The detrimental influence of humans on the environment is of increasing concern. Humans, their livestock, and their pets have caused fecal contamination of waterways throughout the United States. Understanding the sources of fecal indicator bacteria (FIB) and the environmental processes that affect them can be crucial to reducing the number of impaired streams and limiting the negative impacts on the environment. Antibiotic resistance is an emerging issue facing human health in the United States and across the world. Antibiotic resistant bacteria (ARB) have antibiotic resistance genes (ARGs) that prevent antibiotics from killing them. Limited research has been done on the role of the environment in the propagation of antibiotic resistance. As the use of antibiotics increases, it is critical to examine how this impacts human health through the environment. Models of watersheds in Patillas, Puerto Rico and Christiansburg, Virginia were created using the Soil and Water Assessment Tool (SWAT) to compare how the differences in spatial and temporal sampling of FIB, climate, and population affect FIB movement. The performances of the calibrated bacteria models were comparable to other published studies. A primary challenge faced in this study was the use of grab samples taken months apart as monthly averages of FIB. The high precipitation and constant warm climate made the model for Patillas more difficult to fit because of the high variability in the observed data. While the Patillas watershed had a lower population of people and livestock, the Christiansburg watershed had more available data on wildlife. The lack of spatial variance of data and the use of data from 1993-2018, hindered the ability for the model for Patillas to model FIB. Additionally, the model's performance was limited due to the strong hurricanes that affect land use, soils, and populations of humans and animals in the watershed. Using open-source data needs to be explored further as a faster and more cost-effective way of developing SWAT FIB models. The feasibility to use data collected in the Christiansburg and Patillas watershed to calibrate a SWAT-ARB model was determined based on available ARG data. The results indicate that the bacteria models need to be improved before an effective SWAT-ARB model can be calibrated. One limitation in the available ARG data for the two watersheds was that they were only sampled once. Out of the ARGs sampled, sul1 was the best modeled in both watersheds because it has the highest normalized values and correlated with the amount of developed land. / Master of Science / Humans negatively impact the environment. Humans and animals contribute to the bacteria contamination of waterways. Investigation into where the contamination sources are and environmental processes that contribute can help researchers limit the impact on the environment. Bacteria can build resistance to antibiotics, which can be especially dangerous to humans and livestock when exposed. Little research has been done on how the environment has contributed to the spread of antibiotic resistance in bacteria. The Soil and Water Assessment Tool (SWAT) was used to investigate bacteria in the Patillas, Puerto Rico and Christiansburg, Virginia watershed. These models used data published by the United States Geological Survey (USGS) and Environmental Protection Agency (EPA) to improve performance. When comparing simulated data to observed data, the performances of the models were comparable to other published studies. The Patillas watershed was particularly difficult to model because of the warm climate and high precipitation that caused high variability in bacteria concentrations. Strong weather events including hurricanes and a lack of available data on wildlife were other hinderances to the Patillas model. In comparison, more published data on wildlife was available in the Christiansburg watershed and it had a more temperate climate. The SWAT-ARB model was reviewed and recommendations were made to improve the model. Using the previously collected antibiotic resistance bacteria data in the Christiansburg and Patillas watersheds, it would be impossible to create accurate models. More antibiotic resistance data needs to be taken across as a greater time period before the performance of the models can be assessed.

This dissertation is composed of three essays investigating three aspects of future water issues. The first essay focuses on an examination of water scarcity issues caused by rapid population growth and economic development in Texas. The second essay examines water scarcity under climate change scenarios in Texas. The third essay discusses arsenic-related water quality issues in the drinking water. An integrated economic, hydrological, and environmental model is developed for the first two essays by implicitly incorporating uncertainty about future climate, water demand from all types of water use, a spatial river flow relationship, interaction between ground and surface water, institutional regulations, and the possibilities of inter-basin water transfers (IBTs). In studying water scarcity under economic growth and population growth, we find that while some cities and counties have sufficient water, there are some other cities and counties (especially Dallas, Fort Worth and Austin) facing different degrees of water scarcity problems. In studying the climate change impact, four Global Circulation Models (GCMs) with three Special Report on Emissions Scenarios (SRESs) yield consistent results. Water scarcity becomes even more severe for cities. Texas realizes slight gains in earlier periods and a net loss beginning in 2060. This study finds that twelve IBTs, if there is no climate change, and fourteen IBTs, under the climate change scenario, will be economically feasible in 2060. These IBTs can not only greatly reduce water scarcity, but also create new growth opportunity for Houston. Water is transferred from in-stream flow in source basins. There is no significant impact on other sectors except in-stream flow and water flow out to bay. In the third essay, a two-stage structural model is developed to model household risk-averting behavior with respect to arsenic-related mortality risk in the drinking water. The empirical results suggest that risk perceptions for the parents and children are important in the decision of how much to spend on water treatment, but not in whether or not to treat water. Parents in our sample displayed mixed altruism. The information generated by this dissertation can help state agencies to manage water resources and to improve water-related human health, especially health for children, more effectively and more efficiently.

[pt] O tratamento de ambientes contaminados e a elaboração de programas de monitoramento requerem estimativas dos níveis de concentrações das substâncias,bem como um conhecimento de seu destino, taxa de transporte e tempos de residência. Na ausência de dados obtidos através de monitoramento, modelos ambientais constituem freqüentemente o único modo capaz de prever as concentrações aproximadas dos contaminantes nos compartimentos (meios) que formam o ambiente. A aplicação do modelo ambiental de multimeios Quantitative Water Air Sediment Interaction (QWASI) a um determinado ambiente exige conhecer parâmetros relacionados à área em estudo e aos contaminantes. Para o caso da Baía de Guanabara, muitos desses parâmetros não estão disponíveis. Desse modo, eles serão aproximados com técnicas do problema inverso a partir das concentrações de contaminantes medidas no sedimento e no mexilhão perna-perna. Entre os parâmetros estimados estão as emissões de 10 hidrocarbonetos policíclicos aromáticos (HPAs) nas águas da Baía de Guanabara. Este trabalho também apresenta simulações da evolução da concentração de alguns hidrocarbonetos em função do tempo considerando uma emissão inicial de um HPA em um ponto arbitrário da Baía de Guanabara. / [en] The treatment of polluted environments and the elaboration of monitoring programs request estimates of the levels of concentrations of the substances, as well as a knowledge of its destiny, rates of transport and times of residence. In the absence of data obtained through monitoring, environmental models often provide the only way to predict the approximate concentrations of the pollutants in the compartments (media) that form the environmental. The application of the multimedia environmental model Quantitative Water Air Sediment Interaction (QWASI) to a certain environment demands the knowledge of parameters related to the area in study and to the pollutants. For the case of the Guanabara Bay, many of those parameters are not available. Therefore, they will be approximated with inverse problem techniques starting from the measured concentrations of pollutants in the sediment and in the mussel perna-perna. Among the estimated parameters are the emissions of 10 polycyclic aromatic hydrocarbons (PAHs) in the waters of the Guanabara Bay. This work also presents simulations of the evolution of the concentration of some hydrocarbons infunction of the time considering an initial emission of a PAH in an arbitrary point of the Guanabara Bay.

[pt] Este estudo propõe a apresentação de um modelo de multimeios, denominado CAPA, capaz de analisar e comparar um elenco de 39 pesticidas num ambiente pré-determinado sob regime estacionário. O CAPA (Calculadora para Avaliação de Pesticidas no Ambiente) foi desenvolvido baseado no modelo ESTAC FATE (desenvolvido pelo Canadian Environmental Modelling Centre,Trent University, Canadá ). O modelo funciona no Excel, é programado em Visual Basic, usa a fugacidade como critério de equilíbrio e avalia os pesticidas em três diferentes níveis: Nível 1 (equilíbrio), Nível 2 (equilíbrio com entradas e saídas advectivas e reativas) e Nível 3( sem equilíbrio com entradas e saídas advectivas e reativas e transporte difusivo entre meios). Cada pesticida é comparado com os demais em função dos fatores de bioacumulação (FBA),Persistência (P), Toxicidade (T) e Transporte de Longo Alcance (TLA). / [en] This study proposes the presentation of a multimedia model, named CAPA, which is able to evaluate and compare a collection of 39 pesticides in a predetermined environment under steady state. The CAPA (Calculadora para Avaliação de Pesticidas no Ambiente) was based in the ESTAC FATE model (originally developed by the Canadian Environmental Modelling Centre, Trent University, Canada). The model works in Excel, is programmed in Visual Basic, assumes fugacity as the equilibrium criterion and evaluates the pesticides in three different levels: Level 1 (equilibrium), Level 2 (equilibrium with advective and reative input and output) and Level 3 (no equilibrium with advective and reative input and output and diffusive transport between media). Each pesticide is also compared with the others as a function of the bioaccumulation fator, persistence, toxicity and long range transport.

The final thesis is focused on a process management in praxes. The theoretical part of thesis concludes different techniques of mapping and analysing of a process. The practical part is focused on a practical analyse and mapping of the certain process in international financial institution. On the base of the process analyse are suggested changes to optimize the process.