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At least 1,387 records · Page 77Linked to original sources
USGS1993

Beach profile modification and sediment transport by ice: an overlooked process on Lake Michigan

Coastal lake ice includes a belt of mobile crash and slush ice and a stable nearshore-ice complex (NIC). Sediment concentrations indicate that the NIC and the belt of brash and slush contains 180 to 280 t (113 to 175m3) of sand per kilometer of coast. This static sediment load is roughly equivalent to the average amount of sand eroded from the bluffs and to the amount accumulating in the deep lake basin each year. Sediment is being rafted alongshore in the mobile brash and slush at rates of 10 to 30 cm/sec. -from Authors

Journal of Coastal Research↗
USGS1997

Physical processes affecting the sedimentary environments of Long Island Sound

A modeling study was undertaken to simulate the bottom tidal-, wave-, and wind-driven currents in Long Island Sound in order to provide a general physical oceanographic framework for understanding the characteristics and distribution of seafloor sedimentary environments. Tidal currents are important in the funnel-shaped eastern part of the Sound, where a strong gradient of tidal-current speed was found. This current gradient parallels the general westward progression of sedimentary environments from erosion or non-deposition, through bedload transport and sediment sorting, to fine-grained deposition. Wave-driven currents, meanwhile, appear to be important along the shallow margins of the basin, explaining the occurrence of relatively coarse sediments in regions where tidal currents alone are not strong enough to move sediment. Finally, westerly wind events are shown to locally enhance bottom currents along the axial depression of the sound, providing a possible explanation for the relatively coarse sediments found in the depression despite tide- and wave-induced currents below the threshold of sediment movement. The strong correlation between the near-bottom current intensity based on the model results and the sediment response as indicated by the distribution of sedimentary environments provides a framework for predicting the long-term effects of anthropogenic activities.

Conference Paper↗
USGS2004

Holocene alluvium around Lefkosia (Nicosia), Cyprus: An archive of land-use, tectonic processes, and climate change

Holocene alluvium of the Pedhicos River around Lefkosia (Nicosia), Cyprus, was studied. Alluvial stratigraphy was found to present serial flood deposits underlying river terraces and an extensive alluvial fan. It was found that the stratigraphy and geomorphology of the alluvium can be interpreted to distinguish not only the effects of climate change, but also land-use change, and the impact of particular engineering works. It was suggested that details of the physical properties of the flood deposit sequences and paleosols can contribute to modeling various geophysical and engineering properties and in predicting response to vertical acceleration during earthquakes.

Conference Paper↗
USGS2004

Continuous thermochemical conversion process to produce oil from swine manure

Thermochemical conversion (TCC) of livestock manure is a novel technology that has shown very promising results in treating waste and producing oil. A batch TCC system that was previously developed successfully converted 70% of swine manure volatile solids to oil and reduced manure chemical oxygen demand by ??? 75%. The necessary retention time to achieve an oil product was largely dependent on the operating temperature. The highest oil production efficiency was 80% of the volatile solids (or 70 wt % of the total solids). The average carbon and hydrogen contents were ??? 72 and 9%, respectively. The heating values for 80% of the oil products ranged from 32,000 to 36,700 kJ/kg. This is an abstract of a paper presented at the AWMA 97th Annual Conference and Exhibition (Indianapolis, IN 6/22-25/2004).

Conference Paper↗
USGS2006

Modelling and understanding volcanic processes using high-quality seismological data

At an active volcano, Very-Long-Period (VLP) seismicity (with typical periods in the range 2-100 s) reflects pressure fluctuations resulting from unsteady mass transport in the sub-surface plumbing system, and hence provides a glimpse of the internal dynamics of the volcanic edifice. Understanding the fundamental fluid-flow mechanisms involved in the generation of VLP seismic events is, therefore, key to improving eruption prediction and developing insight into the dynamics of fluid movement in volcanoes.

Géosciences↗
USGS1987

Digital processing techniques and film density calibration for printing image data

Satellite image data that cover a wide range of environments are being used to make prints that represent a map type product. If a wide distribution of these products is desired, they are printed using lithographic rather than photographic procedures to reduce the cost per print. Problems are encountered in the photo lab if the film products to be used for lithographic printing have the same density range and density curve characteristics as the film used for photographic printing. A method is presented that keeps the film densities within the 1.1 range required for lithographic printing, but generates film products with contrast similar to that in photographic film for the majority of data (80 percent). Also, spatial filters can be used to enhance local detail in dark and bright regions, as well as to sharpen the final image product using edge enhancement techniques.

Conference Paper↗