Authorities of municipal separate storm sewer systems (MS4s) are required to address illicit discharges as part of the National Pollutant Discharge Elimination System (NPDES) stormwater program. Field reconnaissance is an effective measure to detect and identify illicit discharges, but requires substantial staff and financial resources to conduct. While risk analysis techniques and guidelines have been developed to facilitate MS4 prioritization of field operations, neither a standard set of indicators nor a standard operating procedure has been adopted. This study investigates the relationships among indicators of illicit discharge potential (IDP) and the locations of illicit discharges in two Virginia MS4s. Results of the study indicate that certain risk factors are statistically more effective at predicting IDP, suggesting that a core set of factors can be used to map illicit discharge risk. The results also show that risk mapping tools are significantly impacted by uncertainty in model inputs. Recommendations are provided for MS4s interested in pursuing IDP risk mapping as a tool to improve cost-effectiveness and guide illicit discharge program implementation. / Master of Science

The development and rapid growth of computer mapping has led to many discussions concerning the accuracy of techniques used to generate these computer representations. The purpose of this study is to analyze the accuracy of thinning methods applied to scanned map data, which is only one in a series of processes used to accomplish digital conversion of conventional maps. In preliminary tests, nine thinning methods based on the successive layer removal process are evaluated. Seven raster images are thinned using these methods. The raster results are compared based on the number of pixels deleted and on the number of retained pixels that fall either on or off the medial axis of the original matrix. The four algorithms that produce the best results are then used for final testing. For the final tests, 25 digital lines are plotted and scanned. The raster images are thinned using the four successive layer removal methods and a line following method developed for this study. The raster output is evaluated using the preliminary testing method. The final vector output is compared to the original input based on line length, anchor line length, and fractal dimension. / Master of Science

Standalone computer modules for county to county travel demand forecasting have been integrated. The Trip Generation, Trip Distribution and Mode Choice modules have been unified under one Graphical User Interface (GUI). The outputs are automatically mapped using Geographic Information Systems (GIS) technology to allow immediate and spatial analysis. The integrated model allows for faster running times and quicker analysis of the results. The ability to calculate travel time savings for travelers was also included to the final model. The modeling framework developed is known as the Transportation Systems Analysis Model (TSAM). / Master of Science

Children are conceptualized many ways by economists-- as sources of utility for their parents, investments, recipients of care, and public goods. Despite the understanding that children are also people, the economic literature is lacking in analysis of children as actors, making choices with consequences for economic development. Using a capability-driven approach and an emphasis on co-evolutionary processes of institutional and individual change, with mixed qualitative and quantitative methods, my dissertation analyzes the role of children in long-term economic development at the community level. I use a case study of community-based, out-of-school time (OST) programs for low-income youth funded through the 21st Century Community Learning Center (21st CCLC) to analyze the role of youth in economic development. OST programs provide community-level benefits such as reductions in juvenile crime and foster economic development by creating linkages between the state, the market, the community, and the family. My study contributes to the body of interdisciplinary research on OST programs, and is situated in the middle ground between case studies with very small samples and quantitative studies with a narrow focus on academic performance as measured by grades. The 21st CCLC programs in New York State are unique in their emphasis on partnerships between schools and community-based organizations. An analysis of the costs and benefits of OST programs shows that the benefits of programs such as 21st CCLC substantially outweigh the costs. Using Geographic Information Systems and statistical analysis, I examine the relationship between eligibility for 21st CCLC funding, demographic characteristics related to the need for free or low-cost OST programs, and the presence of 21st CCLC programs, and find that the presence of these programs cannot be explained solely through the characteristics of people who will be served by them. Additionally, it is clear that there are not enough 21st CCLC programs to serve all eligible communities, raising questions about the scale of funding as well as its distribution.

As land cover throughout the Chesapeake Bay watershed is modified and climate patterns alter, changes in runoff occur which can impact water quality. A study was conducted using the Soil and Water Assessment Tool (SWAT) for the James River watershed in Virginia, the southernmost tributary of the Chesapeake Bay, for 1986 to 2018. A comparison of land cover changes throughout that time frame was included in the analysis. Land cover data was derived from satellite imagery with values extracted using Geographic Information System (GIS) analysis. The SWAT model was run within the web-based Hydrologic and Water Quality System (HAWQS). The research focuses on land use, precipitation, and water quality indicators. Findings suggest links between land cover modification, such as residential development, to degraded water quality indicators. Also denoted are direct improvements in water quality when forest land areas are preserved throughout the watershed terrain.

Increasing suburban poverty and the extremely high housing costs of growing metropolitan areas amplify the importance of suburban low-income housing programs. Aside from traditional hurdles to social and economic mobility, suburban low-income households are confronted by impediments that are inherent to sprawling, fragmented suburban landscapes with poor access. This research investigates the site suitability of a booming suburban region, Fairfax County, Virginia, for low-income housing. To do so, this research identifies and explains location amenities and neighborhood characteristics that maximize the success of low-income housing programs for low-income households, and explores how suburban landscapes constrict the ability of policymakers and planners to incorporate such location considerations into low-income housing planning. Using a Geographic Information Systems (GIS) model, the site suitability of Fairfax County, Virginia for low-income housing is examined. Results highlight numerous location amenities in a heavily developed suburban environment, yielding overall decent low-income housing site suitability scores across Fairfax County. However, the sprawling nature of Fairfax County also provides few optimal locations for low-income housing development. The incorporation of key location amenities in strategic locations as well as modern planning techniques hinging on new urbanism and smart growth concepts are emphasized to improve low-income housing suitability in many American suburbs. This research links GIS methodology with social policy, providing policymakers and planners with a tool to analyze the spatial distribution of critical location amenities and low-income housing development. / Master of Science

The vast majority of severe storm and tornado research is conducted in the natural laboratory of the Great Plains region of the United States. As a result, much of the knowledge and technology applied to storm forecasting is developed in the Great Plains environment. However, it has been shown that there is a maximum of strong and violent tornadoes in the region extending from Arkansas eastward into Alabama. In addition, various researchers have found strong severe storm thermodynamic signatures unique to regions such as the Northeast and Mid-Atlantic. This study has analyzed five decades of tornado data for the state of Mississippi. Thermodynamic results indicate that Mississippi has a tornado environment distinctly different than that of the Great Plains. The spatial distribution of the tornado events also indicates that mesoscale processes between the Earth's surface and the lower troposphere may play a significant role in determining the genesis location of violent tornadoes in the historical Delta region of Mississippi. It is anticipated that an understanding of environments unique to Mississippi tornadoes will lead to better forecasts and more comprehensive storm analysis, which will ultimately save lives and property.

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