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At least 1,027 records · Page 57Linked to original sources
USGS2018

Great Lakes coastal fish habitat classification and assessment

Basin-scale assessment of fish habitat in Great Lakes coastal ecosystems would increase our ability to prioritize fish habitat management and restoration actions. As a first step in this direction, we identified key habitat factors associated with highest probability of occurrence for several societally and ecologically important coastal fish species as well as community metrics, using data from the Great Lakes Aquatic Habitat Framework (GLAHF), Great Lakes Environmental Indicators (GLEI) and Coastal Wetland Monitoring Program (CWMP). Secondly, we assessed whether species-specific habitat was threatened by watershed-level anthropogenic stressors. In the southern Great Lakes, key habitat factors for determining presence/absence of several species of coastal fish were chlorophyll concentrations, turbidity, and wave height, whereas in the northern ecoprovince temperature was the major habitat driver for most of the species modeled. Habitat factors best explaining fish richness and diversity were bottom slope and chlorophyll a . These models could likely be further improved with addition of high-resolution submerged macrophytecomplexity data which are currently unavailable at the basin-wide scale. Proportion of invasive species was correlated primarily with increasing maximum observed inorganic turbidity and chlorophyll a . We also demonstrate that preferred habitat for several coastal species and high-diversity areas overlap with areas of high watershed stress. Great Lakes coastal wetland fish are a large contributor to ecosystem services as well as commercial and recreational fishery harvest, and scalable basin-wide habitat models developed in this study may be useful for informing management actions targeting specific species or overall coastal fish biodiversity.

Great Lakes↗
USGS2002

Stable isotope composition of waters in the Great Basin, United States 1. Air-mass trajectories

Isentropic trajectories, calculated using the NOAA/Climate Monitoring and Diagnostics Laboratory's isentropic transport model, were used to determine air-parcel origins and the influence of air mass trajectories on the isotopic composition of precipitation events that occurred between October 1991 and September 1993 at Cedar City, Utah, and Winnemucca, Nevada. Examination of trajectories that trace the position of air parcels backward in time for 10 days indicated five distinct regions of water vapor origin: (1) Gulf of Alaska and North Pacific, (2) central Pacific, (3) tropical Pacific, (4) Gulf of Mexico, and (5) continental land mass. Deuterium (??D) and oxygen-18 (??18O) analyses were made of precipitation representing 99% of all Cedar City events. Similar analyses were made on precipitation representing 66% of the precipitation falling at Winnemucca during the same period. The average isotopic composition of precipitation derived from each water vapor source was determined. More than half of the precipitation that fell at both sites during the study period originated in the tropical Pacific and traveled northeast to the Great Basin; only a small proportion traversed the Sierra Nevada. The isotopic composition of precipitation is determined by air-mass origin and its track to the collection station, mechanism of droplet formation, reequilibration within clouds, and evaporation during its passage from cloud to ground. The Rayleigh distillation model can explain the changes in isotopic composition of precipitation as an air mass is cooled pseudo-adiabatically during uplift. However, the complicated processes that take place in the rapidly convecting environment of cumulonimbus and other clouds that are common in the Great Basin, especially in summer, require modification of this model because raindrops that form in the lower portion of those clouds undergo isotopic change as they are elevated to upper levels of the clouds from where they eventually drop to the ground.

Journal of Geophysical Research D: Atmospheres↗
USGS2007

Warming may create substantial water supply shortages in the Colorado River basin

The high demand for water, the recent multiyear drought (1999-2007), and projections of global warming have raised questions about the long-term sustainability of water supply in the southwestern United States. In this study, the potential effects of specific levels of atmospheric warming on water-year streamflow in the Colorado River basin are evaluated using a water-balance model, and the results are analyzed within the context of a multi-century tree-ring reconstruction (1490-1998) of streamflow for the basin. The results indicate that if future warming occurs in the basin and is not accompanied by increased precipitation, then the basin is likely to experience periods of water supply shortages more severe than those inferred from the longterm historical tree-ring reconstruction. Furthermore, the modeling results suggest that future warming would increase the likelihood of failure to meet the water allocation requirements of the Colorado River Compact.

Geophysical Research Letters↗
USGS2023

Beyond simple trend tests: Detecting significant changes in design-flood quantiles

Changes in annual maximum flood (AMF), which are usually detected using simple trend tests (e.g., Mann-Kendall test (MKT)), are expected to change design-flood estimates. We propose an alternate framework to detect significant changes in design-flood between two periods and evaluate it for synthetically generated AMF from the Log-Pearson Type-3 (LP3) distribution due to changes in moments associated with flood distribution. Synthetic experiments show MKT does not consider changes in all three moments of the LP3 distribution and incorrectly detects changes in design-flood. We applied the framework on 31 river basins spread across the United States. Statistically significant changes in design-flood quantiles were observed even without a significant trend in AMF and basins with statistically significant trend did not necessarily exhibit statistically significant changes in design-flood. We recommend application of the framework for evaluating changes in design-flood estimates considering changes in all the moments as opposed to simple trend tests.

Geophysical Research Letters↗
USGS1975

The Nectarian System, a new lunar time-stratigraphic unit

Geologic mapping of the limbs and far side of the Moon has demonstrated the desirability of subdividing the pre-Imbrian rocks. A convenient datum is the Janssen Formation, the ejecta blanket of the Nectaris basin. A new system, herein named the Nectarian System, extends from the base of the Janssen Formation up to, but not including, the Fra Mauro Formation, which is the ejecta blanket of the Imbrium basin and the basal unit of the Imbrian System. As all rocks older than the Janssen Formation are informally called pre-Nectarian, the name "pre-Imbrian" is superseded by Nectarian and pre-Nectarian where rocks of these ages can be recognized.

Journal of Research of the U.S. Geological Survey↗
USGS2026

Identifying headwater streams across the conterminous United States

Headwater streams play critical roles in hydrologic and biogeochemical processes and functions, yet their spatial distribution and land cover context remain poorly understood at continental scales, and no dedicated geospatial dataset exists. Building from a high-resolution conterminous United States (CONUS) hydrography network dataset, we quantified the spatial extent, density, and upstream catchment characteristics of headwater stream segments across the CONUS. We identified approximately 8.4 million kilometers of headwater streams, finding that 77% of the total stream network consists of headwaters, nearly double the total length represented in prior estimates. Stream density varied fivefold across regions, from < 1 km·km −2 in arid basins to > 5 km·km −2 in humid, forested areas. Over 73% of the CONUS landmass drains from headwater streams. The majority of headwater stream length occurred in forested and cultivated catchments across the CONUS, while substantial regional differences were evident for headwater stream distribution in other land cover classes (for example, wetlands, urban areas, shrublands, and herbaceous-dominated catchments). The dedicated and novel geospatial dataset, HELiOS (HEadwater streams and Low-Order Systems) is introduced for management and research use. The HELiOS dataset provides the first continental-scale, high-resolution characterization of headwater streams, offering new insights and opportunities for hydrologic modeling, ecological assessments, and environmental policy.

conterminous United States↗
USGS2013

Data-driven modeling of background and mine-related acidity and metals in river basins

A novel application of self-organizing map (SOM) and multivariate statistical techniques is used to model the nonlinear interaction among basin mineral-resources, mining activity, and surface-water quality. First, the SOM is trained using sparse measurements from 228 sample sites in the Animas River Basin, Colorado. The model performance is validated by comparing stochastic predictions of basin-alteration assemblages and mining activity at 104 independent sites. The SOM correctly predicts (>98%) the predominant type of basin hydrothermal alteration and presence (or absence) of mining activity. Second, application of the Davies–Bouldin criteria to k-means clustering of SOM neurons identified ten unique environmental groups. Median statistics of these groups define a nonlinear water-quality response along the spatiotemporal hydrothermal alteration-mining gradient. These results reveal that it is possible to differentiate among the continuum between inputs of background and mine-related acidity and metals, and it provides a basis for future research and empirical model development.

Environmental Pollution↗
USGS1993

Allostratigraphy of the U.S. middle Atlantic continental margin; characteristics, distribution, and depositional history of principal unconformity-bounded upper Cretaceous and Cenozoic sedimentary units

Publication of Volumes 93 and 95 ('The New Jersey Transect') of the Deep Sea Drilling Project's Initial Reports completed a major phase of geological and geophysical research along the middle segment of the U. S. Atlantic continental margin. Relying heavily on data from these and related published records, we have integrated outcrop, borehole, and seismic-reflection data from this large area (500,000 km^2 ) to define the regional allostratigraphic framework for Upper Cretaceous and Cenozoic sedimentary rocks. The framework consists of 12 alloformations, which record the Late Cretaceous and Cenozoic depositional history of the contiguous Baltimore Canyon trough (including its onshore margin) and Hatteras basin (northern part). We propose stratotype sections for each alloformation and present a regional allostratigraphic reference section, which crosses these basins from the inner edge of the coastal plain to the inner edge of the abyssal plain. Selected supplementary reference sections on the coastal plain allow observation of the alloformations and their bounding unconformities in outcrop. Our analyses show that sediment supply and its initial dispersal on the middle segment of the U. S. Atlantic margin have been governed, in large part, by hinterland tectonism and subsequently have been modified by paleoclimate, sea-level changes, and oceanic current systems. Notable events in the Late Cretaceous to Holocene sedimentary evolution of this margin include (1) development of continental-rise depocenters in the northern part of the Hatteras basin during the Late Cretaceous; (2) the appear ance of a dual shelf-edge system, a marked decline in siliciclastic sediment accumulation rates, and widespread acceleration of carbonate production during high sea levels of the Paleogene; (3) rapid deposition and progradation of thick terrigenous delta complexes and development of abyssal depocenters during the middle Miocene to Quaternary interval; and (4) deep incision of the shelf edge by submarine canyons, especially during the Pleistocene. Massive downslope gravity flows have dominated both the depositional and erosional history of the middle segment of the U. S. Atlantic Continental Slope and Rise during most of the last 84 million years. The importance of periodic widespread erosion is recorded by well-documented unconformities, many of which can be traced from coastal-plain outcrops to coreholes on the continental slope and lower continental rise. These unconformities form the boundaries of the 12 allostratigraphic units we formally propose herein. Seven of the unconformities correlate with supercycle boundaries (sequence boundaries) that characterize the Exxon sequence-stratigraphy model.

Professional Paper↗
USGS2018

Groundwater discharge characteristics for selected streams within the Loup River Basin, Nebraska, 2014–16

Streams in the Loup River Basin are sensitive to groundwater withdrawals because of the close hydrologic connection between groundwater and surface water. Groundwater discharge is the primary component of streamflow in the Loup River Basin and constitutes more than 90 percent of streamflow in the central part of the Sand Hills. To improve the understanding of geologic controls and various climatic and land-use changes on groundwater discharge, the U.S. Geological Survey (USGS), in cooperation with the Upper Loup Natural Resources District (NRD), the Lower Loup NRD, and the Nebraska Environmental Trust, studied the spatial and temporal characteristics of groundwater discharge within the Loup River Basin. This report documents the methods of data collection and analysis, which include the collection of approximately 350 river miles of aerial thermal infrared imagery and continuous groundwater-level and temperature data from six streamflow-gaging stations within the Loup River Basin. The results from the stream reconnaissance and examination of aerial thermal infrared imagery demonstrated the influence of the surficial and subsurface geology on the spatial characteristics of groundwater discharge to streams in the Loup River Basin. At the headwaters of the South Loup River, streamflow is sustained and increased from focused groundwater discharge emanating from Quaternary deposits at many small (less than 0.1 cubic foot per second) focused points. The volume of water produced from this dense network of focused groundwater discharge points along the North Fork South Loup River is sufficient to provide approximately 40 percent of the flow measured at the South Loup River at Arnold, Nebraska streamflow-gaging station (USGS station 06781600) during the irrigation season. Approximately 5 miles downstream from the South Loup River at Arnold, Nebr., streamflow-gaging station, the river incises into Pliocene-age sand and gravel deposits, which provide additional groundwater discharge to the stream. The streamflow of the South Loup River increases by a factor of 5 across a 62-mile reach of the middle South Loup River. Increases in streamflow along the upper Dismal River result from a dense network of focused groundwater discharge points within semiconsolidated Pliocene-age deposits. Below the Dismal River near Thedford, Nebr., streamflow-gaging station (USGS station 06775900), the Dismal River incises into the Ogallala Formation over a short reach before flowing over coarser, more permeable Quaternary-age alluvial deposits. Diffuse groundwater discharge sustains and increases the streamflow of the lower Dismal River in this reach. Groundwater sapping was evident on some stream reaches and has increased the size and flow of focused groundwater discharge points. Previous researchers have documented streambed incision and groundwater sapping on the upper Dismal River that have created and enlarged focused groundwater discharge points capturing additional groundwater. Similar processes appear to have played a role in the formation of larger focused groundwater discharge points, which sustain the flow of the middle South Loup River. The constant flow of groundwater into the South Loup River has removed finer-grained Quaternary sediments and further exposed Pliocene-age gravel deposits. Headward erosion is evident where some of the large focused groundwater discharge points have incised their own draws and terminate in bowl-like depressions away from the stream. Within the Loup River NRDs, the percentage of groundwater-irrigated land in a stream basin is one factor that affects groundwater discharge to streams. A striking example was at the South Loup River at Saint Michael, Nebr., groundwater and streamflow-gaging station (USGS station 06784000) where the shallow groundwater levels declined below the level of the stream during the middle to late part of the growing season (July to September) when consumptive groundwater use was at its peak. The South Loup River Basin above the South Loup River at Saint Michael, Nebr., streamflow-gaging station has the highest percentage of groundwater-irrigated row crops of all the basins examined in this study. Continuous groundwater and surface-water levels measured at the North Loup River at the Taylor, Nebr., streamflow-gaging station (USGS station 06786000) indicate that the stream is receiving groundwater throughout the year; however, when consumptive groundwater use peaks during the middle to late part of the growing season (July to September), the difference in elevation between the groundwater level and the stream elevation decreases, which indicates a reduction in the amount of groundwater discharge received.

Nebraska↗
USGS2015

Mapping the 3-D extent of the Northern Lobe of the Bushveld layered mafic intrusion from geophysical data

Geophysical models image the 3D geometry of the mafic portion of the Bushveld Complex north of the Thabazimbi-Murchison Lineament (TML), critical for understanding the origin of the world's largest layered mafic intrusion and platinum group element deposits. The combination of the gravity and magnetic data with recent seismic, MT, borehole and rock property measurements powerfully constrains the models. The intrusion north of the TML is generally shallowly buried (generally <1500 m) with a modeled area of &sim;160 km &times; &sim;125 km. The modeled thicknesses are not well constrained but vary from &sim;<1000 to >12,000 m, averaging &sim;4000 m. A feeder, suggested by a large modeled thickness (>10,000 m) and funnel shape, for Lower Zone magmas could have originated near the intersection of NS and NE trending TML faults under Mokopane. The TML has been thought to be the feeder zone for the entire Bushveld Complex but the identification of local feeders and/or dikes in the TML in the models is complicated by uncertainties on the syn- and post-Bushveld deformation history. However, modeled moderately thick high density material near the intersection of faults within the central and western TML may represent feeders for parts of the Bushveld Complex if deformation was minimal. The correspondence of flat, high resistivity and density regions reflect the sill-like geometry of the Bushveld Complex without evidence for feeders north of Mokopane. Magnetotelluric models indicate that the Transvaal sedimentary basin underlies much of the Bushveld Complex north of the TML, further than previously thought and important because the degree of reaction and assimilation of the Transvaal rocks with the mafic magmas resulted in a variety of mineralization zones.

Precambrian Research↗
USGS2021

How will baseflow respond to climate change in the Upper Colorado River Basin?

Baseflow is critical to sustaining streamflow in the Upper Colorado River Basin. Therefore, effective water resources management requires estimates of baseflow response to climatic changes. This study provides the first estimates of projected baseflow changes from historical (1984 – 2012) to thirty-year periods centered around 2030, 2050, and 2080 under warm/wet, median, and hot/dry climatic conditions using a hybrid statistical-deterministic baseflow model. Total baseflow supplied to the Lower Colorado River Basin may decline by up to 33%, although this value may increase in the near future by 6% under warm/wet conditions. The percentage of baseflow lost during in-stream transport is projected to increase by 1 - 5% relative to historical conditions. Results highlight that climate driven changes in high elevation hydrology have impacts on basin-wide water availability. Study results have implications for human and ecological water availability in one of the most heavily managed watersheds in the world.

Arizona, Colorado, New Mexico, Utah, Wyoming↗
USGS2023

Long-term trends in Arctic riverine chemistry signal multi-faceted northern change

Rivers integrate processes occurring throughout their watersheds and are therefore sentinels of change across broad spatial scales. River chemistry also regulates ecosystem function across Earth’s land–ocean continuum, exerting control from the micro- (for example, local food web) to the macro- (for example, global carbon cycle) scale. In the rapidly warming Arctic, a wide range of processes—from permafrost thaw to biological uptake and transformation—might reasonably alter river water chemistry. Here we use data from major rivers that collectively drain two-thirds of the Arctic Ocean watershed to assess widespread change in biogeochemical function within the pan-Arctic basin from 2003 to 2019. While the oceanward flux of alkalinity and associated ions increased markedly over this time frame, nitrate and other inorganic nutrient fluxes declined. Fluxes of dissolved organic carbon showed no overall trend. This divergence in response indicates the perturbation of multiple processes on land, with implications for biogeochemical cycling in the coastal ocean. We anticipate that these findings will facilitate refinement of conceptual and numerical models of current and future functioning of Arctic coastal ecosystems and spur research on scale-dependent change across the river-integrated Arctic domain.

Arctic↗
USGS2018

Faunal and vegetation monitoring in response to harbor dredging in the Port of Miami

Seagrasses are highly productive ecosystems. A before-after-control-impact (BACI) design was used to examine effects of dredging on seagrasses and the animals that inhabit them. The control site North Biscayne Bay and the affected site Port of Miami had seagrass densities decrease during both the before, Fish and Invertebrate Assessment Network 2006-2011, and after, Faunal Monitoring in Response to Harbor Dredging 2014-2016, studies. Turbidity levels increased at North Biscayne Bay and Port of Miami basins during the Faunal Monitoring in Response to Harbor Dredging study, especially in 2016. Animal populations decreased significantly in North Biscayne Bay and Port of Miami in the Faunal Monitoring in Response to Harbor Dredging study compared to the Fish and Invertebrate Assessment Network study. Predictive modeling shows that numbers of animal populations will likely continue to decrease if the negative trends in seagrass densities continue unabated. There could be effects on several fisheries vital to the south Florida economy. Additional research could determine if animal populations and seagrass densities have rebounded or continued to decrease.

Florida↗
USGS2011

Changes in low-flow frequency from 1976-2006 at selected streamgages in New York, excluding Long Island

Many Federal, State, and local agencies use low-flow data to establish water-use policy and help determine the total maximum daily loads and effluent limits of point and nonpoint sources of contamination of surface water during periods of decreased streamflow. Low-flow magnitude and frequency are used often by water-supply planners, reservoir managers, and hydroelectric facilities to manage water availability for supply and power generation. Low-flow statistics for eight selected U.S. Geological Survey streamgages in New York State were calculated for the period from 1976 through 2006 and for the entire period of continuous streamflow record. The 7-day, 2-year and 10-year low flows were computed and compared with those low flows published in the1979 U.S. Geological Survey report, Low-flow frequency analysis of streams in New York, Bulletin 74. Observed changes in low-flow frequency at each gage were then examined and compared to changes in precipitation and land use to determine whether a relation between similar patterns could be identified. A statewide U.S. Geological Survey study has not been done to develop equations for estimating low flows on rural unregulated streams in New York. Currently (2010) only one regional study developed for parts of the lower Hudson River Basin in 1986 is available to assist in estimating low flows on rural streams with unregulated streamflow in New York. Low-flow statistics published in the 1979 report need to be updated by using additional data collected since 1976 to determine current low-flow conditions across New York State. At-site low-flow statistics were updated for eight streamgages in New York by using continuous daily streamflow data through 2006 for the future development of a statewide research study. Selection of the eight streamgages used in this study identified a major deficiency in the number of available unregulated long-term U.S. Geological Survey streamgages needed for the development of regional low-flow equations in New York. A limited analysis of the changes in land use for the contributing drainage areas for each streamgage, changes in precipitation, and trends in the annual 7-day minimum flow also are presented. The 7-day, 2-year low flow showed increases of 14 to 35 percent and the 7-day 10-year low flow showed zero to 19 percent increases at rural streamgages with unregulated streamflows when statistics were computed by using data from 1976 through 2006 and compared with published data in Bulletin 74. When the entire period of record was used to compute low flow frequencies, the 7-day, 2-year low flows increased from about 6 to 15 percent whereas the 7-day 10-year low flows showed zero to 5 percent increases. Streamgages affected by urbanization and regulation for water supply showed the most significant changes in the 7-day, 2-year and 10-year low-flow frequencies. These streamgages are included to help identify the effects of urbanization and regulation on streamflow at these locations. The 7-day 10-year low flow increased by 65 percent at the U.S. Geological Survey streamgage Hackensack River at West Nyack, N.Y., and increased 120 percent at the U.S. Geological Survey streamgage Neversink River at Godeffroy, N.Y., when statistics were computed by using data from 1976 through 2006 and compared with the statistics for the regulated period computed in Bulletin 74.

New York↗
USGS2011

Risk management in a large-scale CO2 geosequestration pilot project, Illinois, USA

Like most large-scale infrastructure projects, carbon dioxide (CO 2) geological sequestration (GS) projects have multiple success criteria and multiple stakeholders. In this context "risk evaluation" encompasses multiple scales. Yet a risk management program aims to maximize the chance of project success by assessing, monitoring, minimizing all risks in a consistent framework. The 150,000-km2 Illinois Basin underlies much of the state of Illinois, USA, and parts of adjacent Kentucky and Indiana. Its potential for CO2 storage is first-rate among basins in North America, an impression that has been strengthened by early testing of the injection well of the Midwest Geological Sequestration Consortium's (MGSC's) Phase III large scale demonstration project, the Illinois Basin - Decatur Project (IBDP). The IBDP, funded by the U.S. Department of Energy's National Energy Technology Laboratory (NETL), represents a key trial of GS technologies and project-management techniques. Though risks are specific to each site and project, IBDP risk management methodologies provide valuable experience for future GS projects. IBDP views risk as the potential for negative impact to any of these five values: health and safety, environment, financial, advancing the viability and public acceptability of a GS industry, and research. Research goals include monitoring one million metric tonnes of injected CO2 in the subsurface. Risk management responds to the ways in which any values are at risk: for example, monitoring is designed to reduce uncertainties in parameter values that are important for research and system control, and is also designed to provide public assurance. Identified risks are the primary basis for risk-reduction measures: risks linked to uncertainty in geologic parameters guide further characterization work and guide simulations applied to performance evaluation. Formally, industry defines risk (more precisely risk criticality) as the product L*S, the Likelihood multiplied by the Severity of negative impact. L and S are each evaluated on five-point scales, yielding a theoretical spread in risk values of 1 through 25. So defined, these judgment-based values are categorical and ordinal - they do not represent physically measurable quantities, but are nonetheless useful for comparison and therefore decision support. The "risk entities" first evaluated are FEPs - conceptual Features, Events, and Processes based on the list published by Quintessa Ltd. After concrete scenarios are generated based on selected FEPs, scenarios become the critical entities whose associated risks are evaluated and tracked. In IBDP workshops, L and S values for 123 FEPs were generated through expert elicitation. About 30 experts in the project or in GS in general were assigned among six facilitated working groups, and each group was charged to envision risks within a sphere of project operations. Working groups covered FEPs with strong spatial characteristics - such as those related to the injection wellbore and simulated plume footprint - and "nonspatial" FEPs related to finance, regulations, legal, and stakeholder issues. Within these working groups, experts shared information, examined assumptions, refined and extended the FEP list, calibrated responses, and provided initial L and S values by consensus. Individual rankings were collected in a follow-up process via emailed spreadsheets. For each of L and S, three values were collected: Lower Bound, Best Guess, and Upper Bound. The Lower-Upper Bound ranges and the spreads among experts can be interpreted to yield rough confidence measures. Based on experts' responses, FEPs were ranked in terms of their L*S risk levels. FEP rankings were determined from individual (not consensus or averaged) results, thus no high-risk responses were damped out. The higher-risk FEPs were used to generate one or more concrete, well defined risk-bearing scenarios for each FEP. Any FEP scored by any expert as having associated risk of

Conference Paper↗
USGS2004

Identification of larval Pacific lampreys (Lampetra tridentata), river lampreys (L. ayresi), and western brook lampreys (L. richardsoni) and thermal requirements of early life history stages of lampreys. Annual report 2002-2003

Two fundamental aspects of lamprey biology were examined to provide tools for population assessment and determination of critical habitat needs of Columbia River Basin (CRB) lampreys (the Pacific lamprey, Lampetra tridentata, and the western brook lamprey, L. richardsoni). We evaluated the usefulness of current diagnostic characteristics for identification of larval lampreys (i.e., pigment patterns) and collected material for development of meristic and morphometric descriptions of early life stage CRB lampreys, and we determined the effects of temperature on survival and development of early life stage CRB lampreys. Thirty-one larval lampreys were collected from locations throughout the CRB and transported to the Columbia River Research Laboratory. Lampreys were sampled at six-week intervals at which time they were identified to the species level based on current diagnostic characteristics. Sampling was repeated until lampreys metamorphosed, at which time species identification was validated based on dentition, or until they died, at which time they were preserved for genetic examination. These lampreys were sampled 30 times with two individuals metamorphosing, both of which were consistently identified, and subsequently validated, as Pacific lampreys. Of the remaining lampreys, only one was inconsistently identified (Pacific lamprey in 83% of the sampling events and western brook lamprey in 17% of the sampling events). These data suggest that pigmentation patterns do not change appreciably through time. In 2001 and 2002 we artificially spawned Pacific and western brook lampreys in the laboratory to provide material for meristic and morphometric descriptions. We collected, digitized, preserved, and measured the mean chorion diameter of Pacific and western brook lamprey embryos. Embryos ranged in development from 1 d post fertilization to just prior to hatch, and were incubated at 14 C. Mean chorion diameter was greater and more variable for Pacific lampreys (mean {+-} SD; 1.468 {+-} 0.107 mm, N = 320) than for western brook lampreys (1.237 {+-} 0.064 mm, N = 280). An unpaired t-test showed that the difference in mean chorion diameter between species was highly significant (t = 32.788, df = 528.62, P < 0.0001). For larvae, we collected, digitized, and preserved 156 individuals from each species. Eight homologous landmarks defining a two-cell truss network with two appended triangles were selected for morphometric analyses and species discrimination. A full model discriminant analysis correctly classified 92% of the Pacific lampreys and 93% of the western brook lampreys in a classification data set. When applied to a test data set, the classification functions correctly classified 91% of the Pacific lampreys and 85% of the western brook lampreys. A backward elimination discriminant analysis removed four variables from the full model, and the reduced model correctly classified 91% of the Pacific lampreys and 93% of the western brook lampreys in a classification data set. The reduced model classification functions correctly classified 91% of the Pacific lampreys and 85% of the western brook lampreys in a test data set. In 2001 and 2002 Pacific and western brook lampreys were artificially spawned and resulting progeny were reared in the laboratory at 10 C, 14 C, 18 C, and 22 C. The estimated temperature for zero development was 4.85 C for Pacific and 4.97 C for western brook lampreys. Survival was greatest at 18 C followed by 14 C, 10 C, and 22 C, with significant differences observed between 22 C and other temperatures. Overall survival was significantly greater for western brook than for Pacific lampreys, although the difference in proportion of individuals surviving was only 0.02. Survival to hatch was significantly greater than survival to the larval stage with a difference of only 0.03. The proportion of individuals exhibiting abnormalities at the larval stage was greatest at 22 C followed by 18 C, 10 C, and 14 C, with significant differences observed between 22 C and other temperatures.

Report↗
USGS2019

Potential sea level rise for the Chitimacha Tribe of Louisiana

Situated in the Mississippi Alluvial Plain of the Gulf Coast Prairie Landscape Conservation Cooperative (GCP LCC), the Chitimacha Tribe is one of four federally recognized tribes in Louisiana. The Tribal seat, trust lands/ reservation, and adjacent Tribal owned lands are located near Charenton, Louisiana, totaling nearly 1,000 acres. The Chitimacha, with a population of approximately 1,400 people, are currently impacted by storm surge, which is expected to increase with climate change. The additional stress from storms will likewise increase the vulnerability to catastrophic impact in the event of a breach in the Atchafalaya Basin Spillway levee. A collaborative effort between the U.S. Geological Survey (USGS) and the Chitimacha Tribe has been initiated to provide resources and expertise to increase the Tribe’s ability to prevent, plan, and prepare for these environmental challenges. By enhancing technical skills, providing access to environmental data, and increasing awareness of environmental issues, the Chitimacha will be better prepared to plan and adapt to the environmental impacts facing their lands related to land use and climate change. For this project, USGS researchers asked how Chitimacha Tribal Lands might be impacted by future sea level rise scenario projections. These models illustrate some flooding within the northernmost boundary of Chitimacha Tribal Lands.

Louisiana↗
USGS1972

Annual compilation and analysis of hydrologic data for urban studies in the Bryan, Texas, metropolitan area, 1969

Hydrologic investigations of urban areas in Texas were begun by the U.S. Geological Survey in 1954. These studies are now in progress in Austin, Houston, Dallas, Dallas County, Fort Worth, San Antonio, and Bryan. Hydrologic investigations of urban areas in Texas were begun by the U.S. Geological Survey in 1954. These studies are now in progress in Austin, Houston, Dallas, Dallas County, Fort Worth, San Antonio, and Bryan. 1. To determine, on the basis of historical data and hydrologic analyses, the magnitude and frequency of floods. 2. To document and define the areal extent of floods of greater than ordinary magnitude. 3. To determine the effect of urban development on flood peaks and volume. 4. To provide applied research facilities for studies at Texas A & M University at College Stations. This report, the first in a series of reports to be published annually, is primarily applicable to objectives 2, 3, and 4. The report presents the basic hydrologic data collected in two study areas during the 1969 water year (October 1, 1968, to September 30, 1969) and basic hydrologic data collected during part of the 1968 water year (April 5, 1968, to September 30, 1968). The locations of the two basins within the study area, Burton Creek and Hudson Creek, are shown on figure 1.

Texas↗