USGS Science⌕ Search

SEARCH · USGS Science

Results for “Sensors”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,747 records · Page 97Linked to original sources
USGS2003

Determining temperature and thermal properties for heat-based studies of surface-water ground-water interactions: Appendix A of Heat as a tool for studying the movement of ground water near streams (Cir1260)

Advances in electronics leading to improved sensor technologies, large-scale circuit integration, and attendant miniaturization have created new opportunities to use heat as a tracer of subsurface flow. Because nature provides abundant thermal forcing at the land surface, heat is particularly useful in studying stream-groundwater interactions. This appendix describes methods for obtaining the thermal data needed in heat-based investigations of shallow subsurface flow.

Report↗
USGS2018

Crop water productivity estimation with hyperspectral remote sensing

Crop water productivity (CWP) is the ratio of accumulated crop biomass or yield (Y) to the water utilized to produce it, which is typically estimated using transpiration (ET C ). CWP is an important metric to test and monitor water-saving strategies in agroecosystems across the globe. Red and near-infrared broadbands have been used to estimate CWP, because they capture biophysical constraints based on crop-light interaction principles at pixel level (e.g., 30-meter resolution) over large areas through time. Hyperspectral remote sensing, which allows for the more precise measurement of crop-light interactions at higher spectral resolution, should in theory provide higher accuracy in CWP estimation but has been underutilized by the remote sensing community due to computational challenges and lack of availability. In this study, a simple methodology is presented to demonstrate how CWP could be estimated using hyperspectral remote sensing. Due to a lack of hyperspectral data, Landsat-7 Enhanced Thematic Mapper Plus (ETM+) data were used for the demonstration. Landsat is a broadband sensor that provides considerable spectral information for CWP estimation. New bands were identified in the workflow outside the typical Landsat bands used to estimate CWP and its components (Y and ET C ). Landsat bands 1 and 3 were the most effective at estimating CWP and Y with an R 2 of 0.72 (RMSE = 0.50 kg m −3 ) and 0.64 (RMSE = 0.31 kg m −2 ), respectively. All of the bands were poor at estimating ET C , with Landsat bands 1 and 7 being the most highly correlated (R 2 = 0.13, RMSE = 0.08 m). Future work should train models with multiple estimates of CWP and Y over the growing season, while ET C may be better estimated with thermal infrared bands not considered in this study. Finally, studies should also consider estimating CWP categorically, instead of continuously, if the same objectives of testing and monitoring are met.

Book chapter↗
USGS2002

A prototype drought monitoring system integrating climate and satellite data

Droughts are natural hazards with varying patterns in space, time, and intensity. Their dynamic character challenges our ability in planning, predicting, monitoring, and providing relief to affected areas. Because of the spatial and temporal variability and multiple impacts of droughts, we need to improve the tools and data available for mapping and monitoring this phenomenon on all scales. A team of researchers from the US Geological Survey’s EROS Data Center, the National Drought Mitigation Center, and the High Plains Regional Climate Center are developing methods for regional-scale mapping and monitoring drought conditions for the conterminous U.S. Currently in its first year, the project is focusing on developing a prototype model for the central U.S. The ultimate goal of the project is to deliver timely geo-referenced information (in the form of maps and data) about areas where the vegetation is impacted by drought, using the Internet as the primary delivery mechanism. Data collected from the Advanced Very High Resolution Radiometer (AVHRR) sensor provide synoptic, near real time measurements of surface conditions. Previous studies have established significant relationships between climate variables and satellite-derived vegetation indices over non-irrigated croplands and grasslands. We are researching methods for integrating information provided by satellite-derived metrics on seasonal vegetation performance and climate-based drought indicators to produce a timely and spatially-detailed drought monitoring product. Eventually, this information, coupled with map products of key drought indicators, will be available to many end users for making critical and timely decisions, from farm to regional scale.

Conference Paper↗
USGS2002

Issues in characterizing phenology from satellite observations

Over the past decade, many investigators have published techniques for deriving phenological parameters, especially the start of the growing season (SOS), from time-series satellite imagery. The principal satellite sensor for these studies is the advanced very high resolution radiometer (AVHRR). This study investigates the characteristics of four of the primary methods for identifying SOS; maximum curvature, delayed moving average, time of greatest NDVI increase and time of half-maximum NDVI. Comparisons between the methods illustrate biases for earlier or later SOS in the various methods and a relatively low statistical relationship among all four methods (r 2 =.10 to .35). Our analysis indicates that each of the methods is detecting fundamentally different stages of the start of season. These stages include snow melt, initial growth of herbaceous plants and understory, and first leaf; each of which is important in determining differences in land/atmosphere interactions. Users of these types of datasets need to be aware of the different environmental conditions being measured by the various approaches and use careful judgment in selecting the proper method.

Conference Paper↗
USGS2007

Ultrahigh resolution topographic mapping of Mars with HiRISE stereo images: Methods and first results

The Mars Reconnaissance Orbiter (MRO) arrived at Mars on 10 March 2006 and began its primary science phase in November. The High Resolution Imaging Science Experiment (HiRISE) on MRO is the largest, most complex camera ever flown to another planet. Plans call for this scanner to image roughly 1% of Mars by area at a pixel scale of 0.3 m during the next Mars year. Among the thousands of images will be hundreds of stereopairs that will provide an unprecedented three-dimensional view of the Martian surface at meter scale. These stereopairs will provide a tremendous amount of information for focused scientific studies, landing site selection and validation, and the operation of landers and rovers. In this paper, we describe our approach to generating geodetically controlled digital topographic models (DTMs) from such stereopairs, our early results, and plans for future DTM production. Our approach to the photogrammetric processing of HiRISE images follows that which we have previously described for the MOC and the Mars Express High Resolution Stereo Camera (HRSC). We use the USGS in-house digital cartographic software ISIS to do initial processing, including ingestion, decompression, and radiometric calibration of the images. "Three-dimensional" photogrammetric processing steps, including control and DTM creation and editing, are performed on a photogrammetric workstation running the commercial software SOCET SET (® BAE Systems). Noteworthy departures from past practice are the use of ISIS 3, the object-oriented successor to the older ISIS 2 system, and pre-processing in ISIS to correct geometric complications of the HiRISE images that cannot be modelled in the SOCET sensor model: multiple CCD detectors in the focal plane, optical distortion around an axis far from the detectors, and (ultimately) the small "jitter" motions of spacecraft pointing that distort the images and hence the DTMs. The first HiRISE stereopair analyzed covered the location of the Opportunity rover near the 750-m crater informally named Victoria in Meridiani Planum. This scene was extremely unfavorable for automated stereomatching, with extensive areas that are almost featureless, extremely steep, or both, but these problems were offset by the high quality of the HiRISE imagery, permitting us to obtain a 1 m/post DTM that required only limited interactive editing. Subsequent mapping of the Spirit rover site and a variety of scientifically interesting sites has proven that the greater surface texture found at most places on Mars leads to even better DTMs with even less editing required. We are currently working to refine and streamline our procedures in order to maximize the number of sites that can be mapped and studied in three dimensions with HiRISE.

Conference Paper↗
USGS2018

Landsat benefiting society for fifty years

Since 1972, data acquired by the Landsat series of satellites have become integral to land management for both government and the private sector, providing scientists and decision makers with key information about agricultural productivity, ice sheet dynamics, urban growth, forest monitoring, natural resource management, water quality, and supporting disaster response. Landsat 9 continues the mission of unrivaled space-based Earth observation and will lead the Landsat program into its second half century of Earth imagery provided to users, worldwide, at no charge. More than 8 million Landsat scenes held in the USGS archive to date are used in conjunction with advanced geographic information systems, image processing software, and cloud computing capabilities to enable Landsat users to study changes on the Earth’s surface across continental regions and extended time periods. The Operational Land Imager 2 (OLI-2) and the Thermal Infrared Sensor 2 (TIRS-2) instruments onboard Landsat 9 —which replicate the technologically-advanced instruments introduced onboard Landsat 8—allow for the collection of continuous high-quality data required for advancing Earth applications, including our ability to map surface temperature and surface water quality. Landsat 9 will build on the Landsat legacy, achieving a half-century record of global Earth observations.

Report↗
USGS2019

Diving behavior of Pink-footed Shearwaters Ardenna creatopus rearing chicks on Isla Mocha, Chile

Recent information reporting Pink-footed Shearwater Ardenna creatopus mortality from fisheries bycatch throughout its range has encouraged fisheries managers in Chile to evaluate and consider shearwater foraging behaviors to better evaluate risk. In response, we tracked six chickrearing adult Pink-footed Shearwaters from Isla Mocha, off south-central Chile, from 19 to 28 March 2015 using global positioning sensors and time-depth recorders. We recorded seven complete trips averaging 4.2 ± 2.5 d (mean ± SD). Chick-provisioning adults foraged within 334 km (i.e., 175 ± 100 km) of Isla Mocha. Dives (n = 515) occurred throughout the measured foraging range but most frequently occurred within 5–30 km from the mainland coast, in continental shelf waters north of Valdivia. Other regions with diving behavior were within ~20 km of Isla Mocha, and from Lebu to north of Talcahuano. Based on movement behavior analysis, adults spent most of their time at sea “resting/ foraging” (62% ± 6%), with the remainder spent “searching” (16% ± 4%) and “transiting” (20% ± 5%). The proportions of total number of dives associated with these three behaviors were similar. On average, dives were relatively shallow (1.6 ± 1.2 m, maximum depth = 10.1 m) and brief (4.7 ± 4.8 s, maximum duration = 25.7 s). Dives occurred during the day, at night, and at twilight, with most activity occurring at twilight and during the day. Although based on a small sample size, our results may be useful for informing modifications to fishing gear or fisheries policy to reduce the likelihood of bycatch and thus meet Chilean conservation goals for Pink-footed Shearwaters.

Isla Mocha↗
USGS2019

Time-series sediment acoustics and LISST-ABS testing

Acoustics and other surrogates can be used to accurately and cost-effectively provide time-series estimates of suspended-sediment concentration and load, which is essential for creating informed solutions to many sediment-related environmental, engineering, and agricultural concerns. Interagency efforts in recent years have advanced the testing, methods development, operational guidelines, and training on sediment acoustics. This extended abstract provides an update on horizontal profiling methodologies and introduces the testing of the LISST-ABS (Acoustic Backscatter Sensor).

Conference Paper↗
USGS2019

Exploring controls on debris-flow surge velocity and peak discharge at Chalk Cliffs, Colorado, USA

We present a series of debris-flow events and use combined sensor and video data to explore how sediment concentration and triggering rainfall intensity affect the velocity and discharge of debris-flow surges generated by surface-water runoff. We analyze an initial data set of 49 surges from four debris-flow events recorded by a monitoring system at Chalk Cliffs, Colorado and compare measurements of surge height, velocity, peak discharge, triggering rainfall intensity, and qualitative estimates of sediment concentration. Measurements of sediment concentration and velocity were obtained using an automated camera system with a high resolution and frame rate. We find that the triggering rainfall intensity of the debris flows, which affects the sediment-to-water ratio, is a strong control on surge velocity and peak discharge. While surges with high and low sediment concentrations both exceed the peak discharge of water-only flow, fluid-rich surges generated by high rainfall intensities have much greater velocities and peak discharges than sediment-rich surges generated by lower rainfall intensities. These observations suggest that rainfall intensity may be an important predictive variable in empirical relationships for estimating the velocity and peak discharge of runoff generated debris flows, which are common in alpine areas and burned steeplands.

Colorado↗
USGS2019

Near-field remote sensing of Alaskan Rivers

The U.S. Geological Survey (USGS) Geomorphology and Sediment Transport Laboratory (GSTL), in collaboration with the U.S. Army Corps of Engineers Cold Regions Research and Engineering Laboratory (CRREL), acquired remotely sensed data from several Alaskan rivers in 2017 and 2018 with the goal of developing a methodology for measuring streamflow from a helicopter. CRREL operates a custom airborne lidar system that can be deployed in a helicopter-based pod (HeliPod). Data were collected with the HeliPod near existing USGS streamflow information stations on the Knik, Matanuska, Chena, and Salcha Rivers in both 2017 and 2018. Sites on the Tanana and Snow Rivers were added in 2018. In 2018, the HeliPod was modified to accommodate both a thermal infrared and a visible camera. The cameras were integrated with the flight management software to simultaneously acquire imagery with lidar. The Global Navigation Satellite System (GNSS) and inertial measurement unit (IMU) in the HeliPod were used to compute trajectories with precise position and orientation information needed for image orthorectification. The HeliPod sensors provide data for measuring river channel characteristics. Lidar can map the elevation of the water surface and thus be used to measure water-surface slopes and return intensity can be used to delineate the extent of the wetted river channel. Various approaches are currently being evaluated to estimate surface flow velocity from visible and thermal image time series. In this paper, we examine and compare water-surface elevation returns and slopes derived from the HeliPod lidar and found good agreement with measurements made using conventional field-based techniques.

Alaska↗
USGS1995

Wind shear stress measurements in a coastal marsh during Hurricane Andrew

Hurricane Andrew produced changes to the Louisiana wetlands not normally observed after lesser, more common storms. For example, the <25 m/s wind speeds generated by cold fronts and winter storms, and any accompanying storm surge, do not cause substantial, wide-spread alteration of marsh vegetation. During Hurricane Andrew, however, the wind, the wind-driven storm surge, or both produced severe, wide-spread wetland alteration, especially in areas that primarily consisted of densely vegetated floating mats. In a few hours, vegetated brackish marsh was severely torn and large areas were converted to open water, a process that takes decades when driven by geologic subsidence, human intervention, and lesser storms. During the passage of Hurricane Andrew, wind measurements were taken inside an impoundment within a brackish part of Louisiana's coastal wetlands system. At its closest point, the site lay 50 km to the right of the north-trending storm track, placing it in or near the zone of maximum wind (the eye wall). As the hurricane approached, the wind blew from the north; after it passed, the wind direction swung around to the southeast. Several hours after the eye passed, the southeasterly wind drove a 1.5-m storm surge through the area, causing the collapse of the meteorology tower. Wind shear stress calculations, based on data from two vertically stacked sensors, showed a direct correlation between wind shear stress and wind speed. The greatest increase in wind shear stress occurred when wind speed exceeded 20 m/s. Overall, wind shear stress increased more than three orders of magnitude — from approximately 0.01 N/m² at a wind speed of 6 m/s through 1 N/m² at 20 m/s to 18 N/m² at the maximum sustained speed of 43 m/s. Drag-coefficient calculations show that the open-ocean CD formulations, such as the popular WAMDI model, cannot be employed for wetland use because it overestimates CD for velocities less than approximately 20 m/s and underestimates it for higher velocities.

Louisiana↗
USGS2006

Using optical proxies for biogeochemical properties to study land coverage and terrestrial inputs of organic carbon into coastal waters from the Penobscot Watershed to the Gulf of Maine

Coastal waters are physically, biogeochemically, and therefore optically complex as a result of the commingling of waters arising from terrestrial, freshwater and marine ecosystems. Separating the influences of these three ecosystems on the optical properties of the resulting mixture is challenging, particularly given the variability within each. The longterm goals of this project are twofold: (1) to investigate the feasibility of identifying landuse changes using inwater optical observations, (2) to quantify the input of terrestrial organic carbon into the coastal marine environment. Our approach is to study the Penobscot River Watershed in Maine, from its many tributaries and subwatersheds into the main branch of the Penobscot River, Penobscot Bay and ultimately into the coastal waters of the Eastern Maine Coastal Current. The first step towards this goal is to define optical signatures associated with specific watershed land coverages measured at the source (optical proxies). The next step is to track those proxies from their respective sources to the coast, characterizing the dilution and transformative processes. Using analyses of discrete samples collected monthly from the subwatersheds, we have quantified optical proxies for both dissolved and particulate organic carbon, particulate carbon to nitrogen ratios and fluorophores unique to certain land coverages (e.g. wetlands, residence ponds, lumber mills, agriculture). We apply these proxies to in situ optical observations retrieved from sensors moored within the lower river and upper estuary to quantify the temporal patterns in the biogeochemical properties. To date we have approximately 2 years of observations, including the wettest year on record for the last century in this region. The proxies associated with the dissolved fraction are the most robust and provide signatures for both land coverage and for organic carbon concentration. Those associated with particles are robust proxies for carbon but are less informative about land coverage.

Maine↗
USGS2020

Pacific Continental Shelf Environmental Assessment (PaCSEA): Characterization of Seasonal Water Masses within the Northern California Current System Using Airborne Remote Sensing off Northern California, Oregon, and Washington, 2011–2012

Here, we use ocean color measurements (Figure 1) and sea surface temperature (SST) data collected using sensors mounted on low-flying aircraft to characterize NCCS water masses and identify patterns among seasons and between years. To accomplish this, we applied k-means clustering to measured and derived ecologically-relevant physical and bio-optical variables (SST, Chla, absorbance by colored dissolved organic matter [aCDOM], proxy particle load). These classifications will be used in the future to evaluate species habitat distributions in the NCCS.

California, Oregon, Washington↗
USGS2020

Impacts of grade control structure installations on hydrology and sediment transport as an adaptive management strategy

The goal of this research was to examine the impacts of Grade Control Structure (GCS) installations at the Heard Scout Pueblo (HSP) study site in the City of Phoenix, Arizona, USA. The study site is around a high-use trail system and is comprised of eroded and incised channels that conduct high flows and associated sediments into a residential neighborhood downstream, a noted stormwater control problem. We established baseline conditions associated with rainfall/runoff response before structures were installed so we could have some data for comparison afterwards. Innovative monitoring equipment, including video cameras and pressure transducers (to calculate discharge); digital terrain models, sediment samplers and sediment chains (to measure erosion and deposition); soil moisture sensors in monitoring wells (to document infiltration and potential recharge); and weather stations (to track temperature and relative humidity) were established and a small Unmanned Aircraft System (sUAS) survey was completed by July, 11, 2017, in time for the typical summer monsoon season which officially runs from June 15th to September 30th. Only one pre-GCS installation rain event incurred a significant flow event (October 13, 2018). Natural Channel Design (NCD), a landscape restoration company with decades of experience, was hired through a competitive bid process to develop a novel layout of ~30 GCS installations (sills, modified one-rock dams (ORD), and plugs, as well as a modified Zuni-bowl). The American Conservation Experience (ACE) hand-built the structures based on these designs in the main channel from November 13, 2018 through December 1, 2018. ACE built another ten structures in locations adjacent to the channel from January 15 through January 18, 2019. NCD worked with the landscape forensics to identify a historic channel and reinstate it using GCS. A surface-water model was also applied, using some of the baseline measurements (terrain and hydraulic conductivity) to track the flows of water and potential infiltration associated with rainfall events before GCS installation, to assist NCD in their design. The same model was applied using the installed GCS locations to simulate impacts of the structures on flow and infiltration. Our model was able to predict the slight reduction and delay in peak flows for small events and simulate infiltration, which was measured and occurred in the channel. Results demonstrated that structures could increase infiltration by ~15% over time. More data describing geomorphology and hydrology after repeated rainfall events will allow for increased analyses. Innovative monitoring, including the large‐scale particle image velocimetry (LSPIV) were invaluable to this research. Given the arid-land location and added drought conditions, the water levels were not high enough to compute, even using the continuous slope-area method, so discharge was calculated solely using the LSPIV. The careful redundancy of data acquisition is extremely important when studying dryland hydrology. Weather data indicated that the HSP GCS installations created roughly a three-degree microclimate cooling effect for at least two days following rainfall events, as compared with the untreated channel. The cooling was attributed to increased moisture, evaporation, and latent heat expulsion from the evaporation.

Arizona↗
USGS1977

International training in remote sensing

The training and assistance programme at the Earth Resources Observation Systems (EROS) Data Center, Sioux Falls, South Dakota (United States of America), is designed to provide for the transfer of remote-sensing technology to land managers and resource specialists, both domestic and foreign. The programme does not emphasize research and development (i.e., sensor development, feasibility analysis, applications research etc.) nor does it provide services to operational remote-sensing applications projects. Instead, the objectives of the programme are to comprehend, interpret, assess and translate state-of-the-art remote-sensing techniques and transfer to users those techniques in such manner that they can be easily understood. The purpose of this paper is to describe briefly the user assistance programmes available at the EROS Data Center, with emphasis on the international activities.

Conference Paper↗
USGS1981

Digital processing techniques for small digital arrays (FLD data set)

The purpose of the Workshop on Luminescence Techniques was threefold: (1) to review the state-of-the-art capabilities of luminescence methods, (2) to consider a variety of concepts for the development of future luminescence sensor systems, and (3) to discuss appropriate research and development strategies for advancing the current state-of-the-art.

Conference Paper↗
USGS1981

Workshop on applications of luminescence techniques to Earth resource studies

The purpose of the Workshop on Luminescence Techniques was threefold: (1) to review the state-of-the-art capabilities of luminescence methods, (2) to consider a variety of concepts for the development of future luminescence sensor systems, and (3) to discuss appropriate research and development strategies for advancing the current state-of-the-art.

Technical Report↗