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USGS2024

Infrasound for volcano monitoring

Introduction Volcanic eruptions produce acoustic waves when volcanic gases and hot material rapidly expand in the atmosphere. Volcanic activity can produce acoustic signals with a wide range of frequencies, from very long period (>10 seconds) to audible (>20 hertz [Hz]), but the most energetic band is typically in the infrasound from 0.5 to 20 Hz. Studies of volcanic infrasound and the deployment of infrasound for volcano monitoring have increased rapidly in the past two decades as sensors have improved and as analytical tools have become more widely available. Improved sensors and tools have led to a growing diversity of eruptive activity being recorded and characterized, from Hawaiian to Plinian eruption styles at scales from local to global (Johnson and Ripepe, 2011; Fee and Matoza, 2013). Infrasound sensors on volcanoes are most commonly deployed locally with seismic stations, and the combination of co-located seismic and infrasound is more useful for characterizing unrest and detecting changes in activity than either data stream alone (for example, Lyons and others, 2016; Fee and others, 2017a; Matoza and others, 2018). At local (<15 kilometers [km]) to regional (15–250 km) distances from volcanoes, arrays of infrasound sensors are commonly deployed to detect coherent signals, constrain the direction to the source, and provide information on eruption dynamics; thus, infrasound is well suited to regional monitoring of volcanoes when local sensor networks are not feasible. A common usage of infrasound data in an observatory is to provide rapid confirmation that an explosion has occurred (for example, Coombs and others, 2018), although near-real-time eruption intensity quantification is also possible (Fee and others, 2010a; Ripepe and others, 2018; fig. C1). Infrasound is well suited to this task because it is not affected by clouds or precipitation and can propagate long distances with little attenuation. However, wind and ocean noise also produce infrasound, and spatiotemporal variability in the atmosphere can affect the propagation of infrasound, so care must be taken when deploying, analyzing, and interpreting the data. In addition to detecting and monitoring explosive activity, investigations of infrasound records from eruptions help constrain source processes, which in turn enhance syneruptive forecasting capabilities (for example, Fee and others, 2017b; Lyons and others, 2019). The following is a description of the capabilities recommended for real-time monitoring of eruptive phenomena with infrasound. Infrasound is also beginning to be used for tracking hazardous surface flows that occur on volcanoes, including pyroclastic density currents (Ripepe and others, 2010), lahars (Johnson and Palma, 2015), debris flows (Marchetti and others, 2019), snow avalanches (Havens and others, 2014), and lava flows (Patrick and others, 2019). Please refer to the chapter on lahars (this volume; Thelen and others, 2024a) for more information on this application.

Scientific Investigations Report↗

USGS2026

Estimation of impounded sediment volume in the Similkameen River upstream of Enloe Dam, Okanogan County, Washington

The Enloe Dam was built in 1920 for hydropower generation and impounds a steep-banked, narrow reach of the Similkameen River in north-central Washington. During the subsequent century, sediment from the Similkameen River watershed, which includes historical mining operations, accumulated within Enloe Dam’s impoundment. Enloe Dam ceased hydropower production in 1958 and is currently under consideration for removal, but there are concerns that the remobilization of sediments may have harmful impacts on downstream water quality. To complement previously published analyses of heavy metal concentrations within sediments and assess the total volume that may be transported following dam removal, this report presents estimates of the volume of sediment trapped behind Enloe Dam which was measured in 2020. The volume of sediment was estimated by comparing a bathymetric survey, collected using an acoustic Doppler continuous profiler, and a survey of the bedrock-sediment interface, collected using a continuous resistivity profiler. The study area spanned a 2.6-kilometer reach of the Similkameen River upstream from Enloe Dam. The volume of impounded sediment was calculated in 2020 by subtracting the elevation of the bedrock-sediment interface measured using the continuous resistivity profiler from a bathymetric surface measured by the acoustic Doppler current profiler. In 2020, the estimated volume of sediment impounded by Enloe Dam was 2.17±0.04 million cubic meters (Mm 3 ) compared to 1.37 Mm 3 measured in 1971. This equates to a deposition rate of approximately 16,300 cubic meters per year from 1971 to 2020. Continuous resistivity profiles revealed that bedrock within Enloe Dam’s impoundment was deepest (about 20 m) in the southern, downstream end of the profiles and shallowest (less than 5 m) in the northern upstream end of the profiles.

Washington↗

USGS1990

Borehole geophysics applied to ground-water investigations

The purpose of this manual is to provide hydrologists, geologists, and others who have the necessary background in hydrogeology with the basic information needed to apply the most useful borehole-geophysical-logging techniques to the solution of problems in ground-water hydrology. Geophysical logs can provide information on the construction of wells and on the character of the rocks and fluids penetrated by those wells, as well as on changes in the character of these factors over time. The response of well logs is caused by petrophysical factors, by the quality, temperature, and pressure of interstitial fluids, and by ground-water flow. Qualitative and quantitative analysis of analog records and computer analysis of digitized logs are used to derive geohydrologic information. This information can then be extrapolated vertically within a well and laterally to other wells using logs. The physical principles by which the mechanical and electronic components of a logging system measure properties of rocks, fluids, and wells, as well as the principles of measurement, must be understood if geophysical logs are to be interpreted correctly. Plating a logging operation involves selecting the equipment and the logs most likely to provide the needed information. Information on well construction and geohydrology is needed to guide this selection. Quality control of logs is an important responsibility of both the equipment operator and the log analyst and requires both calibration and well-site standardization of equipment. Logging techniques that are widely used in ground-water hydrology or that have significant potential for application to this field include spontaneous potential, resistance, resistivity, gamma, gamma spectrometry, gamma-gamma, neutron, acoustic velocity, acoustic televiewer, caliper, and fluid temperature, conductivity, and flow. The following topics are discussed for each of these techniques: principles and instrumentation, calibration and standardization, volume of investigation, extraneous effects, and interpretation and applications.

Techniques of Water-Resources Investigations↗

USGS2001

Use of advanced borehole geophysical techniques to delineate fractured-rock ground-water flow and fractures along water-tunnel facilities in northern Queens County, New York

Advanced borehole geophysical methods were used to assess the geohydrology of crystalline bedrock along the course of a new water tunnel for New York City. The logging methods include natural gamma, spontaneous potential, single-point resistance, mechanical and acoustic caliper, focused electromagnetic induction, electromagnetic resistivity, magnetic susceptibility, borehole-fluid temperature and conductance, differential temperature, heat-pulse flowmeter, acoustic televiewer, borehole deviation, optical televiewer, and borehole radar. Integrated interpretation of the geophysical logs from an 825-foot borehole (1) provided information on the extent, orientation, and structure (foliation and fractures) within the entire borehole, including intensely fractured intervals from which core recovery may be poor; (2) delineated transmissive fracture zones intersected by the borehole and provided estimates of their transmissivity and hydraulic head; and (3) enabled mapping of the location and orientation of structures at distances as much as 100 ft from the borehole. Analyses of the borehole-wall image and the geophysical logs from the borehole on Crescent Street, in northern Queens County, are presented here to illustrate the application of the methods. The borehole penetrates gneiss and other crystalline bedrock that has predominantly southeastward dipping foliation and nearly horizontal and southeastward-dipping fractures. The heat-pulse flowmeter logs obtained under pumping and nonpumping conditions, together with the other geophysical logs, indicate five transmissive fracture zones. More than 90 percent of the open-hole transmissivity is associated with a fracture zone 272 feet BLS (below land surface). A transmissive zone at 787 feet BLS that consists of nearly parallel fractures lies within the projected tunnel path; here the hydraulic head is 12 to 15 feet lower than that of transmissive zones above the 315-foot depth. The 60-megahertz directional borehole radar logs indicate the location and orientation of two closely spaced radar reflectors that would intersect the projection of the borehole below its drilled depth. Subsequent excavation of the tunnel past the borehole allowed comparison of the log analysis with conditions observed in the tunnel. The tunnel was found to intersect gneiss with southeastward dipping foliation; many nearly horizontal fractures; and a southeastward dipping fracture zone whose location, character, and orientation was consistent with that of the mapped radar reflectors. The fracture zone produced inflow to the tunnel at a rate of 50 to 100 gallons per minute. All conditions indicated by the logging methods were consistent with those observed within the tunnel.

New York↗

USGS2002

Borehole-geophysical investigation of the University of Connecticut landfill, Storrs, Connecticut

A borehole-geophysical investigation was conducted to help characterize the hydrogeology of the fractured-rock aquifer and the distribution of unconsolidated glacial deposits near the former landfill and chemical waste-disposal pits at the University of Connecticut in Storrs, Connecticut. Eight bedrock boreholes near the landfill and three abandoned domestic wells located nearby were logged using conventional and advanced borehole-geophysical methods from June to October 1999. The conventional geophysical-logging methods included caliper, gamma, fluid temperature, fluid resistivity, and electromagnetic induction. The advanced methods included deviation, optical and acoustic imaging of the borehole wall, heat-pulse flowmeter, and directional radar reflection. Twenty-one shallow piezometers (less than 50-feet deep) were logged with gamma and electromagnetic induction tools to delineate unconsolidated glacial deposits. Five additional shallow bedrock wells were logged with conventional video camera, caliper, electromagnetic induction, and fluid resistivity and temperature tools. The rock type, foliation, and fracturing of the site were characterized from high-resolution optical-televiewer (OTV) images of rocks penetrated by the boreholes. The rocks are interpreted as fine- to medium-grained quartz-feldsparbiotite-garnet gneiss and schist with local intrusions of quartz diorite and pegmatite and minor concentrations of sulfide mineralization similar to rocks described as the Bigelow Brook Formation on regional geologic maps. Layers containing high concentrations of sulfide minerals appear as high electrical conductivity zones on electromagneticinduction and borehole-radar logs. Foliation in the rocks generally strikes to the northeast-southwest and dips to the west, consistent with local outcrop observations. The orientation of foliation and small-scale gneissic layering in the rocks, however, varies locally and with depth in some of the boreholes. In two of the boreholes, the foliation strikes predominantly to the northwest and dips to the northeast. Although small-scale faults and lithologic discontinuities were observed in the OTV data, no large-scale faults were observed that appear on regional geologic maps. Fractures were located and characterized through the use of conventional geophysical, OTV, acoustic-televiewer (ATV), and borehole-radar logs. The orientation of fractures varies considerably across the site; some fractures are parallel to the foliation, whereas others cross-cut the foliation. Many of the transmissive fractures in the bedrock boreholes strike about N170°E and N320°E with dips of less than 45°. Other transmissive fractures strike about N60°E with dips of more than 60°. Most of the transmissive fractures in the domestic wells strike about N60°E and N22°E with dips of more than 45°. The strike of N60°E is parallel to the trend of a thrust fault that appears on regional geologic maps. Vertical flow in the boreholes was measured with the heat-pulse flowmeter under ambient and (or) pumping conditions. Results of ATV, OTV, and conventional logs were used to locate specific zones for flowmeter testing. Ambient downflow was measured in three boreholes, ambient upflow was measured in two other boreholes, and both ambient downflow and upflow were measured in a sixth borehole. The other five bedrock boreholes and domestic wells did not have measurable vertical flow. The highest rate of ambient flow was measured in the background borehole in which upflow and downflow converged and exited the borehole at a fracture zone near a depth of 62 feet. Ambient flow of about 340 gallons per day was measured. In the other five wells, ambient flow of about 20 to 35 gallons per day was measured. Under low-rate pumping (0.25 to 1 gallon per minute), one to six inflow zones were identified in each well. Usually the fractures that are active under ambient conditions contribute to the well under pumping conditions. To prevent ambient vertical flow and the potential for cross-contamination, temporary borehole liners were installed in five of the boreholes. Specific-capacity and open-hole transmissivity values were determined in eight boreholes completed in bedrock. The specific capacity estimated for these boreholes ranges from 0.14 to 1.6 gallons per minute per foot. The values for open-hole transmissivity range over two orders of magnitude and when proportioned to individual fracture transmissivity, range from 23 to 340 feet squared per day. Two boreholes had been drilled to intersect electrically conductive zones identified by previous surface-geophysical investigations. The borehole-geophysical results indicate that the boreholes penetrate electrically conductive structures consistent with the anomalies interpreted from the surface-geophysical data. Borehole MW121R was located to intersect a dipping electrically conductive anomaly at about 60 feet, interpreted from the two-dimensional direct currentresistivity survey conducted on the western side of the landfill. The electromagnetic-conductivity log in the borehole contains a high electrical conductivity anomaly at a depth of 69 feet. The magnitude of this anomaly is nearly 10,000 millisiemens per meter and is coincident with a layer containing sulfide mineralization, rather than fractures. The other borehole, MW105R, was located to intersect another anomaly south of the landfill. This anomaly was interpreted as a north-south striking, westward dipping feature. In the borehole, two south-striking, westward dipping fractures were identified in the ATV, OTV, and radar logs. The specific conductance of the fluid measured near these fractures was as high as 1,250 microsiemens per centimeter. Water-quality samples collected in October 1999 from an isolated zone from 71.5 to 76.5 feet indicated high specific conductance (810 microsiemens per centimeter), high concentrations of iron and cadmium, negative oxidation-reduction potential, and chlorobenzene. Collectively, these parameters indicate that the high specific conductance in the borehole logs for MW105R was caused by landfill leachate. Therefore, the anomaly identified by boreholeand surface-geophysical surveys is interpreted as a conductive lithologic feature and a permeable fracture zone that contains landfill leachate.

Connecticut↗

USGS1978

Interpretation of well logs in a carbonate aquifer

This report describes the log analysis of the Randolph and Sabial core holes in the Edwards aquifer in Texas, with particular attention to the principles that can be applied generally to any carbonate system. The geologic and hydrologic data were obtained during the drilling of the two holes, from extensive laboratory analysis of the cores, and from numerous geophysical logs run in the two holes. Some logging methods are inherently superiors to others for the analysis of limestone and dolomite aquifers. Three such systems are the dentistry, neutron, and acoustic-velocity (sonic) logs. Most of the log analysis described here is based on the interpretation of suites of logs from these three systems. In certain instances, deeply focused resistivity logs can be used to good advantage in carbonate rock studies; this technique is used to computer the water resistivity in the Randolph core hole. The rocks penetrated by the Randolph core hole are typical of those carbonates that have undergone very little solution by recent ground-water circulation. There are few large solutional openings; the water is saline; and the rocks are dark, dolomitic, have pore space that is interparticle or intercrystalline, and contain unoxidized organic material. The total porosity of rocks in the saline zone is higher than that of rocks in the fresh-water aquifer; however, the intrinsic permeability is much less in the saline zone because there are fewer large solutional openings. The Sabinal core hole penetrates a carbonate environment that has experienced much solution by ground water during recent geologic time. The rocks have high secondary porosities controlled by sedimentary structures within the rock; the water is fresh; and the dominant rock composition is limestone. The relative percentages of limestone and dolomite, the average matrix (grain) densities of the rock mixtures , and the porosity of the rock mass can be calculated from density, neutron, and acoustic logs. With supporting data from resistivity logs, the formation water quality can be estimated, as well as the relative cementation or tortuosity of the rock. Many of these properties calculated from logs can be verified by analysis of the core available from test holes drilled in the saline and fresh water zones.

Texas↗

USGS1999

Characteristics of fractures in crystalline bedrock determined by surface and borehole geophysical surveys, eastern surplus superfund site, Meddybemps, Maine

Surface and borehole geophysical methods were used to determine fracture orientation in crystalline bedrock at the Eastern Surplus Superfund Site in Meddybemps, Maine. Fracture-orientation information is needed to address concerns about the fate of contaminants in ground water at the site. Azimuthal square-array resistivity surveys were conducted at 3 locations at the site, borehole-acoustic televiewer and borehole-video logs were collected in 10 wells, and single-hole directional radar surveys were conducted in 9 wells. Borehole-video logs were used to supplement the results of other geophysical techniques and are not described in this report. Analysis of azimuthal square-array resistivity data indicated that high-angle fracturing generally strikes northeast-southwest at the three locations. Borehole-acoustic televiewer logs detected one prominent low-angle and two prominent high-angle fracture sets. The low-angle fractures strike generally north-northeast and dip about 20 degrees west-northwest. One high-angle fracture set strikes north-northeast and dips east-southeast; the other high-angle set strikes east-northeast and dips south-southeast. Single-hole directional radar surveys identified two prominent fracture sets: a low-angle set striking north-northeast, dipping west-northwest; and a high-angle fracture set striking north-northeast, dipping east-southeast. Two additional high-angle fracture sets are defined weakly, one striking east-west, dipping north; and a second striking east-west, dipping south. Integrated results from all of the geophysical surveys indicate the presence of three primary fracture sets. A low-angle set strikes north-northeast and dips west-northwest. Two high-angle sets strike north-northeast and east-northeast and dip east-southeast and south-southeast. Statistical correction of the fracture data for orientation bias indicates that high-angle fractures are more numerous than observed in the data but are still less numerous than the low-angle fractures. The orientation and distribution of water-yielding fractures sets were determined by correlating the fracture data from this study with previously collected borehole-flowmeter data. The water-yielding fractures are generally within the three prominent fracture sets observed for the total fracture population. The low-angle water-yielding fractures primarily strike north-northeast to west-northwest and dip west-northwest to south-southwest. Most of the high-angle water-yielding fractures strike either north-northeast or east-west and dip east-southeast or south. The spacing between water-yielding fractures varies but the probable average spacing is estimated to be 30 feet for low-angle fractures; 27 feet for the east-southeast dipping, high-angle fractures; and 43 feet for the south-southeast dipping, high-angle fractures. The median estimated apparent transmissivity of individual water-yielding fractures or fracture zones was 0.3 feet squared per day and ranged from 0.01 to 382 feet squared per day. Ninety-five percent of the water-yielding fractures or fracture zones had an estimated apparent transmissivity of 19.5 feet squared per day or less. The orientation, spacing, and hydraulic properties of water-yielding fractures identified during this study can be used to help estimate recharge, flow, and discharge of ground water contaminants. High-angle fractures provide vertical pathways for ground water to enter the bedrock, interconnections between low-angle fractures, and, subsequently, pathways for water flow within the bedrock along fracture planes. Low-angle fractures may allow horizontal ground-water flow in all directions. The orientation of fracturing and the hydraulic properties of each fracture set strongly affect changes in ground-water flow under stress (pumping) conditions.

Maine↗

USGS1964

Apparatus and techniques for measuring bedload

The need for accurate determinations of the total sediment discharge of particles of bedload size has prompted this investigation of available and possible measuring apparatus and procedures. The accuracy of measurements of sediment discharge made with trap-type samplers is affected by the variability of sampler efficiency, by the oscillatory variation of bedload discharge, and by sampler placement. Equations that were developed for determining total discharge from measured bedioad discharge and measured suspended-sediment discharge are simplest if the bedload apparatus measures only the true bedload. Early bedload samplers are generally unsatisfactory. Recently developed or suggested apparatus include various improved samplers of the pressure-difference type, a pumping sampler, a magnetic sampler, acoustical instruments that measure the magnitude of the sound of particle collisions, an ultrasonic bedload sampler designed to measure and integrate electronically the concentration and velocity, and a tiltmeter designed to measure the total sediment discharge from the ground tilt that results from the passage of flow. All the pressure-difference samplers are improvements over early samplers, but none are void of the inherent shortcomings of trap-type apparatus; probably the Sphinx (Dutch) and VUV (Hungarian) samplers are the most satisfactory. The acoustical instruments are capable of measuring only the relative discharge. The ultrasonic sampler and the tiltmeter are not adequate without further development. Some new possible apparatus and means for measuring or aiding in measuring bedload discharge are small pit samplers, ultrasonic sounders, pressure transducers, and photography. A small pit sampler for measuring bedload discharge was designed to provide self-placement and portability ; however, its practicability and efficiency are undetermined. Exploratory films show that by using slowmotion photography the discharge of particles larger than about pea size can be determined provided the flow is clear; however, photography generally is not practical. Ultrasonic sounders provide continuous and accurate data on bed configuration and dune movement for use in equations that were developed for computing the bedload discharge. Computations with the equations indicate that the interpretation of the sounding data needs further study. Pressure transducers placed beneath the bed surface possibly can be used to provide information on dune movement; however, their installation would be difficult. The time required for collecting data on bed configuration and dune movement throughout a cross section could be substantially reduced by using several transducers simultaneously in conjunction with an ultrasonic sounder. A modified ultrasonic sounder that provides information on the shape and velocity of large particles and a method for determining the discharge of such particles were proposed; the method seems most feasible for particles of high sphericity.

Water Supply Paper↗

USGS2022

Seasonal activity patterns of bats in high-elevation conifer sky islands

In the southern Appalachian Mountains of the southeastern USA, bat communities in high-elevation habitats tend to be relatively under-surveyed. High-elevation habitats may provide important habitat to certain species (i.e., migratory tree bats), and may serve as climate refugia during droughts or high temperatures. We conducted an opportunistic acoustic survey of bat communities in ten survey areas in high elevation (1,585–1,920 m a.s.l.) montane Picea rubens (red spruce)- Abies fraseri (Fraser fir) forest in the southern Appalachian Mountains of western North Carolina. In each survey area, we randomly placed three full spectrum acoustic detectors ( N = 30) during three seasons (spring, summer and fall) in 2015. We deployed each detector for two five-day periods during each season ( n = 900 survey nights). Although we detected seven bat species/groups during the surveys, 73% of echolocation files were attributed to Lasiurus cinereus (hoary bat) and Lasionycteris noctivagans (silver-haired bat). Generally rare in the Appalachians and typically present only at low densities in the summer at mid- and low-elevations, both species were detected at all sites during all seasons. Overall, mean nightly activity of bats was higher in the summer than the spring or fall. We observed 3.7–5 times greater activity of L. cinereus in spruce-fir forests during the summer compared to spring and fall, whereas L. noctivagans had 1.3–5 times more activity in the summer compared to other seasons. After accounting for precipitation events, our finite mixture models showed that season, temperature, elevation, and canopy height influenced L. cinereus activity, whereas season and temperature affected L. noctivagans activity. Our observations suggest that high-elevation spruce-fir forests are providing summer foraging and possibly day-roosting habitat of tree bats not previously documented this far south in North America.

North Carolina↗

USGS2021

Local explosion detection and infrasound localization by reverse time migration using 3-D finite-difference wave propagation

Infrasound data are routinely used to detect and locate volcanic and other explosions, using both arrays and single sensor networks. However, at local distances (<15 km) topography often complicates acoustic propagation, resulting in inaccurate acoustic travel times leading to biased source locations when assuming straight-line propagation. Here we present a new method, termed Reverse Time Migration-Finite-Difference Time Domain (RTM-FDTD), that integrates numerical modeling into the standard RTM back-projection process. Travel time information is computed across the entire potential source grid via FDTD modeling to incorporate the effects of topography. The waveforms are then back-projected and stacked at each grid point, with the stack maximum corresponding to the likely source. We apply our method to three volcanoes with different network configurations, source-receiver distances, and topography. At Yasur Volcano, Vanuatu, RTM-FDTD locates explosions within ∼20 m of the source and differentiates between multiple vents. RTM-FDTD produces a more accurate location for the two Yasur subcraters than standard RTM and doubles the number of detected events. At Sakurajima Volcano, Japan, RTM-FDTD locates the source within 50 m of the active vent despite notable topographic blocking. The RTM-FDTD location is similar to that from the Time Reversal Mirror method, but is more computationally efficient. Lastly, at Shishaldin Volcano, Alaska, RTM and RTM-FDTD both produce realistic source locations (<50 m) for ground-coupled airwaves recorded on a four-station seismic network. We show that RTM is an effective method to detect and locate infrasonic sources across a variety of scenarios, and by integrating numerical modeling, RTM-FDTD produces more accurate source locations and increases the detection capability.

Alaska↗

USGS2025

Identifying novel Sea Lamprey (Petromyzon marinus) spawning areas in a large unimpounded river system

Introduction: Despite the success of the Sea Lamprey Control Program (SLCP) in reducing Sea Lamprey ( Petromyzon marinus ) abundance throughout the Laurentian Great Lakes, control remains a significant challenge in the Saint Clair-Detroit River System (SCDRS) due to the system's size, flow dynamics, and amount of potentially suitable spawning habitat. Methods: We used acoustic telemetry to identify repeated patterns in habitat use, presumed spawning areas, and migratory routes for 271 acoustic-tagged Sea Lamprey in the SCDRS during the 2016 and 2017 spawning seasons. Results: Sixty-nine percent of tagged Sea Lamprey appeared to spawn in the Saint Clair River with many individuals displaying commonly shared movement histories in terms of timing and channel use. Probable spawning locations were associated with the main river channel upstream of major bifurcations (e.g., Stag and Fawn Islands) in the Saint Clair River and overlapped with areas of high bottom flow. Discussion: Selection for low flow refugia during migration appears water temperature dependent. Traditional control methods are likely to be inefficient in the SCDRS, highlighting the need for novel supplemental strategies tailored to large river systems.

Michigan, Ontario↗

USGS2024

Assessing grass carp (Ctenopharyngodon idella) occupancy and detection probability within Lake Erie from environmental DNA

Grass carp ( Ctenopharyngodon idella ), an invasive cyprinid within the Laurentian Great Lakes, is naturally reproducing in several Lake Erie tributaries, which has raised concerns of the species’ spread throughout Lake Erie and the other Great Lakes. Knowledge of the recent invasion extent outside of the western basin of Lake Erie, particularly in eastern tributaries and nearshore waters, is limited. Understanding the invasion extent would improve the efficacy of ongoing coordinated multi-agency control efforts. Molecular tools, such as environmental DNA (eDNA), have shown promise for early detection of aquatic invasive species. In this study, water samples (N = 476) were collected for grass carp eDNA monthly between May and November in 2018 and 2019, at three sites in the Michigan waters of Lake Erie and the Detroit River. We fit Bayesian multi-scale occupancy models to determine differences in eDNA capture and detection probability among grass carp qPCR assays, sampling sites, and across time. To determine whether grass carp were physically present, and to validate eDNA samples, we quantified recent grass carp presence in sampled areas using an existing acoustic telemetry and field sampling framework. Our results indicate that grass carp eDNA capture probability differed among sites, but there was no difference among months. Positive grass carp eDNA detections were observed across multiple months at each site, with 69% of site-specific sampling events testing positive for grass carp eDNA on at least one assay and replicate. The majority (65%) of weeks where positive eDNA sampling detections occurred also concurrently had one or more grass carp detected via acoustic telemetry 1–6 days prior. Our results highlight the potential utility of using eDNA to monitor the invasion extent of grass carp within the nearshore waters of Lake Erie. However, further evaluation of the factors that influence grass carp eDNA characteristics among sites within Lake Erie are needed to determine its efficacy for surveillance protocols by natural resource management agencies.

Lake Erie↗

USGS1999

Properties of samples containing natural gas hydrate from the JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well, determined using Gas Hydrate And Sediment Test Laboratory Instrument (GHASTLI)

As part of an ongoing laboratory study, preliminary acoustic, strength, and hydraulic conductivity results are presented from a suite of tests conducted on four natural-gas-hydrate-containing samples from the Mackenzie Delta JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well. The gas hydrate samples were preserved in pressure vessels during transport from the Northwest Territories to Woods Hole, Massachusetts, where multistep tests were performed using GHASTLI (Gas Hydrate And Sediment Test Laboratory Instrument), which recreates pressure and temperature conditions that are stable for gas hydrate. Properties and changes in sediment behaviour were measured before, during, and after controlled gas hydrate dissociation. Significant amounts of gas hydrate occupied the sample pores and substantially increased acoustic velocity and shear strength.

Bulletin of the Geological Survey of Canada↗

USGS2012

Telemetry techniques: A user guide for fisheries research

Telemetry provides a powerful and flexible tool for studying fish and other aquatic animals, and its use has become increasingly commonplace. However, telemetry is gear intensive and typically requires more specialized knowledge and training than many other field techniques. As with other scientific methods, collecting good data is dependent on an understanding of the underlying principles behind the approach, knowing how to use the equipment and techniques properly, and recognizing what to do with the data collected. This book provides a road map for using telemetry to study aquatic animals, and provides the basic information needed to plan, implement, and conduct a telemetry study under field conditions. Topics include acoustic or radio telemetry study design, tag implantation techniques, radio and acoustic telemetry principles and case studies, and data management and analysis. Chapters are written by biologists, technicians, and engineers from the private, academic, and government sectors, with decades of experience using these technologies.

Book↗

USGS2009

Population density estimated from locations of individuals on a passive detector array

The density of a closed population of animals occupying stable home ranges may be estimated from detections of individuals on an array of detectors, using newly developed methods for spatially explicit capture–recapture. Likelihood-based methods provide estimates for data from multi-catch traps or from devices that record presence without restricting animal movement ("proximity" detectors such as camera traps and hair snags). As originally proposed, these methods require multiple sampling intervals. We show that equally precise and unbiased estimates may be obtained from a single sampling interval, using only the spatial pattern of detections. This considerably extends the range of possible applications, and we illustrate the potential by estimating density from simulated detections of bird vocalizations on a microphone array. Acoustic detection can be defined as occurring when received signal strength exceeds a threshold. We suggest detection models for binary acoustic data, and for continuous data comprising measurements of all signals above the threshold. While binary data are often sufficient for density estimation, modeling signal strength improves precision when the microphone array is small.

Ecology↗

USGS1998

Well log evaluation of gas hydrate saturations

The amount of gas sequestered in gas hydrates is probably enormous, but estimates are highly speculative due to the lack of previous quantitative studies. Gas volumes that may be attributed to a gas hydrate accumulation within a given geologic setting are dependent on a number of reservoir parameters; one of which, gas-hydrate saturation, can be assessed with data obtained from downhole well logging devices. The primary objective of this study was to develop quantitative well-log evaluation techniques which will permit the calculation of gas-hydrate saturations in gas-hydrate-bearing sedimentary units. The `standard' and `quick look' Archie relations (resistivity log data) yielded accurate gas-hydrate and free-gas saturations within all of the gas hydrate accumulations assessed in the field verification phase of the study. Compressional wave acoustic log data have been used along with the Timur, modified Wood, and the Lee weighted average acoustic equations to calculate accurate gas-hydrate saturations in this study. The well log derived gas-hydrate saturations calculated in the field verification phase of this study, which range from as low as 2% to as high as 97%, confirm that gas hydrates represent a potentially important source of natural gas.

Conference Paper↗

USGS1999

Techniques for accurate estimation of net discharge in a tidal channel

An ultrasonic velocity meter discharge-measurement site in a tidally affected region of the Sacramento-San Joaquin rivers was used to study the accuracy of the index velocity calibration procedure. Calibration data consisting of ultrasonic velocity meter index velocity and concurrent acoustic Doppler discharge measurement data were collected during three time periods. The relative magnitude of equipment errors, acoustic Doppler discharge measurement errors, and calibration errors were evaluated. Calibration error was the most significant source of error in estimating net discharge. Using a comprehensive calibration method, net discharge estimates developed from the three sets of calibration data differed by less than an average of 4 cubic meters per second. Typical maximum flow rates during the data-collection period averaged 750 cubic meters per second.

Proceedings of the IEEE Working Conference on Curr↗

USGS2002

Velocity and Sediment Concentration Measurements over Bedforms in Sand-Bed Rivers

Bedforms often are present on the bed of alluvial sand-bed rivers. Bedforms, such as dunes, impact the flow field. In this field study, velocity and suspended-sediment concentration measurements were made longitudinally along a dune field in large (5-15 meters deep) alluvial sand-bed rivers. The velocity and suspended-sediment concentration data was collected using an acoustic Doppler current profiler, acoustic Doppler velocimeters, an optical backscatter sensor, and, two sediment intakes. This paper presents a description of these measurement devices and techniques for the collection of this data. Some preliminary results observed at the Missouri River at St. Charles, Missouri are presented.

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