نتایج جستجو برای: surficial geology
تعداد نتایج: 11614 فیلتر نتایج به سال:
Soil plays a crucial role in ecosystem functioning, e.g., soil minerals provide important provisioning and regulating services. The determination of mineral composition can help to link geochemical processes underlying bedrock surficial geology, however analysing quantitative mineralogy by X-ray diffraction be expensive. This study used data from the North American Geochemical Landscapes Projec...
The seabed can be classified using data from vertical, split-beam echosounders. This was demonstrated recently using amodel parameterized with acoustic estimates of slope, roughness, normal-incidence backscattering strength, and variation of backscattering strength by frequency and incidence angle. These seabed classifications were interpreted and validated using published surficial geology map...
Ground motions recorded within sedimentary basins are variable over short distances. One important cause of the variability is that local soil properties are variable at all scales. Regional hazard maps developed for predicting site effects are generally derived from maps of surficial geology; however, recent studies have shown that mapped geologic units do not correlate well with the average s...
Landslide occurrence in the Salmon Arm and Vernon forest districts in the last five years has stimulated research to determine how small drainage basins might be classified into debris flow prone, debris flood prone, or flood prone. Alluvial fans situated at the base of several entrenched stream systems may have people dwelling on them. In addition to safety concerns, water quality and habitat ...
This paper introduces two parsimonious models for predicting runoff for ungauged basins from the observed river flow data in gauged basins and precipitation data from rain gauging stations in the same area. The models assume the runoff is related to the precipitation subject to variance of drainage basins. The runoff can be modeled as a function of precipitation and parameters determined by bas...
Viruses are important pathogens in both marine and fresh water environments. There is a strong interest in using bacteriophages as tracers because of their role as model viruses, since dissolved chemical tracers may not adequately describe the behavior of viruses that are suspended colloids. Despite a large number of studies that examined the transport of bacteriophages in the subsurface enviro...
An assemblage of fossil sockeye salmon was discovered in Pleistocene lake sediments along the South Fork Skokomish River, Olympic Peninsula, Washington. The fossils were abundant near the head of a former glacial lake at 115 m elevation. Large adult salmon are concentrated in a sequence of death assemblages that include individuals with enlarged breeding teeth and worn caudal fins indicating mi...
Significant population growth over the last three decades, as well as efforts to improve surface-water quality mandated by the Clean Water Act, potentially have had opposing influences on aquatic ecosystems in the U.S. Because historical data on water-quality trends are limited over this time period, we developed a diatom-based transfer function to reconstruct chloride, color, acid neutralizing...
Sediment transport by surficial flow likely occurs on Titan. Titan is thought to have a volatile cycle, such as on Earth and likely in the past on Mars, which would entail surficial liquid flow. And surficial flow is implied in interpretations of Cassini–Hyugens data as showing fluvial channels, which would require sediment transport by surficial flow to form the observable features. We present...
Stream habitat assessments are conducted to evaluate biological potential, determine anthropogenic impacts, and guide restoration projects. Utilizing these procedures, managers must first select a representative stream reach, which is typically selected based on several criteria. To develop a consistent and unbiased procedure for choosing sampling locations, the Illinois Department of Natural R...
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