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At least 163 records · Page 9Linked to original sources

USGS2005

Use of an urban intensity index to assess urban effects on streams in three contrasting environmental settings

To assess the effects of urbanization on assemblages (fish, invertebrate, and algal), physical habitat, and water chemistry, we investigated the relations among varying intensities of basin urbanization and stream ecology in three metropolitan areas: the humid northeastern United States around Boston, Massachusetts; the humid southeastern United States around Birmingham, Alabama; and the semiarid western United States around Salt Lake City, Utah. A consistent process was used to develop a multimetric urban intensity index (UII) based on locally important variables (land-use/land-cover, infrastructure, and socioeconomic variables) in each study area and a common urban intensity index (CUII) based on a subset of five variables common to all study areas. The UII was used to characterize 30 basins along an urban gradient in each metropolitan area. Study basins were located within a single ecoregion in each of the metropolitan areas. The UII, ecoregions, and site characteristics provided a method for limiting the variability of natural landscape characteristics while assessing the magnitude of urban effects. Conditions in Salt Lake City (semiarid climate and water diversions) and Birmingham (topography) required nesting sites within the same basin. The UII and CUII facilitated comparisons of aquatic assemblages response to urbanization across different environmental settings. ?? 2005 by the American Fisheries Society.

American Fisheries Society Symposium↗

USGS2020

Potential impacts of future urbanization and sea level rise on Florida’s natural resources

As urban development continues to encroach into natural systems, these ecosystems experience increasing degradation to their form and function. Losses in biodiversity and ecosystem function are further compounded by changing climatic conditions. The State of Florida is known for its biodiversity but has experienced declines in species populations and habitats because of urbanization and sea level rise. These declines are particularly challenging in an economy that benefits from a multibillion-dollar income from natural resources tourism. In this study, we assessed the potential future impacts of urbanization and sea level rise on a suite of conservation targets that have been set for the State. We developed six scenarios of all combinations of intermediate and high sea level rise paired with two types of urbanization (sprawling and compact) in both 2040 and 2070 to examine the potential future threats to conservation targets in High Pine and Scrub, Coastal Uplands, and Freshwater Aquatics ecosystems. Our results show projected decreases in extent and area of these priority ecosystems into the future. Florida's current trend in urbanization practices are projected to have a greater impact on conservation targets than if sprawl reduction practices are implemented. Coastal Uplands are projected to experience the greatest loss in area, at up to 47%. Conservation-focused urban planning and climate adaptation strategies can help protect Florida's natural resources with benefits to Florida's tourism economy as well as critical ecosystem functions and services such as coastal flood protection and storm surge risk reduction.

Florida↗

USGS2012

Characterizing invertebrate traits in wadeable streams of the contiguous US: differences among ecoregions and land uses

Much is known about invertebrate community traits in basins across Europe, but no comprehensive description of traits exists for the continental US. Little is known about the trait composition of invertebrates in reference or least-disturbed basins of the US, how trait composition varies among ecoregions, or how consistently traits respond to land use. These elements are essential to development of trait-based tools for conservation and assessment of biological integrity. We compared invertebrate traits of least-disturbed basins among ecoregions of the US. Benthic invertebrate data (presence/absence) from 1987 basins were translated into 56 binary traits (e.g., bivoltine, clinger). Basins were classified as least-disturbed, agricultural, or urban, and grouped into 9 ecoregions. Landuse, climatic, physiographic, and hydrologic data were used to describe ecoregions and to evaluate least-disturbed basin quality. The unique habitat template of each ecoregion selected for trait compositions in least-disturbed basins that differed among ecoregions. Among the traits examined, life-history (e.g., voltinism, development) and ecological traits (e.g., rheophily, thermal preference) differed most among ecoregions. Agricultural and urban land uses selected for trait compositions that differed from least-disturbed, but the extent of the differences depended on ecoregion and quality of the least-disturbed basins. No trait compositions unique to specific land uses were found. However, a disturbance syndrome was observed in that the magnitude and direction of trait responses to urban and agricultural land uses were consistent among ecoregions. Each ecoregion had a unique trait composition, but trait compositions could be used to aggregate ecoregions into 3 broad regions: Western Mountains, Plains and Lowlands, and Eastern Highlands. Our results indicate that large-scale trait-based assessment tools for the US will require calibration to account for regional differences in the trait composition of basins and in the quality of least-disturbed basins.

Freshwater Science↗

USGS2014

Ecological role and services of tropical mangrove ecosystems: a reassessment

Aim To reassess the capacity of mangroves for ecosystem services in the light of recent data. Location Global mangrove ecosystems. Methods We review four long-standing roles of mangroves: (1) carbon dynamics – export or sink; (2) nursery role; (3) shoreline protection; (4) land-building capacity. The origins of pertinent hypotheses, current understanding and gaps in our knowledge are highlighted with reference to biogeographic, geographic and socio-economic influences. Results The role of mangroves as C sinks needs to be evaluated for a wide range of biogeographic regions and forest conditions. Mangrove C assimilation may be under-estimated because of flawed methodology and scanty data on key components of C dynamics. Peri-urban mangroves may be manipulated to provide local offsets for C emission. The nursery function of mangroves is not ubiquitous but varies with spatio-temporal accessibility. Connectivity and complementarity of mangroves and adjacent habitats enhance their nursery function through trophic relay and ontogenetic migrations. The effectiveness of mangroves for coastal protection depends on factors at landscape/geomorphic to community scales and local/species scales. Shifts in species due to climate change, forest degradation and loss of habitat connectivity may reduce the protective capacity of mangroves. Early views of mangroves as land builders (especially lateral expansion) were questionable. Evidence now indicates that mangroves, once established, directly influence vertical land development by enhancing sedimentation and/or by direct organic contributions to soil volume (peat formation) in some settings. Main conclusions Knowledge of thresholds, spatio-temporal scaling and variability due to geographic, biogeographic and socio-economic settings will improve the management of mangrove ecosystem services. Many drivers respond to global trends in climate change and local changes such as urbanization. While mangroves have traditionally been managed for subsistence, future governance models must involve partnerships between local custodians of mangroves and offsite beneficiaries of the services.

Global Ecology and Biogeography↗

USGS1997

Potential effects of climate change on aquatic ecosystems of the Great Plains of North America

The Great Plains landscape is less topographically complex than most other regions within North America, but diverse aquatic ecosystems, such as playas, pothole lakes, ox-bow lakes, springs, groundwater aquifers, intermittent and ephemeral streams, as well as large rivers and wetlands, are highly dynamic and responsive to extreme climatic fluctuations. We review the evidence for climatic change that demonstrates the historical importance of extremes in north-south differences in summer temperatures and east-west differences in aridity across four large subregions. These physical driving forces alter density stratification, deoxygenation, decomposition and salinity. Biotic community composition and associated ecosystem processes of productivity and nutrient cycling respond rapidly to these climatically driven dynamics. Ecosystem processes also respond to cultural effects such as dams and diversions of water for irrigation, waste dilution and urban demands for drinking water and industrial uses. Distinguishing climatic from cultural effects in future models of aquatic ecosystem functioning will require more refinement in both climatic and economic forecasting. There is a need, for example, to predict how long-term climatic forecasts (based on both ENSO and global warming simulations) relate to the permanence and productivity of shallow water ecosystems. Aquatic ecologists, hydrologists, climatologists and geographers have much to discuss regarding the synthesis of available data and the design of future interdisciplinary research.

Hydrological Processes↗

USGS2025

Salting behaviors influence urban stream conductivity in Boston, Massachusetts (USA)

Freshwater salinization is a major concern in temperate climates where road salt is used as a deicer to manage snow and ice on roadways. In urban and suburban areas, wastewater, weathering of infrastructure, and salting on parking lots and sidewalks can also contribute to salt contamination, but little is known about how well these sources explain variation in stream conductivity and what factors may mitigate high conductivity in streams. We collected specific conductance samples seasonally over 1 y at 100 stream sites in the greater Boston (Massachusetts, USA) metropolitan area, which reflected a gradient of land use/cover and sociodemographic variables. We also continuously monitored specific conductance over 1 y (November 2021–December 2022) at 3 streams with different levels of impervious cover. Baseflow conductivity from grab samples was best explained by % impervious cover (positive relationship) and season (highest median conductivity in summer and early autumn) ( r 2 = 0.47, p < 0.001). At high impervious cover, watersheds with higher housing vacancy had lower conductivity, suggesting that resident salting behavior may affect conductivity. Continuous conductivity varied with discharge, with spikes in conductivity coincident with increases in discharge in the winter, likely due to the influx of road salt into waterways. In the summer, higher discharge was linked with sharp decreases in conductivity, suggesting that storm flows dilute high baseflow conductivity, although combined sewer overflows caused secondary conductivity pulses. Overall, conductivity was highest during winter storm pulses, but elevated conductivity levels persisted throughout the year, especially in more impervious watersheds. Our research suggests that reduced salt application and street sweeping may reduce conductivity but will not prevent continued salinization. Temporal patterns of conductivity highlight the importance of seasonal road-salt application (winter), seasonal climate (low-flow summers), and precipitation (storm events, droughts) in influencing stream conductivity and can guide monitoring design, policymaking, and management decisions under climate uncertainty.

Massachusetts↗

USGS2013

Extreme rainfall, vulnerability and risk: a continental-scale assessment for South America

Extreme weather continues to preoccupy society as a formidable public safety concern bearing huge economic costs. While attention has focused on global climate change and how it could intensify key elements of the water cycle such as precipitation and river discharge, it is the conjunction of geophysical and socioeconomic forces that shapes human sensitivity and risks to weather extremes. We demonstrate here the use of high-resolution geophysical and population datasets together with documentary reports of rainfall-induced damage across South America over a multi-decadal, retrospective time domain (1960–2000). We define and map extreme precipitation hazard , exposure , affected populations, vulnerability and risk , and use these variables to analyse the impact of floods as a water security issue. Geospatial experiments uncover major sources of risk from natural climate variability and population growth, with change in climate extremes bearing a minor role. While rural populations display greatest relative sensitivity to extreme rainfall, urban settings show the highest rates of increasing risk. In the coming decades, rapid urbanization will make South American cities the focal point of future climate threats but also an opportunity for reducing vulnerability, protecting lives and sustaining economic development through both traditional and ecosystem-based disaster risk management systems.

Philosophical Transactions of the Royal Society A:↗

USGS1994

Effects of mesoscale vegetation distributions in mountainous terrain on local climate

Even a casual observer from an aircraft will note the varied landscape of mountainous terrain. These variations in land surface include the terrain features themselves as well as patchiness from different vegetation types, surface geology, urbanization, etc. There are two major questions related to climate system dynamics that need to be addressed concerning this landscape heterogeneity: (i) how would a large-scale climate change influence this landscape, and (ii) does landscape spatial and temporal structure influence the larger-scale climate?

Book chapter↗

USGS2023

Pollinator conservation and climate science at the U.S. Geological Survey

Introduction Ecosystems—whether agricultural, urban, or natural—depend on pollinators, great and small. Pollinators in the form of bees, birds, butterflies, bats, and even moths provide vital, but often invisible services, from contributing to biodiverse terrestrial wildlife and plant communities to supporting healthy watersheds. Pollinator declines worldwide have been noted as land-use and climate changes occur on the landscape. This is alarming because up to 75 percent of crop species that are important for human food production depend on pollinators for production. Biodiversity of pollinators in the United States includes more than 4,000 species of insects, birds, and mammals. Pollinator species in the United States are in crisis based on broad-scale changes in land-use and climate. The Committee on the Status of Pollinators in North America summarized active and passive management alternatives to benefit pollinators and reduce their decline. Because assessment of pollinators in the United States has historically lagged behind other regions of the world, the Committee challenged the U.S. Geological Survey (USGS) and U.S. Fish and Wildlife Service (USFWS) to develop conservation plans, for pollinators, including quantification of the effects of climate change. As an example of the immediate need to focus efforts on pollinator conservation, Inouye and others cited the USFWS’s 2017 listing of the rusty-patched bumble bee ( Bombus affinis ) as Endangered under the U.S. Endangered Species Act (ESA) of 1973. Strategies are developed to accomplish pollinator conservation goals and the USGS is contributing scientific expertise toward those goals.

Fact Sheet↗

USGS2026

Large streamflow differences between forested and urbanized watersheds in the energy-limited eastern United States: The role of evapotranspiration and impervious surfaces

Urban forests and other green infrastructures have been viewed as part of the “Nature-based Solutions” (NbS) to mitigate emerging urban environmental change. This study focuses on the role of evapotranspiration (ET) in regulating water balances of small watersheds in the eastern United States. We compared streamflow and ET patterns at daily, monthly and annual scales and linked these hydrological variables to the physical properties of 11 paired watersheds dominated by forests (FW) or urban (UW) land covers. The annual precipitation ranged from 1028 mm to 1683 mm and potential ET (PET) from 815 mm to 1450 mm. The mean annual flow/precipitation (Q/P) ratios were 0.26 ± 0.13 and 0.41 ± 0.1 for FW and UW, respectively. Overall, UW had lower annual ET (772 mm in UW vs. 947 mm in FW), but higher mean annual and (∼58% higher), monthly water yield (17%–186% higher), and peakflow rates (up to 100 times higher) than FW. The streamflow differences between FW and UW were most pronounced during the growing season and early winter (June-November). The mean Q/P ratios for 30 large hurricane events (2016–2021) were 0.12 ± 0.11 and 0.38 ± 0.23 for FW and UW, respectively. The flow rates in the dormant season (around December-May) in UW were similar or lower than FW. We developed conceptual models to explain the seasonal and storm event streamflow differences using background climate (PET), ET, and land surface characteristics. Urban NbS designs should factor in strategies that maximize ET while minimizing impervious surfaces enhancing watershed “sponge” and “pump” functions.

eastern United States↗

USGS2016

Vulnerabilities of national parks in the American Midwest to climate and land use changes

Many national parks in the American Midwest are surrounded by agricultural or urban areas or are in highly fragmented or rapidly changing landscapes. An environmental stressor is a physical, chemical, or biological condition that affects the functioning or productivity of species or ecosystems. Climate change is just one of many stressors on park natural resources; others include urbanization, land use change, air and water pollution, and so on. Understanding and comparing the relative vulnerability of a suite of parks to projected climate and land use changes is important for region-wide planning. A vulnerability assessment of 60 units in the 13-state U.S. National Park Service Midwestern administrative region to climate and land use change used existing data from multiple sources. Assessment included three components: individual park exposure (5 metrics), sensitivity (5 metrics), and constraints to adaptive capacity (8 metrics) under 2 future climate scenarios. The three components were combined into an overall vulnerability score. Metrics were measures of existing or projected conditions within park boundaries, within 10-kilometer buffers surrounding parks, and within ecoregions that contain or intersect them. Data were normalized within the range of values for all assessed parks, resulting in high, medium, and low relative rankings for exposure, sensitivity, constraints to adaptive capacity, and overall vulnerability. Results are consistent with assessments regarding patterns and rates of climate change nationwide but provide greater detail and relative risk for Midwestern parks. Park overall relative vulnerability did not differ between climate scenarios. Rankings for exposure, sensitivity, and constraints to adaptive capacity varied geographically and indicate regional conservation planning opportunities. The most important stressors for the most vulnerable Midwestern parks are those related to sensitivity (intrinsic characteristics of the park) and constraints on adaptive capacity (characteristics of the surrounding landscape) rather than exposure to external forces, including climate change. Output will allow individual park managers to understand which metrics weigh most heavily in the overall vulnerability of their park and can be used for region-wide responses and resource allocation for adaptation efforts.

Arkansas, Illinois, Indiana, Iowa, Kansas, Michiga↗

USGS2008

Effects of urbanization on stream ecosystems in the Willamette River basin and surrounding area, Oregon and Washington

This report describes the effects of urbanization on physical, chemical, and biological characteristics of stream ecosystems in 28 watersheds along a gradient of urbanization in the Willamette River basin and surrounding area, Oregon and Washington, from 2003 through 2005. The study that generated the report is one of several urban-effects studies completed nationally by the U.S. Geological Survey National Water-Quality Assessment Program. Watersheds were selected to minimize natural variability caused by factors such as geology, elevation, and climate, and to maximize coverage of different stages of urban development among watersheds. Because land use or population density alone often are not a complete measure of urbanization, a combination of land use, land cover, infrastructure, and socioeconomic variables were integrated into a multimetric urban intensity index (UII) to represent the degree of urban development in each watershed. Physical characteristics studied include stream hydrology, stream temperature, and habitat; chemical characteristics studied include sulfate, chloride, nutrients, pesticides, dissolved and particulate organic and inorganic carbon, and suspended sediment; and biological characteristics studied include algal, macroinvertebrate, and fish assemblages. Semipermeable membrane devices, passive samplers that concentrate trace levels of hydrophobic organic contaminants such as polycyclic aromatic hydrocarbons and polychlorinated biphenyls, also were used. The objectives of the study were to (1) examine physical, chemical, and biological responses along the gradient of urbanization and (2) determine the major physical, chemical, and landscape variables affecting the structure of aquatic communities. Common effects documented in the literature of urbanization on instream physical, chemical, and biological characteristics, such as increased contaminants, increased streamflow flashiness, increased concentrations of chemicals, and changes in aquatic community structure toward a more tolerant community associated with organically enriched conditions, generally were observed in this study. The strongest correlations to the UII and to many of the algal, macroinvertebrate, and fish assemblage metrics and community ordination involved water-chemistry metrics including the total pesticide concentration, toxic equivalents (extract assay from semipermeable membrane devices), and dissolved oxygen. Hydrologic variability metrics, such as flashiness, that normally are considered to be one of the main processes of urban disturbance had a strong association to the algal and fish assemblages in this study; however, the hydrologic variables for macroinvertebrates were secondary to the water-chemistry metrics mentioned above. Generally, the high urban intensity sites had high abundances of eutrophic and lower dissolved oxygen-indicating diatoms, high abundances of noninsects and tolerant insects, and high abundances of nonnative fish species. On the other hand, the low urban intensity sites had higher abundances of pollution sensitive diatoms, larger numbers of the sensitive macroinvertebrate EPT taxa (Ephemeroptera, Plecoptera and Trichoptera Orders), and fish assemblages with higher abundances of sensitive salmonids. The percent salmonid and macroinvertebrate EPT richness metrics plotted against the UII indicated a possible threshold response at about 25 on the UII, which is equivalent to an impervious surface value of about 5 percent. However, due to the added agricultural land use at sites within the 25 to 60 UII range, this possible threshold probably is not solely due to urbanization, but a combination of urban and agricultural land use. The effects of agricultural and urban land use could not be distinguished from each other, yet combined they provide a good assessment of overall watershed disturbance.

Oregon, Washington↗

USGS2018

Changing environmental gradients over forty years alter ecomorphological variation in Guadalupe Bass Micropterus treculii throughout a river basin

Understanding the degree of intraspecific variation within and among populations is a key aspect of predicting the capacity of a species to respond to anthropogenic disturbances. However, intraspecific variation is usually assessed at either limited temporal, but broad spatial scales or vice versa, which can make assessing changes in response to long-term disturbances challenging. We evaluated the relationship between the longitudinal gradient of changing flow regimes and land use/land cover patterns since 1980 and morphological variation of Guadalupe Bass Micropterus treculii throughout the Colorado River Basin of central Texas. The Colorado River Basin in Texas has experienced major alterations to the hydrologic regime due to changing land- and water-use patterns. Historical collections of Guadalupe Bass prior to rapid human-induced change present the unique opportunity to study the response of populations to varying environmental conditions through space and time. Morphological differentiation of Guadalupe Bass associated with temporal changes in flow regimes and land use/land cover patterns suggests that they are exhibiting intraspecific trait variability, with contemporary individuals showing increased body depth, in response to environmental alteration through time (specifically related to an increase in herbaceous land cover, maximum flows, and the number of low pulses and high pulses). Additionally, individuals from tributaries with increased hydrologic alteration associated with urbanization or agricultural withdrawals tended to have a greater distance between the anal and caudal fin. These results reveal trait variation that may help to buffer populations under conditions of increased urbanization and sprawl, human population growth, and climate risk, all of which impose novel selective pressures, especially on endemic species like Guadalupe Bass. Our results contribute an understanding of the adaptability and capacity of an endemic population to respond to expected future changes based on demographic or climatic projection.

Texas↗

USGS2017

Hydrologic metrics for status-and-trends monitoring in urban and urbanizing watersheds

Local governmental agencies are increasingly undertaking potentially costly “status-and-trends” monitoring to evaluate the effectiveness of stormwater control measures and land-use planning strategies, or to satisfy regulatory requirements. Little guidance is presently available for such efforts, and so we have explored the application, interpretation, and temporal limitations of well-established hydrologic metrics of runoff changes from urbanization, making use of an unusually long-duration, high-quality data set from the Pacific Northwest (USA) with direct applicability to urban and urbanizing watersheds. Three metrics previously identified for their utility in identifying hydrologic conditions with biological importance that respond to watershed urbanization—T Qmean (the fraction of time that flows exceed the mean annual discharge), the Richards-Baker Index (characterizing flashiness relative to the mean discharge), and the annual tally of wet-season day-to-day flow reversals (the total number of days that reverse the prior days’ increasing or decreasing trend)—are all successful in stratifying watersheds across a range of urbanization, as measured by total contributing area of urban development. All metrics respond with statistical significance to multi-decadal trends in urbanization, but none detect trends in watershed-scale urbanization over the course of a single decade. This suggests a minimum period over which dependable trends in hydrologic alteration (or improvement) can be detected with confidence. The metrics also prove less well suited to urbanizing watersheds in a semi-arid climate, with only flow reversals showing a response consistent with prior findings from more humid regions. We also explore the use of stage as a surrogate for discharge in calculating these metrics, recognizing potentially significant agency cost savings in data collection with minimal loss of information. This approach is feasible but cannot be implemented under current data-reporting practices, requiring measurement of water-depth values and preservation of the full precision of the original recorded data. With these caveats, however, hydrologic metrics based on stage should prove as or more useful, at least in the context of status-and-trends monitoring, as those based on subsequent calculations of discharge.

Hydrological Processes↗

USGS2023

Mapping the Surface Urban Heat Island effect using the Landsat Surface Temperature Product

Urban development and associated land cover and land use change alter the thermal, hydrological, and physical properties of the land surface. Urban areas usually exhibit relatively warmer air and surface temperatures than surrounding non-urban lands, a phenomenon recognized as Surface Urban Heat Island (SUHI). As urban areas continue to develop and the climate continues to warm, it has become increasingly important to quantify and map the SUHI effect and learn how to mitigate it. To help meet the expanding need of analysis ready data for SUHI based studies, a methodology was developed to evaluate Land Surface Temperature (LST) using the Landsat Collection 1 Provisional Surface Temperature Science Product. The Landsat derived LST products were processed for 50 major cities throughout the Conterminous U.S. The SUHI product package includes per-pixel annual surface temperature, annual intensity, annual hotspot, and hotspot probability bands from 1985 to 2020.

Conterminous United States↗

USGS2006

Effects of urbanization on stream ecosystems in the South Platte River basin, Colorado and Wyoming

This report describes the effects of urbanization on physical, chemical, and biological characteristics of stream ecosystems in 28 basins along an urban land-use gradient in the South Platte River Basin, Colorado and Wyoming, from 2002 through 2003. Study basins were chosen to minimize natural variability among basins due to factors such as geology, elevation, and climate and to maximize coverage of different stages of urban development among basins. Because land use or population density alone often are not a complete measure of urbanization, land use, land cover, infrastructure, and socioeconomic variables were integrated in a multimetric urban intensity index to represent the degree of urban development in each study basin. Physical characteristics studied included stream hydrology, stream temperature, and habitat; chemical characteristics studied included nutrients, pesticides, suspended sediment, sulfate, chloride, and fecal bacteria concentrations; and biological characteristics studied included algae, fish, and invertebrate communities. Semipermeable membrane devices (SPMDs), passive samplers that concentrate trace levels of hydrophobic organic contaminants like polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), also were used. The objectives of the study were to (1) examine physical, chemical, and biological responses along the gradient of urbanization; (2) determine the major physical, chemical, and landscape variables affecting the structure of aquatic communities; and (3) evaluate the relevance of the results to the management of water resources in the South Platte River Basin. Commonly observed effects of urbanization on instream physical, chemical, and biological characteristics, such as increased flashiness, higher magnitude and more frequent peak flows, increased concentrations of chemicals, and changes in aquatic community structure, generally were not observed in this study. None of the hydrologic, temperature, habitat, or chemical variables were correlated strongly (Spearman's rho greater than or equal to 0.7) with urban intensity, with the exception of some of the SPMD-based toxicity and chemical variables. SPMD-based measures of potential toxicity and PAH concentrations were positively correlated with urban intensity. The PAH concentrations also were positively correlated with measures of road density and negatively correlated with distance to the nearest road, indicating that automobile exhaust is a major source of these compounds in the study area. This source may be localized enough that the transport of PAHs would be minimally affected by water-management practices such as diversion or storage upstream. In contrast, the predominant sources of nutrients, bacteria, suspended sediment, sulfate, chloride, and pesticides may be more dispersed throughout the drainage area and, therefore, their transport to downstream sites may be subject to greater disruption by water regulation. Although no direct link was found between most water-chemistry characteristics and urbanization, invertebrate, algae, and fish-community characteristics were strongly associated with nutrients, pesticides, sulfate, chloride, and suspended sediment. None of the biological community variables were strongly correlated with the urban intensity index. Algal biomass predominantly was associated with total nitrogen concentrations, nitrite-plus-nitrate concentrations, and the duration of high flows. Fish communities predominantly were associated with housing age, the percentage of suspended sediment finer than 0.063 millimeters and chloride concentrations. Invertebrate communities predominantly were associated with the frequency of rising and falling flow events, the duration of high flows, total nitrogen concentrations, nitrite-plus-nitrate concentrations, and total herbicide concentrations. Historical records indicate that aquatic communities in the region may have been altered prior to any substantial urban development by early agricultural and water-management practices. Present-day aquatic communities are composed primarily of tolerant species even in areas of minimal urban development; when development does occur, the communities already may be resistant to disturbance. In addition to the effects of historical stressors on aquatic community structure, it is possible that current water-management practices in the study basins are having an effect. In the absence of natural, unaltered hydrologic conditions, more sensitive taxa may be unable to recolonize urban streams. The movement and storage of water also may lead to a disconnect between the land surface and streams, resulting in instream physical, chemical, and biological characteristics that, to some degree, are independent of land-cover characteristics.

Colorado, Wyoming↗

USGS1996

Environmental setting and factors that affect water quality in the Georgia-Florida Coastal Plain study unit

The Georgia-Florida Coastal Plain study unit covers an area of nearly 62,000 square miles in the southeastern United States, mostly in the Coastal Plain physiographic province. Land resource provinces have been designated based on generalized soil classifications. Land resource provinces in the study area include: the Coastal Flatwoods, the Southern Coastal Plain, the Central Florida Ridge, the Sand Hills, and the Southern Piedmont. The study area includes all or parts of seven hydrologic subregions: the Ogeechee-Savannah, the Altamaha- St.Marys, the Suwannee, the Ochlockonee, the St. Johns, the Peace-Tampa Bay, and the Southern Florida. The primary source of water for public supply in the study area is ground water from the Upper Floridan aquifer. In 1990, more than 90 percent of the 2,888 million gallons per day of ground water used came from this aquifer. The population of the study area was 9.3 million in 1990. The cities of Jacksonville, Orlando, St. Petersburg, Tallahassee, and Tampa, Florida, and parts of Atlanta and Savannah, Georgia, are located in the study area. Forest and agricultural areas are the most common land uses in the study area, accounting for 48 percent and 25 percent of the study area, respectively. Climatic conditions range from temperate in Atlanta, Georgia, where mean annual temperature is about 61.3 degrees Fahrenheit, to subtropical in Tampa, Florida, where mean annual temperature is about 72.4 degrees Fahrenheit. Long-term average precipitation (1961-90) ranges from 43.9 inches per year in Tampa, Florida, and 44.6 in Macon, Georgia, to 65.7 inches per year in Tallahassee, Florida. Floods in the study area result from frontal systems, hurricanes, tropical storms, or severe thunderstorms. Droughts are not common in the study area,especially in the Florida part of the study area due to extensive maritime exposure. The primary physical and cultural characteristics in the study area include physiography, soils and land resource provinces, geologic setting, ground-water systems, surface- water systems, climate, floods, droughts, population, land use, and water use. Factors affecting water quality in the study area are land use (primarily urban and agricultural land uses), water use in coastal areas, hydrogeology, ground-water/surface-water interaction, geology, and climate. Surface-water quality problems in urban areas have occurred in the Ogeechee, Canoochee, Ocmulgee, St. Marys, Alapaha, Withlacoochee (north), Santa Fe, Ochlockonee, St. Johns, and Oklawaha Rivers and include nitrogen and phosphorus loading, low dissolved oxygen, elevated bacteria, sediment, and turbidity, and increased concentrations of metals. In agricultural areas, surface-water quality problems include elevated nitrogen and phosphorus concentrations, erosion, and sedimentation and have occurred in the Ocmulgee, St. Marys, Santa Fe, Ochlockonee, St. Johns, Oklawaha, Withlacoochee (South), Hillsborough, and Alafia Rivers. Ground water-quality problems such as saltwater intrusion have occurred mostly in coastal areas and were caused by excessive withdrawals.

Florida, Georgia↗

USGS2021

Subsurface temperature properties for three types of permeable pavements in cold weather climates and implications for deicer reduction

Permeable pavement has been shown to be an effective urban stormwater management tool although much is still unknown about freeze-thaw responses and the implications for deicer reduction in cold weather climates. Temperature data from the subsurface of three permeable pavement types—interlocking concrete pavers (PICP), concrete (PC), and asphalt (PA)—were collected over a seven-year period and evaluated. Temperature profiles of all pavements indicate favorable conditions to allow infiltration during winter rain and melting events, with subsurface temperatures remaining above freezing even when air temperatures were below freezing. Data show that PICP surpassed PC and PA with fewer days below freezing, higher temperatures on melt days, slower freeze and faster thaw times, and less penetration of freezing temperatures at depth.

Water↗