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 70 for “"ditches"”.
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Computational fluid dynamics modelling of dissolved oxygen in oxidation ditches.
This research aims to reveal new knowledge about the factors that affect the hydrodynamics, dissolved oxygen (DO) and aeration performance of a wastewater oxidation ditch. The literature is reviewed on the Computational Fluid Dynamics (CFD) modelling of wastewater aeration tanks. This study …
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Lines in the landscape: greenhouse gas emissions from ditches and sediments
Contains fulltext : 333008.pdf (Publisher’s version ) (Closed access)
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Evaluation of Oxidation Ditches; Based on Existing Plant Data and Site Trials
This thesis evaluates the Oxidation Ditch as a form of domestic effluent treatment. It uses as its basis a survey of the performance of existing plants in operation and reflective site trials of an existing plant in operation. <br/><br/>Based on the survey of existing plants, the design elements of …
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Abundance, Biomass, and Diversity of Aquatic Invertebrates in Level Ditches and Adjacent Natural Emergent Marsh in an Eastern South Dakota Wetland
The aquatic invertebrate communities of level ditches and adjacent natural emergent marsh in a South Dakota prairie wetland were sampled during the summer of 1982. Collections were made in both the water column and the bottom substrates. Forty-five taxa were collected. Analysis of variance …
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Perspectives on the Geomorphic Evolution and Ecology of Modified Channels and Two-Stage Ditches in the Agriculturally-Dominated Midwestern United States
… to examination of managing agricultural drainage ditches for ecosystem benefits. Work by dissertation collaborators on alternative ditch designs has led to the two-stage ditch approach, which creates floodplain benches stabilized by vegetation and an inset channel that effectively transports water …
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Impact of Substrate on Nutrient Removal in In-Ditch Bioreactors
Drainage ditches, or grassed waterways, collect nutrient-laden runoff from agricultural fields and transport it to nearby waterbodies. The high nitrogen and phosphorus content in this water leads to negative effects, such as eutrophication in the receiving waters. In-ditch bioreactors are a simple, …
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The Effects of Commercial Harvest on the Density and Demography of Aquatic Turtles in Arkansas
… density, and demography in agricultural ditches and aquaculture ponds of eastern Arkansas, two abundant wetland habitats which are often targeted by commercial turtle harvesters. We captured and marked over 4,000 individual turtles of nine species including red-eared sliders (Trachemys …
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The use of right of ways by primary burrowing crayfishes in the Ouachita Mountains Ecoregion of Arkansas
Roadside ditches can harbor beneficial and detrimental attributes for animal persistence. I sought to determine if roadside ditches could be preferred by two narrowly endemic primary burrowing crayfish species, Fallicambarus harpi and Procambarus reimeri. To investigate this interaction, I …
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HOW SEWAGE POLLUTION AFFECTS DISTRIBUTION AND LIFE HISTORY TRAITS OF THE SOUTHERN HOUSE MOSQUITO, CULEX QUINQUEFASCIATUS
… St. Tammany Parish has over 600 miles of septic ditches, which receive effluent directly from aerated treatment units. <em>Culex quinquefasciatus</em> oviposit in polluted waters, and larvae perform well in water with high levels of decomposing organic matter. The goal of my thesis was to …
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Ecological effects of ditching and ditch-plugging in New England salt marshes
… have received little attention. Specifically, ditches have existed on salt marshes for decades, but the effects of these hydrologic alterations are only poorly understood. Ditch-plugging is a more recent methodology used for salt marsh habitat enhancement and mosquito control, but the long-term …
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Freshwater Mussels as Biofilters
… reserve, mussels were placed in three eutrophic ditches to assess their potential use in the biomanipulation of these ditches. Although mussels suffered high mortality in two ditches, in the third ditch 70% of mussels survived, and the section of ditch containing mussels remained clear of …
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Survival and space use of riparian muskrats (Ondatra zibethicus) within an agroecosystem
… and occur in small streams and agricultural ditches throughout the Midwest. However, information regarding space use and survival of muskrats in these highly altered habitats is lacking. I examined predation risk, survival, home ranges, and space use of muskrats within small streams and …
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Landscape organization in Magna Graecia
… features in these territories, such as roads and ditches, so that it is by now generally recognized that Greek colonists organized their territories, to some extent, in order to increase the efficiency of agricultural and pastoral activity and therefore increase the overall productivity of the …
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Reframing the Ditch
… of native vegetation often become constrained to ditches and pipes with little or no vegetation within the conveyance corridor. Reframing the Ditch creates an approach to help municipalities improve water quality of headwater streams by addressing water quality in ditches before water reaches the …
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Modeling and measurement of tile drain controls in intensively managed landscapes
… and its outlets feed directly into streams and ditches, tile flow can affect various hydrologic, biotic and biogeochemical processes in the watershed the streams. However, the effects of spatially resolved micro-topographic variability, such depressions and roadside ditches, on tile flow and …
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Accumulation of sediment and radionuclides in tidal marshes of the Murderkill River Estuary, Delaware
… processes. An understanding how these ditches have affected sediment delivery to and retention on the marsh platform will provide insight into how ditched marshes are likely to respond to changes in sea level, sediment availability and vegetative growth. To investigate historical …
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Ecological Limitations and Potentials of Artificial Aquatic Systems
… for science and society.</p><p> Irrigation ditches are ubiquitous features of water networks in rural and urban settings in drylands, and are thus potentially important habitats within the modern hydroscape. The habitat value of ditches and other artificial systems depends on whether these …
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The ecology of the mosquito Culex modestus, a potential vector of West Nile virus in the UK
… sampled, collecting larvae from wetland drainage ditches along with information on both abiotic and biotic factors at each Sample Point. Culex modestus larvae were present from early July until late October at all four Locations, with populations peaking between late August and September. In 2016, …
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Roadside Ditch Design and Erosion Control on Virginia Highways
… of Transportation. Erosion failures of roadside ditches have occurred frequently enough to indicate that it may be desirable to revise the current design practice. Through the Virginia Transportation Research Council, VDOT has sponsored this research to investigate the state of design practice …
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