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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Keeping Dirt in Its Place: Runoff, Sediment Loss, and Cost Effectiveness of Three Erosion Control Practices on Steep Slopes

Hill, Michael 01 March 2010 (has links) (PDF)
Erosion is a natural process that occurs when soil particles are detached from one site and transported to another by water or wind, and can occur naturally or be accelerated by humans. Sediment can cause direct mortality or reduce growth of fish and other aquatic resources, particularly larval fish and eggs. Three treatments consisting of compost and jute netting, crimped straw with native seeds, and jute netting and vegetation filter strip were used to evaluate loss of runoff water and sediment on steep slopes. Erosion plots were built on slopes of 27 percent and filled with soil. The treatments were applied in triplicate and irrigated at 14-day intervals. Each erosion plot was irrigated with approximately 79 gallons of water for 10 hours and runoff was collected in pre-weighed containers during each period. After each collection, runoff from each plot was measured and recorded by subtracting the weight of each empty container from the combined weight of water and sediment. Turbidity, pH, and electrical conductivity were measured, and the separate weights of runoff and dry sediment were determined. The combination of jute netting over a layer of commercially available compost was over 99 percent effective at reducing runoff and sediment loss as compared to the untreated control erosion plots. Jute netting combined with a vegetative filter strip of creeping wild rye was over 94 percent and 99 percent effective at reducing runoff and sediment loss when compared to the untreated control erosion plots, respectively. Runoff and sediment loss from plots treated with crimped straw and native seeds was significantly greater than that of the other treatments, yet this treatment was over still 80 percent effective at reducing runoff and nearly 97 percent effective at reducing sediment loss. The cost-effectiveness of each treatment was evaluated based on the cost of the total treatment compared to the amount of water each treatment prevented from leaving the site, using the control plots as a baseline. The combination of jute and vegetation filter strip cost approximately $0.47 per liter of water prevented from leaving the site and was almost as effective at reducing runoff and sediment loss as was jute combined with compost, which cost $1.04 per liter. While each of the three treatments significantly reduced runoff and sediment loss when compared to the barren control plots, the jute and filter strip treatment was the most cost-effective of the three treatments. All treatments were effective at decreasing runoff and sediment loss when compared to the control, though no significant difference in runoff was observed between the control and any of the treatments after ten weeks. Thus, erosion control BMPs should be implemented well before the first storm causing runoff in order to be most effective.
2

A legal and economic analysis of the Virginia Chesapeake Bay Preservation Act

Richardson, Jesse J. 12 September 2009 (has links)
This paper focuses on the Virginia Chesapeake Bay Preservation Act (the Act), the regulations promulgated thereunder and several questions arising from an examination of the Act and regulations. Specifically, the analysis examines the agricultural provisions within the regulations and asks whether the provisions are economically desirable, as well as legally enforceable. The provisions of the Act and the regulations constitute the major focus of Chapter One. Chapter One's discussion concludes with an analysis of the regulations’ main pollution prevention tool, the vegetative buffer strip, and a brief listing of various issues and controversies involving the Act and the regulations. Chapter Two introduces a linear programming model designed to determine the most cost-effective means of pollution control based on farmer profits under several regulatory scenarios. The results imply that the mandatory provisions of the regulation prevent farmers from achieving the desired level of pollution reduction in the least costly fashion. The takings issue, a major concern for all environmental legislation, forms the major focus of Chapter Three. This analysis considers the provisions of the Act and regulations within the historic context of the takings clause of the Fifth Amendment of the United States Constitution, as well as the takings clause of the Virginia Constitution, and determines the legal validity of the provisions. Finally, Chapter Four presents several criticisms of the regulations as presently constituted. Suggestions for a more cost effective regulatory scheme conclude the analysis. / Master of Science
3

Watershed-based design of stormwater treatment facilities : model development and applications

Larm, Thomas January 2000 (has links)
No description available.
4

Watershed-based design of stormwater treatment facilities : model development and applications

Larm, Thomas January 2000 (has links)
No description available.
5

Evaluation of Pond/Wetland/Vegetative Filter System to Treat Beef Manure Pile and Outdoor Confinement Area Runoff

Mejia Franco, Maria Juliana 10 December 2018 (has links)
Regulations with respect to the storage and handling of animal waste by livestock operations state that no person shall keep animals in a permanent confinement area unless there is a nutrient management strategy. Various studies indicate that constructed wetlands and vegetative filters are effective add-on technologies to supplement the treatment provided by conventional sedimentation pond systems in livestock operations. Seven months of data from a Pond/Wetland/Vegetative Filter system receiving cattle feedlot runoff were used to i) evaluate its efficiency removing organic matter, solids and nutrients from water, (ii) quantify constructed wetland kinetic removal rates described by the P-C-k model and examine the impact of temperature, (iii) evaluate and compare the performance of a two types of vegetative filter systems at different hydraulic loading rates; and (iv) recommend an optimum management option with design loading for beef producers. Results indicate that the effect of isolated rain events on the performance of the wetland showed to be contingent on the intensity of the event, former humidity conditions of the feedlot and the hydraulic capacity of the wetland. This experiment suggests that even relatively small VFSs or short FPs can markedly improve quality of runoff from livestock operations, and that it is possible to achieve significant mass and concentration removals if they are properly operated and maintained in conjunction with a pre-treatment system. The Pond/Wetland/Vegetative Filter system was effective at reducing Chemical Oxygen Demand COD (+92%), Total Phosphorus (+93%), Orthophosphate as P (+91%), Total Inorganic Nitrogen (+96%), Ammonia as N (+97%) and Nitrate as N (+82%) from manure and exercise yard runoff, providing a cost-effective treatment option for beef producers.

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