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At least 415 records · Page 23Linked to original sources
USGS2003

Effects of hydrology on red mangrove recruits

Coastal wetlands along the Gulf of Mexico have been experiencing significant shifts in hydrology and salinity levels over the past century as a result of changes in sea level and freshwater drainage patterns. Local land management in coastal zones has also impacted the hydrologic regimes of salt marshes and mangrove areas. Parks and refuges in south Florida that contain mangrove forests have, in some cases, been ditched or impounded to control mosquito outbreaks and to foster wildlife use. And while mangroves dominate the subtropical coastlines of Florida and thrive in saltwater environments, little is known about how they respond to changes in hydrology under managed or variable tidal conditions. USGS researchers designed a study to evaluate the basic hydrological requirements of mangroves so that their health and survival may be more effectively managed in controlled impoundments and restored wetlands. Mangroves are commonly found in the intertidal zone (between low and high tides) in a rather broad spectrum of hydrologic settings. Because they thrive at the interface of land and sea, mangroves are subject to changes in freshwater flow (flow rate, nutrients, pollutants) and to marine influences (sea-level rise, salinity). Salinity has long been recognized as a controlling factor that determines the health and distribution of mangrove forests. Field and experimental observations indicate that most mangrove species achieve their highest growth potential under brackish conditions (modest salinity) between 10 and 20 parts per thousand (ppt). Yet, if provided with available propagules, successful regeneration, and limited competition from other plants, then mangroves can survive and thrive in freshwater systems as well. Because little is known about the growthand survival patterns of mangrove species relative to changing hydrology, USGS scientists conducted greenhouse and field experiments to determine how flooded or drained patterns of hydrology would influence growth of the red mangrove, Rhizophora mangle (fig. 1). Red mangrove propagules (recruits) of select sizes and genotypes (i.e., genetically similar groups) were planted both in greenhouses and in the field. Seedling growth was monitored in both studies on a quarterly basis for over a year; measurements included shoot growth, seedling height, and a final harvest of plant biomass.

Fact Sheet↗
USGS2019

Improving eDNA yield and inhibitor reduction through increased water volumes and multi-filter isolation techniques

To inform management and conservation decisions, environmental DNA (eDNA) methods are used to detect genetic material shed into the water by imperiled and invasive species. Methodological enhancements are needed to reduce filter clogging, PCR inhibition, and false-negative detections when eDNA is at low concentrations. In the first of three simple experiments, we sought to ameliorate filter clogging from particulates and organic material through a scaled-up, multi-filter protocol. We combined four filters in a 5 mL Phenol-Chloroform-Isoamyl (PCI) procedure to allow for larger volumes of water (~1 L) to be filtered rapidly. Increasing the filtered water volume by four times resulted in 4.4X the yield of target DNA. Next, inhibition from organic material can reduce or block eDNA detections in PCR-based assays. To remove inhibitory compounds retained during eDNA isolation, we tested three methods to chemically strip inhibitors from eDNA molecules. The use of CTAB as a short-term (5–8 day) storage buffer, followed by a PCI isolation, resulted in the highest eDNA yields. Finally, as opposed to a linear relationship among increasing concentrations of filtered genomic eDNA, we observed a sharp change between the lower (70–280 ng) and higher (420–560 ng) amounts. This may be important for effectively precipitating eDNA during protocol testing.

Scientific Reports↗
USGS2025

Evaluating how changing climate and water clarity can affect restoration of native coregonine fishes in midwestern lakes

In the upper midwestern United States, coregonine fishes (e.g., ciscoes and whitefishes) have provided a key food source for Indigenous peoples since time immemorial. In the last century, however, several anthropogenic stressors including overfishing, declining quality of key habitat (e.g., dams, algal blooms), and negative interactions with invasive species have led to declines in the fisheries that coregonines support. Hence, fishery managers have undertaken steps to conserve existing diversity or re-introduce species that have been locally extirpated. This study assessed the extent to which changes in water clarity and climate pose challenges for conservation of coregonines and sought to provide information to inform management decisions about which populations would be best for reintroduction. Through experiments, we found that a Cisco ( Coregonus artedi ) population at the southern edge of its range had no marked advantages in respiration or thermal tolerance, relative to a northern Great Lake population. This result indicates that the latter population would be a reasonable candidate for reintroduction in Lake Erie, where warming water could be a potential impediment. Other laboratory experiments revealed that Cisco could be vulnerable to increasing ultraviolet radiation (UV; 280 – 320 nm) penetration in lakes due to reduced ice cover and increased water clarity owing to water quality improvements and/or invasive mussel filtration. Our experiments found that UV exposure causes earlier hatching, more irregular pigmentation near the head and yolk-sac region, and reduced heart rate. Therefore, UV could be a heretofore unrealized threat to Cisco populations. Through the completion of additional final products from this project and additional research connecting laboratory and field data together, the extent to which the eggs and larvae of coregonine species could be vulnerable to increased UV associated with increasing water clarity or reduced ice cover will help inform restoration or conservation planning for these fish.

Cooperator Report↗
USGS1997

Digital simulation of ground-water flow in the Warwick Aquifer, Fort Totten Indian Reservation, North Dakota

The demand for water from the Warwick aquifer, which underlies the Fort Totten Indian Reservation in northeastern North Dakota, has been increasing during recent years. Therefore, the Spirit Lake Sioux Nation is interested in resolving questions about the quantity and quality of water in the aquifer and in developing a water-management plan for future water use. A study was conducted to evaluate the surface-water and ground-water resources of the Fort Totten Indian Reservation and, in particular, the ground-water resources in the area of the Warwick aquifer. A major component of the study, addressed by this report, was to define the ground-water flow system of the aquifer. The Warwick aquifer consists of outwash deposits of the Warwick outwash plain that are as much as 30 feet thick and buried-valley deposits beneath the outwash plain that are as much as 200 feet thick. The aquifer is bounded on the north and west by end-moraine deposits and Devils Lake, on the south by the Sheyenne River Valley, and on the east by outwash deposits and ravines. The aquifer is underlain by Pierre Shale or by glacial till, clay, or silt. Ground-water gradients generally are small and rarely are more than 3 or 4 feet per mile. From 1982 to 1993, withdrawals from the Devils Lake well field averaged 1.5 cubic feet per second, and withdrawals from irrigation wells averaged 1.29 cubic feet per second. The combined discharge from springs may be about 3 cubic feet per second. During the early 1990s, the Warwick aquifer probably was in a steady-state condition with regard to storage change in the aquifer. A finite-difference, three-dimensional, ground-water flow model provided a reasonable simulation of ground-water flow in the Warwick aquifer. The aquifer was divided vertically into two layers and horizontally into a grid of 83 by 109 cells, each measuring 656 feet (200 meters) per side. The steady-state simulation was conducted using 1992 pumpage rates and October 1992 water levels. The mean absolute difference between simulated and derived water-level altitudes during final calibration of the model was 1.52 feet. The two transient simulations were conducted for 20 time intervals of 1 year each using both the small and large storage estimates, doubled 1992 pumpage from the Devils Lake well field, 1992 irrigation pumpage, and initial water-level altitudes simulated by the October 1992 steady-state simulation. In the simulation using the small storage estimate and doubled pumpage, model cells in the area of the well field went dry after 13 years. Assumptions made in the design of the model generally are supported by the digital simulation. Except in the area of Warwick Springs and smaller springs, lateral and basal boundaries of the aquifer are impermeable. The flow system is dominated by recharge and evapotranspiration. Recharge rates obtained during the calibration process were lower in topographically high areas than in topographically low areas. Hydraulic conductivity in the area of the Devils Lake well field was larger than that in the rest of the aquifer.

Water-Resources Investigations Report↗
USGS2024

Estimation and comparison of 1-percent annual exceedance probability flood flows at Federal Emergency Management Agency flood insurance study flow locations across Pennsylvania

Flood-flow estimates were computed at over 5,000 Federal Emergency Management Agency (FEMA) flood insurance study (FIS) flow locations across Pennsylvania for the 1-percent annual exceedance probability flood event (1-percent AEP). Depending on a point of interest’s proximity to a streamgage, weighting techniques may be applied to obtain flood-flow estimates for ungaged flow locations using observed peak-flow data from a nearby streamgage. Following the U.S. Geological Survey’s (USGS) published guidance, stream segments were identified where the drainage-area ratio method could be leveraged. Using updated regional regression equations and recently published flood-flow estimates at USGS streamgage locations following USGS Bulletin 17C guidelines, weighted and transferred flood flows were computed, where appropriate. For locations not applicable for the drainage-area ratio method, regression equations were used to compute flood-flow estimates. These flood-flow estimates were then compared to FEMA FIS 1-percent AEP flood-flow estimates. Percentage-difference values were computed for 3,599 FIS flow locations determined to be suitable for analysis, finding that USGS-derived flood-flow estimates were consistently lower than FEMA FIS flood-flow estimates with a statewide median percentage difference of −10.1 percent. The dataset was normally distributed with a standard deviation of 45.7 percent. Allegheny County was found to have 74 FIS flow locations with percentage-difference values greater than or equal to 67 percent or less than or equal to −67 percent. The flood-flow region in which Allegheny County is contained, Region 2, had a median percentage-difference value of −39 percent. Although removed from the final analysis, flow locations with drainage-area values above the recommended threshold for regression-based estimation (about 1,000 square miles [mi 2 ]) were observed to have consistently higher percentage-difference values; a reminder of the limitations of use for regression-based flood-flow estimates. This report, the comparisons within, and a companion data release are intended to serve as tools to FEMA in assisting with the ongoing assessment of FIS flow locations across Pennsylvania.

Pennsylvania↗
USGS2008

Derivation of ground surface and vegetation in a coastal Florida wetland with airborne laser technology

The geomorphology and vegetation of marsh-dominated coastal lowlands were mapped from airborne laser data points collected on the Gulf Coast of Florida near Cedar Key. Surface models were developed using low- and high-point filters to separate ground-surface and vegetation-canopy intercepts. In a non-automated process, the landscape was partitioned into functional landscape units to manage the modeling of key landscape features in discrete processing steps. The final digital ground surface-elevation model offers a faithful representation of topographic relief beneath canopies of tidal marsh and coastal forest. Bare-earth models approximate field-surveyed heights by + 0.17 m in the open marsh and + 0.22 m under thick marsh or forest canopy. The laser-derived digital surface models effectively delineate surface features of relatively inaccessible coastal habitats with a geographic coverage and vertical detail previously unavailable. Coastal topographic details include tidal-creek tributaries, levees, modest topographic undulations in the intertidal zone, karst features, silviculture, and relict sand dunes under coastal-forest canopy. A combination of laser-derived ground-surface and canopy-height models and intensity values provided additional mapping capabilities to differentiate between tidal-marsh zones and forest types such as mesic flatwood, hydric hammock, and oak scrub. Additional derived products include fine-scale shoreline and topographic profiles. The derived products demonstrate the capability to identify areas of concern to resource managers and unique components of the coastal system from laser altimetry. Because the very nature of a wetland system presents difficulties for access and data collection, airborne coverage from remote sensors has become an accepted alternative for monitoring wetland regions. Data acquisition with airborne laser represents a viable option for mapping coastal topography and for evaluating habitats and coastal change on marsh-dominated coasts. Such datasets can be instrumental in effective coastal-resource management.

Florida↗
USGS2009

Terrestrial ecosystems - Isobioclimates of the conterminous United States

As part of an effort to map terrestrial ecosystems, the U.S. Geological Survey has generated isobioclimate classes to be used in creating maps depicting standardized, terrestrial ecosystem models for the conterminous United States, using an ecosystems classification developed by NatureServe . A biophysical stratification approach, developed for South America (Sayre and others, 2008) and now being implemented globally, was used to model the ecosystem distributions. Bioclimate regimes strongly influence the differentiation and distribution of terrestrial ecosystems, and are therefore one of the key input layers in this biophysical stratification. The Rivas-Martínez methodology is based on the concept of establishing a quantifiable classification system which would closely relate the distribution of vegetation to climatic parameters and indices. This method first establishes bioclimatic indices calculated from various ranges of temperature and precipitation data, compares these indices to defined thresholds, and finally applies sets of decision rules to identify the climate classes. The climate classification is hierarchical with four levels: macrobioclimates, bioclimates, thermotypes, and ombrotypes. Thermotypes, which represent thermoclimatic belts, are identified using the positive annual temperature (Tp) thresholds or the compensated thermicity index (Itc) thresholds. Ombrotypes, which represent ombroclimatic belts, are based on the ombrothermic index (Io) which is calculated as a function of both the total positive precipitation and temperature . For this national implementation the source data used for establishing the bioclimatic indices was Daymet. Daymet temperature and precipitation data were developed from 18 years (1980–1997) of climatological records and is available at a spatial resolution of 1 kilometer . This implementation of the Rivas-Martínez methodology resulted in the generation of four climate layers for the conterminous United States: macroclimates, bioclimates, thermotypes, and ombrotypes. However, the biophysical stratification approach used for the ecosystems modeling effort required a single climate layer that accurately reflected regional variation in wet/dry gradients and hot/cold gradients, with a manageable number of classes. Therefore, the data layers for thermotypes and ombrotypes were combined, yielding 127 unique thermotype-ombrotype combinations.The isobioclimates image shows ombrotypic regions (dry/wet gradients) for each thermotypic (warm/cold) region. Additional information about this map and any of the data developed for the ecosystems modeling of the conterminous United States is available online at http://rmgsc.cr.usgs.gov/ecosystems/ .

Scientific Investigations Map↗
USGS2024

2023-2024 Coastal sage scrub and chaparral community monitoring for western San Diego County

Western San Diego County is dominated by shrublands supporting biologically diverse native plant and animal communities. Widespread urbanization has led to regional habitat loss and fragmentation, and many species in these shrubland communities are rare, threatened, or endangered. Large-scale, multiple-species conservation planning has resulted in a regional preserve system that focuses on these shrubland communities. Several large-scale threats are leading to type conversion from shrub-dominated to non-native invasive annual grass-dominated vegetation. To understand the changes that are occurring to native shrublands, we have developed a vegetation monitoring program with several components at multiple spatial scales, focused on quantifying coastal sage scrub (CSS) and chaparral vegetation community characteristics. Several drivers of change associated with type conversion of native shrubland to non-native annual grassland have been identified by previous research including increasing fire frequency, nitrogen deposition from air pollution, and prolonged and intense drought associated with changing climate. Loss of ecological integrity indices have been proposed as useful measures of the threat of degradation and type conversion of shrublands in San Diego County. For this study, ecological integrity is defined as a system’s ability to maintain species’ relationships and functions comparable to natural habitat in the region. Previous studies have identified the percent cover of invasive non-native annual grasses as a proxy for overall ecological degradation (loss of integrity) that is consistent across native taxonomic groups. Increased cover of non-native grass is associated with lower integrity of the shrubland vegetation community as shrub-associated plant and animal species are replaced by species preferring grassy and disturbed habitats. The objectives of this CSS and chaparral vegetation community monitoring plan are to: 1) Determine the distribution, composition, structure, and integrity of CSS and chaparral vegetation communities on conserved lands in western San Diego County, 2) Identify whether these attributes of the vegetation communities are changing over time, and 3) Evaluate relationships of known drivers of change (threats) and environmental factors in association with changes in vegetation community attributes. The CSS and chaparral vegetation community monitoring program is divided into four components: 1) vegetation mapping, 2) GIS/remote sensing office analysis of landscape-scale data, 3) permanent field plots using Unmanned Aerial Systems (UAS) and field data collections, and 4) animal and target species surveys and rapid assessment protocols. The first component, which is not detailed in this vegetation monitoring plan, aims to map vegetation communities every 10-15 years based on a classification developed for western San Diego County. High resolution aerial imagery will be used to update the 2012 vegetation map and expand it across the entire study area. The second component uses remote sensing models to annually track ecological integrity of shrublands across the study area and will include a map of areas of change and areas of stability over several decades. These landscape-scale integrity classifications will be used to analyze ecological processes, threats, and abiotic factors relative to changes to shrubland ecological integrity over time and space. The third component includes field surveys of 100 permanent plots across areas historically mapped as shrublands. Surveys in the 1930s mapped vegetation types using plot data. By using this historical classification map, we included areas that have already type-converted from shrubland to non-native annual grassland. The plots were split between CSS (55 plots) and chaparral (45 plots) and stratified into four geographical eco-subregions to guarantee coverage over small patches of habitat along the heavily developed coast. Surveys will include the collection of UAS imagery at a very high resolution. Species-level identifications will be made from the imagery based on a plant list compiled of all species detected in the plot during a thorough field survey by botanists, combined with geo-referenced samples of plant species locations. In addition, herbaceous cover will be estimated in the field using nine 1-m diameter circles (one per subplot) to obtain ocular estimates of cover for each plant species within the circle frame. Soil samples will be collected and analyzed for important element compositions. These data will be analyzed to evaluate plot-level ecological integrity based on species composition and cover. Repeated monitoring will allow evaluation of changes in vegetation attributes over time with known drivers or threats and other environmental factors. In addition, analyses will focus on indicator species and various measures of biological diversity for the vegetation communities. Finally, animal species and rare plants will be assessed using either taxa-based rapid assessment protocols or specialized species-specific protocols for rarer species. The purpose of these assessments is to document the status, habitat, and threat covariates of specific species and confirm the species composition and diversity of animal taxonomic groups (e.g., pollinators). Diversity and abundance of animal species at vegetation plots will be used to refine measures and thresholds of ecological integrity. Rapid assessment protocols for animal taxonomic groups can include multiple detection methods such as, camera traps, cover boards, and bird point counts. Pollinators will be monitored at plots using a protocol currently being developed in conjunction with but separately from this plan. Target rare plant species will be monitored using the regional Inspect and Manage (IMG) protocol that measures the status of rare plant occurrences and habitat and threat covariates over time. Species-specific animal survey methods will be refined as these species are prioritized for future monitoring. The goal of this monitoring program is to classify CSS and chaparral vegetation community integrity, identify areas of degradation across western San Diego County, and characterize drivers, and environmental factors associated with loss of ecological integrity. A combination of vegetation mapping, landscape-scale remote sensing, and field plots will be used to address all the aspects of our research questions. Data compiled and collected will be available to conservation partners to help inform future management decisions.

California↗
USGS2015

Sources of fine-grained sediment in the Linganore Creek watershed, Frederick and Carroll Counties, Maryland, 2008-10

Sediment fingerprinting quantifies the delivery of fine-grained sediment from a watershed and sediment-budget measurements quantify the erosion and deposition of fine-grained sediment. Both approaches were used in the agricultural and forested 147-square-kilometer (km 2 ) Linganore Creek watershed in Maryland from August 1, 2008 through December 31, 2010, to determine the sources of fine-grained (less than 63 microns) sediment, and the amount of fine-grained sediment eroded from and deposited on streambanks, flood plains, channel beds, and agricultural and forested uplands. Sediment-weighted results of sediment fingerprinting for 194 suspended-sediment samples collected during 36 storms indicate that streambanks contributed 52 percent of the annual fine-grained suspended-sediment load, agriculture (cropland and pasture) contributed 45 percent, and forests contributed 3 percent. Fifty-four percent of the Linganore Creek watershed is agriculture and 27 percent is forest. Sediment-budget calculations were based on field measurements and photogrammetric analyses and indicated that the highest percentage of fine-grained sediment was eroded from agriculture (86 percent), followed by streambanks (10 percent), forests (3 percent), and the channel bed (less than 1 percent). Results of the sediment budget indicated that the highest percentage of fine-grained sediment was stored in ponds (57 percent), followed by flood plains (32 percent), streambanks (6 percent), and the channel bed (5 percent). Typical of most sediment budgets, the final sediment budget indicated erosion of 4.70 x 10 7 kilograms per year (kg/yr), which is higher than the fine-grained suspended-sediment load leaving the watershed (5.45 x 10 6 kg/yr). The differences in the sediment budget and the measured mass leaving the watershed could be due to an overestimation of erosion using the Cesium-137 method and (or) not adequately defining and measuring storage areas. Management implications of this study indicate that both agriculture and streambanks are important sources of sediment in Linganore Creek where the delivery of agriculture sediment was 4 percent and the delivery of streambank sediment was 44 percent. Fourth order streambanks, on average, had the highest rates of bank erosion. Combining the sediment fingerprinting and sediment budget results indicates that 96 percent of the eroded fine-grained sediment from agriculture went into storage. Flood plains and ponds are effective storage sites of sediment in the Linganore Creek watershed. Flood plains stored 8 percent of all eroded sediment with 4th and 5th order flood plains, on average, storing the most sediment. Small ponds in the Linganore Creek watershed, which drained 16 percent of the total watershed area, stored 15 percent of all eroded sediment. Channel beds were relatively stable with the greatest erosion generally occurring in 4th and 5th order streams.

Maryland↗
USGS2023

Latency and geofence testing of wireless emergency alerts intended for the ShakeAlert® earthquake early warning system for the West Coast of the United States of America

ShakeAlert, the earthquake early warning (EEW) system for the West Coast of the United States, attempts to provides crucial warnings before strong shaking occurs. However, because the alerts are triggered only when an earthquake is already in progress, and the alert latencies and delivery times are platform dependent, the time between these warnings and the arrival of shaking is variable. The ShakeAlert system uses, among other public alerting platforms like a mobile phone operating system, smartphone apps, and the Federal Emergency Management Agency Integrated Public Alert & Warning System (IPAWS). IPAWS sends Wireless Emergency Alerts (WEAs) informing people via their smartphones and other mobile devices about various events, such as natural hazards, child abductions, or public health information about COVID-19. However, little is known about the IPAWS delivery latencies. Given that people may have only a few seconds of notice after they receive an alert to take a protective action before they feel earthquake shaking, quantifying latencies is critical to understanding whether the IPAWS system is useful for EEW. In this study, we developed new methods to test the IPAWS distribution system's performance, both with devices in a controlled environment and as well as with a 2019 community-based feedback form, in Oakland and San Diego County, California, respectively. The controlled environment test used mobile phones (including smart and non-smart phones) and associated devices to determine alert receipt times; the community research form had participants self-report their receipt times. By triangulating the data between the controlled test environment and the community research, we determined the latency statistics as well as whether the geofence (the geographic area where the alert was intended to be sent) held broadly. We found that the latencies were similar between the two tests despite the large differences in population sizes. WEA messages were received within a median time frame of 6–12 s, and the geofence held with only a few exceptions. We use this latency to assess how the system would have performed in two large earthquakes, the 1989 M6.9 Loma Prieta and 2019 M7.1 Ridgecrest earthquakes, which both occurred near our WEA test locations. Our analysis revealed that had IPAWS been available during those earthquakes, particularly Loma Prieta, it would have provided crucial seconds of notice that damaging shaking was imminent in some locations relatively far from the epicenter. Further, we find affordable non-smart phones can receive WEAs as fast as smartphones. Finally, our new method can be used for latency and geospatial testing going forward for IPAWS and other similar alerting systems.

California↗
USGS2016

The Impacts of flow alterations to crayfishes in Southeastern Oklahoma, with an emphasis on the mena crayfish (orconectes menae)

Human activities can alter the environment to the point that it is unsuitable to the native species resulting in a loss of biodiversity. Ecologists understand the importance of biodiversity and the conservation of vulnerable species. Species that are narrowly endemic are considered to be particularly vulnerable because they often use specific habitats that are highly susceptible to human disturbance. The basic components of species conservation are 1) delineation of the spatial distribution of the species, 2) understanding how the species interacts with its environment, and 3) employing management strategies based on the ecology of the species. In this study, we investigated several crayfish species endemic to the Ouachita Mountains in Oklahoma and Arkansas. We established the spatial distributions (i.e., range) of the crayfish using Maximum Entropy species distribution modeling. We then investigated crayfish habitat use with quantitative sampling and a paired movement study. Finally, we evaluated the ability of crayfish to burrow under different environmental conditions in a controlled laboratory setting. Crayfish distribution at the landscape scale was largely driven by climate, geology and elevation. In general, the endemic crayfish in this study occurred above 300-m elevation where the geology was dominated by sandstone and shale, and rainfall totals were the highest compared to the rest of the study region. Our quantitative data indicated crayfish did not select for specific habitat types at the reach scale; however, crayfish appeared to continue to use shallow and dry habitat even as the streams dried. Movement by passive integrated transponder (PIT) tagged crayfish was highly variable but crayfish tended to burrow in response to drought rather than migrate to wet habitat. Controlled laboratory experiments revealed smaller substrate size (pebble) restricted crayfish burrowing more than larger substrates (cobble). We also found excess fine sediment restricted crayfish burrowing regardless of dominant substrate size. Our results suggest climate change and sedimentation resulting from land-use practices, combined with increased water withdrawals have the potential to alter crayfish distributions and affect persistence of some crayfish populations.

Report↗
USGS2010

U.S. Geological Survey Streamgage Operation and Maintenance Cost Evaluation...from the National Streamflow Information Program

To help meet the goal of providing earth-science information to the Nation, the U.S. Geological Survey (USGS) operates and maintains the largest streamgage network in the world, with over 7,600 active streamgages in 2010. This network is operated in cooperation with over 850 Federal, tribal, State, and local funding partners. The streamflow information provided by the USGS is used for the protection of life and property; for the assessment, allocation, and management of water resources; for the design of roads, bridges, dams, and water works; for the delineation of flood plains; for the assessment and evaluation of habitat; for understanding the effects of land-use, water-use, and climate changes; for evaluation of water quality; and for recreational safety and enjoyment. USGS streamgages are managed and operated to rigorous national standards, allowing analyses of data from streamgages in different areas and spanning long time periods, some with more than 100 years of data. About 90 percent of USGS streamgages provide streamflow information real-time on the web. Physical measurements of streamflow are made at streamgages multiple times a year, depending on flow conditions, to ensure the highest level of accuracy possible. In addition, multiple reviews and quality assurance checks are performed before the data is finalized. In 2006, the USGS reviewed all activities, operations, equipment, support, and costs associated with operating and maintaining a streamgage program (Norris and others, 2008). A summary of the percentages of costs associated with activities required to operate a streamgage on an annual basis are presented in figure 1. This information represents what it costs to fund a 'typical' USGS streamgage and how those funds are utilized. It should be noted that some USGS streamgages have higher percentages for some categories than do others depending on location and conditions. Forty-one percent of the funding for the typical USGS streamgage is for labor costs of the USGS staff responsible for the measurement of the streamflow in the field and the time in the office to quality assure and finalize the data. It is reasonable that funding for the entire national streamgage network would closely follow the percentages shown in figure 1 as to how the funds are invested in the network. However, actual costs are specific to a particular streamgage and can vary substantially depending on location and operational issues.

Fact Sheet↗
USGS2016

Shifting currents: Progress, setbacks, and shifts in policy and practice

The Wisconsin Academy’s initial Waters of Wisconsin project (WOW I) facilitated a statewide conversation between 2000 and 2003 around one main question: How can we ensure healthy aquatic ecosystems and clean, abundant water supplies for tomorrow’s Wisconsin? Robust participation in this conversation underscored the important role citizens have in the stewardship of our waters, and we found enthusiastic support for farsighted policies—based on sound science—to manage our water legacy. Overall, we found that Wisconsinites cherish water and see our waters as essential to our way of life in Wisconsin. Nationally, our state ranks 25th in land area but has the fourth-highest area covered by water. Wisconsin is 20th in population but is second only to Florida in the number of fishing licenses sold each year. Clean water supports billions of dollars’ worth of economic activity through tourism, agriculture, and industry. From the Northwoods cabin to the Port of Milwaukee to the Wisconsin Dells, water shapes our state’s identity. Our tradition of safeguarding Wisconsin’s waters is grounded in values such as responsibility to family and future generations, respect for land and wildlife, protecting public health and safety, and caring for water as a common good, as articulated in the state’s Public Trust Doctrine (see page 9). These deeply held values have also shaped a conservation ethic, and its legacy has served many generations who depend upon and enjoy the waters of the state. Through WOW I, we identified the need to overcome the institutional and disciplinary separation of science, policy, and management protocols through a more integrated approach to water management. WOW also affirmed that the Wisconsin Department of Natural Resources (DNR) and other public agencies play a critical role in sound scientific application, citizen participation, and the practical implementation of policy while balancing public and private interests toward the goal of a clean water future. More than a decade has passed since our first statewide WOW conversation and the report that captured recommendations from its participants: Waters of Wisconsin: The Future of Our Aquatic Ecosystems and Resources. Drawing from a diverse and growing set of stakeholders from across the state, the Wisconsin Academy initiated a new conversation in 2012 (known as WOW II) to assess progress in regard to our 2003 recommendations. We also sought to review the status of waters in Wisconsin today. The result of this renewed conversation is Shifting Currents: Progress, Setbacks, and Shifts in Policy and Practice. The new report assesses progress in brief, and explores in greater depth the continuing and emerging challenges to water quality, supply, and aquatic ecosystems in Wisconsin. In this report, we first review the context and frameworks for public decision-making about water and then examine some of the root causes—or “drivers”—and ecological stressors that underlie many of the symptoms we see in the form of pollution or ecosystem degradation in Wisconsin. This is followed by a summary of current water issues, many of which had been identified in the 2003 report and remain relevant today. We examine progress since 2003 but also setbacks, and discuss issues that we are likely to continue to face in the coming decades, including controlling agricultural runoff, mitigating climate change and grappling with its effects on the state’s waters, protecting groundwater from bacterial contamination and other pollutants, and preventing groundwater depletion. We also attempt to anticipate issues on the horizon. We offer a deeper look at some particular challenges, such as phosphorus pollution and groundwater contamination. We then consider the current decision-making framework and how it is shaping our capacity to respond to water challenges in Wisconsin. Finally, we offer recommendations and identify opportunities to safeguard Wisconsin’s waters in the decades ahead. From its inception, the Wisconsin Academy’s Waters of Wisconsin Initiative has brought together a diverse community of experts from across the state and from varied fields and areas of interest, to address challenges and seize opportunities related to our precious waters. We have done so as a matter of both principle and practical reality: the state of our waters reflects the ways we interact not only with them, but also with one another and our institutions. The WOW Initiative has aimed to provide guidance for Wisconsin citizens in sustaining the health of our aquatic ecosystems and the resilience of our water supplies over the long term.

Report↗
USGS2014

Methods for estimating the magnitude and frequency of floods for urban and small, rural streams in Georgia, South Carolina, and North Carolina, 2011

Reliable estimates of the magnitude and frequency of floods are essential for the design of transportation and water-conveyance structures, flood-insurance studies, and flood-plain management. Such estimates are particularly important in densely populated urban areas. In order to increase the number of streamflow-gaging stations (streamgages) available for analysis, expand the geographical coverage that would allow for application of regional regression equations across State boundaries, and build on a previous flood-frequency investigation of rural U.S Geological Survey streamgages in the Southeast United States, a multistate approach was used to update methods for determining the magnitude and frequency of floods in urban and small, rural streams that are not substantially affected by regulation or tidal fluctuations in Georgia, South Carolina, and North Carolina. The at-site flood-frequency analysis of annual peak-flow data for urban and small, rural streams (through September 30, 2011) included 116 urban streamgages and 32 small, rural streamgages, defined in this report as basins draining less than 1 square mile. The regional regression analysis included annual peak-flow data from an additional 338 rural streamgages previously included in U.S. Geological Survey flood-frequency reports and 2 additional rural streamgages in North Carolina that were not included in the previous Southeast rural flood-frequency investigation for a total of 488 streamgages included in the urban and small, rural regression analysis. The at-site flood-frequency analyses for the urban and small, rural streamgages included the expected moments algorithm, which is a modification of the Bulletin 17B log-Pearson type III method for fitting the statistical distribution to the logarithms of the annual peak flows. Where applicable, the flood-frequency analysis also included low-outlier and historic information. Additionally, the application of a generalized Grubbs-Becks test allowed for the detection of multiple potentially influential low outliers. Streamgage basin characteristics were determined using geographical information system techniques. Initial ordinary least squares regression simulations reduced the number of basin characteristics on the basis of such factors as statistical significance, coefficient of determination, Mallow’s Cp statistic, and ease of measurement of the explanatory variable. Application of generalized least squares regression techniques produced final predictive (regression) equations for estimating the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probability flows for urban and small, rural ungaged basins for three hydrologic regions (HR1, Piedmont–Ridge and Valley; HR3, Sand Hills; and HR4, Coastal Plain), which previously had been defined from exploratory regression analysis in the Southeast rural flood-frequency investigation. Because of the limited availability of urban streamgages in the Coastal Plain of Georgia, South Carolina, and North Carolina, additional urban streamgages in Florida and New Jersey were used in the regression analysis for this region. Including the urban streamgages in New Jersey allowed for the expansion of the applicability of the predictive equations in the Coastal Plain from 3.5 to 53.5 square miles. Average standard error of prediction for the predictive equations, which is a measure of the average accuracy of the regression equations when predicting flood estimates for ungaged sites, range from 25.0 percent for the 10-percent annual exceedance probability regression equation for the Piedmont–Ridge and Valley region to 73.3 percent for the 0.2-percent annual exceedance probability regression equation for the Sand Hills region.

Georgia, North Carolina, South Carolina↗
USGS2016

Development of an adaptive harvest management program for Taiga bean geese

This report describes recent progress in specifying the elements of an adaptive harvest program for taiga bean goose. It describes harvest levels appropriate for first rebuilding the population of the Central Management Unit and then maintaining it near the goal specified in the AEWA International Single Species Action Plan (ISSAP). This report also provides estimates of the length of time it would take under ideal conditions (no density dependence and no harvest) to rebuild depleted populations in the Western and Eastern Management Units. We emphasize that our estimates are a first approximation because detailed demographic information is lacking for taiga bean geese. Using allometric relationships, we estimated parameters of a thetalogistic matrix population model. The mean intrinsic rate of growth was estimated as r = 0.150 (90% credible interval: 0.120 – 0.182). We estimated the mean form of density dependence as   2.361 (90% credible interval: 0.473 – 11.778), suggesting the strongest density dependence occurs when the population is near its carrying capacity. Based on expert opinion, carrying capacity (i.e., population size expected in the absence of hunting) for the Central Management Unit was estimated as K  87,900 (90% credible interval: 82,000 – 94,100). The ISSAP specifies a population goal for the Central Management Unit of 60,000 – 80,000 individuals in winter; thus, we specified a preliminary objective function as one which would minimize the difference between this goal and population size. Using the concept of stochastic dominance to explicitly account for uncertainty in demography, we determined that optimal harvest rates for 5, 10, 15, and 20-year time horizons were h = 0.00, 0.02, 0.05, and 0.06, respectively. These optima represent a tradeoff between the harvest rate and the time required to achieve and maintain a population size within desired bounds. We recognize, however, that regulation of absolute harvest rather than harvest rate is more practical, but our matrix model does not permit one to calculate an exact harvest associated with a specific harvest rate. Approximate harvests for current population size in the Central Management Unit are 0, 1,200, 2,300, and 3,500 for the 5, 10, 15, and 20-year time horizons, respectively. Populations of taiga bean geese in the Western and Eastern Units would require at least 10 and 13 years, respectively, to reach their minimum goals under the most optimistic of scenarios. The presence of harvest, density dependence, or environmental variation could extend these time frames considerably. Finally, we stress that development and implementation of internationally coordinated monitoring programs will be essential to further development and implementation of an adaptive harvest management program.

Conference Paper↗
USGS2025

Preliminary field report of landslide hazards following Hurricane Helene

Executive Summary This report reflects our knowledge regarding the widespread landslide activity associated with Hurricane Helene observed during the U.S. Geological Survey’s (USGS) mission assignment to North Carolina in October 2024. The material in this report was originally prepared for the Federal Emergency Management Agency under mission assignment DR-4827-NC. The data and commentary in this report are reflective of a report provided to the Federal Emergency Management Agency (FEMA) on October 18, 2024, as well as information provided in briefings at the Buncombe County Emergency Operations Center. The report has been modified for public dissemination. This assessment was based on systematic visual examination and mapping of landslide locations from aerial and satellite imagery, visual and photographic observations from low-level helicopter overflights and conversations with local landslide experts from the North Carolina Geological Survey and Appalachian Landslide Consultants PLLC, and more than 50 years of combined landslide hazard professional experience of the mission-assigned field team. No systematic field investigations were done by the USGS. While responding to the event, the USGS did not identify any landslides that posed an immediate major threat to recovery personnel in parts of nine counties in North Carolina (Avery, Buncombe, Henderson, McDowell, Mitchell, Polk, Rutherford, Watauga, and Yancey); however, threats from renewed landslide activity may remain heightened in localized areas for months or even years. Known areas of the most abundant landslide occurrence include Bat Cave, Lake Lure, Chimney Rock, Swannanoa, Black Mountain, Fairview, steep areas in Asheville, and the Blue Ridge Parkway. The USGS shared detailed locations of known landslides with the Emergency Operations Centers. The thousands of landslide scars on hillsides and landslide deposits on flatter ground may present some threat to recovery activities. Soil and rocks will continue to erode from newly exposed landslide scars and may pose a threat to people and infrastructure who are immediately nearby. In general, the steeper and taller the landslide scar, the greater the potential threat. This threat is heightened during periods of rainfall and increases with the duration and intensity of rainstorms. Very heavy rainfall, or repeated rainfall events during short periods, could also initiate new landslides on steep slopes. Excavation of landslide deposits, particularly excavation of those deposits directly adjacent to steep slopes, may also pose a threat to nearby people and equipment. An interagency collaborative mapping effort led by the USGS that informed this assessment identified 1,155 landslide locations by the October 2024 briefings, but that number increased to 2,217 in a final reviewed version of the locations published in January 2025. Locations were mapped from satellite imagery, fixed-wing and helicopter surveys, media and social media, and field reports in the 3 weeks following the passage of the remnants of Hurricane Helene. USGS products outlined in this report are publicly available and include geotagged photographs from aerial reconnaissance, hazard models, an interactive view of mapped landslide locations, and landslide safety and education resources.

North Carolina, South Carolina, Tennessee, Virgini↗
USGS2014

Simulation of groundwater flow and saltwater movement in the Onslow County area, North Carolina: predevelopment-2010

Onslow County, North Carolina, is located within the designated Central Coastal Plain Capacity Use Area (CCPCUA). The CCPCUA was designated by law as a result of groundwater level declines of as much as 200 feet during the past four decades within aquifers in rocks of Cretaceous age in the central Coastal Plain of North Carolina and a depletion of water in storage from increased groundwater withdrawals in the area. The declines and depletion of water in storage within the Cretaceous aquifers increase the potential for saltwater migration—both lateral encroachment and upward leakage of brackish water. Within the CCPCUA, a reduction in groundwater withdrawals over a period of 16 years from 2003 to 2018 is mandated. Under the CCPCUA rules, withdrawals in excess of 100,000 gallons per day from any of the Cretaceous aquifer well systems are subject to water-use reductions of as much as 75 percent. To assess the effects of the CCPCUA rules and to assist with groundwater-management decisions, a numerical model was developed to simulate the groundwater flow and chloride concentrations in the surficial Castle Hayne, Beaufort, Peedee, and Black Creek aquifers in the Onslow County area. The model was used to (1) simulate groundwater flow from 1900 to 2010; (2) assess chloride movement throughout the aquifer system; and (3) create hypothetical scenarios of future groundwater development. After calibration of a groundwater flow model and conversion to a variable-density model, five scenarios were created to simulate future groundwater conditions in the Onslow County area: (1) full implementation of the CCPCUA rules with three phases of withdrawal reductions simulated through 2028; (2) implementation of only phase 1 withdrawal reductions of the CCPCUA rules and simulated through 2028; (3) implementation of only phases 1 and 2 withdrawal reductions of the CCPCUA rules and simulated through 2028; (4) full implementation of the CCPCUA rules with the addition of withdrawals from the Castle Hayne aquifer in Onslow County at the fully permitted amount in the final stress period and simulated through 2028; and (5) full implementation of the CCPCUA rules as in scenario 1 except simulated through 2100. Results from the scenarios give an indication of the water-level recovery in the Black Creek aquifer throughout each phase of the CCPCUA rules in Onslow County. Furthermore, as development of the Castle Hayne aquifers was increased in the scenarios, cones of depression were created around pumping centers. Additionally, the scenarios indicated little to no change in chloride concentrations for the time periods simulated.

North Carolina↗
USGS2004

Basic ground-water hydrology

Ground water is one of the Nation's most valuable natural resources. It is the source of about 40 percent of the water used for all purposes exclusive of hydropower generation and electric powerplant cooling. Surprisingly, for a resource that is so widely used and so important to the health and to the economy of the country, the occurrence of ground water is not only poorly understood but is also, in fact, the subject of many widespread misconceptions. Common misconceptions include the belief that ground water occurs in underground rivers resembling surface streams whose presence can be detected by certain individuals. These misconceptions and others have hampered the development and conservation of ground water and have adversely affected the protection of its quality. In order for the Nation to receive maximum benefit from its ground-water resource, it is essential that everyone, from the rural homeowner to managers of industrial and municipal water supplies to heads of Federal and State water-regulatory agencies, become more knowledgeable about the occurrence, development, and protection of ground water. This report has been prepared to help meet the needs of these groups, as well as the needs of hydrologists, well drillers, and others engaged in the study and development of ground-water supplies. It consists of 45 sections on the basic elements of ground-water hydrology, arranged in order from the most basic aspects of the subject through a discussion of the methods used to determine the yield of aquifers to a discussion of common problems encountered in the operation of ground-water supplies. Each section consists of a brief text and one or more drawings or maps that illustrate the main points covered in the text. Because the text is, in effect, an expanded discussion of the illustrations, most of the illustrations are not captioned. However, where more than one drawing is included in a section, each drawing is assigned a number, given in parentheses, and these numbers are inserted at places in the text where the reader should refer to the drawing. In accordance with U.S. Geological Survey policy to encourage the use of metric units, these units are used in most sections. In the sections dealing with the analysis of aquifer (pumping) test data, equations are given in both consistent units and in the inconsistent inch-pound units still in relatively common use among ground-water hydrologists and well drillers. As an aid to those who are not familiar with metric units and with the conversion of ground-water hydraulic units from inch-pound units to metric units, conversion tables are given on the inside back cover. Definitions of ground-water terms are given where the terms are first introduced. Because some of these terms will be new to many readers, abbreviated definitions are also given on the inside front cover for convenient reference by those who wish to review the definitions from time to time as they read the text. Finally, for those who need to review some of the simple mathematical operations that are used in ground-water hydrology, a section on numbers, equations, and conversions is included at the end of the text.

Water Supply Paper↗