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At least 559 records · Page 31Linked to original sources
USGS2012

Remote sensing of evapotranspiration for operational drought monitoring using principles of water and energy balance

Evapotranspiration (ET) is an important component of the hydrologic budget because it režects the exchange of mass and energy between the soil-water-vegetation system and the atmosphere. Prevailing weather conditions inžuence potential or reference ET through variables such as radiation, temperature, wind, and relativity humidity. In addition to these weather variables, actual ET (ETa) is also affected by land cover type and condition, as well as soil moisture. The dependence of ETa on land cover and soil moisture, and its direct relationship with carbon dioxide assimilation in plants, makes it an important variable for monitoring drought, crop yield, and biomass-a critical capability for decision makers interested in food security, grain markets, water allocation, and carbon sequestration (Bastiaanssen et al., 2005).

Book chapter↗
USGS2012

Role of remote sensing for land-use and land-cover change modeling

As the impacts of land-use and land-cover (LULC) change on carbon dynamics, climate change, hydrology, and biodiversity have been recognized, modeling of this transformational force has become increasingly important. Given the wide variety of applications that rely on the availability of LULC projections, modeling approaches have originated from a variety of disciplines, including geography, landscape ecology, economics, biology, and others. Initial modeling was often isolated within each discipline, but multidisciplinary modeling frameworks were developed as LULC modelers began to integrate the socioeconomic and biophysical components of LULC change. The empirical and theoretical basis for this work falls within land-use science, and this ‡eld documents both land-use and land-cover change, explains the coupled human-environment dynamics that produce the changes, and provides tools for producing spatially explicit LULC models (Mertens and Lambin, 1999; Rindfuss et al., 2004).

Book chapter↗
USGS2012

Ecosystem performance monitoring of rangelands by integrating modeling and remote sensing

Monitoring rangeland ecosystem dynamics, production, and performance is valuable for researchers and land managers. However, ecosystem monitoring studies can be difficult to interpret and apply appropriately if management decisions and disturbances are inseparable from the ecosystem's climate signal. This study separates seasonal weather influences from influences caused by disturbances and management decisions, making interannual time-series analysis more consistent and interpretable. We compared the actual ecosystem performance (AEP) of five rangeland vegetation types in the Owyhee Uplands for 9 yr to their expected ecosystem performance (EEP). Integrated growing season Normalized Difference Vegetation Index data for each of the nine growing seasons served as a proxy for annual AEP. Regression-tree models used long-term site potential, seasonal weather, and land cover data sets to generate annual EEP, an estimate of ecosystem performance incorporating annual weather variations. The difference between AEP and EEP provided a performance measure for each pixel in the study area. Ecosystem performance anomalies occurred when the ecosystem performed significantly better or worse than the model predicted. About 14% of the Owyhee Uplands showed a trend of significant underperformance or overperformance ( P <0.10). Land managers can use results from weather-based rangeland ecosystem performance models to help support adaptive management strategies.

Oregon;Idaho↗
USGS1978

Remote-sensing and subsurface definition of facies and structure related to uranium deposits, Powder River Basin, Wyoming

Computer-enhanced Landsat images of the southern Powder River Basin have been used to define facies and linear structural features within the Wasatch Formation. The facies distribution is detectable primarily because of a relation of vegetation density and type to the local substrate. The surface indications of facies are confirmed by sandstone/ mudstone ratios determined from logs of abundant exploration drill holes. These newly defined geologic features are spatially related to known uranium mineral occurrences and are believed to be related to mineralization in the following ways. (1) Major uranium occurrences are virtually restricted to an intermediate grain-size facies of the Wasatch, probably marking the axial zone of the depositional basin. (2) The axial zone is also marked by a change from one structural lineament domain to another, and the structures may have influenced details of fluvial-system patterns and sedimentation and (subsequently) the flow of uranium-bearing ground water. (3) A recently active linear structure may mark the current basin axis; it appears to have some relationship both to groundwater chemistry and the distribution of uranium occurrences, suggesting structural influence on relatively modern ground-water transport and uranium deposition. © 1978 Society of Economic Geologists, Inc.

Wyoming↗
USGS1985

Remotely sensed limonite anomaly on Lordsburg Mesa, New Mexico: Possible implications for uranium deposits

We have identified a large, anomalously limonitic area in Cenozoic gravels on Lordsburg Mesa near Lordsburg, New Mexico, using Landsat images. Our interpretation of the geophysical and geochemical data suggests the exploration hypothesis that the Lordsburg Mesa limonite anomaly is the surface expression of a chemical trap that may contain concentrations of uranium similar to calcrete-uranium deposits. Ground water originating in the Big Burro Mountains, where uranium vein deposits are known, drains through the Lordsburg Mesa area. This ground water is apparently forced near the surface by a buried bed-rock ridge along the west side of the limonite anomaly. The resulting changes in ground-water chemistry may be precipitating uranium along the eastern margin of the limonite anomaly.

Economic Geology↗
USGS1967

Radar remote sensing in biology

The present status of research on discrimination of natural and cultivated vegetation using radar imaging systems is sketched. The value of multiple polarization radar in improved discrimination of vegetation types over monoscopic radars is also documented. Possible future use of multi-frequency, multi-polarization radar systems for all weather agricultural survey is noted.

BioScience↗
USGS1990

Temporal variability of remotely sensed suspended sediment and sea surface temperature patterns in Mobile Bay, Alabama

Distribution patterns of suspended sediments and sea surface temperatures in, Mobile Bay were derived from algorithms using digital data from the visible, near infrared, and infrared channels of the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-TIROS-N satellite. Closely spaced AVHRR scenes for January 20, 24, and 29, 1982, were compared with available environmental information taken during the same period. A complex interaction between river discharge, winds, and astronomical tides controlled the distribution patterns of suspended sediments. These same variables, coupled with air temperatures, also governed the distribution patterns of sea surface temperatures.

Alabama↗
USGS1987

The Badain Jaran Desert: Remote sensing investigations.

Approximately half the Badain Jaran Desert in the north-western Alashan Plain of northern China is a sand sea. The remainder is gravel or bedrock. The north-western border of the desert is a playa. The desert has been imaged by both Landsat and the Shuttle Imaging Radar (SIR-A). Landsat analysis indicates there are two dune patterns in the sand sea, north-east oriented crescentic dunes along the northern and western borders, and complex star dunes in the central and eastern desert. Although the orientation and morphology of the dunes are easily visible on Landsat, they cannot be determined with the radar image obtained from the aspect angle used during the SIR-A mission. An abrupt change in wavelength of the dune pattern near the Badain Jaran Playa is mappable on Landsat, but not seen on the radar image. The playa appears to be considerably larger on radar than on the Landsat, and we may be seeing subsurface penetration of dry surficial sands with the radar. Archaeological evidence suggests the playa was the location of prehistoric and historic human activity. SIR-A data indicate the playa was formerly a considerably larger inland lake.

Badain Jaran Desert↗
USGS1998

Remote sensing in the USGS Mineral Resource Surveys Program in the eastern United States

Mineral deposits commonly occur within special geologic units or structures, such as fault zones, which can be detected and mapped from aircraft and satellite images. Modern techniques analyze multispectral images that record the way solar energy is reflected or emitted by the materials exposed at the Earth's surface. In sparsely vegetated regions, including most of the Western United States, mineral composition is determined directly by analyzing the spectral properties of rock outcrops. In more densely vegetated terrain, such as the Eastern United States, rock and soil composition can be determined directly in manmade exposures, such as plowed fields and construction sites, or much more general determinations can be made indirectly by analyzing the distribution and apparent health of naturally occurring plants. The association of certain plants with particular rock or soil types has been known for decades. For example, coniferous trees grow preferentially on well-drained sandy soil, whereas deciduous trees dominate on shaly bedrock. These two forest types reflect solar radiation quite differently and, therefore, are distinguished readily in conventional aerial photographs. More subtle plant-bedrock associations require digital multispectral image analysis to infer compositional information from the spectral characteristics of the forest canopy.

Information Handout↗
USGS2010

Remotely sensed imagery revealing the effects of hurricanes Gustav and Ike on coastal Louisiana

Hurricane Gustav, a category 2 storm with 170 kilometers per hour (km/h) winds, approached the Louisiana coast from the south-southeast, making landfall near Cocodrie, La., on September 1, 2008 (Beven and Kimberlain, 2009); Hurricane Ike, a category 2 storm with 175 km/h winds, approached the Texas coast from the southeast, paralleling offshore of the Louisiana coast, before making landfall along the north end of Galveston Island, Tex., on September 13, 2008 (Berg, 2009). Hurricane Ike's large wind field elevated water levels, increasing coastal flooding well before making landfall (Berg, 2009). An initial land area change assessment, based on comparison of Landsat Thematic Mapper (TM) satellite imagery, acquired before 2006 and after the 2008 landfalls of Hurricanes Gustav and Ike and classified to identify land and water, reported that the water area increased by 323 square kilometers (km2) in coastal Louisiana as a result of the storms (Barras, 2009). The land area decrease of 195 km2 was less than the 513 km2 decrease reported between 2004 and 2006 (Barras and others, 2008) after the landfalls of Hurricane Katrina, a strong category 3 storm that made landfall near Buras, La., on August 29, 2005, and Hurricane Rita, a category 3 storm that made landfall just west of Johnsons Bayou, La., on September 29, 2005. The 2004 to 2006 land area decrease is 49 km2 less than the 562 km2 initial change estimate based on satellite imagery obtained two months after the 2005 storms (Barras, 2007a). The comparison area used to identify the 2004 to 2006 land area change matches the extent of historical land and water data used to quantify coastal land loss from 1956 to 2006 (Barras and others, 2008) and is 3,841 km2 less than the 33,457.7 km2 used for Barras (2006) and Barras (2009). The greater comparison area used for the 2006 to 2008 period (Barras, 2009) resulted in a 2004 to 2006 loss estimate of 525.8 km2, 13.0 km2 greater than the 512.8 km2 estimate reported in Barras (2008).

Louisiana↗