UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item An Ecological Analysis of the Potential for Moss-Based Green Roof Design(2016) Prince, Benjamin Alan; Kangas, Patrick C; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Green roofs are a maturing application of best management practices for controlling urban stormwater runoff. The majority of green roofs are planted with drought resistant, higher plant species, such as the genus Sedum. However, other plant varieties, such as mosses, may be equally applicable. Residential roofs and natural terrestrial communities were sampled in both Maryland and Tennessee to determine moss community structure and species water composition. This served as a natural analog for potential green roof moss communities. During sampling, 21 species of moss were identified throughout the 37 total sites. The average percent moss cover and water composition across all roof sites was 40.7% and 38.6%, respectively and across all natural sites, 76.7% and 47.7%, respectively. Additional maximum water holding capacity procedures were completed on sedum and 19 of the 21 sampled moss species to assess their individual potential for stormwater absorption. Sedum species on average held 166% of their biomass in water, while moss species held 732%. The results of this study are used as a basis to propose moss species that will improve green roof performance.Item Energy Balance, Water Balance, and Plant Dynamics of a Sloped, Thin Extensive Green Roof Installed in the Mid-Atlantic Region of the United States(2014) Tjaden, Scott William; Tilley, David; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Vegetated extensive green roofs can reduce peak runoff amounts during rain events. As the desire to install green roofs expands beyond roofs with little slope to those with steeper slopes, often found on residential homes, there is a need to understand how slope affects runoff. WaterShed, the University of Maryland's winning entry in the 2011 U.S. Department of Energy Solar Decathlon competition, is used as an applied research site where studies like the runoff analysis can be completed, while helping to promote and demonstrate environmental sustainability and energy consumption efficiency. Instrumentation installed on the roof will allow high-resolution data analysis, producing hydrographs. The research has related the sloped green roof to different moisture holding capacities throughout the different elevations, resulting in a unique energy balance for the installed green roof. The thin substrate did not significantly contribute to overall runoff reduction, rather it helped to reduce the overall peak runoff and elongate the runoff lag after a rain event. This living technology's performance over time in a new application to sloped roofs is crucial both to ensure regulatory standards are met and to provide feedback for future improvements to the design and technology itself.Item DESIGNING FOR BIODIVERSITY TO INFLUENCE HABITAT ON A GREEN ROOF IN THE DISTRICT OF COLUMBIA(2012) Myers, Chris H.; Ellis, Christopher D.; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This paper will discuss design elements to enhance pollinator and avian diversity on a green roof in the District of Columbia. Biodiversity trends on green roofs in Canada, the United Kingdom, Switzerland, and the United States are discussed. Focusing on North America, reconciliation ecology is explored through the use of case studies. The design process for designing a green roof is divided into three parts: identifying program goals, site analysis, and design concept. Design guidelines are extrapolated from conservation literature for the creation of green roofs that support pollinator and avian habitat. These "bioroofs" will be draped over the United States Coast Guard Headquarters building which will serve as a template for creating a green roof to target the least tern, the killdeer, the butterfly and the bee, in the District of Columbia.Item The Hydrologic Design of Green Roofs(2011) Ahmadian, Soudeh; McCuen, Richard H.; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Green roofs are increasingly being used as part of primary urban strategies to improve stormwater management and reduce energy costs. Different methods for green roof design are based on different assumptions and parameters. However, the input parameters are uncertain, which influences design accuracy. A mathematical model was developed to simulate the water movement across and through a green roof. This model was used to assess the sensitivity of the hydrological response of a green roof to roof and rainfall characteristics. Peak discharge rates and depths of runoff mainly depend on the rainfall characteristics. Green roofs can significantly reduce both the peak discharge rates and runoff depths for small storms but they have little effect on large storms. Furthermore, roof characteristics mainly the roof slope is an important design criteria. The model benefits from using the NRCS infiltration equation and curve number, as well as the specific yield of the soil.