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At least 883 records · Page 49Linked to original sources

USGS2005

Impact of anthropogenic development on coastal ground-water hydrology in southeastern Florida, 1900-2000

Southeastern Florida is an area that has been subject to widely conflicting anthropogenic stress to the Everglades and coastal ecosystems. This stress is a direct consequence of the 20th century economic competition for limited land and water resources needed to satisfy agricultural development and its expansion, its displacement by burgeoning urban development, and the accompanying growth of the limestone mining industry. The development of a highly controlled water-management system designed to reclaim land for urban and agricultural development has severely impacted the extent, character, and vitality of the historic Everglades and coastal ecosystems. An extensive conveyance system of canals, levees, impoundments, surface- water control structures, and numerous municipal well fields are used to sustain the present-day Everglades hydrologic system, prevent overland flow from moving eastward and flooding urban and agricultural areas, maintain water levels to prevent saltwater intrusion, and provide an adequate water supply. Extractive mining activities expanded considerably in the latter part of the 20th century, largely in response to urban construction needs. Much of the present-day urban-agricultural corridor of southeastern Florida lies within an area that is no more than 15 feet above NGVD 1929 and formerly characterized by freshwater marsh, upland, and saline coastal wetland ecosystems. Miami- Dade, Broward, and Palm Beach Counties have experienced explosive population growth, increasing from less than 4,000 inhabitants in 1900 to more than 5 million in 2000. Ground-water use, the principal source of municipal supply, has increased from about 65 Mgal/d (million gallons per day) obtained from 3 well fields in 1930 to more than 770 Mgal/d obtained from 65 well fields in 1995. Water use for agricultural supply increased from 505 Mgal/d in 1953 to nearly 1,150 Mgal/d in 1988, but has since declined to 764 Mgal/d in 1995, partly as a result of displacement of the agricultural industry by urban growth. Present-day agricultural supplies are obtained largely from surface-water sources in Palm Beach County and ground-water sources in Miami-Dade County, whereas Broward County agricultural growers have been largely displaced. The construction of a complex canal drainage system and large well fields has substantially altered the surface- and ground-water hydrologic systems. The drainage system constructed between 1910 and 1928 mostly failed to transport flood flows, however, and exacerbated periods of low rainfall and drought by overdraining the surficial aquifer system. Following completion of the 1930s Hoover Dike levee system that was designed to reduce Lake Okeechobee flood flows, the Central and Southern Florida Flood Control Project initiated the restructure of the existing conveyance system in 1948 through canal expansion, construction of protective levees and control structures, and greater management of ground-water levels in the surficial aquifer system. Gated canal control structures discharge excess surface water during the wet season and remain closed during the dry season to induce recharge by canal seepage and well withdrawals. Management of surface water through canal systems has successfully maintained lower ground-water levels inland to curb urban and agricultural flooding, and has been used to increase ground-water levels near the coast to impede saltwater intrusion. Coastal discharge, however, appears to have declined, due in part to water being rerouted to secondary canals, and to induced recharge to the surficial aquifer system by large municipal withdrawals. Southeastern Florida is underlain by Holocene- to Tertiary-age karstic limestone deposits that form (in descending order): a highly prolific surficial aquifer system, a poorly permeable intermediate confining system, and a permeable Floridan aquifer system. Prior to construction of a complex drainage netwo

Florida↗

USGS1998

Population demographics of two local South Carolina mourning dove populations

The mourning dove ( Zenaida macroura ) call-count index had a significant (P < 0.01) negative trend in South Carolina and the Eastern Management Unit (EMU) during 1988-97. We initiated a banding study in 2 areas in the Coastal Plain of South Carolina to estimate population demographic parameters of doves to generate hypotheses that address the purported population declines. During 1992-96, we banded >2,300 doves and examined >6,000 individuals during harvest bag checks. An age-specific band recovery model with time- and area-specific recovery rates, and constant survival rates, was chosen for estimation via Akaike's Information Criterion (AIC), likelihood ratio, and goodness-of-fit criteria. After-hatching-year (AHY) annual survival rate was 0.359 (SE = 0.056), and hatching-year (HY) annual survival rate was 0.118 (SE = 0.042). Average estimated recruitment per adult female into the prehunting season population was 3.40 (SE = 1.25) and 2.32 (SE = 0.46) for the 2 study areas. Our movement data support earlier hypotheses of nonmigratory breeding and harvested populations in South Carolina. Low survival rates and estimated population growth rate in the study areas may be representative only of small-scale areas that are heavily managed for dove hunting. Source-sink theory was used to develop a model of region-wide populations that is composed of source areas with positive growth rates and sink areas of declining growth. We suggest management of mourning doves in the Southeast might benefit from improved understanding of local population dynamics, as opposed to regional-scale population demographics.

South Carolina↗

USGS2024

Application of lidar to assess the habitat selection of an endangered small mammal in an estuarine wetland environment

Light detection and ranging (lidar) has emerged as a valuable tool for examining the fine-scale characteristics of vegetation. However, lidar is rarely used to examine coastal wetland vegetation or the habitat selection of small mammals. Extensive anthropogenic modification has threatened the endemic species in the estuarine wetlands of the California coast, such as the endangered salt marsh harvest mouse ( Reithrodontomys raviventris ; SMHM). A better understanding of SMHM habitat selection could help managers better protect this species. We assessed the ability of airborne topographic lidar imagery in measuring the vegetation structure of SMHM habitats in a coastal wetland with a narrow range of vegetation heights. We also aimed to better understand the role of vegetation structure in habitat selection at different spatial scales. Habitat selection was modeled from data compiled from 15 small mammal trapping grids collected in the highly urbanized San Francisco Estuary in California, USA. Analyses were conducted at three spatial scales: microhabitat (25 m 2 ), mesohabitat (2025 m 2 ), and macrohabitat (~10,000 m 2 ). A suite of structural covariates was derived from raw lidar data to examine vegetation complexity. We found that adding structural covariates to conventional habitat selection variables significantly improved our models. At the microhabitat scale in managed wetlands, SMHM preferred areas with denser and shorter vegetation and selected for proximity to levees and taller vegetation in tidal wetlands. At the mesohabitat scale, SMHM were associated with a lower percentage of bare ground and with pickleweed ( Salicornia pacifica ) presence. All covariates were insignificant at the macrohabitat scale. Our results suggest that SMHM preferentially selected microhabitats with access to tidal refugia and mesohabitats with consistent food sources. Our findings showed that lidar can contribute to improving our understanding of habitat selection of wildlife in coastal wetlands and help to guide future conservation of an endangered species.

Ecology and Evolution↗

USGS2026

Strengthening ties between the U.S. Geological Survey and Interstate Fisheries Commissions

Fish inhabiting marine coastal and Great Lakes waters of the United States forage, migrate, and reproduce without regard to human-made boundaries. In the mid-20th century, the 32 states along the U.S. coasts and Great Lakes recognized the growing need for coordinated, interjurisdictional fisheries management and formed four interstate or international fisheries commissions through federal legislation. While distinct in their authorities, each commission shares functions to support their regional partners, including coordinating fisheries science and supporting information sharing. The U.S. Geological Survey (USGS) is a federal bureau focused exclusively on science with substantial fisheries research capacity. This empowers USGS to serve as an independent broker of scientific information, which is greatly appreciated by decision-making agencies. The USGS does not maintain broad infrastructure for engaging partners across regions. Therefore, collaboration between the USGS and fisheries commissions ensures that USGS fisheries science helps address the most pressing interjurisdictional management priorities. The USGS has worked with fisheries commissions for decades to a greater or lesser extent in each of the four coastal regions: Atlantic, Pacific, Gulf, and Great Lakes. In 2020, the USGS began efforts to cohesively strengthen these partnerships across the regions. In 2024, leadership from four USGS fisheries science centers and headquarters met with the four fisheries commissions in person for the first time during the American Fisheries Society Annual Meeting. During the gathering, the new Interstate Fisheries Commissions–USGS Partnership developed coordination mechanisms and identified shared science priorities where the USGS capacity best aligns with the science needs of the commissions. Here we describe the history of collaboration between the USGS and fisheries commissions and the emerging interregional partnership.

Fisheries↗

USGS2017

Quantifying changes and influences on mottled duck density in Texas

Understanding the relative influence of environmental and intrinsic effects on populations is important for managing and conserving harvested species, especially those species inhabiting changing environments. Additionally, climate change can increase the uncertainty associated with management of species in these changing environments, making understanding factors affecting their populations even more important. Coastal ecosystems are particularly threatened by climate change; the combined effects of increasing severe weather events, sea level rise, and drought will likely have non-linear effects on coastal marsh wildlife species and their associated habitats. A species of conservation concern that persists in these coastal areas is the mottled duck ( Anas fulvigula ). Mottled ducks in the western Gulf Coast are approximately 50% below target abundance numbers established by the Gulf Coast Joint Venture for Texas and Louisiana, USA. Although evidence for declines in mottled duck abundance is apparent, specific causes of the decrease remain unknown. Our goals were to determine where the largest declines in mottled duck population were occurring along the system of Texas Gulf Coast National Wildlife Refuges and quantify the relative contribution of environmental and intrinsic effects on changes to relative population density. We modeled aerial survey data of mottled duck density along the Texas Gulf Coast from 1986–2015 to quantify effects of extreme weather events on an index to mottled duck density using the United States Climate Extremes Index and Palmer Drought Severity Index. Our results indicate that decreases in abundance are best described by an increase in days with extreme 1-day precipitation from June to November (hurricane season) and an increase in drought severity. Better understanding those portions of the life cycle affected by environmental conditions, and how to manage mottled duck habitat in conjunction with these events will likely be key to persistence of the species under future environmental conditions.

Texas↗

USGS2021

Rigorously valuing the impact of Hurricanes Irma and Maria on coastal hazard risks in Florida and Puerto Rico

The degradation of coastal habitats, particularly coral reefs, raises risks by increasing the exposure of coastal communities to flooding hazards. In the United States, the physical protective services provided by coral reefs were recently assessed in social and economic terms, with the annual protection provided by U.S. coral reefs off the coasts of the State of Florida and the Commonwealth of Puerto Rico estimated to be more than 9,800 people and $859 million (2010 U.S. dollars). Hurricanes Irma and Maria in 2017 caused widespread damage to coral reefs in the State of Florida and the Commonwealth of Puerto Rico. These damages were measured in post-storm surveys of reefs and assessed in terms of their impact on reef condition and height, which are critical parameters for evaluating the coastal defense benefits of reefs. We combined engineering, ecologic, geospatial, social, and economic data and tools to value the increased risks in Florida and Puerto Rico from hurricane-induced damages to their adjacent coral reefs. We followed risk-based valuation approaches to map flooding at 10-square-meter resolution along all 980 kilometers of Florida and Puerto Rico’s reef-lined shorelines considering reef condition before (undamaged) and after (damaged) the 2017 hurricanes. We quantified the coastal flood risk increase caused by the hurricane-induced damage to the coral reefs using the latest information from the U.S. Census Bureau, Federal Emergency Management Agency, and Bureau of Economic Analysis for return-interval storm events. Using the damages associated with each storm probability, we also calculated the change in annual expected damages, a measure of the annual protection lost because of the reef damage caused by the 2017 hurricanes. We found that the damages to the coral reefs off Florida and Puerto Rico from Hurricanes Irma and Maria increased future risks significantly. In particular, we estimated the protection lost by Florida and Puerto Rico’s coral reefs from the 2017 hurricanes to result in: Increased flooding to more than 10.72 square kilometers (4.14 square miles) of land annually; Increased flooding affecting more than 4,300 people annually; Increased direct damages of more than $57.2 million to more than 1,800 buildings annually; and Increased indirect damages to more $124.3 million in economic activity owing to housing and business damage annually. Thus, the annual value of increased flood risk caused by the damage to Florida and Puerto Rico’s coral reefs from hurricanes in 2017 is more than 4,300 people and $181.5 mil-lion (2010 U.S. dollars) in economic impacts. These data provide stakeholders and decision makers with a spatially explicit, rigorous valuation of how, where, and when the damage from the 2017 hurricanes decreased critical coastal storm flood reduction benefits to Florida and Puerto Rico’s coral reefs. These results help identify areas where reef management, recovery, and restoration could potentially help reduce the risk to, and increase the resiliency of, Florida and Puerto Rico’s coastal communities.

Florida↗

USGS2005

Coastal change rates and patterns: Kaloko-Honokohau National Historical Park, Hawai'i

A collaborative project between the U.S. Geological Survey's Coastal and Marine Geology Program and the National Park Service (NPS) has been developed to create an inventory of geologic resources for National Park Service lands on the Big Island of Hawai'i. The NPS Geologic Resources Inventories are recognized as essential for the effective management, interpretation, and understanding of vital park resources. In general, there are three principal components of the inventories: geologic bibliographies, digital geologic maps, and geologic reports. The geologic reports are specific to each individual park and include information on the geologic features and processes that are important to the management of park resources, including ecological, cultural and recreational resources. This report summarizes a component of the geologic inventory concerned specifically with characterizing the coastal geomorphology of the beach system within Kaloko-Honokohau National Historical Park (NHP) and describes an analysis that utilizes georeferenced and orthorectified aerial photography to understand the spatial and temporal trends in shoreline change from 1950 to 2002. In addition, spatial patterns of beach change were examined and a beach stability map was developed. Both the shoreline change rates and the beach stability map are designed to help Park personnel effectively manage the valuable park resources within the context of understanding natural changes to the KAHO beach system.

Hawaii↗

USGS2016

Quantifying resilience

The biosphere is under unprecedented pressure, reflected in rapid changes in our global ecological, social, technological and economic systems. In many cases, ecological and social systems can adapt to these changes over time, but when a critical threshold is surpassed, a system under stress can undergo catastrophic change and reorganize into a different state. The concept of resilience, introduced more than 40 years ago in the ecological sciences, captures the behaviour of systems that can occur in alternative states. The original definition of resilience forwarded by Holling ( 1973 ) is still the most useful. It defines resilience as the amount of disturbance that a system can withstand before it shifts into an alternative stable state. The idea of alternative stable states has clear and profound implications for ecological management. Coral reefs, for example, are high-diversity systems that provide key ecosystem services such as fisheries and coastal protection. Human impacts are causing significant, ongoing reef degradation, and many reefs have shifted from coral- to algal-dominated states in response to anthropogenic pressures such as elevated water temperatures and overfishing. Understanding and differentiating between the factors that help maintain reefs in coral-dominated states vs. those that facilitate a shift to an undesired algal-dominated state is a critical step towards sound management and conservation of these, and other, important social–ecological systems. Resilience has gained popularity among both academicians and laypeople, as a term meant to describe a systems’ ability to withstand disturbance. Resilience has become a buzzword in the last decade, as shown by its increasing appearance in calls for research proposals and scientific citation data bases. The term resilience has in many cases lost the clarity of the original definition and in fact is frequently used in a manner in direct opposition to the original definition. Many current uses of the concept are loose and incorrect. The term is becoming increasingly used in a normative sense (Brand & Jax 2007 ), as if resilience were a desirable quality of systems. However, even systems in highly undesirable states, such as macro-algae dominated reefs, or city cores in poverty traps, may be highly resilient, which is to say they withstand attempts to transform them into different (desirable) states. Operationalizing the concept of resilience for application and management has been difficult. Misuse of the term can have significant negative impacts, because resilience is being used to help guide responses to natural disasters and to assess the sustainability of ecosystems and urban systems and has been driving international research priorities. Resilience has been argued to be a basic emergent property of systems, a process or a rate. We focus on the original concept as described by Holling, which is that of an emergent system property; when a system is in a desirable state and managers wish to enhance resilience, or when the system is in an undesirable state and managers wish to erode resilience and foster a transformation to an alternative state. Fostering or eroding resilience is a process. When a system is perturbed but resilience is not exceeded, then the recovery can be measured as a rate. Several frameworks to operationalize resilience have been proposed. A decade ago, a special feature focused on quantifying resilience was published in the journal Ecosystems (Carpenter, Westley & Turner 2005 ). The approach there was towards identifying surrogates of resilience, but few of the papers proposed quantifiable metrics. Consequently, many ecological resilience frameworks remain vague and difficult to quantify, a problem that this special feature aims to address. However, considerable progress has been made during the last decade (e.g. Pope, Allen & Angeler 2014 ). Although some argue that resilience is best kept as an unquantifiable, vague concept (Quinlan et al . 2016 ), to be useful for managers, there must be concrete guidance regarding how and what to manage and how to measure success (Garmestani, Allen & Benson 2013 ; Spears et al . 2015 ). Ideas such as ‘resilience thinking’ have utility in helping stakeholders conceptualize their systems, but provide little guidance on how to make resilience useful for ecosystem management, other than suggesting an ambiguous, Goldilocks approach of being just right (e.g. diverse, but not too diverse; connected, but not too connected). Here, we clarify some prominent resilience terms and concepts, introduce and synthesize the papers in this special feature on quantifying resilience and identify core unanswered questions related to resilience.

Journal of Applied Ecology↗

USGS2005

Forestry practices and aquatic biodiversity: Fish

In the Pacific Northwest, fish communities are found in a diverse array of aquatic habitats ranging from the large coastal rivers of the temperate rainforests, to the fragmented and sometimes ephemeral streams of the xeric interior basins, and high-elevation streams and lakes in the mountainous areas (Rieman et al. 2003). Only high-elevation lakes and streams isolated above barriers to fish passage remained historically devoid of fish because they were never invaded following Pleistocene glaciation (Smith 1981). Despite this widespread distribution and once great population abundances, taxonomic diversity of fishes in these forested systems is naturally lower than in aquatic habitats in the eastern U.S. (Reeves, Bisson, and Dambacher 1998). Interactions among factors that influence species richness in aquatic systems (e.g., basin size, long-term stability of habitat, and barriers to colonization; Smith 1981) continue to influence the occurrence and persistence of fishes in these systems today. Consequently, the larger low-elevation rivers and estuaries support the greatest variety of fish species. In the high-elevation tributary streams, fish communities are less complex because these aquatic systems were less climatically and geologically stable, and fish populations were smaller and more prone to local extirpation. Furthermore, barriers to fish passage inhibited dispersal and colonization (Smith 1981). Streams in forested landscapes generally support salmon and trout, Oncorhynchus spp., whitefish Prosopium spp., sculpins Cottus spp., suckers Catostomus spp., and minnows (Cyprinidae), but in some of the colder streams, chars (e.g., Salvelinus confluentus and Salvelinus malma ) and lampreys (Petromyzontidae)may also occur (Rieman et al. 2003). Although biodiversity defined in terms of fish species richness is low in the Pacific Northwest, intraspecific variability is high, and polytypic fish species are common in the diverse aquatic habitats of the region. For example, the salmonids in the coastal rivers and streams, and the larger interconnected streams, rivers, and lakes of the interior exhibit a variety of ecotypes and migratory life histories (Healey 1986; Trotter 1989; Larson and McIntire 1993; Northcote 1997). This life-history variation appears to be associated with adaptation to spatial and temporal variation in environment (e.g., Schaffer and Elson 1975; Carl and Healey 1984; Beacham and Murray 1987), and there is some evidence of the genetic heritability of life-history traits (Carl and Healey 1984; Gharrett and Smoker 1993; Hankin, Nicholas, and Downey 1993). Persistence of any level of biological organization (e.g., life-history type, population, metapopulation, subspecies, species, community) is related to the interaction of environmental and biological components, and intraspecific diversity is a means of spreading risk ( sensu den Boer 1968) of extirpation in dynamic environments (Gresswell 1999). Unfortunately, despite the broad distribution and extensive intraspecific diversity, persistence of native fishes is uncertain in the Pacific Northwest. Many populations of anadromous salmonids, once synonymous with vigorous biological communities throughout the region, are threatened with extinction (Nehlsen, Williams, and Lichatowich 1991; Frissell 1993; Thurow, Lee, and Rieman 1997). Furthermore, over half of the native taxa in the Columbia River Basin are either listed under the Endangered Species Act, are being considered for listing, or are deemed sensitive by the management agencies (Lee et al. 1997; Thurow, Lee, and Rieman 1997). Potamodromous species like bull trout Salvelinus confluentus are estimated to occur as strong populations in less than 5% of their potential range (Rieman, Lee, and Thurow 1997). Although not currently listed under the endangered species list, the coastal cutthroat trout Oncorhynchus clarki is managed as a sensitive species in Oregon and California (Hall, Bisson, and Gresswell 1997). Native non-game fishes have rarely been monitored, but populations of species such as large-scale suckers ( Catostomus macrocheilus ), squawfish ( Ptychocheilus umpquae ), and Pacific lamprey ( Lampetra tridentata ) also are declining in some drainages (Oregon Department of Fish and Wildlife, unpublished data).

Pacific Northwest↗

USGS2016

Hg concentrations in fish from coastal waters of California and Western North America

The State of California conducted an extensive and systematic survey of mercury (Hg) in fish from the California coast in 2009 and 2010. The California survey sampled 3483 fish representing 46 species at 68 locations, and demonstrated that methylHg in fish presents a widespread exposure risk to fish consumers. Most of the locations sampled (37 of 68) had a species with an average concentration above 0.3 μg/g wet weight (ww), and 10 locations an average above 1.0 μg/g ww. The recent and robust dataset from California provided a basis for a broader examination of spatial and temporal patterns in fish Hg in coastal waters of Western North America. There is a striking lack of data in publicly accessible databases on Hg and other contaminants in coastal fish. An assessment of the raw data from these databases suggested the presence of relatively high concentrations along the California coast and in Puget Sound, and relatively low concentrations along the coasts of Alaska and Oregon, and the outer coast of Washington. The dataset suggests that Hg concentrations of public health concern can be observed at any location on the coast of Western North America where long-lived predator species are sampled. Output from a linear mixed-effects model resembled the spatial pattern observed for the raw data and suggested, based on the limited dataset, a lack of trend in fish Hg over the nearly 30-year period covered by the dataset. Expanded and continued monitoring, accompanied by rigorous data management procedures, would be of great value in characterizing methylHg exposure, and tracking changes in contamination of coastal fish in response to possible increases in atmospheric Hg emissions in Asia, climate change, and terrestrial Hg control efforts in coastal watersheds.

Science of the Total Environment↗

USGS2016

The Water-Quality Partnership for National Parks—U.S. Geological Survey and National Park Service, 1998–2016

The U.S. Geological Survey (USGS) and the National Park Service (NPS) work together through the USGS–NPS Water-Quality Partnership to support a broad range of policy and management needs related to high-priority water-quality issues in national parks. The program was initiated in 1998 as part of the Clean Water Action Plan, a Presidential initiative to commemorate the 25th anniversary of the Clean Water Act. Partnership projects are developed jointly by the USGS and the NPS. Studies are conducted by the USGS and findings are used by the NPS to guide policy and management actions aimed at protecting and improving water quality. The National Park Service manages many of our Nation’s most highly valued aquatic systems across the country, including portions of the Great Lakes, ocean and coastal zones, historic canals, reservoirs, large rivers, high-elevation lakes and streams, geysers, springs, and wetlands. So far, the Water-Quality Partnership has undertaken 217 projects in 119 national parks. In each project, USGS studies and assessments ( http://water.usgs.gov/nps_partnership/pubs.php ) have supported science-based management by the NPS to protect and improve water quality in parks. Some of the current projects are highlighted in the NPS Call to Action Centennial initiative, Crystal Clear, which celebrates national park water-resource efforts to ensure clean water for the next century of park management ( http://www.nature.nps.gov/water/crystalclear/ ). New projects are proposed each year by USGS scientists working in collaboration with NPS staff in specific parks. Project selection is highly competitive, with an average of only eight new projects funded each year out of approximately 75 proposals that are submitted. Since the beginning of the Partnership in 1998, 189 publications detailing project findings have been completed. The 217 studies have been conducted in 119 NPS-administered lands, extending from Denali National Park and Preserve in Alaska to Everglades National Park in Florida, and from Acadia National Park in the Northeast to park lands in Hawaii and Pacific Island territories in the West. Project goals range from periodic stream monitoring, to determining the occurrence and concentrations of contaminants and the potential for them to exceed human health or aquatic life criteria, to conducting interpretive studies to evaluate the effect(s) on or vulnerability of national park resources to visitor usage and other natural and anthropogenic activities.

Fact Sheet↗

USGS2026

Streamflow and surface-water presence data availability across the conterminous United States: A review for headwater systems

Water is essential for life on Earth, supporting ecosystems, human health, and economic activities. Hydrology relies on observational data, and this paper discusses regional and national datasets for the conterminous United States (CONUS) publicly available as of 2023, focusing on headwaters, defined as first- and second-order streams at 1:24000 scale. It identifies 72 primary and secondary datasets and 11 repositories and argues how better integration and accessibility of hydrological data can improve research. The paper distinguishes between datasets where streamflow was the primary data collection objective and those where it was secondary. This distinction highlights opportunities to consider data from efforts peripheral to hydrology but is still useful for understanding hydrologic conditions. The analysis reveals that out of about 118 000 active and inactive stream observation sites, about 6.6% and 25% are located on first- and second-order streams, respectively. This indicates a substantial data gap for headwater systems, which account for over 77% of stream length in CONUS. Federal agencies manage 72% of hydrologic monitoring sites across all stream orders, but only 34% of these are in headwater systems. Academic institutions operate about 2% of sites, with almost half (48%) in headwater systems, focusing on ecosystem research. State agencies also operate about 2% of sites, primarily on larger systems, with 19% on headwaters. Additionally, 23% of sites are managed by multiple agencies. Spatial patterns further reveal pronounced disparities among physiographic regions. Eastern and coastal provinces show relatively dense monitoring, while central and western regions show sparse coverage. These gaps reflect historical priorities, logistical constraints, funding limitations, and the high cost of continuous instrumentation. To address biases in monitoring networks, data collection could be enhanced with low-cost monitoring, community science, and remote sensing technologies. This study also notes the benefits of long-term monitoring and prioritizing retention of streamgages with longer records.

conterminous United States↗

USGS2013

Sediment transport patterns in the San Francisco Bay Coastal System from cross-validation of bedform asymmetry and modeled residual flux

The morphology of ~ 45,000 bedforms from 13 multibeam bathymetry surveys was used as a proxy for identifying net bedload sediment transport directions and pathways throughout the San Francisco Bay estuary and adjacent outer coast. The spatially-averaged shape asymmetry of the bedforms reveals distinct pathways of ebb and flood transport. Additionally, the region-wide, ebb-oriented asymmetry of 5% suggests net seaward-directed transport within the estuarine-coastal system, with significant seaward asymmetry at the mouth of San Francisco Bay (11%), through the northern reaches of the Bay (7-8%), and among the largest bedforms (21% for λ > 50 m). This general indication for the net transport of sand to the open coast strongly suggests that anthropogenic removal of sediment from the estuary, particularly along clearly defined seaward transport pathways, will limit the supply of sand to chronically eroding, open-coast beaches. The bedform asymmetry measurements significantly agree (up to ~ 76%) with modeled annual residual transport directions derived from a hydrodynamically-calibrated numerical model, and the orientation of adjacent, flow-sculpted seafloor features such as mega-flute structures, providing a comprehensive validation of the technique. The methods described in this paper to determine well-defined, cross-validated sediment transport pathways can be applied to estuarine-coastal systems globally where bedforms are present. The results can inform and improve regional sediment management practices to more efficiently utilize often limited sediment resources and mitigate current and future sediment supply-related impacts.

California↗

USGS2012

Geologic effects and coastal vulnerability to sea-level rise, erosion, and storms

A combination of natural and human factors are driving coastal change and making coastal regions and populations increasingly vulnerable. Sea level, a major agent of coastal erosion, has varied greatly from -120 m below present during glacial period low-stands to + 4 to 6 m above present during interglacial warm periods. Geologic and tide gauge data show that global sea level has risen about 12 to 15 cm during the past century with satellite measurements indicating an acceleration since the early 1990s due to thermal expansion and ice-sheet melting. Land subsidence due to tectonic forces and sediment compaction in regions like the mid-Atlantic and Louisiana increase the rate of relative sea-level rise to 40 cm to 100 cm per century. Sea- level rise is predicted to accelerate significantly in the near future due to climate change, resulting in pervasive impacts to coastal regions and putting populations increasingly at risk. The full implications of climate change for coastal systems need to be understood better and long-term plans are needed to manage coasts in order to protect natural resources and mitigate the effects of sea-level rise and increased storms on human infrastructure.

Conference Paper↗

USGS2016

Lidar-based mapping of flood control levees in south Louisiana

Flood protection in south Louisiana is largely dependent on earthen levees, and in the aftermath of Hurricane Katrina the state’s levee system has received intense scrutiny. Accurate elevation data along the levees are critical to local levee district managers responsible for monitoring and maintaining the extensive system of non-federal levees in coastal Louisiana. In 2012, high resolution airborne lidar data were acquired over levees in Lafourche Parish, Louisiana, and a mobile terrestrial lidar survey was conducted for selected levee segments using a terrestrial lidar scanner mounted on a truck. The mobile terrestrial lidar data were collected to test the feasibility of using this relatively new technology to map flood control levees and to compare the accuracy of the terrestrial and airborne lidar. Metrics assessing levee geometry derived from the two lidar surveys are also presented as an efficient, comprehensive method to quantify levee height and stability. The vertical root mean square error values of the terrestrial lidar and airborne lidar digital-derived digital terrain models were 0.038 m and 0.055 m, respectively. The comparison of levee metrics derived from the airborne and terrestrial lidar-based digital terrain models showed that both types of lidar yielded similar results, indicating that either or both surveying techniques could be used to monitor geomorphic change over time. Because airborne lidar is costly, many parts of the USA and other countries have never been mapped with airborne lidar, and repeat surveys are often not available for change detection studies. Terrestrial lidar provides a practical option for conducting repeat surveys of levees and other terrain features that cover a relatively small area, such as eroding cliffs or stream banks, and dunes.

Louisiana↗

USGS2006

Continuous resistivity profiling to delineate submarine groundwater discharge - Examples and limitations

Aquifer-ocean interaction, saline intrusion, and submarine groundwater discharge (SGD) are emerging topics in hydrology and oceanography with important implications for water-resource management and estuarine ecology. Although the threat of saltwater intrusion has long been recognized in coastal areas, SGD has, until recently, received much less attention. It is clear that SGD constitutes a major nutrient flux to coastal waters, with implications for estuarine ecology, eutrophication, and loss of coral reefs; however, fundamental questions regarding SGD remain unanswered: What are the spatial and temporal distributions of SGD offshore? How do seasonal and storm-related variations in aquifer recharge affect SGD flux and nutrient loading? What controls do aquifer structure and heterogeneity impose? How are SGD and saline recirculation related? Geophysical methods can provide insights to help answer these questions and improve the understanding of this intriguing and environmentally relevant hydrologic phenomenon.

Leading Edge (Tulsa, OK)↗

USGS2016

Wetlands postcard

Wetlands Postcard Research conducted by scientists at the U.S. Geological Survey provides reliable scientific information for the management of wetlands ranging from small freshwater alpine lakes in the Western United States to coastal wetlands of the Great Lakes and salt marshes along the Southeastern coast. Learn more about USGS wetlands research at: http://www.usgs.gov/ecosystems/environments/wetlands.html .

General Information Product↗

USGS2007

Seagrass status and trends in the northern Gulf of Mexico: 1940-2002

Over the past century, seagrass habitats from the bays of Texas to the gulf shores of Florida have decreased. Seagrass beds, which are highly dependent on water quality and clarity for survival, are home to a multitude of aquatic plants and animals and a source of economic activity through commercial and recreational fishing and ecotourism. The U.S. Environmental Protection Agency’s Gulf of Mexico Program (GMP) and its partners have made a commitment to restore, enhance, and protect this important ecosystem. As seagrass habitats decrease, the need for information on the causes and effects of seagrass loss, current mapping information, and education on the importance of seagrassess becomes greater. This report is the initial effort of the GMP’s research and restoration plan for seagrasses. The purpose of this report is to provide scientists, managers, and citizens with valuable baseline information on the status and trends of seagrasses in coastal waters of the Gulf of Mexico. Within the northern Gulf of Mexico region, 14 individual estuarine systems where seagrasses occur, as well as statewide summaries for Texas, Louisiana, Mississippi, Alabama, and Florida, are examined in this study. Each estuarine system is detailed in vignettes that address current and historical extent and quality of seagrasses, seagrass mapping and monitoring, causes of status change, restoration and enhancement activities, background information for the entire study area as well as the subareas for study, and the methodology employed to analyze and document the historical trends and current status of seagrasses. The systems, moving from west to east, include the Laguna Madre, Texas Coastal Bend region, and Galveston Bay in Texas; the Chandeleur Islands in Louisiana; the Mississippi Sound; and Perdido Bay, Pensacola/Escambia Bay, Choctawhatchee Bay, St. Andrew Bay, Florida’s Big Bend region, Tampa Bay/St. Joseph Sound, Sarasota Bay, Greater Charlotte Harbor, and Florida Bay in Florida. (Mobile Bay is dealt with only in the statewide summary for Alabama.)

Gulf Of Mexico↗