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

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At least 325 records · Page 18Linked to original sources

USGS2026

Patterns of recent brook trout invasion in bull trout streams in relation to habitat, source connectivity, biotic resistance, and disturbance

Knowledge of which habitats are at risk of invasion by nonnative species is essential to conservation, but a changing climate often complicates assessments of where future invasions may occur. Nonnative brook trout Salvelinus fontinalis threaten cold-adapted native salmonids throughout western North America, and the extent of future invasions in coldwater streams is recognized as an area of uncertainty with important consequences. We addressed this uncertainty using spatial-stream-network (SSN) modeling to develop a species distribution model (SDM) for brook trout in Idaho, creating high-resolution prediction maps of suitable (i.e., invadable) habitat under baseline (1990–2015) and future (2080s) climate scenarios, and querying predictions within natal bull trout S. confluentus habitat patches (stream–subwatershed scale) for each scenario. Results indicated that brook trout will experience a net loss of suitable habitat in Idaho, but a large increase of suitable habitat in cold streams. The total proportion of bull trout habitat invadable by brook trout increased from 0.33 during the baseline scenario to 0.44 during the future scenario—a result of upstream expansions of brook trout habitat that were partially offset by contractions in bull trout habitat. Changes in the proportion of invadable habitat varied widely among bull trout patches. Between scenarios, the largest increases in suitable habitat occurred in small, low-gradient, unconfined streams with mean August water temperatures of 7–9 °C during the baseline period. A relatively small proportion of patches contained the majority of invadable habitat in both scenarios, particularly patches in “U-shaped” glacial valleys. A changing climate will broadly increase the threat that brook trout pose to bull trout, but the degree of change experienced by individual populations will vary with local context. The high-resolution prediction maps created by our SSN model will help conservation planners identify and prioritize control efforts on the small proportion of brook trout populations that most threaten bull trout.

Idaho↗

USGS2009

Distribution and conservation status of coastal sage scrub in southwestern California

A landscape-based characterization of vegetation has been developed for southwestern California using satellite imagery, air photos, existing vegetation maps, and field data. Distribution maps of nine dominant coastal scrub species and 13 species assemblages that were identified by divisive information analysis have been analyzed to quantify spatial patterns of species co-occurrence. Three general distribution patterns are identified that suggest the Diegan, Ventaran and Riversidian Associations identified by other workers. Vegetation data have also been related to land ownership and management to assess the conservation status of upland plant communities. A large proportion of the mapped distribution of species and vegetation types is on private land, and several taxa show less than 4 % of mapped distribution in nature reserves. The analysis highlights the need to extend current conservation planning efforts into the northern part of the region to encompass areas where Salvia leucophylla is a frequent community dominant.

Journal of Vegetation Science↗

USGS1991

Ground-penetrating radar: A tool for mapping reservoirs and lakes

Ground-penetrating radar was evaluated as a tool for mapping reservoir and lake bottoms and providing stage-storage information. An impulse radar was used on a 1.4-ha (3.5-acre) reservoir with 31 transects located 6.1 m (20 feet) apart. Depth of water and lateral extent of the lake bottom were accurately measured by ground-penetrating radar. A linear (positive) relationship existed between measured water depth and ground-penetrating radar-determined water depth (R 2 =0.989). Ground-penetrating radar data were used to create a contour map of the lake bottom. Relationships between water (contour) elevation and water surface area and volume were established. Ground-penetrating radar proved to be a useful tool for mapping lakes, detecting lake bottom variations, locating old stream channels, and determining water depths. The technology provides accurate, continuous profile data in a relatively short time compared to traditional surveying and depth-sounding techniques.

Journal of Soil and Water Conservation↗

USGS2017

A framework for modeling connections between hydraulics, water surface roughness, and surface reflectance in open channel flows

This paper introduces a framework for examining connections between the flow field, the texture of the air-water interface, and the reflectance of the water surface and thus evaluating the potential to infer hydraulic information from remotely sensed observations of surface reflectance. We used a spatial correlation model describing water surface topography to illustrate the application of our framework. Nondimensional relations between model parameters and flow intensity were established based on a prior flume study. Expressing the model in the spatial frequency domain allowed us to use an efficient Fourier transform-based algorithm for simulating water surfaces. Realizations for both flume and field settings had water surface slope distributions positively correlated with velocity and water surface roughness. However, most surface facets were gently sloped and thus unlikely to yield strong specular reflections; the model exaggerated the extent of water surface features, leading to underestimation of facet slopes. A ray tracing algorithm indicated that reflectance was greatest when solar and view zenith angles were equal and the sensor scanned toward the Sun to capture specular reflections of the solar beam. Reflected energy was concentrated in a small portion of the sky, but rougher water surfaces reflected rays into a broader range of directions. Our framework facilitates flight planning to avoid surface-reflected radiance while mapping other river attributes, or to maximize this component to exploit relationships between hydraulics and surface reflectance. This initial analysis also highlighted the need for improved models of water surface topography in natural rivers.

Journal of Geophysical Research F: Earth Surface↗

USGS1995

How wet is wet? Precipitation constraints on late Quaternary climate in the southern Arabian Peninsula

It is generally recognized that the southern Arabian Peninsula has had two wet periods in the late Quaternary. To quantify ‘wet’ a 28 000 year old capillary surface associated with a paleowater-table was mapped and used as a surrogate for the water table in a ground-water model. Analysis of this model suggests 1.4 mm year −1 of recharge is necessary to support the water table at the mapped elevations during the wet period. Climatic relations between rainfall and recharge in arid areas infer that annual rainfall during this wet period was approximately 200 ± 50 mm year −1 or approximately five times the present rate.

Journal of Hydrology↗

USGS2013

Effects of climate change and urban development on the distribution and conservation of vegetation in a Mediterranean type ecosystem

Climate and land-use changes are projected to threaten biodiversity over this century. However, few studies have considered the spatial and temporal overlap of these threats to evaluate how ongoing land-use change could affect species ranges projected to shift outside conservation areas. We evaluated climate change and urban development effects on vegetation distribution in the Southwest ecoregion, California Floristic Province, USA. We also evaluated how well a conservation network protects suitable habitat for rare plant species under these change projections and identified primary sources of uncertainty. We used consensus-based maps from three species distribution models (SDMs) to project current and future suitable habitat for 19 species representing different functional types (defined by fire-response – obligate seeders, resprouting shrubs – and life forms – herbs, subshrubs), and range sizes (large/common, small/rare). We used one spatially explicit urban growth projection; two climate models, emission scenarios, and probability thresholds applied to SDMs; and high-resolution (90 m) environmental data. We projected that suitable habitat could disappear for 4 species and decrease for 15 by 2080. Averaged centroids of suitable habitat (all species) were projected to shift tens (up to hundreds) of kilometers. Herbs showed a small-projected response to climate change, while obligate seeders could suffer the greatest losses. Several rare species could lose suitable habitat inside conservation areas while increasing area outside. We concluded that (i) climate change is more important than urban development for vegetation habitat loss in this ecoregion through 2080 due to diminishing amounts of undeveloped private land in this region; (ii) the existing conservation plan, while extensive, may be inadequate to protect plant diversity under projected patterns of climate change and urban development, (iii) regional assessments of the dynamics of the drivers of biodiversity change based on high-resolution environmental data and consensus predictive mapping, such as this study, are necessary to identify the species expected to be the most vulnerable and to meaningfully inform regional-scale conservation.

California↗

USGS2019

Remote sensing of tracer dye concentrations to support dispersion studies in river channels

In river channels the flow field influences the dispersion of biota, contaminants, and other suspended or dissolved materials. Insight on patterns and rates of dispersion can be gained by injecting a pulse of visible dye and observing spatial and temporal variations in dye concentration as the pulse moves downstream. We evaluated the potential of passive optical remote sensing to enhance such tracer experiments by providing spatially distributed concentration information. During tests performed in both an experimental flume facility and a large natural channel, we made field measurements of Rhodamine WT dye concentration and above-water spectral reflectance. At Korea's River Experiment Center, a small unmanned aircraft system (sUAS) was used to acquire hyperspectral images of a sinuous outdoor flume. On the Kootenai River in northern Idaho, USA, field spectra were collected from a boat and hyperspectral image data and high resolution aerial photographs were obtained from manned aircraft. We modified an Optimal Band Ratio Analysis (OBRA) algorithm to identify wavelength combinations that yielded strong correlations between a spectrally based quantity X and dye concentration C. For both the flume and field tests, we obtained very strong (R^2 from 0.94 to 0.99) relationships between X and C across a broad range of visible wavelengths. On the Kootenai, we found that X vs. C relations derived from field spectra could be applied to airborne hyperspectral images and that dye concentrations could be estimated nearly as reliably from relatively simple three-band images as from hyperspectral data. These results imply that remote sensing could become a powerful tool for mapping dye patterns. Such a capability would advance our understanding of dispersion processes by enabling more rigorous testing of numerical flow models.

Journal of Ecohydraulics↗

USGS2023

Mapping stream and floodplain geomorphometry with the Floodplain and Channel Evaluation Tool

Broad-scale mapping of stream channel and floodplain geomorphic metrics is critical to improve the understanding of geomorphic change, biogeochemical processes, riverine habitat quality, and opportunities for management intervention. The Floodplain and Channel Evaluation Tool (FACET) was developed to provide an open-source tool for automated processing of digital elevation models (DEMs) to generate regional-scale estimates of bank height, channel width, floodplain width, and a suite of other fluvial geomorphic dimensions that can be summarized at the stream reach- or catchment-scale. FACET was tested on 3-m DEMs covering the Delaware River watershed and 85% of the Chesapeake Bay watershed in the United States (U.S.) and on 1-m DEMs for a subset of the study area. Accuracy was assessed from data collected at 67 field sites in the study area. FACET successfully measured geomorphometry for over 270,000 stream reaches (88% of streams attempted) in the study area. Factors that reduced the ability of FACET to accurately estimate geomorphic metrics included errors in DEM hydro-conditioning, gradually sloping banks, incised stream channels, and the use of fixed input parameters to define buffer lengths. Even with these limitations, FACET was able to map regional patterns in stream and floodplain geomorphometry providing a robust dataset that can enhance modeling and management efforts throughout the mid-Atlantic region, U.S.

Delaware, New Jersey, New York, Maryland, Pennsylv↗

USGS2007

Application of GPS and GIS to map channel features in Walnut Creek, Iowa

A 12-km reach of Walnut Creek was mapped at the Neal Smith National Wildlife Refuge in Jasper County, Iowa to identify and prioritize areas of the stream channel in need of further investigation or restoration. Channel features, including streambank conditions, bottom sediment materials and thickness, channel cross-sections, debris dams, tile lines, tributary creeks, and cattle access points, were located to one-meter accuracy with global positioning system (GPS) equipment and described while traversing the stream. The GPS data were exported into a Geographic Information System (GIS) format, and field descriptions were added to create a series of coverages. Channel features were coupled with existing land cover data for analysis. Left and right streambank erosion rates varied from slight in many areas to severe at outside meander bends, debris dams or cattle access points. Erosion estimates from this study suggest that stream banks contribute about 50 percent of the annual suspended sediment load in the channel. Substrate materials varied from bare or thinly mantled pre-Illinoian till to thick silty muck (> 0.3 m) behind some debris dams and cattle access points. Occurrences of sand and gravel areas were generally restricted to cattle access areas and bridge crossings. A total of 81 debris dams were identified in the stream channel, ranging from fallen trees and beaver dams to several large debris dams. Numerous tile lines (52 total) and tributary creeks (45 total) were mapped as contributing flow to the main channel. Cross-sections measured at 34 locations indicated Walnut Creek averages 10.64 m wide and 2.77 m deep, with the width and depth increasing downstream. Channelization and tile discharge in row crop land use areas have contributed to increased bed degradation and channel widening throughout the watershed. The results of this study indicate the effectiveness of a one-time detailed mapping program to characterize stream system variability and identify spatial relationships among many stream characteristics. Stream survey data are being used to model watershed conditions, identify water sampling points and evaluate and select appropriate channel rehabilitation measures.

Iowa↗

USGS2015

Measurement of slow-moving along-track displacement from an efficient multiple-aperture SAR interferometry (MAI) stacking

Multiple-aperture SAR interferometry (MAI) has demonstrated outstanding measurement accuracy of along-track displacement when compared to pixel-offset-tracking methods; however, measuring slow-moving (cm/year) surface displacement remains a challenge. Stacking of multi-temporal observations is a potential approach to reducing noise and increasing measurement accuracy, but it is difficult to achieve a significant improvement by applying traditional stacking methods to multi-temporal MAI interferograms. This paper proposes an efficient MAI stacking method, where multi-temporal forward- and backward-looking residual interferograms are individually stacked before the MAI interferogram is generated. We tested the performance of this method using ENVISAT data from Kīlauea Volcano, Hawai‘i, where displacement on the order of several centimeters per year is common. By comparing results from the proposed stacking methods with displacements from GPS data, we documented measurement accuracies of about 1.03 and 1.07 cm/year for the descending and ascending tracks, respectively—an improvement of about a factor of two when compared with that from the conventional stacking approach. Three-dimensional surface-displacement maps can be constructed by combining stacked InSAR and MAI observations, which will contribute to a better understanding of a variety of geological phenomena.

Hawaii↗

USGS2019

High-Resolution mapping of biomass and distribution of marsh and forested wetlands in southeastern coastal Louisiana

This study estimates herbaceous and forested wetland coverage and aboveground biomass (AGB) within the Atchafalaya and Terrebonne coastal basins representing sediment rich and sediment poor coastal regions of southern Louisiana. Louisiana coastal wetlands account for approximately one third (37%) of the estuarine wetland area in the conterminous United States, yet the spatial distribution of their extent and aboveground biomass estimates are not well defined. Despite the importance of Louisiana’s coastal wetlands, existing maps on their extent are often outdated yet repeatedly used in national greenhouse gas (GHG) inventories and within regional aboveground biomass and carbon content estimates. Sentinel-2 optical satellite data was used within an object-oriented machine learning approach to classify wetland extent, mapping the spatial distribution of the coastal wetlands at high-resolution. A total wetland extent of 2950 km2 was mapped during a period of peak biomass in September 2017, comprised of forested and herbaceous wetlands (accuracy >90%) and demonstrated considerable differences (793.7 km2) from currently available estimates of wetland area. The distribution of aboveground biomass (AGB) was mapped using class averaged values derived from field data collected during May and September 2015. Total herbaceous biomass at the study site increased by 108.9% from May (668,684.5 Mg) to September (1,396,969.2 Mg) whilst the total woody vegetation biomass (27,667,232.1 Mg) was sampled in May only. This method provides a tractable means of mapping wetland extent and biomass, in a region threatened with wetland loss under projections of increasing sea-level rise and local subsidence.

Louisiana↗

USGS2019

Monitoring, forecasting collapse events, and mapping pyroclastic deposits at Sinabung volcano with satellite imagery

During the ongoing (2013–present) eruption of Sinabung volcano, north Sumatra, we have routinely used a variety of satellite remote sensing data to observe and forecast lava dome and lava flow collapse events, to map the resulting pyroclastic deposits, and to estimate effusion rates. In this paper, we focus on the first two years of the current eruption (September 2013–December 2015), and we summarize major events in 2016. We divide the eruption into 5 major phases: 1) phreatomagmatic (July 2013–18 December 2013), 2) first dome growth and collapse (18 December 2013–10 January 2014), 3) lava-flow (10 January 2014–mid-September 2014), 4) second lava dome and collapse (mid-September 2014–July 2015), 5) lava dome collapse and ash explosion phase (August 2015–present). Throughout the eruption, remotely sensed information has been instrumental in assessing the stability of the lava dome and flow and to forecast collapse events that produce pyroclastic density currents (PDCs: block-and-ash flows, co-ignimbrite surges, and blasts). Forecasts based on remote sensing data in combination with seismic, geodetic and gas-monitoring data have also helped inform decisions related to alert levels and evacuations. Relatively unusual aspects of the Sinabung eruption include the transition from dome to flow morphology (phase 2 to phase 3 transition) and the frequent occurrence during phase 3 of collapses from the lava flow-front and flow-margins—collapses that produced extensive pyroclastic density currents. By analogy to the well-known “Merapi type” collapses and pyroclastic deposits, we propose that lava flow-front and flow-margin collapses with associated PDCs be known as “Sinabung type.” Although detailed study of deposits has not been possible due to continuing hazards, our observations suggest that the transition from lava dome to lava flow and the occurrence of flow-front and flow-margin collapses reflect a particular combination of lava viscosity and steepness of slope. Our observations also show clear evidence of at least one slope-parallel high-velocity and dilute PDC (a “blast”) that emanated from a lava-margin collapse site 500 m downslope from the vent. This 1 February 2014 blast downed and singed a forest out to at least 3.9 km from the collapse site and killed 16 people. We also use a combination of field and remotely sensed data to map the distribution of Sinabung deposits. We estimate eruptive volumes and extrusion rates by combining sequential measurements of lava surface and pyroclastic flow areas with thickness estimates derived from simple geometric assumptions, oblique photographs and Digital Elevation Models (DEMs) derived from remotely sensed data. Our estimates of short-term effusion rates vary widely on a daily to weekly basis, from <1 to >20 m 3 s −1 . In a few cases, periods of increased extrusion precede lava flow-front collapses by a few days to a week, suggesting delays in transmittance of effusion pulses as lava moves from vent to flow front. We find that, as of 1 January 2016, the total area of deposits is 10 7 m 2 , and their approximate deposit volume is about 0.3 km 3 , equivalent to 0.2 km 3 Dense Rock Equivalent (DRE). We anticipate that our deposit maps will be valuable in the future as a framework for the study of the magmatic and textural evolution of eruptive products through time.

Sinabung volcano↗

USGS2023

Crop water use dynamics over arid and semi-arid croplands in the lower Colorado River Basin

Numerous studies have evaluated the application of Remote Sensing (RS) techniques for mapping actual evapotranspiration (ETa) using Vegetation-Index-based (VI-based) and surface energy balance methods (SEB). SEB models computationally require a large effort for application. VI-based methods are fast and easy to apply and could therefore potentially be applied at high resolution; however, the accuracy of VI-based methods in comparison to SEB-based models remains unclear. We tested the ETa computed with the modified 2-band Enhanced Vegetation Index (METEVI2) implemented in the Google Earth Engine – for mapping croplands’ water use dynamics in the Lower Colorado River Basin. We compared METEVI2 with the well-established RS-based products of OpenET (Ensemble, eeMETRIC, SSEBop, SIMS, PT_JPL, DisALEXI and geeSEBAL). METEVI2 was then evaluated with measured ETa from four wheat fields (2017–2018). Results indicated that the monthly ETa variations for METEVI2 and OpenET models were comparable, though of varying magnitudes. On average, METEVI2 had the lowest difference rate from the average observed ETa with 17 mm underestimation, while SIMS had the highest difference rate (82 mm). Findings show that METEVI2 is a cost-effective ETa mapping tool in drylands to track crop water use. Future studies should test METEVI2’s applicability to croplands in more humid regions.

Lower Colorado River basin↗

USGS2000

Map data in support of forest management

Now widely available and inexpensive, prepackaged map data are easy to use--and just as easy to use incorrectly. To select the proper scale and appropriate thematic attributes so that the data actually inform the project at hand, managers need to know the basics.

Journal of Forestry↗

USGS1992

Precipitation estimation in mountainous terrain using multivariate geostatistics. Part II: isohyetal maps

Values of average annual precipitation (AAP) may be important for hydrologic characterization of a potential high-level nuclear-waste repository site at Yucca Mountain, Nevada. Reliable measurements of AAP are sparse in the vicinity of Yucca Mountain, and estimates of AAP were needed for an isohyetal mapping over a 2600-square-mile watershed containing Yucca Mountain. Estimates were obtained with a multivariate geostatistical model developed using AAP and elevation data from a network of 42 precipitation stations in southern Nevada and southeastern California. An additional 1531 elevations were obtained to improve estimation accuracy. Isohyets representing estimates obtained using univariate geostatistics (kriging) defined a smooth and continuous surface. Isohyets representing estimates obtained using multivariate geostatistics (cokriging) defined an irregular surface that more accurately represented expected local orographic influences on AAP. Cokriging results included a maximum estimate within the study area of 335 mm at an elevation of 7400 ft, an average estimate of 157 mm for the study area, and an average estimate of 172 mm at eight locations in the vicinity of the potential repository site. Kriging estimates tended to be lower in comparison because the increased AAP expected for remote mountainous topography was not adequately represented by the available sample. Regression results between cokriging estimates and elevation were similar to regression results between measured AAP and elevation. The position of the cokriging 250-mm isohyet relative to the boundaries of pinyon pine and juniper woodlands provided indirect evidence of improved estimation accuracy because the cokriging result agreed well with investigations by others concerning the relationship between elevation, vegetation, and climate in the Great Basin. Calculated estimation variances were also mapped and compared to evaluate improvements in estimation accuracy. Cokriging estimation variances were reduced by an average of 54% relative to kriging variances within the study area. Cokriging reduced estimation variances at the potential repository site by 55% relative to kriging. The usefulness of an existing network of stations for measuring AAP within the study area was evaluated using cokriging variances, and twenty additional stations were located for the purpose of improving the accuracy of future isohyetal mappings. Using the expanded network of stations, the maximum cokriging estimation variance within the study area was reduced by 78% relative to the existing network, and the average estimation variance was reduced by 52%.

Nevada↗

USGS1984

Midseason mapping of sunflowers using Landsat digital data

The mapping results suggest that for the midsummer Landsat data used, there was not a sufficiently reliable relationship between Landsat-derived spectral clusters and sunflowers to allow 'automated' production of useful sunflower location maps. The occurrence of sunflower pixels in all cluster classes was a consequence of the diversity in sunflower appearance at the point in the growing season when the Landsat image used for digital processing was acquired. -Authors

Journal of Wildlife Management↗

USGS2023

National Land Cover Database 2019: A comprehensive strategy for creating the 1986-2019 forest disturbance product

The National Land Cover Database (NLCD) 2016 products show that, between 2001 and 2016, nearly half of the land cover change in the conterminous United States (CONUS) involved forested areas. To ensure the quality of NLCD land cover and land cover change products, it is important to accurately detect the location and time of forest disturbance. We designed a comprehensive strategy to integrate a continuous time series forest change detection method and a discrete 2-date forest change detection method to produce the NLCD 1986–2019 forest disturbance product, which shows the most recent forest disturbance date between the years 1986 and 2019 for every 2- to 3-year interval. This method, the Time-Series method Using Normalized Spectral Distance (NSD) index (TSUN), uses NSD to detect multi-date forest land cover changes and was shown to be easily extended to a new date even when new images were processed in a different way than previous date images. The discrete 2-date method uses the Multi-Index Integrated Change Analysis (MIICA) method to detect changes between 2-date images. A method based on confidence and object grouping was designed to combine the multiple MIICA outputs to improve change detection accuracy. Finally, an aggregation scheme was implemented to combine the TSUN output, the integrated MIICA results, and ancillary data to produce the NLCD 2019 forest disturbance 1986–2019 product. The initial accuracy assessments from 1,600 samples over 4 Landsat path/rows show that the producer’s and user’s accuracies of the 2001–2019 forest disturbance map are 76% and 74%, respectively. The final CONUS-wide forest disturbance product is provided at https://www.mrlc.gov/nlcd-2019-science-research-products .

conterminous United States↗

USGS2014

Spatial variability and landscape controls of near-surface permafrost within the Alaskan Yukon River Basin

The distribution of permafrost is important to understand because of permafrost's influence on high-latitude ecosystem structure and functions. Moreover, near-surface (defined here as within 1 m of the Earth's surface) permafrost is particularly susceptible to a warming climate and is generally poorly mapped at regional scales. Subsequently, our objectives were to (1) develop the first-known binary and probabilistic maps of near-surface permafrost distributions at a 30 m resolution in the Alaskan Yukon River Basin by employing decision tree models, field measurements, and remotely sensed and mapped biophysical data; (2) evaluate the relative contribution of 39 biophysical variables used in the models; and (3) assess the landscape-scale factors controlling spatial variations in permafrost extent. Areas estimated to be present and absent of near-surface permafrost occupy approximately 46% and 45% of the Alaskan Yukon River Basin, respectively; masked areas (e.g., water and developed) account for the remaining 9% of the landscape. Strong predictors of near-surface permafrost include climatic indices, land cover, topography, and Landsat 7 Enhanced Thematic Mapper Plus spectral information. Our quantitative modeling approach enabled us to generate regional near-surface permafrost maps and provide essential information for resource managers and modelers to better understand near-surface permafrost distribution and how it relates to environmental factors and conditions.

Alaska↗