ScholarWorks@UMassAmherst
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Recent Submissions
Publication EMPLOYING LONG-TERM DATA ASSESSMENT, ENVIRONMENTAL TRACERS, AND MODELING TO ASSESS DRINKING WATER SUPPLY QUALITY TO SUPPORT DECISION-MAKING(2024-05)Drinking water quality management is a challenging task for water suppliers due to changing land use, human practices, and climate patterns. This dissertation seeks to provide tools for water managers to support the decision-making process. The first chapter consists of the investigation of water quality patterns at the Wachusett drinking water supply watershed, MA, USA, assessing nutrients and road salt trends at the surface water level, incorporating land use analysis to identify potential sources of pollutants in the natural environment. Land use data suggest association with altered drainage landscapes as potential sources of increased constituent transport. Despite watershed programs aimed at reducing salt applications, conductivity is increasing in streams, indicating a long-term legacy of salt accumulation, as is the case in many Northeastern watersheds. To better understand trends, the second chapter consists of characterizing the temporal and spatial distribution of salinity in freshwater across Massachusetts. This assessment shows that higher levels of electrical conductivity (EC) in surface water are related to the higher presence of urbanized areas. The size of the drainage area can contribute to dilution processes in the streams, attenuating these trends for larger basins. To better elucidate surface-subsurface water interactions and contaminant pathways in water systems, in the third chapter the pathways by which groundwater concentrations of salt indicators may be increasing in the Wachusett watershed are assessed using stable water isotopes. The analyses indicate that the groundwater recharge is winter dominant, thus the applied road salt during winter months can contribute to sustained increases in conductivity in the groundwater. Finally, investigating surface and groundwater concentrations allows water quality assessments using reservoir modeling to evaluate scenarios considering changes in management of local salting practices. The goal of the last chapter is to estimate the impact and the time to observe effects of pollutant migration in a watershed after remediation strategies would be implemented to provide the tools to achieve water management goals. Results indicate that efforts of reducing salt application should target the subbasins with the highest flows, however it is crucial to manage high concentration subbasins due to acute toxicity for aquatic life.Publication TRANSFORMATIVE CONTACT: ADDRESSING INDIVIDUAL, RELATIONAL, AND STRUCTURAL-INTERACTIVE CHANGE THROUGH THE JUSTICE AMBASSADORS YOUTH COUNCIL PROGRAM(2024-05)This dissertation documents the evolution, outcomes, and replicable framework of the Justice Ambassadors Youth Council (JAYC), a criminal legal system intervention based in NYC invested in transforming not only the pathways of its participants, but also the broader relationships they hold to each other, to their communities, and to the political and institutional structures that inform their lives. I first outline the critical gap in the United States’ criminal legal system in which those who are most impacted by the realities of mass incarceration (e.g., Black and Hispanic men) are often the least represented in developing and/or enacting related policies and laws. Next, through a review of interdisciplinary academic literature, I discuss the challenges and possibilities of contact-based interventions that bring together individuals from different group memberships (specifically to JAYC, youth participants impacted by the criminal legal system and government representatives acting on the system’s behalf) for not only reducing intergroup prejudice, but also providing necessary resources to bolster individual skill-building and agency and opening up new avenues for social change engagement. In the following chapters, I discuss the founding and development of the JAYC program and highlight the many successful outcomes it demonstrates across multiple levels of change (inclusive of individual, relational, and structural-interactive outcomes). Then, in a comprehensive qualitative study that thematically analyzes 58 JAYC participant interview responses, I demonstrate how nine essential components of the JAYC program are mechanistically related to these three levels of outcomes. Finally, I document - via a recently published, first-author peer-reviewed journal article - how the JAYC program, by encompassing a human development / ecological approach to resiliency that considers the reciprocal importance of community and societal resources - can serve as a powerful model as an intervention capable of creating transformative change across a variety of contexts.Publication THREE ESSAYS on INNOVATION POLICY and INEQUALITY(2024-05)In this dissertation, I examine how state and national policies impact the participation of underrepresented groups in commercialization and entrepreneurial activities. I use empirical methods, experiments, and large datasets to investigate how institutions exacerbate or alleviate existing disparities within the innovation economy. Chapter 1 investigates the impact of state R&D tax credits on the engagement of small high-tech firms with Federal funding opportunities. Combining data on state business registrations and firm enrollment in the Federal System for Award Management (SAM), I examine the effects of state-level policies on firms’ interest in pursuing Federal grants and contracts. A staggered difference-in-difference analysis of state policy adoption shows that state R&D tax credits reduce SAM enrollment for women- and minority-owned high-tech firms (by 6% and 1%) and have no effect on SAM enrollment for non-minority high-tech firms. These findings underscore the need for more effective policy interventions to foster interest among small firms in Federal innovation initiatives and the importance of targeted support for women- and minority-owned firms. In Chapter 2, co-authored with Ina Ganguli and Nilanjana Dasgupta, we examine gender differences in the social impact and commercial motives for academic entrepreneurship using the National Science Foundation’s Innovation Corps (NSF I- Corps) program. Analysis of survey data and 1,267 NSF-funded I-Corps project abstracts, alongside a field experiment manipulating recruitment emails, shows women’s pronounced preference for social impact over commercial motive compared to men. This suggests that low-cost interventions that emphasize the social impact value of entrepreneurial opportunities may increase gender diversity in participation in entrepreneurship activities. In Chapter 3, I investigate the impact of the Small Business Technology Development Center (SBTDC) on new-firm formation in North Carolina’s rural and economically depressed Cleveland County using difference-in-difference and synthetic control methods. I find null effects with difference-in-differences and positive effects with the synthetic controls for Cleveland County for new firm creation. The findings underscore the significance of tailored government policies in catalyzing quality entrepreneurship and resource allocation, particularly in areas lacking robust entrepreneurial frameworks. This investigation contributes to the broader discourse on the strategic deployment of public resources to uplift economically depressed regions.Publication STUDY ON MULTILINE ANCHORS FOR FLOATING OFFSHORE WIND TURBINES(2024-05)Renewable energy is crucial, and floating offshore wind energy has immense potential. However, the current exorbitant cost of the substructure of a floating offshore wind turbine (FOWT) poses a significant challenge to its development. Thus, this thesis proposed a groundbreaking concept: instead of individual anchors, FOWTs could share anchors to enhance substructure efficiency and reduce costs. The purpose of this study was to analyze the strength dynamics of multiline anchors with varying parameters, such as floater type, turbine capacity, different mooring types and environmental factors. The National Renewable Energy Laboratory (NREL) 5 MW reference turbine and the OC3 Hywind spar platform were utilized to simulate multiline anchor forces and compared with the OC4 semisubmersible. In the wave-dominant survival load case, the peak value of net multiline anchor force in a spar was only 13% of that in a semisubmersible, while in operational conditions, the spar’s maximum anchor tension was 29% of that in a semisubmersible. Thus, it is unequivocal that wave forces have less impact on the spar platform than the semisubmersible platform. The multiline anchor was studied through numerical simulations using the layout geometry of an existing wind farm with two types of offshore platforms to compare multiline anchor forces. It was discovered that the maximum three-line anchor force in the case of a semisubmersible was 70% of the single-line force, while it was 50% in the case of a spar for a 0° Wind Wave Current (WWC) load condition. The directionality also revealed that the anchor forces in the case of a semisubmersible were more sensitive to wave forces than wind/current, while also more stable and undisturbed in the spar case. Multiline anchor forces were studied for two scenarios, with and without wake effects, using Jensen’s wake model. Reduced thrust forces due to wake caused lesser individual anchor forces and, therefore, lesser net multiline anchor forces. In cases where more turbines were in the downstream condition experiencing wake effects, the percentage of reduction in the multiline anchor force was higher. In contrast, if the downstream turbines were spaced farther apart, the percentage of reduction in the multiline force was almost negligible. Collective parametric studies were conducted in a taut mooring system for deeper water. It was discovered that the multiline anchor force increased with an increase in taut angle and water depth. An increase in turbine capacity by a factor of three caused the multiline anchor force to increase by a factor of 1.5. The 60 wind-wave-current direction caused the peak multiline anchor force as many mooring lines connected to the multiline anchor were under a similar and higher state of tension in WWC direction.Publication Taking the Pulse of Global Rivers(2024-05)As Earth’s surficial pulse, the world’s rivers beat in response to precipitation and transport water, nutrients, and pollutants downstream or to the atmosphere. Contextualizing surface water resources requires a toolkit of models, algorithms, and data. Despite significant progress, at global scales we often model all rivers the same way: as lumped units with homogenous geomorphology and only implicit representation of their drainage networks, hydraulic geometry, and hydrologic connectivity. This can have cascading effects on our ability to understand, contextualize, and in turn manage surface water quantity and quality across scales. To overcome these challenges, this dissertation advances a place-based ‘hydro-bio-geo-morpho-chemical’ approach to global river science that uniquely characterizes every river at scale. Herein I develop, expand upon, and combine remote sensing algorithms, river transport models, techniques for efficient geoprocessing at scale, synthesis of large field databases, and hydrologic connectivity and hydraulic geometry theories to better understand water and carbon transport through the world’s river systems. Ultimately, this dissertation provides an improved framework for taking the pulse of global rivers to better inform water resources science and management at present and into the future.
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