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At least 1,765 records · Page 98Linked to original sources
USGS2016

Dissolved oxygen: Chapter 6

Dissolved oxygen (DO) concentration serves as an important indicator of estuarine habitat condition, because all aquatic macro-organisms require some minimum DO level to survive and prosper. The instantaneous DO concentration, measured at a specific location in the water column, results from a balance between multiple processes that add or remove oxygen (Figure 6.1): primary production produces O2; aerobic respiration in the water column and sediments consumes O2; abiotic or microbially-mediated biogeochemical reactions utilize O2 as an oxidant (e.g., oxidation of ammonium, sulfide, and ferrous iron); O2 exchange occurs across the air:water interface in response to under- or oversaturated DO concentrations in the water column; and water currents and turbulent mixing transport DO into and out of zones in the water column. If the oxygen loss rate exceeds the oxygen production or input rate, DO concentration decreases. When DO losses exceed production or input over a prolonged enough period of time, hypoxia ( (<2-3 mg/L) or anoxia can develop. Persistent hypoxia or anoxia causes stress or death in aquatic organism populations, or for organisms that can escape a hypoxic or anoxic area, the loss of habitat. In addition, sulfide, which is toxic to aquatic organisms and causes odor problems, escapes from sediments under low oxygen conditions. Low dissolved oxygen is a common aquatic ecosystem response to elevated organic

Report↗
USGS2016

Using structure from motion photogrammetry to examine glide snow avalanches

Structure from Motion (SfM), a photogrammetric technique, has been used extensively and successfully in many fields including geosciences over the past few years to create 3D models and high resolution digital elevation models (DEMs) from aerial or oblique photographs. SfM has recently been used in a limited capacity in snow avalanche research and shows promise as a tool for broader applications. In this study, we used SfM to examine glide avalanches along the Going-to-the-Sun Road (GTSR) corridor in Glacier National Park (GNP), Montana. Glide avalanches pose substantial hazard to railroads, highways, and other infrastructure in many avalanche prone regions around the world, and yet basic measurements of crown depth and ground/snow interface can be hard to observe. Along the GTSR, glide avalanches can impact worker and public safety, but accessing glide avalanche crowns or glide cracks is often prohibited by inaccessible terrain or residual avalanche hazard. We used SfM techniques to derive high resolution DEMs for four glide avalanches that occurred in the spring of 2016. This allowed us to estimate selected full depth glide avalanche dimensions without visiting the site. However, our analysis was limited to qualitative assessments of the glide avalanche dimensions as the high resolution coordinates necessary to analyze the vertical dimension of avalanche crowns were not available. Despite this, our results suggest SfM can be a robust tool for examining glide avalanche crowns and of sufficient resolution to accurately characterize glide avalanche dimensions. Under a warming and more variable future climate, glide avalanches could become a more prevalent problem, and using SfM as a tool to help characterize glide avalanches over a larger spatial area will help us to better document and further understand these phenomena.

Conference Paper↗
USGS2005

Bird use of reforestation sites: Influence of location and vertical structure

In the Lower Mississippi Valley, more than 300,000 acres of agricultural land have been reforested in the last 10 years. Planning decisions on how and where to restore forest are complex and usually reflect landowner objectives. However, initial planning decisions may have a large influence on the value of restored stands for birds and other wildlife. Reforestation of small, isolated tracts will likely result in mature forests where reproductive output of breeding birds does not compensate for adult mortality (sink habitats). This may be due to factors such as lower reproductive success near edges (edge effects), insufficient area of habitat to attract colonizing birds (area effects), or restricted population mixing and mating opportunities because of limited dispersal among tracts (isolation effects). Conversely, reforestation adjacent to existing forest increases contiguous forest area and provides areas buffered from agricultural or urban habitats (interior forest core). Bottomland reforestation has historically focused on planting relatively slow-growing tree species, particularly oaks (Quercus spp.). Thus, restoration sites are often dominated by grasses and forbs for up to a decade after tree planting. Grassland birds are the first birds to colonize reforested sites. However, abundance and productivity of grassland birds is generally poor on sites associated with woody vegetation, such as sites adjacent to mature forest. As woody vegetation develops on reforested sites, birds preferring shrub-scrub habitat displace grassland species (Twedt et al. 2002) (fig. 1). Planting faster-growing trees compresses the time for colonization by shrub-scrub birds and the increased vertical stature of these trees attracts forest birds (Twedt and Portwood 1996). Additionally, planting next to existing mature forests creates transitional edges that reduce the detrimental effects of abrupt forest-agriculture interfaces.

Technical Note↗
USGS1979

Tufted Puffins nesting in estuarine habitat

The Tufted Puffin ( Lunda cirrhata ) apparently has the most extensive breeding distribution of any North Pacific seabird, extending in the western North Pacific from Hokkaido to the north Chukotsk Peninsula on the Chukchi Sea, and in North America from Cape Lisburne on the Chukchi Sea, south to the Farallon Islands off central California (Udvardy 1963). Despite this wide breeding distribution, the reported nesting habitat is generally restricted to steep, rocky islands and continental headlands (see Dement’ev and Gladkov 1951, Kozlova 1957, Gabrielson and Lincoln 1959, Portenko 1973, Sealy 1973, and Sowls et al. 1978). Nests are typically excavated in steep slopes and/or on vegetated plateaus, well above normal tidal influence but occasionally within the spray or storm-wash zone. Nowhere has L. cirrhata or any other puffin species been reported to nest in a flat, estuarine habitat in substrate normally affected by tides during the breeding season. Portenko (1973: 137) refers to Tufted Puffins breeding on Alyumka Island in the Anadyr "estuary" (64°40'N, 177°37'E), but Alyumka Island is a rocky coastal island having immediate offshore waters between 3-18 m deep (A.A. Kistchinski, The Ringing Center, Moscow, and George Tyner, U.S. Defense Mapping Agency, pers. comm.). During the summers of 1976, 1977, and 1978, we found 14-18 pairs of Tufted Puffins nesting on 4 narrow sand islands (5-7 ha each) along the northcentral Alaska Peninsula at Nelson Lagoon (56°00'N, 161°10'W). As of June 1979, 25 active burrows had been reported there (Margaret R. Petersen, pers. comm.). The islands lie approximately 1.3 km from the Bering Sea coast and are protected from the sea by a long, narrow (0.5 kin) sand peninsula. The main deepwater channel in the lagoon, 3-7 m deep and 100-300 m wide at mean low water (MLW), separates the islands from the peninsula. The islands, which are free of permafrost, have a uniformly low profile with the highest elevation 1-2 m above mean high water (MHW) (Fig. 1). Each island is circumscribed by a gently sloping (<5°), narrow (5-15 m) sand/gravel beach that graduates at MLW to intertidal mud- and sandflats. These are extensive on the south and southeast sides (several hundred m) and relatively narrow (10-20 m) on the north and northwest or channel sides. The banks of each island are moderate to near vertical in slope. Puffin burrows face the channel, are located at or near the vegetation/beach interface, and extend into the bank horizontally or slightly downward. Beach rye ( Elymus arenarius mollis ) grows over most of each island and is used as nesting cover by several hundred Glaucous-winged Gulls ( Larus glaucescens ) and lesser numbers of Common Eiders ( Somateria mollissima v-nigra ). Predation by gulls on puffin eggs or chicks was not observed, nor did we see gulls rob food from adult puffins returning to their burrows from foraging in the Bering Sea (cf. Nettleship 1972). Puffins were never observed feeding in the lagoon.

Alaska↗
USGS2002

Distribution, production, and ecophysiology of Picocystis strain ML in Mono Lake, California

A recently described unicellular chlorophytic alga isolated from meromictic Mono Lake, California, occupies a niche that spans two environments: the upper oxic mixolimnion and the deeper anoxic and highly reducing monimolimnion. This organism, Picocystis sp. strain ML, accounts for nearly 25% of the primary production during the winter bloom and more than 50% at other times of the year. In incubations, it is heavily grazed by the brine shrimp, Artemia monica. We assessed growth and photosynthetic parameters over broad ranges of irradiance, salinity, and pH and under oxic and anoxic conditions. Picocystis appears to be particularly adapted to low irradiance; we observed an order of magnitude increase in the cellular pigment concentrations, as well as marked increases in cellspecific photosynthetic parameters for cells acclimated to low-growth irradiance. Growth rates of 0.3–1.5 d21 were observed over a salinity range of 0–260‰ and a pH range of 4–12, with maximal growth at ;50 mmol photons m22 s21 , 40‰, and pH 6–10. Growth and oxygenic photosynthesis were observed under anoxic conditions at rates comparable to those measured under oxic conditions. The ability of the organism to acclimate and grow under such a broad range of environmental conditions makes it an important component of the Mono Lake ecosystem and likely contributes to its dominance of the monimolimnion/mixolimnion interface.

California↗
USGS2014

Simulating future residential property losses from wildfire in Flathead County, Montana

Wildfire damages to private residences in the United States and elsewhere have increased as a result of expansion of the wildland-urban interface (WUI) and other factors. Understanding this unwelcome trend requires analytical frameworks that simulate how various interacting social, economic, and biophysical factors influence those damages. A methodological framework is developed for simulating expected residential property losses from wildfire [E(RLW)], which is a probabilistic monetary measure of wildfire risk to residential properties in the WUI. E(RLW) is simulated for Flathead County, Montana for five, 10-year subperiods covering the period 2010-2059, under various assumptions about future climate change, economic growth, land use policy, and forest management. Results show statistically significant increases in the spatial extent of WUI properties, the number of residential structures at risk from wildfire, and E(RLW) over the 50-year evaluation period for both the county and smaller subareas (i.e., neighborhoods and parcels). The E(RLW) simulation framework presented here advances the field of wildfire risk assessment by providing a finer-scale tool that incorporates a set of dynamic, interacting processes. The framework can be applied using other scenarios for climate change, economic growth, land use policy, and forest management, and in other areas.

Montana↗
USGS1996

A digital system for surface reconstruction

A digital photogrammetric system, STEREO, was developed to determine three dimensional coordinates of points of interest (POIs) defined with a grid on a textureless and smooth-surfaced specimen. Two CCD cameras were set up with unknown orientation and recorded digital images of a reference model and a specimen. Points on the model were selected as control or check points for calibrating or assessing the system. A new algorithm for edge-detection called local maximum convolution (LMC) helped extract the POIs from the stereo image pairs. The system then matched the extracted POIs and used a least squares “bundle” adjustment procedure to solve for the camera orientation parameters and the coordinates of the POIs. An experiment with STEREO found that the standard deviation of the residuals at the check points was approximately 24%, 49% and 56% of the pixel size in the X, Y and Z directions, respectively. The average of the absolute values of the residuals at the check points was approximately 19%, 36% and 49% of the pixel size in the X, Y and Z directions, respectively. With the graphical user interface, STEREO demonstrated a high degree of automation and its operation does not require special knowledge of photogrammetry, computers or image processing.

Photogrammetric Engineering and Remote Sensing↗
USGS2003

The use of sea ice habitat by female polar bears in the Beaufort Sea

Polar bears ( Ursus maritimus ) depend on ice-covered seas to satisfy life history requirements. Modern threats to polar bears include oil spills in the marine environment and changes in ice composition resulting from climate change. Managers need practical models that explain the distribution of bears in order to assess the impacts of these threats. We used stepwise procedures to create resource selection models of habitat use for radio-collared female polar bears in the Beaufort Sea. Sea ice characteristics and ocean depths at known polar bear locations were compared to the same features at randomly selected locations. Models generated for each of four seasons confirmed complexities of habitat use by polar bears and their response to numerous factors. Bears preferred shallow water areas where ice concentrations were > 80 % and different ice types intersected. Variation among seasons was reflected mainly in differential selection of ice stages, floe sizes, and their interactions. Water depth, total ice concentration and distance to the nearest interface between different ice types were significant terms in models for most seasons. Variation in ice stage and form also appeared in three models, and several interaction effects were identified. Habitat selection by polar bears is likely related to prey abundance and availability. Use of habitats in shallow water possibly reflects higher productivity in those areas. Habitat use in close proximity to ice edges is probably related to greater access of prey in those habitats.

Conference Paper↗
USGS2004

Using discrete choice modeling to generate resource selection functions for female polar bears in the Beaufort Sea

Polar bears ( Ursus maritimus ) depend on ice-covered seas to satisfy life history requirements. Modern threats to polar bears include oil spills in the marine environment and changes in ice composition resulting from climate change. Managers need practical models that explain the distribution of bears in order to assess the impacts of these threats. We explored the use of discrete choice models to describe habitat selection by female polar bears in the Beaufort Sea. Using stepwise procedures we generated resource selection models of habitat use. Sea ice characteristics and ocean depths at known polar bear locations were compared to the same features at randomly selected locations. Models generated for each of four seasons confirmed complexities of habitat use by polar bears and their response to numerous factors. Bears preferred shallow water areas where different ice types intersected. Variation among seasons was reflected mainly in differential selection of total ice concentration, ice stages, floe sizes, and their interactions. Distance to the nearest ice interface was a significant term in models for three seasons. Water depth was selected as a significant term in all seasons, possibly reflecting higher productivity in shallow water areas. Preliminary tests indicate seasonal models can predict polar bear distribution based on prior sea ice data.

Alaska↗
USGS2011

Programming PHREEQC calculations with C++ and Python a comparative study

The new IPhreeqc module provides an application programming interface (API) to facilitate coupling of other codes with the U.S. Geological Survey geochemical model PHREEQC. Traditionally, loose coupling of PHREEQC with other applications required methods to create PHREEQC input files, start external PHREEQC processes, and process PHREEQC output files. IPhreeqc eliminates most of this effort by providing direct access to PHREEQC capabilities through a component object model (COM), a library, or a dynamically linked library (DLL). Input and calculations can be specified through internally programmed strings, and all data exchange between an application and the module can occur in computer memory. This study compares simulations programmed in C++ and Python that are tightly coupled with IPhreeqc modules to the traditional simulations that are loosely coupled to PHREEQC. The study compares performance, quantifies effort, and evaluates lines of code and the complexity of the design. The comparisons show that IPhreeqc offers a more powerful and simpler approach for incorporating PHREEQC calculations into transport models and other applications that need to perform PHREEQC calculations. The IPhreeqc module facilitates the design of coupled applications and significantly reduces run times. Even a moderate knowledge of one of the supported programming languages allows more efficient use of PHREEQC than the traditional loosely coupled approach.

Conference Paper↗
USGS2017

Development and utilization of USGS ShakeCast for rapid post-earthquake assessment of critical facilities and infrastructure

The ShakeCast system is an openly available, near real-time post-earthquake information management system. ShakeCast is widely used by public and private emergency planners and responders, lifeline utility operators and transportation engineers to automatically receive and process ShakeMap products for situational awareness, inspection priority, or damage assessment of their own infrastructure or building portfolios. The success of ShakeCast to date and its broad, critical-user base mandates improved software usability and functionality, including improved engineering-based damage and loss functions. In order to make the software more accessible to novice users—while still utilizing advanced users’ technical and engineering background—we have developed a “ShakeCast Workbook”, a well documented, Excel spreadsheet-based user interface that allows users to input notification and inventory data and export XML files requisite for operating the ShakeCast system. Users will be able to select structure based on a minimum set of user-specified facility (building location, size, height, use, construction age, etc.). “Expert” users will be able to import user-modified structural response properties into facility inventory associated with the HAZUS Advanced Engineering Building Modules (AEBM). The goal of the ShakeCast system is to provide simplified real-time potential impact and inspection metrics (i.e., green, yellow, orange and red priority ratings) to allow users to institute customized earthquake response protocols. Previously, fragilities were approximated using individual ShakeMap intensity measures (IMs, specifically PGA and 0.3 and 1s spectral accelerations) for each facility but we are now performing capacity-spectrum damage state calculations using a more robust characterization of spectral deamnd.We are also developing methods for the direct import of ShakeMap’s multi-period spectra in lieu of the assumed three-domain design spectrum (at 0.3s for constant acceleration; 1s or 3s for constant velocity and constant displacement at very long response periods). As part of ongoing ShakeCast research and development, we will also explore the use of ShakeMap IM uncertainty estimates and evaluate the assumption of employing multiple response spectral damping values rather than the single 5%-damped value currently employed. Developing and incorporating advanced fragility assignments into the ShakeCast Workbook requires related software modifications and database improvements; these enhancements are part of an extensive rewrite of the ShakeCast application.

Conference Paper↗
USGS2017

Numerical studies of depressurization-induced gas production from an interbedded marine turbidite gas hydrate reservoir model

The numerical simulation of thin hydrate-bearing sand layers interbedded with mud layers is investigated. In this model, the lowest hydrate layer occurs at the base of gas hydrate stability and overlies a thinly-interbedded saline aquifer. The predicted gas rates reach 6.25 MMscf/day (1.77 x 105 m3 /day) after 90 days of continuous depressurization with manageable water production. Development of horizontal dissociating interfaces between hydrate-bearing sand and mud layers is a primary determinant of reservoir performance. A set of simulations has been executed to assess uncertainty in in situ permeability and to determine the impact of the saline aquifer on productivity.

Conference Paper↗
USGS2017

SToRM: A Model for 2D environmental hydraulics

A two-dimensional (depth-averaged) finite volume Godunov-type shallow water model developed for flow over complex topography is presented. The model, SToRM, is based on an unstructured cell-centered finite volume formulation and on nonlinear strong stability preserving Runge-Kutta time stepping schemes. The numerical discretization is founded on the classical and well established shallow water equations in hyperbolic conservative form, but the convective fluxes are calculated using auto-switching Riemann and diffusive numerical fluxes. Computational efficiency is achieved through a parallel implementation based on the OpenMP standard and the Fortran programming language. SToRM’s implementation within a graphical user interface is discussed. Field application of SToRM is illustrated by utilizing it to estimate peak flow discharges in a flooding event of the St. Vrain Creek in Colorado, U.S.A., in 2013, which reached 850 m3/s (~30,000 f3 /s) at the location of this study.

Colorado↗
USGS2017

Modeling waterfowl habitat selection in the Central Valley of California to better understand the spatial relationship between commercial poultry and waterfowl

Wildlife researchers frequently study resource and habitat selection of wildlife to understand their potential habitat requirements and to conserve their populations. Understanding wildlife spatial-temporal distributions related to habitat have other applications such as to model interfaces between wildlife and domestic food animals in order to mitigate disease transmission to food animals. The highly pathogenic avian influenza (HPAI) virus represents a significant risk to the poultry industry. The Central Valley of California offers a unique geographical confluence of commercial poultry and wild waterfowl, which are thought to be a key reservoir of avian influenza (AI). Therefore, understanding spatio-temporal distributions of waterfowl could improve our understanding of potential risk of HPAI exposure from a commercial poultry perspective. Using existing radio-telemetry data on waterfowl (U.S. Geological Survey) in combination with habitat and vegetation data based on Geographic Information Systems (GIS), we are developing GIS-based statistical models that predict the probability of waterfowl presence (Habitat Suitability Mapping). Near-real-time application can be developed using recent habitat data derived from Landsat imagery (acquired by satellites and publicly available through the U.S. Geological Survey) to predict temporally- and spatially-varying distributions of waterfowl in the Central Valley. These results could be used to provide decision support for the poultry industry in addressing potential risk of HPAI exposure related to waterfowl proximity.

California↗
USGS2017

LANDFIRE 2015 Remap – Utilization of Remotely Sensed Data to Classify Existing Vegetation Type and Structure to Support Strategic Planning and Tactical Response

The LANDFIRE Program produces national scale vegetation, fuels, fire regimes, and landscape disturbance data for the entire U.S. These data products have been used to model the potential impacts of fire on the landscape [1], the wildfire risks associated with land and resource management [2, 3], and those near population centers and accompanying Wildland Urban Interface zones [4], as well as many other applications . The initial LANDFIRE National Existing Vegetation Type (EVT ) and vegetation structure layers, including vegetation percent cover and height, were mapped circa 2001 and released in 2009 [5]. Each EVT is representative of the dominant plant community within a given area. The EVT layer has since been updated by identifying areas of landscape change and modifying the vegetation types utilizing a series of rules that consider the disturbance type, severity of disturbance, and time since disturbance [6, 7]. Non-disturbed areas were adjusted for vegetation growth and succession. LANDFIRE vegetation structure layers also have been updated by using data modeling techniques [see 6 for a full description]. The subsequent updated versions of LANDFIRE include LANDFIRE 2008, 2010, 2012 , and LANDFIRE 2014 is being incrementally released, with all data being released in early 2017. Additionally, a comprehensive remap of the baseline data, LANDFIRE 2015 Remap , is being prototyped, and production is tentatively planned to begin in early 2017 to provide a more current baseline for future updates.

Earthzine↗
USGS2016

Hanson Russian River Ponds floodplain restoration: Feasibility study and conceptual design; Appendix G: Physical evaluation of the restoration alternatives

Appendix G: Hanson Russian River Ponds Floodplain Restoration: Feasibility Study and Conceptual Design |G-1Appendix GPhysical Evaluation of the Restoration AlternativesRichard McDonald and Jonathan Nelson, PhDU.S. Geological Survey Geomorphology and Sediment Transport Laboratory, Golden, ColoradoIntroductionTo assess the relative and overall impacts of the scenarios proposed in Chapters 7 and 9,(Stage I-A–I-D and Stage II-A –II-E), each of the topographic configurations were evaluated over a range of flows. Thisevaluation was carried out using computational flow modeling tools available in the iRIC public-domain river modeling interface (www.i-ric.org, Nelsonet al.in press). Using the iRIC modeling tools described in more detail below, basic hydraulic computations of water-surface elevation, velocity, shear stress, and other hydraulic variables were carried out for the alternatives in the reach surrounding the project area, from the confluence of Dry Creek upstream to the Wohler road bridge downstream, for the full range of observed flows. This methodology allows comparison of the current channel configuration with the proposed alternatives in terms of inundation period and frequency, depth, water velocity, and other hydraulic information. By integrating this kind of information over the reach of interest and the flow record, critical metrics assessing the impacts of various topographic modifications can be compared to those same metrics for the existing condition or other modification scenarios. In addition, because the iRIC tools include predictions of sediment mobility, suspension of fines, and the potential evolution of the land surface in response to flow, these methods provide evaluation of sediment transport, stability of current and proposed surfaces, and evaluation of how these surfaces might evolve into the future. This hydraulic and sediment transport information is critically important for understanding theimpacts of various proposed alternatives on the physical system; perhaps even more importantly given the objectives of the proposed restoration, this information can be related to biological impacts, as is discussed in subsequent chapters of this document.

Book chapter↗
USGS2012

Design and implementation of the next generation Landsat satellite communications system

The next generation Landsat satellite, Landsat 8 (L8), also known as the Landsat Data Continuity Mission (LDCM), uses a highly spectrally efficient modulation and data formatting approach to provide large amounts of downlink (D/L) bandwidth in a limited X-Band spectrum allocation. In addition to purely data throughput and bandwidth considerations, there were a number of additional constraints based on operational considerations for prevention of interference with the NASA Deep-Space Network (DSN) band just above the L8 D/L band, minimization of jitter contributions to prevent impacts to instrument performance, and the need to provide an interface to the Landsat International Cooperator (IC) community. A series of trade studies were conducted to consider either X- or Ka-Band, modulation type, and antenna coverage type, prior to the release of the request for proposal (RFP) for the spacecraft. Through use of the spectrally efficient rate-7/8 Low-Density Parity-Check error-correction coding and novel filtering, an XBand frequency plan was developed that balances all the constraints and considerations, while providing world-class link performance, fitting 384 Mbits/sec of data into the 375 MHz X-Band allocation with bit-error rates better than 10-12 using an earth-coverage antenna.

Conference Paper↗
USGS2011

Remote sensing and geospatial support to burned area emergency response teams

A major concern of land managers in the United States is the response of watersheds to weather after a wildfire. With an ever-expanding wildland-urban interface (WUI), land managers must be cognizant of potential damage to private property and other values at risk. In the United States, land-management agencies from the U.S. Department of Agriculture (USDA) and the U.S. Department of the Interior (DOI) deploy Burned Area Emergency Response (BAER) teams to address these concerns and to “prescribe and implement emergency treatments to minimize threats to life or property or to stabilize and prevent unacceptable degradation to natural and cultural resources resulting from the effects of a fire” (USDA Forest Service 2004, p. 17). BAER teams’ objective is emergency stabilization of burned areas, rather than long-term restoration of the landscape after a fire.

Fire Management Today↗