Search Results

Debris-flow experiments and models commonly use “hot-start” initial conditions in which downslope motion begins when a large force imbalance is abruptly imposed. By contrast, initiation of natural debris flows almost invariably results from small perturbations of static force balances that apply to debris masses poised in steep channels or...

Cretaceous-Paleocene porphyry Cu(±Mo±Au) occurrences are scattered throughout the Yukon-Tanana upland in eastern Alaska. Known occurrences in eastern Alaska are poorly characterized, despite a resurgence in exploration. Porphyry deposits in the upland are emplaced into structurally complex metamorphic rocks representing a variety of tectonic environments, resulting in diverse alteration and mineralization...

This presentation summarizes the proposed updates to earthquake design ground motions for the 2020 edition of the NEHRP Recommended Seismic Provisions, expected to be incorporated into the ASCE 7-22 Standard. The implications of these updates on the values of design ground motions for example locations in both conterminous and nonconterminous...

Executive SummaryIn this report, we describe application of the Stream Salmonid Simulator (S3) to Chinook salmon (Oncorhynchus tshawytscha) in the Klamath River between Keno Dam in southern Oregon and the ocean in northern California. S3 is a deterministic life-stage-structured population model that tracks daily growth, movement, and survival...

The principal motivation for this study is that sagebrush-steppe ecosystems are undergoing significant state changes, and land managers are challenged with optimizing their resources for both short- and long-term use. Yet, limited knowledge is available regarding how the sagebrush-steppe will respond to environmental changes related to precipitation and temperature regimes,...

The Archie Carr National Wildlife Refuge, Florida, USA (27.946°N, − 80.494°W) represents one of the largest loggerhead turtle (Caretta caretta) nesting sites in the Western Hemisphere. Surprisingly, little work has been conducted to determine females’ post-nesting migratory behavior and characteristics of their foraging areas. Between 2008 and 2017,...

Most geothermal resources in the Great Basin region of the western USA are blind, and thus the discovery of new commercial-grade systems requires synthesis of favorable characteristics for geothermal activity. The geothermal play fairway concept involves integration of multiple parameters indicative of geothermal activity to identify promising...

Management of protected lands may enhance ecosystem services that conservation programs were designed to protect. Practices that build soil organic matter (SOM) on agricultural lands also increase soil water holding capacity, potentially reducing climatic water deficit (CWD), increasing actual evapotranspiration (AET) and increasing groundwater recharge (RCH). We developed nine...

Trout are socioeconomically and ecologically important in the Greater Yellowstone Area (GYA); yet these fish face numerous threats. Disease may begin to play a larger role in reducing fish populations, partly because many existing threats may interact to exacerbate the frequency, extent, and severity of fish diseases (Lafferty 2009). For...

Increased oil and gas production in many areas has led to concerns over the effects these activities may be having on nearby groundwater quality. In this study we determine the lateral and vertical extent of groundwater with less than 10,000 milligrams per liter (mg/l) total dissolved solids (TDS) near...

Stakeholder interests have spurred the reintroduction of the critically endangered populations of Chinook Salmon to tributaries upstream of Shasta Dam, in northern California. We released two groups of acoustically tagged, juvenile hatchery, late-fall Chinook Salmon to determine how juvenile salmon would distribute and survive. We measured travel times to Shasta...

Radial and linear dike swarms in the eroded roots of volcanoes and along rift zones are sensitive structural indicators of conduit and eruption geometry that can record regional paleostress orientations. Compositionally diverse dikes and larger intrusions that radiate westward from the polycyclic Platoro caldera complex in the Southern Rocky Mountain...

Electricity from wind energy is a major contributor to the strategy to reduce greenhouse gas emissions from fossil fuel use and thus reduce the negative impacts of climate change. Wind energy, like all power sources, can have adverse impacts on wildlife. After nearly 25 years of focused research, these impacts...

No abstract available....

Black Oystercatchers Haematopus bachmani, a species of conservation concern, depend on marine intertidal prey resources. We examined diet, feeding rates, growth, and survival of Black Oystercatcher broods in southcentral Alaska, 2013-2014. To determine the importance of diet on brood survival, we modeled daily survival rates of broods as a function...

Outdoor recreation facilitates important connections to nature and wildlife but is perceived differently across population segments. As such, we expected that current and past socio-demographic characteristics of individuals would influence intention to participate in outdoor recreation. We solicited 5,000 U.S. residents. (n = 1,030, 23% response) to describe their perceptions...

Coastal erosion outpaces land generation along many of the world’s deltas and a significant percentage of shorelines, and human-caused alterations to coastal sediment budgets can be important drivers of this erosion. For sediment-starved and erosion-prone coasts, large-scale enhancement of sediment supply may be an important, but poorly understood, management option....

In cooperation with the New Mexico County of Bernalillo, the U.S. Geological Survey characterized potential polychlorinated biphenyl (PCB) concentration and estimated loading into the Rio Grande from watersheds that are under the county’s jurisdiction. Water and sediment samples were collected in 2017–18 from six sites within four stormwater drainage basins...

A generalized potentiometric-surface map of the Madison aquifer near Jewel Cave National Monument was constructed using water levels measured from calendar years 1988 to 2019 in 24 groundwater wells and 4 subterranean cave lakes interpreted to be in hydraulic connection with the aquifer. The map indicated that groundwater near Jewel...

This report and its accompanying geospatial data outline many areas of coal in the United States beneath more than 3,000 ft of overburden. Based on depth, these areas may be targets for injection and storage of supercritical carbon dioxide. Additional areas where coal exists beneath more than 1,000 ft of...

The introduction of snakeheads from their origins in Asia is relatively recent to the conterminous United States with the first of many collections beginning in the late 1990s. For decades they have been commercially fished and aquacultured around the world for human food and, to a lesser degree, for the...

The Great Plains Grassland Summit: Challenges and Opportunities from North to South was held April 10-11, 2018 in Denver, Colorado. The geographical focus for the summit was the entire Great Plains. The summit was designed to provide syntheses of information about key grassland topics of interest in the Great Plains;...

As we enter the era of data science (Lortie 2018), quantitative analysis methodologies are proliferating rapidly, leaving ecologists with the task of choosing among many alternatives. The use of structural equation modeling (SEM) by ecologists has increased in recent years, prompting us to ask users a number of questions about...

The dwarf planet Ceres’s outer crust is a complex, heterogeneous mixture of ice, clathrates, salts and silicates. Numerous large domes on Ceres’s surface indicate a degree of geological activity. These domes have been attributed to cryovolcanism, but that is difficult to reconcile with Ceres’s small size and lack of long-lived...

Golden alga Prymnesium parvum Carter is a euryhaline, ichthyotoxic haptophyte (Chromista). Because of its presumed coastal/marine origin where SO42- levels are high, the relatively high SO42- concentration of its brackish inland habitats, and the sensitivity of marine chromists to sulfur deficiency, this study examined whether golden alga growth is sensitive...