Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 41 for “"sediment characteristics"”.
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Suspended-sediment characteristics in four humid tropical watersheds of contrasting land use, Puerto Rico
A hypothetical model of sediment production, delivery, and transport in the humid-tropics of Puerto Rico was developed through statistical analysis of storm-generated sediment loads and hydrologic characteristics from three time categories: (1) the current storm-generated event, (2) previous …
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A comparative study of sediment characteristics of Sand River and Nzhelele River in Limpopo Province, South Africa
To describe a sediment and possibly learn more about its creation and depositional processes, grain size statistics might be used. In order to understand the hydrodynamic conditions, mode of transit, and deposition of detrital sediments, grain size analysis is a dynamic sedimentological tool. …
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Natural and anthropogenic influences on recent sediment characteristics in the Knysna Estuary, South Africa and Yangtze River Estuary, China
… sites for the accumulation of fine-grained sediment, organic matter and metals from various marine and terrestrial sources including those of natural and anthropogenic origin. The coastal zone performs many key ecosystem service functions for sustainable development, thus making them …
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Sand dune movement and its impact on human activities in the North Western coast region of Libya. An analysis of the sediment characteristics of sand dunes, and their movement using satellite images, and the effects of encroachment on farms assessed by a questionnaire survey.
Sand movement is one of the many environmental problems facing humans in the dry and semi-dry areas of the world. This study has investigated the observed changes in sand dune coverage compared to predictions, and has also assessed the impact of sand movement on human activity in the north western …
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Heavy metals partitioning in a stream receiving urban runoff
Water, sediment, detritus, caddisflies, snails, and crayfish were collected from Bull Run between July 31 and October 2, 1977 and analyzed for Fe, Mn, Ni, Pb, Cd, Zn, Cr, and Cu by atomic absorption spectrophotometry after appropriate digestion and extraction procedures. The samples were collected …
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Mangrove ecosystem dynamics and clearance impacts
… into the impact of mangrove clearance on sediment characteristics and macrofaunal communities, best practice for mangrove clearance, and the impact of changes in mangrove ecosystem area on carbon and nitrogen stocks and fluxes. Results showed that smaller hand clearances and locations …
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A laboratory study of the 'shoreline' detected in video imagery
… was undertaken to simulate varying swash zone characteristics and sensor-target geometry found in digital images collected by ARGUS coastal imaging systems. Using a hyperspectral sensor, reflectance data were integrated over the respective red, blue and green wavelengths corresponding to a …
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ΣΥΜΒΟΛΗ ΣΤΗ ΜΕΛΕΤΗ ΤΗΣ ΟΙΚΟΛΟΓΙΑΣ ΚΑΙ ΒΙΟΛΟΓΙΑΣ ΤΗΣ CALLIANASSA TYRRHENA (PETAGNA, 1792) (CRUSTACEA, DECOPODA, THALASSINIDEA)
… OF SETTLING MEGALOPAE THAT ARE DUE TO SEDIMENT CHARACTERISTICS. THE RANDOM SPATIAL DISTRIBUTION OF ADULTS WITHIN THE PATCH CAN BE EXPLAINED BY THE ABSENCE OF SEVERE ECOLOGICAL FORCES: POPULATION DENSITY DOES NOT SEEM TO BE AFFECTED BY BIOTIC FACTORS SUCH AS SEDIMENT ORGANIC CONTENT, …
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Simple models for turbulent wave-current bottom boundary layer flow : theoretical formulations and applications
… and currents in the presence of waves. Wave and sediment characteristics are used to formulate a model for wave-generated ripples based on available laboratory and field data. The two-layer Madsen-Salles (1998) and three-layer Barreto-Acobe (2001) flow models are applied in conjunction with the …
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Modeling the Biogenic Effects of Freshwater Mollusks on Bedload Transport and Dynamics in a Gravel-Bedded Stream
… the influence of biogenic variables on sediment characteristics, the interaction of biogenic alterations in sediment transport modeling, and the range of spatial scales used to identify biogenic effects. Methods used to investigate potential influences include multivariate regression …
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Sediment size effects on self-organisation behaviour of rip channels
… observations indicate the wave conditions and sediment characteristics exert the controlling effects on the states of beaches and determine the development of rip channel system. Although the role of wave conditions on the rip channel dynamics has been extensively studied, little attention has …
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Small-Scale Resuspension and Redistribution of Surface Sediments in the Northeast Gulf of Mexico
… the seafloor contained recently deposited marine sediments contaminated by the oil spill. The initial deposition of these contaminated marine sediments was likely not the end of the journey for the particles. Downslope gravitational processes and events of increased current speed in the deep ocean …
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Holocene Periods of Aggradation and Incision, Hanson Creek, Washington
… channel incision, accumulation of valley floor sediment, channel morphology and gradient were evaluated. The spatial distribution of these channel characteristics was assessed in relation to proximal landforms such as colluvial deposits, basalt outcrops, and bedrock anticlinal ridges. Sixteen …
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Dispersal and remineralisation of biodeposits: Ecosystem impacts of mussel aquaculture
… constituent particles. Consequently they cause sedimentation of material that might otherwise not be deposited. The benthic remineralisation of biodeposits increases sediment oxygen demand and nutrient regeneration, thus enhancing the benthic-pelagic coupling of nearshore ecosystems. In New …
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The Effect of Structure and Lithology on Aspect Ratio of Fluvial Channels: A Field-Based Quantitative Study of the New River in Three Geologic Provinces
… of the river's channel geometry, along with characteristics of bedrock, sediment, and confinement. Fifteen of the 29 sites are bedrock reaches. The data set allows empirical analysis of how width and aspect ratio of the New River are related to different variables, including slope, discharge, …
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Sediment circulation in mixed gravel and shingle bayhead beaches on the South East Dorset coast.
… and attempts to clarify the morphological characteristics, processes and sedimentology of five local mixed gravel and shingle beaches. A conceptual framework of process response has been adopted which considers energy inputs, sediment transport and coastal morphology, under conditions of …
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Lower Kuiseb River sediments and their control on dust emission
… investigation focused predominantly on the size characteristics of 153 surface sediment samples collected from the Kuiseb main channel, its terraces, delta, gravel plain surfaces and tributaries, dunes and interdune, all of which were analysed using a Malvern Mastersizer 2000 laser …
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COMMUNITY ECOLOGY OF CHILEAN SANDY BEACHES
… (Mehuin Beach, Bahia de Maiquillahue). Beach characteristics differed significantly during these years; i.e. more sand erosion and coarser sand occurred during the first year. The lowest abundances of the total macroinfauna (46-111 ind ${\rm m}\sp{-2})$ occurred during winter 1978, while the …
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The geochemistry of groundwater and sediments governing tungsten concentration in the basin-fill aquifers, Fallon, Nevada
… the mineralogical phase association(s) of W in sediments of the basin-fill alluvial aquifer near Fallon, NV, were identified in this study. These sediment characteristics were then compared to groundwater concentrations of W in an attempt to understand the geochemical controls on W in the …
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Stream channel adjustments and persistence of change in response to beaver damming on a fluvial fan, Odell Creek, Montana
… to increase bed elevation through in-channel sediment storage, thus beaver reintroductions are used as a river restoration tool to repair incised stream channels. However, effects of beaver damming are dependent on specific stream hydrologic and geomorphic characteristics. Data on dam effects, …
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