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At least 505 records · Page 28Linked to original sources

USGS1990

Organic matter and thermochemical sulfate reduction in the Viburnum Trend, southeast Missouri

The role of organic matter in Mississippi Valley-type Pb-Zn deposits has been studied by systematically sampling and characterizing various types of organic matter in the Upper Cambrian Bonneterre formation in lead-zinc mines from the Viburnum Trend and from rocks as far as 20 km away from the Trend. Organic matter that is several kilometers from ore consists of insoluble disseminated kerogen in carbonates. Kerogen from brown dolostones yields mainly n-alkane pyrolysis products up to approximately n-C 20 H 42 , whereas gray and white carbonates that are poorer in organic carbon give much smaller quantities of pyrolysis products. Within meters to centimeters of ore in the Milliken mine, at the south end of the Viburnum Trend, organic matter occurs as solid, partly soluble tacky bitumen and insoluble hard blebs of millimeter to centimeter size. These hydrocarbon materials also yield n-alkane pyrolysis products up to C 20 . In contrast, the solid insoluble organic matter in intimate contact (intergrown) with ore (galena and chalcopyrite) is friable and brittle. Products from pyrolysis-gas chromatography-mass spectrometry of this material are quite different from the kerogen in rocks or the hydrocarbon blebs; they are substituted aromatic molecules such as toluene and methyl naphthalene, rather than n-alkanes.The sulfur content of solid organic matter from the Milliken mine varies and is lowest for tacky material away from ore, intermediate for blebs near ore, and highest for friable material in intimate contact with ore.Pyrolysis-gas chromatography of this sample suite documents the progression of kerogen (far from ore) through solid petroleumlike material (near ore) to degraded organic matter (in contact with ore). The change in the organic matter from n-alkane to a hydrogen poorer aromatic character with a higher sulfur content when associated with sulfide ores, suggests that chemical reactions such as nonbiological (thermochemical) sulfate reduction, which consume hydrogen and produce reactive sulfur, were responsible for organic degradation.

Economic Geology↗

USGS2008

Agriculture-related trends in groundwater quality of the glacial deposits aquifer, central Wisconsin

Measuring and understanding trends in groundwater quality is necessary for determining whether changes in land-management practices have an effect on groundwater quality. This paper describes an approach that was used to measure and understand trends using data from two groundwater studies conducted in central Wisconsin as part of the USGS NAWQA program. One of the key components of this approach, determining the age of sampled groundwater, gave a temporal component to the snapshots of water quality that were obtained through synoptic-sampling efforts. This approach can be used at other locations where groundwater quality data are collected, groundwater age can be determined, and associated temporal data are available. Results of these studies indicate measured concentrations of nitrate and atrazine plus deethylatrazine were correlated to historical patterns of fertilizer and atrazine use. Concentrations of nitrate in groundwater have increased over time; concentrations of atrazine plus deethylatrazine increased and then decreased. Concentrations of nitrate also were correlated to screen depth below the water level and concentrations of dissolved O2; concentrations of atrazine plus deethylatrazine were correlated to dissolved O2 and annual precipitation. To measure trends in concentrations of atrazine plus deethylatrazine, the data, collected over a near-decadal period, were adjusted to account for changes in laboratory-reporting levels and analytical recoveries. Only after accounting for these changes was it apparent that the median concentrations of atrazine plus deethylatrazine decreased over the near-decadal interval between sampling efforts. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Conference Paper↗

USGS1999

Historical trends in salinity and substrate in central and northern Florida Bay: A Paleoecological Reconstruction using modern analogue data

Understanding the natural spatial and temporal variability that exists within an ecosystem is a critical component of efforts to restore systems to their natural state. Analysis of benthic foraminifers and molluscs from modern monitoring sites within Florida Bay allows us to determine what environmental parameters control spatial and temporal variability of their assemblages. Faunal assemblages associated with specific environmental parameters, including salinity and substrate, serve as proxies for an interpretation of paleoecologic data. The faunal record preserved in two shallow (<2 m) cores in central Florida Bay (Russell Bank and Bob Allen Bank) provides a record of historical trends in environmental parameters for those sites. Analysis of these two cores has revealed two distinct patterns of salinity change at these sites: 1) a long-term trend of slightly increasing average salinity; and 2) a relatively rapid change to salinity fluctuations of greater frequency and amplitude, beginning around the turn of the century and becoming most pronounced after 1940. The degree of variability in substrate types at each locality limits interpretations of substrate trends to specific sites. A common sequence of change is present in the Russell Bank and Bob Allen Bank cores: from mixed grass and bare-sediment indicators at the bottom of the cores, to bare-sediment dwellers in the center, to a dominance of vegetative-cover indicators at the top of the cores. Changes in interpreted salinity patterns around the turn of the century are consistent with the timing of the construction of the Flagler Railroad from 1905 to 1912, and the Tamiami Trail and the canal and levee systems between 1915 and 1928. Beginning around 1940, the changes in the frequency and amplitude of salinity fluctuations may be related to changes in water management practices, meteorologic events (frequent hurricanes coupled with severe droughts in 1943 and 1944), or a combination of factors. The correspondence of these changes in Florida Bay with changes in the terrestrial Everglades suggests factors affecting the entire ecosystem are responsible for the salinity and substrate patterns seen in Florida Bay.

Florida↗

USGS1985

Trends and effects of organochlorine residues on Oregon and Nevada wading birds, 1979-83

The incidence of DDT (parent compound) declined significantly in the eggs of Black-crowned Night-Herons (Nycticorax nycticorax), White-faced Ibis (Plegadis chihi), and Black-necked Stilts (Himantopus mexicanus), and showed a downward trend in Snowy Egrets (Egretta thula). Mean DDE residues (breakdown product of DDT) in eggs declined significantly in Black-crowned Night-Herons and showed a downward trend in Black-necked Stilts and Snowy Egrets; however, no trend was apparent for White-faced Ibis. Some night-herons, egrets, and ibis laid thin-shelled eggs that cracked; eggshell thickness was negatively correlated with DDE residues in the egg contents. Ibis were the most sensitive species to DDE- induced shell thinning. Generally, reduced reproductive success for ibis started at lower DDE egg residues (3 ppm) than for either Snowy Egrets (5 ppm) or night-herons (8 ppm). Egg residue profiles, band recoveries, biotelemetry studies, and residues in fish and other prey items implicate the southwestern United States (a wintering area) as an important source of DDT-DDE that caused the most serious reproductive problem encountered during the study (in night-herons nesting at Ruby Lake, Nevada). Available evidence indicates that the three other species, together with night- herons from Oregon and Idaho, winter in Latin America.

Idaho, Nevada, Oregon↗

USGS1986

Monitoring grizzly bear population trends

A simple different equation model was developed to provide additional perspective on observed mortality and trend data on Yellowstone grizzly bears ( Ursus arctos horribilis ). Records of mortalities of adult females from 1959 to 1985 were utilized, in conjunction with data on females with cubs. The overall downward trend of observed numbers of females with cubs generally agrees with the model calculations but does not adequately reflect mortality from 1970 to 1974. The model may be useful in developing a composite index of population trend.

Idaho;Montana;Wyoming↗

USGS2020

Dilution and propagation of provenance trends in sand and mud: Geochemistry and detrital zircon geochronology of modern sediment from central California (U.S.A.)

Integrated, multi-method provenance studies of siliciclastic sedimentary deposits are increasingly used to reconstruct the history of source-to-sink transport, paleogeography, and tectonics. Invariably, analysis of large-scale depositional systems must confront issues regarding how to best sample the system and adequately cope with the details of sediment mixing. Potential biases including variations in grain size, sediment flux, and zircon concentration may cause provenance tracking tools to misrepresent the contributions of source-areas that contribute to large drainage networks. We have acquired U-Pb detrital zircon data from modern sand and whole rock geochemistry from mud sampled from the Sacramento-San Joaquin drainage of central California to elucidate conditions that can skew provenance trends along the course of a major river system. This drainage network is fed by headwaters that tap the Mesozoic pluton-dominated southern Sierra Nevada, the Paleozoic-Mesozoic wallrock and volcanic-dominated northern Sierra Nevada, the ultramafic-dominated eastern Klamath Mountains, and the intermediate to mafic Cascades volcanic arc. Analysis of the results indicates that detrital zircon provenance trends effectively record source variations for the southern, granite-dominated portion of the drainage network where contrasts in lithology and inferred zircon fertility are relatively minor. In these circumstances, mixture modeling of U-Pb detrital zircon data calibrated with a measure of zircon fertility approximates relative sediment flux contributed by individual drainages. Alternatively, in the northern parts of the system, source regions underlain by ultramafic and /or volcanic rocks are poorly represented, or entirely missing, in down-stream detrital zircon records. In some cases, mud geochemistry data more faithfully represents sediment provenance trends. Sampling performed at the confluence of the Sacramento, American, Mokolumne, and San Joaquin rivers within the Sacramento Delta region yields a detrital zircon age distribution that is indistinguishable from that of an independently established database of Sierra Nevada batholith crystallization ages. However, when the combined river flows along a recently established passage to the Pacific through the San Francisco Bay region, dredged sediment is found to be significantly contaminated by locally eroded material from the Franciscan Complex and other rocks that crop out within the Coast Ranges. Large variation of Zr concentrations measured throughout the Bay area document that significant hydrodynamic fractionation impacts sediment delivery through this segment of the system. The more Sierra Nevada-like detrital zircon age distribution yielded by a piston-core sample from the continental slope may be explained by either early-stage unroofing of the Coast Ranges or more efficient sand delivery from the delta to the Pacific by a free flowing river driven by a low stand in sea level.

California↗

USGS2021

Estimating trends of common raven populations in North America, 1966—2018

Over the last half century, common raven ( Corvus corax; raven) populations have increased in abundance across much of North America. Ravens are generalist predators known to depredate the eggs and young of several sensitive species. Quantifying raven population increases at multiple spatial scales across North America will help wildlife resource managers identify areas where population increases present the greatest risk to species conservation. We used a hierarchical Bayesian modeling approach to analyze trends of standardized raven counts from 1966 to 2018 using Breeding Bird Survey data within each Level I and II ecoregion of the United States and Canada. We also compared raven abundance within and outside the distributions of 9 sensitive or endangered species. Although we found substantial evidence that raven populations have increased across North America, populations varied in growth rates and relative abundances among regions. We found 73% of Level I (11/15) and II (25/34) ecoregions demonstrated positive annual population growth rates ranging from 0.2–9.4%. We found higher raven abundance inside versus outside the distributions of 7 of the 9 sensitive species included in our analysis. Gunnison sage-grouse ( Centrocercus minimus ) had the highest discrepancy, with 293% more ravens within compared to outside of their range, followed by greater sandhill crane ( Antigone canadensis tabida ; 280%), and greater sage-grouse ( C. urophasianus ; 204%). Only 2 species, least tern ( Sternula antillarum ) and piping plover ( Charadrius melodus ), indicated lower raven abundance within relative to outside their distributions. Our findings will help wildlife resource managers identify regional trends in abundance of ravens and anticipate which sensitive species are at greatest risk from elevated raven populations. Future research directed at identifying the underlying regional drivers of these trends could help elucidate the most appropriate and responsive management actions and, thereby, guide the development of raven population management plans to mitigate impacts to sensitive species.

Human-Wildlife Interactions↗

USGS2023

Northwest Forest Plan — The first 25 years (1994–2018): Watershed condition status and trends

This report describes status and trends in watershed condition across the Northwest Forest Plan (NWFP) area over the first 25 years since its inception in 1994. The program charged with this task is the Aquatic and Riparian Effectiveness Monitoring Program (AREMP), which has assembled information from field data collection, spatial datasets, and a host of landscape models to evaluate the status and trends in aquatic resources in streams and watersheds. Field data included hydrologic measurements (stream wetted widths and temperatures), geomorphic responses (instream wood and sediment), and biological responses (macroinvertebrates and aquatic organism passage). Novel statistical models were used to estimate trends in these measured responses. A suite of complementary modeled results was also employed to describe hydrometeorological drivers (e.g., drought indices and stream discharge), forest cover (upslope and riparian vegetation), and geomorphic conditions (e.g., road-related estimates of chronic and shallow landslide sediment delivery risk). Collectively, information on these responses allowed us to rigorously evaluate instream responses and hypothesize watershed drivers of those responses across the NWFP area and over time. The majority of responses we observed indicated widespread and incremental improvements from active management of forests, forest roads, and road-stream crossings as envisioned by the aquatic conservation strategy of the NWFP. Additionally, many of the responses we observed were consistent with those expected under the influences of changing climates in the Pacific Northwest. Ultimately, the long-term, broad-scale information provided by AREMP is a critical foundation for evaluating the effectiveness of federal land management and the effects of changing climates on water resources that sustain the Pacific Northwest’s human and natural landscapes.

California, Oregon, Washington↗

USGS2004

Strategic plan for the U.S. Geological Survey status and trends of Biological Resources Program: 2004-2009

The mission of the USGS Status and Trends of Biological Resources Program is to measure, predict, assess, and report the status and trends of the Nation's biological resources to facilitate research, enable resource management and stewardship, and promote public understanding and appreciation of our living resources. Determining the status (abundance, distribution, productivity, and health) and trends (how these variables change over time) of our living natural resources is critical for their Trumpeter swan with numbered wing tags. This tech- protection or restoration. The Progg ran nique allows birds to he monitored remotely without the provides the USGS, other agencies of need for recapture to identify individuals. Photo by the Department of the Interior (DOI), Wayne Miller. other federal and state agencies, and the public with science-based monitoring data and information for local, regional, and national assessment of biological resources and the ecosystems that support them.

Circular↗

USGS2024

Range-wide population trend analysis for greater sage-grouse (Centrocercus urophasianus)—Updated 1960–2023

Greater sage-grouse ( Centrocercus urophasianus ) are at the center of state and national land-use policies largely because of their unique life-history traits as an ecological indicator for health of sagebrush ecosystems. This updated population trend analysis provides state and federal land and wildlife managers with best-available science to help guide management and conservation plans aimed at benefitting sage-grouse populations. This analysis relied on previously published population trend modeling methodology from Coates and others (2021, 2022a) and incorporates population lek count data for 1960–2023. Included in this update are changes in terminology. Specifically, we now use the terms Period 1 (previously Long), Period 2 (previously Medium/Long), Period 3 (previously Medium), Period 4 (previously Short/Medium), Period 5 (previously Short), and Period 6 (previously Recent) to identify specific trends. State-space models estimated 2.8-percent average annual decline in sage-grouse populations between 1966 and 2021 (Period 1, six population oscillations) across their geographical range. Average annual decline among climate clusters for the same number of oscillations ranged between 2.1 and 3.1 percent. Cumulative declines were 41.1, 64.5, and 78.4 percent range-wide during Period 5 (19 years), Period 3 (35 years), and Period 1 (55 years), respectively. Population growth during 2022 and 2023 continue to point to 2021 as the most recent range-wide nadir.

Data Report↗

USGS2006

Trends in Streamflow of the San Pedro River, Southeastern Arizona

Total annual streamflow of the San Pedro River at Charleston in southeastern Arizona (fig. 1) decreased by about 66 percent from 1913 to 2002 (fig. 2). The San Pedro River is one of the few remaining free-flowing perennial streams in the arid Southwestern United States, and the riparian forest along the river supports several endangered species and is an important habitat for migratory birds. The decreasing trend in streamflow has led to concerns that riparian habitat may be damaged and that overall long-term water supply for a growing population may be threatened. Resource managers and the public have an interest in learning more about the trend and the possible causes of the trend.

Fact Sheet↗

USGS2013

Trends and causes of historical wetland loss in coastal Louisiana

Wetland losses in the northern Gulf Coast region of the United States are so extensive that they represent critical concerns to government environmental agencies and natural resource managers. In Louisiana, almost 3,000 square kilometers (km 2 ) of low-lying wetlands converted to open water between 1956 and 2004, and billions of dollars in State and Federal funding have been allocated for coastal restoration projects intended to compensate for some of those wetland losses. Recent research at the St. Petersburg Coastal and Marine Science Center (SPCMSC) focused on understanding the physical processes and human activities that contributed to historical wetland loss in coastal Louisiana and the spatial and temporal trends of that loss. The physical processes (land-surface subsidence and sediment erosion) responsible for historical wetland loss were quantified by comparing marsh-surface elevations, water depths, and vertical displacements of stratigraphic contacts at 10 study areas in the Mississippi River delta plain and 6 sites at Sabine National Wildlife Refuge (SNWR) in the western chenier plain. The timing and extent of land loss at the study areas was determined by comparing historical maps, aerial photographs, and satellite imagery; the temporal and spatial trends of those losses were compared with historical subsidence rates and hydrocarbon production trends.

Louisiana↗

USGS2008

Potential effects of a scenario earthquake on the economy of southern California: Baseline county-level migration characteristics and trends 1995-2000 and 2001-2010

The Multi-Hazards Demonstration Project (MHDP) is a collaboration between the U.S. Geological Survey (USGS) and various partners from the public and private sectors and academia, meant to improve Southern California's resiliency to natural hazards. In support of the MHDP objectives, the ShakeOut Scenario was developed. It describes a magnitude 7.8 earthquake along the southernmost 300 kilometers (200 miles) of the San Andreas Fault, identified by geoscientists as a plausible event that will cause moderate to strong shaking over much of the eight-county (Imperial, Kern, Los Angeles, Orange, Riverside, San Bernardino, San Diego, and Ventura) Southern California region. This report uses historical, estimated, and projected population data from several Federal and State data sources to estimate baseline characteristics and trends of the region's population migration (that is, changes in a person's place of residence over time). The analysis characterizes migration by various demographic, economic, family, and household variables for the period 1995-2000. It also uses existing estimates (beginning in 2001) of the three components of population change - births, deaths, and migration - to extrapolate near-term projections of county-level migration trends through 2010. The 2010 date was chosen to provide baseline projections corresponding to a two-year recovery period following the November 2008 date that was selected for the occurrence of the ShakeOut Scenario earthquake. The baseline characteristics and projections shall assist with evaluating the effects of inflow and outflow migration trends for alternative futures in which the simulated M7.8 earthquake either does or does not occur and the impact of the event on housing and jobs, as well as community composition and regional economy changes based on dispersion of intellectual, physical, economic, and cultural capital.

California↗

USGS2010

Preliminary assessment of trends in static water levels in bedrock wells in New Hampshire, 1984 to 2007

Analysis of nearly 60,000 reported values of static water level (SWL, as depth below land surface) in bedrock wells in New Hampshire, aggregated on a yearly basis, showed an apparent deepening of SWL of about 13 ft (4 m) over the period 1984–2007. Water-level data were one-time measurements at each well and were analyzed, in part, to determine if they were suitable for analysis of trends in groundwater levels across the state. Other well characteristics, however, also have been changing over time, such as total well depth, casing length, the length of casing in bedrock, and to some extent, well yield. Analyses indicated that many of the well construction variables are significantly correlated; the apparent declines in water levels may have been caused by some of these factors. Information on changes in water use for the period was not available, although water use may be an important factor affecting water levels. Multiple regression models were used to determine the simultaneous effects of important variables on SWLs statewide. Models also were generated for each county, and the model-calculated results for counties were generally similar to the results for the state wide models. The most significant predictors of mean SWL (aggregated by year and quarter) were total depth, the third quarter of the year (July–September), elevation, and height of well above minimum elevation within a 1,640-foot (500-meter) radius (hillslope factor). Casing length was a significant predictor of SWL for igneous-rock models and curvature of the land surface for metamorphic-rock models. Local geologic as well as landscape features appear to provide further explanation of SWL variation. For example, SWLs in wells completed in specific granites appear to be deeper than in other granites; this relation was also observed for different groups of metamorphic rocks. A more detailed examination of data from six towns that report frequent complaints about low water supply from bedrock aquifer wells showed that hillslope position may play a role in the availability of water in wells. SWLs were commonly deeper (greater depth to water) for wells with more than 100 ft (30 m) of relief between the well and the lowest land-surface elevation within 1,640 ft (500 m) of the well. For these high-relief wells, the depth to SWL was commonly greater for those that were on generally south-facing slopes, compared to wells on north-facing slopes. Concerns about wells with very little water-producing capacity in localized areas of some towns may be better understood by considering some of the relations identified in this study. For example, the data show that the position of a well on a hillslope affects the SWL depth in that well; however, the data also indicate that the average yield of the well is lower for hillslope wells than for wells in lower relief areas. This relation indicates that as the hillslope factor increases (and SWLs become deeper), the amount of available water in the wells decreases. Knowledge of this relation indicates that deeper wells may be needed in areas of higher relief. In areas with less extreme relief, the overall depths of wells have increased substantially more than the depths to the SWL. This indicates that the amount of water stored in wells (wellbore storage) has increased, and thus more water is available for use in the average well. As a result, more water may be used because it is available, possibly adding to the problem of local well interference or exacerbating drought-related well problems. These data provided an opportunity to examine groundwater-level conditions across the state; however, the bedrock wells used in this study would not be suitable for rigorous evaluation of trends in SWL across the state because the locations and characteristics of the wells vary with time. Further, these wells cannot substitute for a carefully designed network of wells selected for the sole purpose of monitoring trends in water levels over time. The SWL data may be useful in the design of a monitoring network, and continued collection of water-level data from the bedrock wells could be used to augment data from monitoring wells.

New Hampshire↗

USGS2013

Bedrock geology and outcrop fracture trends in the vicinity of the Savage Municipal Well Superfund site, Milford, New Hampshire

The Savage Municipal Well Superfund site consists of an eastward-directed plume of volatile organic compounds, principally tetrachloroethylene (PCE), in alluvium and glacial sand and gravel in the Souhegan River valley, just south of the river and about 4 kilometers west of the town of Milford, New Hampshire. Sampling of monitoring wells at the site has helped delineate the extent of the plume and has determined that some contaminant has migrated into the underlying crystalline bedrock, including bedrock north of the river within 200 meters of a nearby residential development that was constructed in 1999. Borehole geophysical logging has identified a northeast preferential trend for bedrock fractures, which may provide a pathway for the migration of contaminant under and north of the Souhegan River. The current study investigates the bedrock geologic setting for the site, including its position relative to known regional geologic structures, and compiles new strike and dip measurements of joints in exposed bedrock to determine if there are dominant trends in orientation similar to what was found in the boreholes. The site is located on the northwestern limb of a northeast-trending regional anticlinorium that is southeast of the Campbell Hill fault zone. The Campbell Hill fault zone defines the contact between granite and gneiss of the anticlinorium and granite and schist to the northwest and is locally marked by lenses of massive vein quartz, minor faults, and fracture zones that could potentially affect plume migration. The fault zone was apparently not intercepted by any of the boreholes that were drilled to delineate the contaminant plume and therefore passes to the north of the northernmost borehole in the vicinity of the new residential area. Joints measured in surface exposures indicate a strong preferred direction of strike to the north-northeast corroborating the borehole data and previous outcrop and geophysical studies. The north-northeast preferred direction matches the direction of elongation of the cone of depression formed during a pump test of the bedrock wells and could explain a potential pathway for the migration of contaminant north of the river.

New Hampshire↗

USGS2019

Trends in mammalian predator control trapping events intended to protect ground-nesting, endangered birds at Haleakalā National Park, Hawaiʻi: 2000–14

Predation and habitat degradation by non-native species are principal terrestrial threats to the federally endangered Hawaiian Petrel (ʻuaʻu, Pterodroma sandwichensis ) and Hawaiian Goose (nēnē, Branta sandvicensis ) within Haleakalā National Park (HALE), Maui, Hawaiʻi. Since 1981, HALE has maintained a network of live traps to control invasive mammalian predators and protect these endangered birds. To evaluate trapping efficiency in HALE, we evaluated four types of trap outcomes for the years 2000–14: Bait Lost (62 percent), No Event (23 percent), Trap Triggered (10 percent), and Predator Event (Rat Caught, Cat Caught, or Mongoose Caught; 4 percent). We used a multinomial logistic regression model to explore trends in the probabilities of broad outcomes (No Event, Other Event [Bait Lost or Trap Triggered], or Predator Event [Rat Caught, Cat Caught, or Mongoose Caught]). Temporal variations in the probabilities of No Event, Other Event, or Predator Event were best explained by ʻuaʻu season (off-season, pre-laying, incubation, or nestling), month, year, and seasonal rainfall with greater probabilities of Predator Event during the ʻuaʻu nestling period (July–October). The probability of Predator Event or Other Event decreased with increased rainfall. Spatial analysis showed that percent vegetative cover and vegetation type best explained variations in the probabilities of trapping outcomes with the probability of Predator Event being greatest in developed and tree covered areas. The proportion of trapping events that resulted in Rat Caught was at least 20 times greater than the proportions of events resulting in Cat or Mongoose Caught throughout the 15-year management period. Temporal analysis showed that season, year, and maximum temperature best explained variations in probabilities of Predator Event; the probability of Rat Caught was greatest during the ʻuaʻu pre-laying and incubation periods (February–June), was greater during periods of warmer maximum temperatures, and overall, increased over the 15-year management period. The probability of Mongoose Caught was greatest during the ʻuaʻu offseason (November–January), decreased through time (2000–14), and decreased with increasing weekly maximum temperatures. Trends in Cat Caught were hard to detect because of small sample sizes, though slight trends indicated cat captures were most frequent during the ʻuaʻu off season and less frequent through time (2000–14). The probability of a Cat Caught event was also negatively correlated with weekly temperatures. Spatial analysis showed elevation best explained variations in probabilities of capture for rats, cats, and mongoose. Overall, predator catches were fewer at higher elevations, and of predators caught at higher elevations, the clear majority were rats. Our results are being used by HALE Endangered Wildlife Management staff to evaluate existing methods for predator control and efficacy of existing trap-based control strategies intended to protect ʻuaʻu and nēnē.

Hawaii↗

USGS2022

Methods for computing 7Q2 and 7Q20 low-streamflow statistics to account for possible trends

Low-streamflow statistics, such as the annual minimum 7-day streamflow (which is the 7-day streamflow likely to be exceeded in 9 out of 10 years on average [7Q10]), that are computed by using the full historical streamflow record may not accurately represent current conditions at sites with statistically significant trends in low streamflow over time. Recent research suggests that using a contemporary subset of the historical streamflow record (specifically, the most recent 30 years) to compute an estimate of 7Q10 more accurately represents current streamflow conditions when a statistically significant trend in the streamflow record is present. This report presents the results of a Monte Carlo simulation experiment on artificial low-streamflow records, derived from the characteristics of streamflows at 174 U.S. Geological Survey streamgages, to test whether a similar approach is appropriate for the computation of the annual minimum 7-day streamflow exceeded in 1 out of 2 years on average (7Q2) and the annual minimum 7-day streamflow exceeded in 19 out of 20 years on average (7Q20). The results indicate that using the most recent 30-year subset of the low-streamflow record also may be the best approach when computing 7Q2 and 7Q20 at sites where a statistically significant trend in low streamflows is detected.

Open-File Report↗

USGS1983

Nonparametric tests for trends in water-quality data using the statistical analysis system

Two nonparametric procedures to test for trends in water-quality data (SEASKEN AND SEASRS) have been developed for the Statistical Analysis System* (SAS). The procedure SEASKEN tests for a monotonic trend in time by a modified form of Kendall's tau, the Seasonal Kendall test. The procedure SEASRS tests for a step trend between two different periods in a time series using a modified form of the Wilcoxon (Mann-Whitney) rank sum test, the Mann-WhitneyWilcoxon rank sum test for seasonal data. Examples are presented using the two procedures. The source code and user's guide for each of the two procedures are also presented. Procedures for flow adjusting water-quality data by the SAS procedures REG and SYSREG and techniques for plotting water-quality data as a time series by the SAS procedure PLOT are presented. Additionally, examples are presented to demonstrate the use of the U.S. Geological Survey procedures QWRETR, DVRETR, QWSAS, and DVINPUT to retrieve data from the Geological Survey WATSTORE system and make it available to SAS.

Open-File Report↗