SEARCH · Search USGS

Results for “Urban Studies”

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

SourceResearch connectionFrom yearThrough year

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

At least 541 records · Page 30Linked to original sources

USGS2025

Freshwater turtle assemblages and densities in agricultural ditches and aquaculture ponds of eastern Arkansas

The Mississippi Alluvial Plain (MAP) of Arkansas is a landscape where many wetlands have been altered for use as aquaculture ponds or agricultural ditches. Commercial harvest of freshwater turtles within the MAP is not restricted or limited, with reported harvest numbers for 2019 alone exceeding 4000 for spiny softshell turtles ( Apalone spinifera ) and 39,000 for red-eared sliders ( Trachemys scripta elegans ). Herein, we attempt to provide baseline estimates of freshwater turtle densities and community composition in aquaculture ponds and agricultural ditches of eastern Arkansas, the habitat types most frequently trapped by commercial harvesters. We used a capture–mark–recapture approach over 3 summers (2019–2021) to evaluate population densities and community composition of freshwater turtles in these anthropogenic aquatic habitats. We captured > 4000 individuals of 9 species of turtle. One species, the red-eared slider, dominated the turtle community in both anthropogenic aquatic habitats, comprising 66% (± 22% SD) of all captures in agricultural ditches and 63% (± 32% SD) in aquaculture ponds. Diversity and richness did not differ between aquaculture ponds and agricultural ditches. We estimated densities of the 2 most commonly captured species, the red-eared slider and spiny softshell turtle. Density of red-eared sliders ranged from 0 turtles/unit area (linear kilometers in ditches or hectares in ponds) to 500 turtles/unit area, with a median of 37 turtles/unit area. The spiny softshell turtle was more frequently captured in ponds than ditches and attained average densities of 25 (± 19) turtles/ha and 7 (± 4) turtles/linear km, respectively. Our mean density estimates were lower than those in reported literature, including estimates from similar habitats, such as urban ditches and farm ponds, which resemble our study sites in structure, use, and geographical placement. We estimate the region contains 22,317 ha of aquaculture ponds and 18,350 linear km of agricultural ditches. By extrapolating our density estimates to each anthropogenic aquatic habitat type, we estimated 2 million red-eared sliders and 427,000 spiny softshell turtles occurred in aquaculture ponds and agricultural ditches across eastern Arkansas. Our results suggest that these altered wetlands provide abundant habitat for only a few generalist turtle species.

Arkansas↗

USGS2008

Total Mercury, Methylmercury, and Ancillary Water-Quality and Streamflow Data for Selected Streams in Oregon, Wisconsin, and Florida, 2002-06

Field and analytical methods, mercury and ancillary water-quality data, and associated quality-control data are reported for eight streams in Oregon, Wisconsin, and Florida from 2002 to 2006. The streams were sampled as part of a U.S. Geological Survey National Water-Quality Assessment Program study of mercury cycling, transport, and bioaccumulation in urban and nonurban stream ecosystems that receive mercury predominantly by way of atmospheric deposition.

Data Series↗

USGS2012

Urban development results in stressors that degrade stream ecosystems

In 2003, eighty-three percent of Americans lived in metropolitan areas, and considerable population increases are predicted within the next 50 years. Nowhere are the environmental changes associated with urban development more evident than in urban streams. Contaminants, habitat destruction, and increasing streamflow flashiness resulting from urban development have been associated with the disruption of biological communities, particularly the loss of sensitive aquatic biota. Every stream is connected downstream to other water bodies, and inputs of contaminants and (or) sediments to streams can cause degradation downstream with adverse effects on biological communities and on economically valuable resources, such as fisheries and tourism. Understanding how algal, invertebrate, and fish communities respond to physical and chemical stressors associated with urban development can provide important clues on how multiple stressors may be managed to protect stream health as a watershed becomes increasingly urbanized. This fact sheet highlights selected findings of a comprehensive assessment by the National Water-Quality Assessment Program of the U.S. Geological Survey (USGS) of the effects of urban development on stream ecosystems in nine metropolitan study areas.

Fact Sheet↗

USGS2007

Miscellaneous High-Resolution Seismic Imaging Investigations in Salt Lake and Utah Valleys for Earthquake Hazards

Introduction In support of earthquake hazards and ground motion studies by researchers at the Utah Geological Survey, University of Utah, Utah State University, Brigham Young University, and San Diego State University, the U.S. Geological Survey Geologic Hazards Team Intermountain West Project conducted three high-resolution seismic imaging investigations along the Wasatch Front between September 2003 and September 2005. These three investigations include: (1) a proof-of-concept P-wave minivib reflection imaging profile in south-central Salt Lake Valley, (2) a series of seven deep (as deep as 400 m) S-wave reflection/refraction soundings using an S-wave minivib in both Salt Lake and Utah Valleys, and (3) an S-wave (and P-wave) investigation to 30 m at four sites in Utah Valley and at two previously investigated S-wave (Vs) minivib sites. In addition, we present results from a previously unpublished downhole S-wave investigation conducted at four sites in Utah Valley. The locations for each of these investigations are shown in figure 1. Coordinates for the investigation sites are listed in Table 1. With the exception of the P-wave common mid-point (CMP) reflection profile, whose end points are listed, these coordinates are for the midpoint of each velocity sounding. Vs30 and Vs100, also shown in Table 1, are defined as the average shear-wave velocities to depths of 30 and 100 m, respectively, and details of their calculation can be found in Stephenson and others (2005). The information from these studies will be incorporated into components of the urban hazards maps along the Wasatch Front being developed by the U.S. Geological Survey, Utah Geological Survey, and numerous collaborating research institutions.

Open-File Report↗

USGS2012

Methods for determining magnitude and frequency of floods in California, based on data through water year 2006

Methods for estimating the magnitude and frequency of floods in California that are not substantially affected by regulation or diversions have been updated. Annual peak-flow data through water year 2006 were analyzed for 771 streamflow-gaging stations (streamgages) in California having 10 or more years of data. Flood-frequency estimates were computed for the streamgages by using the expected moments algorithm to fit a Pearson Type III distribution to logarithms of annual peak flows for each streamgage. Low-outlier and historic information were incorporated into the flood-frequency analysis, and a generalized Grubbs-Beck test was used to detect multiple potentially influential low outliers. Special methods for fitting the distribution were developed for streamgages in the desert region in southeastern California. Additionally, basin characteristics for the streamgages were computed by using a geographical information system. Regional regression analysis, using generalized least squares regression, was used to develop a set of equations for estimating flows with 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities for ungaged basins in California that are outside of the southeastern desert region. Flood-frequency estimates and basin characteristics for 630 streamgages were combined to form the final database used in the regional regression analysis. Five hydrologic regions were developed for the area of California outside of the desert region. The final regional regression equations are functions of drainage area and mean annual precipitation for four of the five regions. In one region, the Sierra Nevada region, the final equations are functions of drainage area, mean basin elevation, and mean annual precipitation. Average standard errors of prediction for the regression equations in all five regions range from 42.7 to 161.9 percent. For the desert region of California, an analysis of 33 streamgages was used to develop regional estimates of all three parameters (mean, standard deviation, and skew) of the log-Pearson Type III distribution. The regional estimates were then used to develop a set of equations for estimating flows with 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities for ungaged basins. The final regional regression equations are functions of drainage area. Average standard errors of prediction for these regression equations range from 214.2 to 856.2 percent. Annual peak-flow data through water year 2006 were analyzed for eight streamgages in California having 10 or more years of data considered to be affected by urbanization. Flood-frequency estimates were computed for the urban streamgages by fitting a Pearson Type III distribution to logarithms of annual peak flows for each streamgage. Regression analysis could not be used to develop flood-frequency estimation equations for urban streams because of the limited number of sites. Flood-frequency estimates for the eight urban sites were graphically compared to flood-frequency estimates for 630 non-urban sites. The regression equations developed from this study will be incorporated into the U.S. Geological Survey (USGS) StreamStats program. The StreamStats program is a Web-based application that provides streamflow statistics and basin characteristics for USGS streamgages and ungaged sites of interest. StreamStats can also compute basin characteristics and provide estimates of streamflow statistics for ungaged sites when users select the location of a site along any stream in California.

California↗

USGS2025

Characterization of stream water quality and groundwater levels in the Central Pine Barrens region, Suffolk County, New York, 2017–23

The area locally known as the “Central Pine Barrens” region, located in Suffolk County, New York, contains most of Long Island’s preserved and undeveloped land. This region overlays an aquifer system that provides potable groundwater for residents of Suffolk County. Between 2017 and 2023, the U.S. Geological Survey, in cooperation with the Central Pine Barrens Joint Planning & Policy Commission and the Town of Brookhaven, monitored groundwater levels and stream water quality in this region. Groundwater levels were measured monthly at five wells and continuously (15-minute intervals) at a sixth well. Water quality was monitored at five locations in the Carmans River and at two locations in the Peconic River, and samples were analyzed for major ions, trace elements, nutrients, pharmaceuticals, and pesticides. The major ion compositions at the sites were mainly sodium-chloride type waters, and compositions varied the most at the furthest upstream sites in both streams. Concentrations above aquatic-life criteria thresholds also occurred most frequently at the furthest upstream sites. The seasonal patterns of nutrient loads and concentrations varied between the Carmans and Peconic Rivers. Several organic compounds including pharmaceuticals, domestic use products, and pesticides were detected at low concentrations in both streams. Metformin was the most frequently detected pharmaceutical compound, and herbicides were the most frequently detected pesticide class. Water-quality conditions influenced by anthropogenic contributions are a result of current and historical land use, and these contributions include onsite wastewater disposal systems, commercial or domestic fertilizers and pesticides, and urban or industrial contaminants in road runoff. This study characterizes and improves understanding of the current hydrologic conditions in the Central Pine Barrens region and the study findings can help inform the development of plans to manage, protect, and restore water resources.

New York↗

USGS2022

Areas contributing recharge to selected production wells in unconfined and confined glacial valley-fill aquifers in Chenango River Basin, New York

In the Chenango River Basin of central New York, unconfined and confined glacial valley-fill aquifers are an important source of drinking-water supplies. The risk of contaminating water withdrawn by wells that tap these aquifers might be reduced if the areas contributing recharge to the wells are delineated and these areas protected from land uses that might affect the water quality. The U.S. Geological Survey, in cooperation with the New York State Department of Environmental Conservation and the New York State Department of Health, began an investigation in 2019 to improve understanding of groundwater flow and delineate areas contributing recharge to 16 production wells clustered in three study areas in the basin as part of an effort to protect the source of water to these wells. Areas contributing recharge were delineated on the basis of numerical steady-state groundwater-flow models representing long-term average hydrologic conditions. In the Cortland study area, four water suppliers operate 10 production wells that withdraw a total average rate of 2,480 gallons per minute from an unconfined aquifer consisting of well-sorted sand and gravel deposits. Simulated areas contributing recharge to these wells at their average pumping rates covered a total area of 6.93 square miles. Simulated areas contributing recharge extend upgradient from the wells to upland till deposits and to groundwater divides. Some simulated areas contributing recharge include isolated areas remote from the wells. Short simulated groundwater traveltimes from recharging locations to discharging wells indicated that the wells are vulnerable to contamination from land-surface activities; 50 percent of the traveltimes were 10 years or less. Land cover in some of the areas contributing recharge included a substantial amount of urban and agriculture land use. The groundwater-flow model of the Cortland study area was calibrated to available hydrologic data by inverse modeling using nonlinear regression. The parameter variance-covariance matrix from model calibration was used to create parameter sets that reflect the uncertainty of the parameter estimates and the correlation among parameters to evaluate the uncertainty associated with the single, predicted contributing areas to the wells. This analysis led to contributing areas expressed as a probability distribution. Because of the effects of parameter uncertainty, the size of the probabilistic contributing areas was larger than the size of the single, predicted contributing area for the wells. Thus, some areas not in the single, predicted contributing area might actually be in the contributing area, including additional areas of urban and agriculture land use that have the potential to contaminate groundwater. Additional areas that might be in the contributing area included recharge originating near the pumping wells that have relatively short groundwater-flow paths and traveltimes. In each of the Greene and Cincinnatus study areas, one water supplier operates three wells that are screened near the top of the bedrock surface in a confined aquifer consisting of poorly to well-sorted sand and gravel deposits. This confined aquifer is overlain by a lacustrine confining unit of very fine sand, silt, and clay, which in turn is overlain by a thin unconfined aquifer of sand and gravel. The groundwater-flow models for these two areas were manually calibrated because of the limited hydrologic data. Simulated areas contributing recharge to the Greene study area wells covered a total area of 0.35 square mile for the average pumping rate of 170 gallons per minute. The contributing areas extended southeastward of the wells to the groundwater divide in the till uplands. The contributing areas also included remote, isolated areas on the opposite side of the Chenango River from the wells primarily in the till uplands. For the Cincinnatus study area wells, which have a low average pumping rate (34 gallons per minute), the simulated contributing areas totaled 0.06 square mile and were on the same side of the river as the wells, but they are isolated areas remote from the wells primarily in the till-covered bedrock uplands. Land cover in these contributing areas for both study areas is primarily agriculture and forested, with the contributing areas to the Greene study area wells also including some urban land uses. Because the Greene and Cincinnatus study area wells are screened relatively deep and some flow paths to the wells partly travel through the confining unit, which impedes the connection with surface sources of recharge, overall groundwater traveltimes are greater than for wells in the Cortland study area. Fifty percent of Cortland study area wells, but only 9 and 44 percent of Greene and Cincinnatus study area wells, respectively, have groundwater traveltimes of 10 years or less.

New York↗

USGS1975

A Study of earthquake losses in the Puget Sound, Washington, area

The Puget Sound Basin has a history of frequent seismic activity, including two recent damaging events. The greatest extent of urban development and the most densely populated area generally correspond to the area where the greatest energy release has been experienced. For this study two earthquakes have been simulated, each having magnitude 7.5, a reasonable maximum value for this area. Analysis of the events indicate that under the worst condition as many as 2,200 people would die, and 8,700 additional persons would suffer injuries requiring hospitalization or immediate medical treatment. Such casualties would occur under the worst conditions of exposure, as during the rush hours, but could be approximately as great at any time during the working day. It is possible that as many as 23,500 people would be homeless or would require temporary shelter pending reestablishment or relocation. Conditions of exposure would be altered during the nighttime, causing a drastic reduction in casulaty potentials to a level of about 5-10 percent of the daytime losses. Thus, the time of greatest concern is during the normal working day, and the areas of concern are the highly urbanized sections of the Puget Sound Basin. This study is intended to inform those agencies serving the region of potential hazard to people, structures, and lifeline functions, in such a way that the administrators of emergency services can proceed with confidence in planning response to earthquake disaster. Figure 1 shows the extent of the study area and the location of the epicenters of the postulated earthquakes. A comparison of the two isoseismal maps as they apply to each county, in tables 1 through 6, emphasizes the marked change in intensity at a site as the simulated earthquake is moved from a close to a distant location. The Modified Mercalli Intensity scale is defined on page 284. The report is concerned not only with human casualties and displacement, but also with impairment or destruction of essential facilities critical to the continuing normal functioning of the area. This includes hospitals and medical personnel, police and fire department equipment and personnel, communications, and utilities. The total damage profile was developed with careful consideration of conditions of the seismicity, geological history, population density and distribution, and physical status of structural and lifeline installations throughout the region. There is a potential for broad fluctuation in the casualty figures resulting from the chance positioning of people at the time of the occurrence of the earthquake. An example is that of the Lafayette Elementary School in West Seattle, where, in the 1949 earthquake, a large brick gable over the entry collapsed directly onto an area normally used for assembly of pupils. Such assembly regularly occurred at 11:55 a.m. The earthquake occurred at 11:57 a.m., but fortunately during the spring vacation. Following a large earthquake, effective remedial steps to maintain or to return to operation the essential public services will depend upon the prompt and informed actions of public agencies. Response planning should include not only consideration of disaster problems within a particular jurisdiction but also sharing of assistance with neighboring jurisdictions. Moderate response requirements experienced in one area can free resources to aid communities in more heavily damaged portions of the affected area. The damage profile is quite different among the six counties within the study. The remainder of the summary is devoted to a brief general assessment of possible problems in each of the counties. A detailed development and presentation of each of the problems is covered in the text of the report.

Washington↗

USGS1972

Preliminary photointerpretation map of landslide and other surficial deposits of the Mount Hamilton quadrangle and parts of the Mount Boardman and San Jose quadrangles, Alameda and Santa Clara Counties, California

The nine San Francisco Bay region counties lie within a geologically active, young, and dynamic part of the central and northern Coast Ranges of California. Significant movements of the earth's crust are occurring here at the present time, posing numerous problems to urbanization, including some of special concern. Geological processes such as fault movements, earthquakes, land subsidence, landsliding, slow downslope movement of bedrock and surficial materials, coastal and stream erosion, flooding, and sedimentation are all potentially hazardous. Because of these factors, an understanding of the operation of physical processes in the bay region is desirable for harmonious, efficient, and safe land-use planning, particularly now, with greatly expanded pressures for urban growth. This map presents preliminary information about one aspect of the physical environment necessary to sound land-use planning--the nature and distribution of surficial deposits. Because surficial deposits are common and well developed in much of the bay region, it is useful to know how and why they have formed, as well as what properties they possess. When maps like this are used in combination with other types of environmental information, such as data on soils, bedrock geology, slopes, vegetation, climatic variation, seismic response, and hydrology, it should be easier to arrive at sound decisions regarding the physical aspects of land use. The U.S. Geological Survey is studying many of these factors in the bay region and hopes to provide the community with much of the required information as part of its San Francisco Bay Region Study in cooperation with the Department of Housing and Urban Development. The representation of surficial deposits on this map reflects the way in which a geologist, working exclusively with aerial photographs, interpreted the origin of various elements of the present landscape. The deposits shown here have not been examined in the field. However, by viewing overlapping vertical aerial photographs through a stereoscope, the geologist sees a three-dimensional relief model of the ground surface and can study and interpret the origins of landforms with considerable ease. In fact, for mapping surficial deposits, particularly in reconnaissance-type studies, photointerpretation has advantages over both ground observations and laboratory studies of surficial materials. Of course, better information can be provided when all aspects of the study are integrated. These preliminary photointerpretation maps are only the first stage in a detailed study of surficial deposits in the bay region, but they should provide land-use planners with immediately useful information about the regional distribution of landslide and other surficial deposits. This map indicates the dominant surficial processes that have probably been operative by showing the distribution of different types of surficial deposits. Processes such as weathering, erosion, sedimentation, and the slow as well as rapid downslope movement of earth materials have constantly reshaped the land surface in the past and will continue to in the future, although at varying rates. The processes are interrelated to varying degrees. For example, crustal uplift of the Coast Ranges will lead to increased erosion and downcutting by streams that in turn generally results in increased deposition of sediments in river valleys, lakes, and shoreline areas. Older flood planes and river deposits may be eroded, leaving elevated terrace deposits. In addition, downcutting by streams may cause adjacent slopes to become unstable, thereby increasing the possibility of slope failures. Man's activities can alter natural physical processes in many ways. Simple acts such as overwatering a lawn or placing a septic tank drainfield in ground that is marginally stable may weaken the bedrock and surficial materials enough to induce landsliding. Relatively stable areas may be made unstable as a result of construction activities that involve cutting or oversteepening of natural slopes. Engineers, builders, conservationists, and others concerned with land use must evaluate the potential effects of all types of development, and maps that show the nature and distribution of surficial deposits should provide much of the basic information they need. This map, then, shows the cumulative effects of various processes that have yielded surficial deposits up to the time the photographs used for photointerpretation were taken. It does not indicate directly areas where processes will be most active, nor does it show the rate at which they will operate. However, knowledge of the history of geologic events is a key to understanding and predicting the evolution of an area, even where man's activities significantly change the character of the land. Almost all new landslides, for example, occur in areas with a history of landslide activity.

California↗

USGS2013

Responses of riparian reptile communities to damming and urbanization

Various anthropogenic pressures, including habitat loss, threaten reptile populations worldwide. Riparian zones are critical habitat for many reptile species, but these habitats are also frequently modified by anthropogenic activities. Our study investigated the effects of two riparian habitat modifications-damming and urbanization-on overall and species-specific reptile occupancy patterns. We used time-constrained search techniques to compile encounter histories for 28 reptile species at 21 different sites along the Broad and Pacolet Rivers of South Carolina. Using a hierarchical Bayesian analysis, we modeled reptile occupancy responses to a site's distance upstream from dam, distance downstream from dam, and percent urban land use. The mean occupancy response by the reptile community indicated that reptile occupancy and species richness were maximized when sites were farther upstream from dams. Species-specific occupancy estimates showed a similar trend of lower occupancy immediately upstream from dams. Although the mean occupancy response of the reptile community was positively related to distance downstream from dams, the occupancy response to distance downstream varied among species. Percent urban land use had little effect on the occupancy response of the reptile community or individual species. Our results indicate that the conditions of impoundments and subsequent degradation of the riparian zones upstream from dams may not provide suitable habitat for a number of reptile species.

North Carolina;South Carolina↗

USGS2003

Trends in chemical concentration in sediment cores from three lakes in New Jersey and one lake on Long Island, New York

Sediment cores were extracted from three lakes in northeastern New Jersey and one lake on western Long Island, New York, as part of the U.S. Geological Survey National Water-Quality Assessment Program. Sediment layers were dated by use of cesium-137 (137Cs), copper, lead, or dichlorodiphenyl-trichloroethane (DDT) profiles. Sediment layers were analyzed for seven selected trace elements, including arsenic, cadmium, chromium, lead, mercury, nickel, and zinc, and five hydrophobic organochlorine compounds, including chlordane, dieldrin, total DDT, total polychlorinated biphenyls (PCBs), and total polycyclic aromatic hydrocarbons (PAHs). All seven trace elements were detected throughout the cores from all four lakes. Concentrations of all elements, except arsenic, were elevated in the three cores from lakes within urbanized watersheds (Packanack Lake, Orange Reservoir, and Newbridge Pond) relative to the concentrations in the lake core collected below the largely forested, reference watershed (Clyde Potts Reservoir). Results of trend analyses indicate that concentrations of all trace elements, with the exception of arsenic and lead, were relatively constant throughout the core from the minimally urbanized Clyde Potts Reservoir. In urban lakes, significant upward trends in concentrations from deeper to shallower sediments were observed either to peak concentrations or throughout the core for all elements, with the exception of chromium at all lakes and arsenic and nickel at Orange Reservoir. This finding indicates that changes in population and land use in the urbanized watersheds over the period of sedimentary record have contributed to upward trends in trace-element concentrations. Although downward trends in concentrations were observed for some trace elements in the years after their concentrations peaked, concentrations of all trace elements in urban lake cores were higher in the most recently deposited sediments than at the base of each respective core. Lead concentrations over time were highly correlated with the population in the vicinity of the lake until the concentration peak in sediment deposited in the mid-1970’s. Concentrations of lead in lake sediment appear to be closely related to the use of leaded gasoline because lead concentrations generally decreased after the use of leaded gasoline was phased-out in the mid-1970’s. Zinc concentrations were highly correlated with population over the entire length of the core. In general, zinc concentrations increased in the three urbanized watersheds, probably in response to increasing population and vehicular use. This trend was not evident at Clyde Potts Reservoir, however, where vehicular traffic in the watershed is minimal. Detectable concentrations of chlordane, total DDT, and total PCBs were present in cores from all lakes; however, dieldrin was detected only in the Newbridge Pond and Packanack Lake cores. Concentrations generally were higher in cores from the urbanized Newbridge Pond and Orange Reservoir watersheds than in those from the minimally urbanized Clyde Potts Reservoir watershed. With the exception of chlordane in the Clyde Potts and Orange Reservoir cores, concentrations of the four organochlorine compounds had significant downward trends from peak concentrations to recently deposited sediment or non-significant trends throughout the core. On the basis of these findings and as a result of regulatory actions prohibiting the production and use of these compounds, downward trends in sedimentary concentrations are expected to continue; however, the persistence of these compounds indicates that a substantial amount of time may be required to purge them from the watersheds. Concentrations of PAHs in sediment generally increased with population growth and urbanization, probably as a result of increased fossil-fuel combustion (gasoline and home-heating fuels and other uses (roads and parking lots paved with asphalt) associated with increased urban development and vehicular traffic. This finding is supported by low concentrations of PAHs in Packanack Lake sediments in the 1930’s, before the watershed was urbanized and when automobiles were comparatively rare. As vehicular use and urbanization increase in these watersheds, the general increase of PAH concentrations in lake sediments can be expected to continue. Data from this study indicate that changes in population, land use, and chemical use in the urbanized watersheds over the period of sedimentary record have contributed to upward trends in concentrations of trace elements and hydrophobic organic compounds. Although downward trends were observed for some constituents in the years after their concentrations peaked, concentrations of most constituents in urban lake cores were higher in the most recently deposited sediments than at the base of each respective core and in the reference lake cores. Similar trends in concentrations of these constituents have been observed in sediment cores from other urban lakes across the United States.

New Jersey, New York↗

USGS2022

Hydrology and water quality in 15 watersheds in DeKalb County, Georgia, 2012–16

The U.S. Geological Survey, in cooperation with DeKalb County Department of Watershed Management, established a long-term water-quantity and water-quality monitoring program in 2012 to monitor and analyze the hydrologic and water-quality conditions of 15 watersheds in DeKalb County, Georgia—an urban and suburban area located in north-central Georgia that includes the easternmost part of the City of Atlanta. This report synthesizes the watershed characteristics and monitoring data collected for the first 5 years of the program, 2012 through 2016. The study area was predominantly medium-density residential (43.9 percent), commercial/industrial/institutional (21.4 percent), forest/park/agriculture (13.6 percent), and high-density residential (11.5 percent) land uses. Land-surface slope averaged 8.7 percent, imperviousness averaged 25.3 percent, and population density averaged 2,936 people per square mile. Watershed imperviousness ranged from 8.7 to 36.6 percent. In the study area for 2014 to 2016 (when streamflow data were available for all watersheds), runoff represented 40.9 percent of precipitation. Hydrograph separations indicated that 43 percent of runoff occurred as base flow, whereas the remainder occurred as stormflow. Higher watershed imperviousness was significantly related to higher amounts of runoff (Pearson product-moment correlation coefficient [ r ] = 0.517), higher runoff ratios ( r = 0.646), and lower amounts ( r = −0.637) and proportions ( r = −0.898) of base-flow runoff. Stormwater best management practices have been implemented in the study watersheds; however, these practices do not appear to fully mitigate the effects of urban development and land use on stream hydrology. Total copper, lead, and zinc concentrations in base-flow and stormflow samples exceeded the national recommended aquatic life criteria for chronic and acute conditions, respectively, to varying degrees. Escherichia coli density predictive regression models indicated that the U.S. Environmental Protection Agency’s Beach Action Value was exceeded at individual watersheds between 44.6 and 100 percent of the time. Exceedance of the Beach Action Value indicates possible unsafe conditions for primary contact recreation and could be used for timely notification of the potential health risks. Annual loads and yields were estimated for 15 constituents. Loads were typically higher for years with higher runoff while variations among watershed yields appear associated with watershed and land use characteristics. The lowest yields for almost all constituents occurred in the Stone Mountain Creek watershed—likely the result of the retention of sediment and reduction of nutrients in Stone Mountain Lake and two smaller downstream reservoirs within the watershed. The Little Stone Mountain Creek watershed also had some of the lowest yields for most constituents, likely due to the lack of many pollutant sources associated with its predominantly medium-density residential land use (95.5 percent), but had the highest total nitrate plus nitrite yields. The Intrenchment Creek watershed consistently had some of the highest yields across all constituents except for total nitrate plus nitrite. The high yields may be related to its high percentage of impervious area (36.0 percent) and high amount of heavily developed land use (high-density residential, 29.9 percent and commercial/industrial/institutional, 26.0 percent). Mean watershed constituent yields in this study were significantly higher than those from a similar analysis of 13 suburban to urban watersheds in adjacent Gwinnett County for 6 of the 10 constituents compared. This study provides a thorough assessment of watershed characteristics, hydrology, and water-quality conditions of the 15 study watersheds and can be used to identify possible factors that affect runoff and water quality. Watershed managers can use these data and analyses to inform management decisions regarding the designated uses of streams, minimization of flooding, protection of aquatic habitats, and optimization of the effectiveness of best management practices.

Georgia↗

USGS2020

Stormwater control impacts on runoff volume and peak flow: A meta-analysis of watershed modelling studies

Decades of research has concluded that the percent of impervious surface cover in a watershed is strongly linked to negative impacts on urban stream health. Recently, there has been a push by municipalities to offset these effects by installing structural stormwater control measures (SCMs), which are landscape features designed to retain and reduce runoff to mitigate the effects of urbanisation on event hydrology. The goal of this study is to build generalisable relationships between the level of SCM implementation in urban watersheds and resulting changes to hydrology. A literature review of 185 peer‐reviewed studies of watershed‐scale SCM implementation across the globe was used to identify 52 modelling studies suitable for a meta‐analysis to build statistical relationships between SCM implementation and hydrologic change. Hydrologic change is quantified as the percent reduction in storm event runoff volume and peak flow between a watershed with SCMs relative to a (near) identical control watershed without SCMs. Results show that for each additional 1% of SCM‐mitigated impervious area in a watershed, there is an additional 0.43% reduction in runoff and a 0.60% reduction in peak flow. Values of SCM implementation required to produce a change in water quantity metrics were identified at varying levels of probability. For example, there is a 90% probability (high confidence) of at least a 1% reduction in peak flow with mitigation of 33% of impervious surfaces. However, as the reduction target increases or mitigated impervious surface decreases, the probability of reaching the reduction target also decreases. These relationships can be used by managers to plan SCM implementation at the watershed scale.

Hydrological Processes↗

USGS1988

Simulation of quantity and quality of storm runoff for urban catchments in Fresno, California

Rainfall-runoff models were developed for a multiple-dwelling residential catchment (2 applications), a single-dwelling residential catchment, and a commercial catchment in Fresno, California, using the U.S. Geological Survey Distributed Routing Rainfall-Runoff Model (DR3M-II). A runoff-quality model also was developed at the commercial catchment using the Survey 's Multiple-Event Urban Runoff Quality model (DR3M-qual). The purpose of this study was: (1) to demonstrate the capabilites of the two models for use in designing storm drains, estimating the frequency of storm runoff loads, and evaluating the effectiveness of street sweeping on an urban drainage catchment; and (2) to determine the simulation accuracies of these models. Simulation errors of the two models were summarized as the median absolute deviation in percent (mad) between measured and simulated values. Calibration and verification mad errors for runoff volumes and peak discharges ranged from 14 to 20%. The estimated annual storm-runoff loads, in pounds/acre of effective impervious area, that could occur once every hundred years at the commercial catchment was 95 for dissolved solids, 1.6 for the dissolved nitrite plus nitrate, 0.31 for total recoverable lead, and 120 for suspended sediment. Calibration and verification mad errors for the above constituents ranged from 11 to 54%.

California↗

USGS2005

Gulf of Mexico Integrated Science - Tampa Bay Study: Watershed and Estuary Mapping

Tampa Bay, Florida, and its environs have experienced phenomenal urban growth and significant changes in land-use practices over the past 50 years. This trend is expected to continue, with human activity intensifying and affecting a wider geographic region. Urbanization creates impervious surfaces, which increase stormwater runoff and contribute to greater amounts of chemicals flowing into coastal waters. Man-made structures including bridges, a gas pipeline, desalination plant, ports, navigation channels, and extensive sea walls have been built and will continue to be maintained and modified. This task of the Tampa Bay Study aims to provide a better understanding of these and other man-made impacts on the Tampa Bay region.

Open-File Report↗

USGS2008

Associations between land use and Perkinsus marinus infection of eastern oysters in a high salinity, partially urbanized estuary

Infection levels of eastern oysters by the unicellular pathogen Perkinsus marinus have been associated with anthropogenic influences in laboratory studies. However, these relationships have been difficult to investigate in the field because anthropogenic inputs are often associated with natural influences such as freshwater inflow, which can also affect infection levels. We addressed P. marinus-land use associations using field-collected data from Murrells Inlet, South Carolina, USA, a developed, coastal estuary with relatively minor freshwater inputs. Ten oysters from each of 30 reefs were sampled quarterly in each of 2 years. Distances to nearest urbanized land class and to nearest stormwater outfall were measured via both tidal creeks and an elaboration of Euclidean distance. As the forms of any associations between oyster infection and distance to urbanization were unknown a priori, we used data from the first and second years of the study as exploratory and confirmatory datasets, respectively. With one exception, quarterly land use associations identified using the exploratory dataset were not confirmed using the confirmatory dataset. The exception was an association between the prevalence of moderate to high infection levels in winter and decreasing distance to nearest urban land use. Given that the study design appeared adequate to detect effects inferred from the exploratory dataset, these results suggest that effects of land use gradients were largely insubstantial or were ephemeral with duration less than 3 months.

Ecotoxicology↗

USGS1981

Floods of September 16, 1975 in the Tallaboa Valley, Puerto Rico

This report provides a record of the flood of September 16, 1975, and associated hydrologic data. These data can be used in making rational decisions in formulating effective flood-plain regulations that would minimize flood problems in the Tallaboa Valley. The Tallaboa Valley (fig. 1) lies on the southwestern coast of Puerto Rico about 12 km (7.5 mi) west of the city of Ponce. The climate is semiarid with a mean annual precipitation of about 1,020 mm (40 in). It is a relatively small valley which until the late fifties was dedicated mainly to the product ion of sugarcane. Since then, the economy started changing from agriculture to industry. At present the lower part of the valley is completely industrialized. The upper part of the valley is used for agriculture--mostly as pastureland. The reach from Highway 132 downstream to the new Highway 2 is mainly agricultural with a few scattered communities. The lower part of the valley that includes the area from the Highway 2 bridge to the mouth is covered with heavy industry concerned with the refinement of oil, and associated industries. The continuous growth of industry and consequently of the urban area of Peñuelas has encouraged growth onto the flood plain. The study area is subject to flooding by the Rio Tallaboa and the Rio Guayanes, its main tributary. The Rio Guayanes is the- cause of flooding in the urban area of Penuelas, encompassing the reach from the northern edge of town downstream to Highway 132 where it joins the Rio Tallaboa. Data are generally referred to in SI (International System) units followed by corresponding inch-pound units in parentheses. The SI units.may be converted to inch-pound units by multiplying the units given by the factors shown.

Tallaboa Valley↗

USGS1981

Floods of September 16, 1975 in the Tallaboa Valley, Puerto Rico

Tallaboa Valley↗