel, based on morphological descriptions from the Rosgen Stream Classification System. The B4c classification describes a single-thread stream channel with a moderate entrenchment ratio of 1.4 to 2.2; a width-to-depth ratio greater than 12; moderate sinuosity of 1.2 or greater; a water-surface slope of less than 2 percent; and a median-particle diameter in the gravel range of 2 to 64 millimeters. Analysis of boundary shear stress indicated larger mean velocities and boundary shear stress values for Minebank Run when compared to relations for non-urban B channel types developed by Rosgen. The slope of the regression line for mean velocity versus boundary shear stress at Minebank Run was considerably less than slopes developed by Rosgen for non-urban channel types. This indicates that relatively small increases in mean velocity can result in large increases in boundary shear stress in stream channels with highly developed watersheds, such as Minebank Run.

Scientific Investigations Report↗
USGS2006

Watershed characteristics and pre-restoration surface-water hydrology of Minebank Run, Baltimore County, Maryland, water years 2002-04

Stream restoration efforts have been ongoing in Maryland since the early 1990s. Physical stream restoration often involves replacement of lost sediments to elevate degraded streambeds, re-establishment of riffle-pool sequences along the channel profile, planting vegetation in riparian zones, and re-constructing channel banks, point bars, flood plains, and stream-meanders. The primary goal of many restoration efforts is to re-establish geomorphic stability of the stream channel and reduce erosive energy from urban runoff. Monitoring streams prior to and after restoration could help quantify other possible benefits of stream restoration, such as improved water quality and biota. This report presents general watershed characteristics associated with the Minebank Run watershed; a small, urban watershed in the south-central section of Baltimore County, Maryland that was physically restored in phases during 1999, 2004, and 2005. The physiography, geology, hydrology, land use, soils, and pre-restoration geomorphic setting of the unrestored stream channel are discussed. The report describes a reach of Minebank Run that was selected for the purpose of collecting several types of environmental data prior to restoration, including continuous-record and partial-record stage and streamflow data, precipitation, and ground-water levels. Examples of surface-water data that were collected in and near the study reach during water years 2002 through 2004, including continuous-record streamflow, partial-record stage and discharge, and precipitation, are described. These data were used in analyses of several characteristics of surface-water hydrology in the watershed, including (1) rainfall totals, storm duration, and intensity, (2) instantaneous peak discharge and daily mean discharge, (3) stage-discharge ratings, (4) hydraulic-geometry relations, (5) water-surface slope, (6) time of concentration, (7) flood frequency, (8) flood volume, and (9) rainfall-runoff relations. Several hydrologic characteristics that are typical of urban environments were quantified by these analyses. These include (1) large ratios of peak discharge to daily mean discharge as an indicator of flashiness, (2) consistent shifting of the stage-discharge rating over short periods of time that indicates instability of the stream channel, (3) analyses of hydraulic-geometry relations that indicate mean velocities of 11 feet per second or more while the flow is contained in the stream channel, (4) discharges that are 4 to 5 times larger in Minebank Run for corresponding flood frequency recurrence intervals than in Slade Run, which is a Piedmont watershed of similar size with smaller percentages of urban development, and (5) flood waves that can travel through the stream channel at a velocity of 412 feet per minute, or 6.9 feet per second.

Maryland↗
USGS2005

Development and analysis of regional curves for streams in the non-urban valley and ridge physiographic province, Maryland, Virginia, and West Virginia

Regression relations for bankfull stream characteristics based on drainage area (often called 'regional curves') are used in natural stream channel design to verify field determinations of bankfull discharge and stream channel characteristics. Bankfull stream characteristics were assessed for stream reaches at 41 streamflow-gaging stations in the Valley and Ridge Physiographic Province in Maryland, Virginia, and West Virginia. Data collected included bankfull cross-sectional geometry, flood plain geometry, and longitudinal profile data. In addition, particle-size distributions of streambed material were determined and data on basin characteristics were compiled for each reach. Regional curves were developed for bankfull cross-sectional area, width, and discharge with R2 values of 0.95, 0.89, 0.87, and 0.91, respectively. Examination of the regional curves residuals indicates that there is more variability in bankfull cross-sectional area, width, and discharge for smaller streams than for larger streams. In contrast, there is more variability for bankfull mean depth for larger streams than for smaller streams. Geographic analysis of regional curve residuals indicated that there were no further subdivisions within the Valley and Ridge Physiographic Province in the three-state study area for which individual sets of regional curves should be developed. In addition, two separate sets of regional curves were developed with data from the 41 sites to examine potential differences in the relations between the southern (n = 9) and central (n = 32) sections of the province. There were differences in slope and intercept between the two bankfull discharge test relations and a difference in intercept for the width test relations at the 95-percent confidence level. However, the results of this analysis were inconclusive and therefore one set of regional curves for the study area is presented in this report. The regional curves were compared to regression models developed from similar data collected in the Pennsylvania and Maryland portions of the province. No statistical difference in the slope or intercept of regression lines of the three data sets was detected for any of the four bankfull parameters at the 95-percent confidence level. Basin characteristics such as percentage of basin forested (percent forested) and percentage of basin underlain by carbonate bedrock (percent carbonate) were analyzed to evaluate variability among regression points. Multivariate regression relations including explanatory terms for percent carbonate and drainage area produced higher R2 values than the regional curves for bankfull cross-sectional area (R2 = 0.95), bankfull width (R2 = 0.92), and bankfull discharge (R2 = 0.93). There was no improvement for the bankfull mean depth relation from adding the additional term. Inclusion of the other basin characteristics in multivariate relations did not improve the regression models. Regression models developed for the 1.5-year discharge for all streamflow-gaging stations with peak discharge data throughout Virginia (n = 486) and throughout the Valley and Ridge Physiographic Province in Virginia (n = 147) were compared to the regional curve relating bankfull discharge to drainage area. A similar trend in decreasing variability with increasing drainage area was observed for the 1.5-year discharge for all stations in Virginia . This indicates that the change in variability observed in the discharge regional curve likely would exist with a larger data set. There was no statistical difference at the 95-percent confidence level between regression relations for the southern section of the province (n = 40) and the central section (n = 107). This finding supports maintaining only one set of regional curves for the study area. Not all of the variability in the regional curves is explained by drainage area alone. Causes of the remaining variability likely vary among study sites. Users of the regional curves developed in this study are cautioned that, because of inherent variability in hydrologic data, a thorough analysis of the fluvial system and the drainage basin is necessary when evaluating the bankfull characteristics of a stream.

Maryland, Virginia, West Virginia↗
USGS2002

Water quality, sediment quality, and stream-channel classification of Rock Creek, Washington, D.C., 1999-2000

Rock Creek Park is within the National Capital Region in Washington, D.C., and is maintained by the National Park Service. Part of Montgomery County, Maryland, and part of the District of Columbia drain into Rock Creek, which is a tributary of the Potomac River. Water quality in Rock Creek is important to biotic life in and near the creek, and in the Potomac River Basin and the Chesapeake Bay. The water quality of the Rock Creek Basin has been affected by continued urban and agricultural growth and development. The U.S. Geological Survey, in cooperation with the National Park Service, investigated water quality and sediment quality in Rock Creek over a 2-year period (1998?2000), and performed a stream-channel classification to determine the distribution of bottom sediment in Rock Creek. This report presents and evaluates water quality and bottom sediment in Rock Creek for water years 1999 (October 1, 1998 to September 30, 1999) and 2000 (October 1, 1999 to September 30, 2000). A synoptic surface-water assessment was conducted at five stations from June 23 to June 25, 1999, a temporal surface-water assessment was conducted at one station from February 18, 1999 to September 26, 2000, and bed-sediment samples were collected and assessed from three stations from August 17 to August 19, 1999. The synoptic surface-water assessment included pesticides (parent compounds and selected transformation products), field parameters, nutrients, and major ions. The temporal surface-water assessment included pesticides (parent compounds and selected transformation products) and field parameters. The bed-sediment assessment included trace elements and organic compounds (including low- and high-molecular weight polycyclic aromatic hydrocarbons, poly-chlorinated biphenyls, pesticides, and phthalates). Some, but not all, of the pesticides known to be used in the area were included in the synoptic water-quality assessment, the temporal water-quality assessment, and the bed-sediment assessment. In addition to the water-quality and sediment-quality assessments, a Rosgen stream-channel classification was performed on a 900-foot-long segment of Rock Creek. In the synoptic water-quality assessment, two pesticides were found to be above published criteria for the protection of aquatic life. In the temporal water-quality assessment, four pesticides were found to be above published criteria for the protection of aquatic life. In the bed-sediment assessment, 8 trace elements, 14 polycyclic aromatic hydrocarbons, 6 pesticides, and 1 phthalate compound were found to be above published criteria for the protection of aquatic life. In the Rosgen classification, a comparison to a previous classification for this segment showed an increase in sands and other fine-grained sediments in the creek bed.

Water-Resources Investigations Report↗
USGS2000

A strategy for a stream-gaging network in Maryland

Water is a keystone resource. In abundance, it supplies cities, industries, and agriculture. To maintain healthy natural and human ecosystems, water must not only be present in adequate quantity, but it must be of suitable quality for its intended use. Water quality depends on the amount, or load, of contaminants, both natural and anthropogenic, that it contains. Accurate assessment of these contaminants requires that the amount of water flowing in a stream or river be known. To quantify streamflow in a given stream or river and the variation of that flow through time, it must be measured by use of stream gages. Monitoring water flow is fundamental to managing and protecting water resources, and requires a collaborative effort by all interested parties, including Federal, State, and local government agencies.

Maryl↗
USGS1999

Index of hydrologic characteristics and data resources for the Gwynns Falls watershed, Baltimore County and Baltimore City, Maryland

The Gwynns Falls watershed has been selected as the primary study area for the Baltimore Ecosystem Study, as part of the National Science Foundation's Long-Term Ecological Research program. Because the Baltimore Ecosystem Study will be investigating long-term hydrologic changes in the Gwynns Falls watershed, a compilation of existing data resources for the watershed is necessary. This report discusses hydrologic characteristics and presents a compilation of historical data resources for the Gwynns Falls watershed. Tables are presented that list active and discontinued continuous-record streamflow-gaging stations, nontidal crest-stage partial-record stations, low-flow partial-record stations, and water-quality partial-record stations operated by the U.S. Geological Survey, Maryland-Delaware-D. C. District, in the Gwynns Falls watershed. Statistics regarding the number of inventoried ground-water wells in or bordering the Gwynns Falls watershed also are presented. A summary of additional data resources for the Gwynns Falls watershed is provided. This includes (1) an inventory of selected U.S. Geological Survey studies and reports that contain historical data or basin characteristics for streams in the watershed, (2) a listing of indirect flood-discharge measurements that have been made at several monitoring stations in the watershed, (3) a brief discussion of channel-stability and bridge-scour data collected by the U.S. Geological Survey in the watershed during 1990?95, (4) a listing of climatological data stations in the watershed and in the surrounding regional area, and (5) a listing of other selected reports that include data or information on the Gwynns Falls watershed.

Maryland↗
USGS1997

Flood-hydrology data for the Potomac River and selected tributaries in the vicinity of the Chesapeake and Ohio Canal National Historical Park, Maryland, West Virginia, and the District of Columbia

This report presents flood-hydrology data for the Potomac River and selected tributaries in the vicinity of the Chesapeake and Ohio Canal National Park (C & O Canal NHP). Data were compiled for the floods of (1) March 17-19, 1936; (2) June 22-24, 1972; (3) November 4-7, 1985; (4) January 19-21, 1996; (5) September 6-8, 1996; and (6) the peak of record for 6 U.S. Geological Survey (USGS) streamflow-gaging stations on the Potomac River and 10 streamflow-gaging stations on selected tributaries to the Potomac River. Peak discharge, peak gage height, the date and time of the peak, and approximate recurrence interval are presented for each flood event at these streamflow-gaging stations.Data compiled from selected high-flow discharge measurements on the six Potomac River streamflow- gaging stations are presented. The gage height, top width, cross-sectional area, mean velocity, maximum velocity, and discharge are presented for each selected discharge measurement. Any corresponding discharge on the C & O Canal that was measured or estimated for these dischrge measurements is presented. Ranges of Manning's roughness coefficient were computed for the range of selected discharge measurements, based on estimates of water-surface slope or the channel-bed slope. These data will be used for subsequent hydraulic studies by engineers for maintenance, protection, or restoration of the C & O Canal. An inventory of selected references, flood studies, and additional USGS data along the Potomac River and the C & O Canal NHP also are presented. Included are (1) a listing of selected flood studies and reports, and (2) a listing of USGS indirect flood-discharge measurements that have been made at the six Potomac River streamflow-gaging stations in the vicinity of the C & O Canal NHP. Information on historical streamflow-gaging station records and discharge measurements on the C & O Canal also is presented.

Open-File Report↗
USGS1996

A modified index for assessment of potential scour at bridges over waterways

The modified potential-scour index described in this report is based on a potential-scour index used by the U.S. Geological Survey Maryland District (Maryland index), and a prototype index developed by the U.S. Geological Survey Tennessee District (Tennessee index). The modifications were made to (1) improve the technical content of theMaryland index, and (2) provide a more extensive set of index variables for assessment of potential scour at bridges. The report demonstrates and describes problems that were encountered when using the Maryland index in a study of county- maintained bridges in Maryland from 1993 to 1995.The modifications made to specific index variables and ranking values in the Maryland index are presented and discussed. A comparison of potential-scour ratings from the modified potential- scour index, as applied to two bridges, is presented.This comparison indicates that the modified potential-scour index produces potential-scour ratings that most consistently reflect scour conditions observed at these bridges.

Open-File Report↗
USGS1993

Relation of channel stability to scour at highway bridges over waterways in Maryland

Data from assessments of channel stability and observed-scour conditions at 876 highway bridges over Maryland waterways were entered into a database. Relations were found to exist among specific, deterministic variables and observed-scour and debris conditions. Relations were investigated between (1) high-flow angle of attack and pier- and abutment-footing exposure, (2)abutment location and abutment-footing exposure, (3) type of bed material and pier-footing exposure, (4) tree cover on channel banks and mass wasting of the channel banks, and (5) land use near the bridge and the presence of debris blockage at the bridge opening. The results of the investigation indicate the following: (1) The number of pier and abutment-footing exposures increased for increasing high-flow angles of attack, (2) the number of abutment-footing exposures increased for abutments that protrude into the channel, (3) pier-footing exposures were most common for bridges over streams with channel beds of gravel, (4) mass wasting of channel banks with tree cover of 50 percent or greater near the bridge was less than mass wasting of channel banks with tree cover of less than 50 percent near the bridge, and (5) bridges blockage than bridge in row crop and swamp basins.

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