In 1968, a 54,000 acre coal mine commenced operations on Black Mesa, Arizona, an arid and semi-arid region inhabited by the Hopi Tribe and Dine Nation. The coal mine fuels the power plant that generates electricity for the Central Arizona Project, which pumps renewable Colorado River water to Phoenix and Tucson. Water for mine-operations is pumped from a non-renewable groundwater aquifer upon which the Hopi and Dine depend. After forty years of development, conflict characterizes industrial groundwater exploitation on Black Mesa; there continues to be little understanding of the relationship between industrial withdrawals and its impacts upon hydrological and social-ecological systems of the region.Large-scale natural resource development is predicated upon deterministic studies required to disclose all potentially adverse impacts. This study performs a postaudit of groundwater model predictions used to determine the significance of these impacts. It demonstrates that drawdown caused by the mine was underestimated; drawdown caused by communities was overestimated; the models failed to capture the linear relationship between water level decline and spring discharge; and water levels predicted to recover by 2007 continue to decline in 2010.The Regulatory Authority developed four criteria for determining if damage to the aquifer had occurred in response to mining; over time, two damage thresholds were crossed and two had never been evaluated. A new model was implemented for regulatory purposes; simulations showed that a distant spring 60 miles from the mine is unaffected by the mine's withdrawals. The postaudit demonstrates how declining discharge from this spring has a strong relationship with industrial withdrawals (r = -0.84; R2 = 0.71; p < 0.0001); local pumping and precipitation have no statistically significant relationship with discharge from this spring.In 2008, the Regulatory Authority revised the four threshold criteria; all negative trends were removed from regulatory purview (including spring discharge) and remaining criteria assumed insurmountable damage thresholds; their condition will be determined by model simulations rather than actual observations.The Black Mesa case study reinforces the argument that the legislatively required process for predetermining environmental impacts is an elaborate ritual in which a manifestly political decision is disguised as unbiased scientific fact.

The US-Mexico border divides the communities of Palomas, Chihuahua and Columbus, New Mexico, but they remain intimately linked. Both communities suffer from inadequate social services, poor public infrastructure, high unemployment and high poverty rates. To confront these challenges, Palomas and Columbus work together, sharing resources like hospitals, firefighters, and even schools. Palomas and Columbus also share another vital resource—groundwater. In the parched Chihuahuan desert, the communities depend on this groundwater as their sole water supply source, yet their aquifer is contaminated with arsenic and fluoride. Local governments acknowledged this contamination as early as the 1970s, but it was not until the 2000s that they received the needed reverse osmosis technology and water/wastewater infrastructure to ameliorate household exposure to water contamination. This thesis compares how Columbus and Palomas have addressed water insecurity over a twenty-year period from 1996-2016, using a 1996 study as the baseline (Tanski et al. 1998). New data include a household survey of 152 households, 60 semi-structured interviews, and participant observations of water practices collected during two months of fieldwork in the summer of 2016. The central research questions of this thesis are Q1) What causes household water insecurity on the US-Mexico border? and Q2) How can water policymakers and providers more equitably provide users with access to clean, reliable, and affordable drinking water? From a human development perspective, water security is defined as having an adequate supply of reliable and affordable water for a healthy life. This thesis uses a political ecological lens to more critically examine how water security connects to socio-political processes of water governance and power imbalances. Following Jepson (2014), this thesis argues that water (in)security is produced by problems in water access, water quality, and water affect (or water distress) and unfolds within a complex, hydrosocial landscape. Applying Jepson’s (2014) water security typology to Columbus and Palomas revealed that each local water utility adopted a distinct approach to addressing groundwater contamination, predicated on their financial and social resources, and structured by national and bi-national water policies as well as their institutional parameters. The survey found household water security has improved in terms of water access and reliability. But, centralized water filtration technology increased costs and reduced affordability in Columbus, while decentralized water filtration technology inadequately resolved household water supply contamination in Palomas. Thus, despite the technological improvements, households remain unevenly exposed to water contamination and costs. This raises concern about approaches to water security, which should be more finely attuned to water equity. Water equity means the rights to access clean water are more equitably distributed within the communities, and there is greater recognition/participation of community members in decision making on water management.

No description available.

Water managers must balance the need for clean and safe drinking water with ever-increasing amounts of waste-water. A technique for treating and storing surface water called “managed aquifer recharge” (MAR) is frequently used to help maintain this balance. When MAR is used to produce drinking water, water managers must ensure that disease-causing microbial contaminants are removed from the water prior to its distribution. This thesis examined the processes responsible for removing a specific class of microbial contaminants called “enteric viruses” during MAR. Viruses are naturally removed in groundwater through adsorption and inactivation mechanisms. This thesis investigated how these virus removal mechanisms were affected by ionic strength (IS), dissolved organic carbon (DOC), and the age of the sand used in a MAR infiltration basin. This was done using batch and flow-through column experiments designed to mimic conditions characteristic of a basin infiltration MAR scheme in Uppsala, Sweden. Bacteriophage MS2 was used as a proxy for enteric viruses. All of the experiments were conducted at 4°C. Experimental data were modeled to describe the fate and transport of viruses in the infiltrated groundwater. Conventional least-squares optimization and generalized likelihood uncertainty estimation (GLUE) were compared as model fitting-approaches in order to determine how data uncertainty affects parameter estimates and model predictions. Results showed that the sand used in the infiltration basins accumulates adsorbed organic matter as it is exposed to infiltrating surface waters. This reduced the amount of MS2 that was removed due to adsorption and inactivation. Results from GLUE indicated that MS2 is more likely to inactivate in a time-dependent manner when in the presence of sand with high concentrations of organic matter. Both model fitting techniques indicated that virus attachment rates were significantly lower for sand with high organic carbon content. Neither methodology was capable of adequately capturing the kinetics of virus adsorption. Uncertainties in the experimental data had a large effect on the conclusions that could be drawn from fitted models. This study showed that the presence of natural organic matter reduces the value of the infiltration basin as a microbial barrier.

Thesis advisor: Rudolph Hon / Thesis advisor: Yvette Kuiper / Chloride-based deicers (NaCl, CaCl₂, MgCl₂), also referred to as road salt, are the most common substances used in maintaining safe roadway surfaces during the winter months. Upon application, road salt reacts with the accumulated snow or ice to form brine equilibrium solutions along the liquidus line in the salt-water system. Dissolved salts dissociate, leading to increased concentrations of the respective ions in nearby soils, surface water, and groundwater. Of the ions present in road salt, chloride has the advantage of tracking all chloride deicers at the same time and since chloride ions are conservative tracers in soils it stays unaffected by ionic exchange interferences. This study explores the mechanisms of chloride return flows by investigating chloride dissolved loads, chloride concentrations in stream waters, seasonal patterns, and changes over the course of four years in two separate watersheds in Massachusetts with differing degrees of urbanization. The chloride tracking technique used in this study is based on calibrated chloride concentrations obtained from specific conductance signals recorded every 15 minutes by automatic recording systems at two locations, one in rural central Massachusetts and the other in urban eastern Massachusetts. These systems are maintained by the USGS, which also provide the simultaneously recorded stream flow datasets. The dissolved chloride load carried by each river is calculated for each single 15-minute interval by multiplying water volume with the corresponding chloride concentration, resulting in a total of over 34,000 data points per annum per site. Hydrograph separation techniques were used to separate dissolved load transported by each river into two separate flow components, event flow resulting from precipitation events, and baseflow resulting from groundwater discharge. Well defined hydrograph baseflow supported periods yield consistent chloride concentrations independent of the season at either urban or rural study sites. Comparison of direct runoff dissolved chloride loads with the total annual dissolved loads suggests that only a small fraction of the deicers actually removed during the overland runoff events and that a minimum of 60% of the total load discharged each year in both urban and rural systems is transported by groundwater. From groundwater recharge by brines rural watersheds are currently retaining as much as 95% of the total chloride applied to roadways each year while urban and suburban watersheds may only retain 75% of the total chloride applied to roadways each year. The increased retention of chloride in rural areas is likely due to the decreased amount of chloride transported during winter seasons as event flow compared to urban watersheds. / Thesis (MS) — Boston College, 2009. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Geology and Geophysics.

O proposto deste estudo é a determinação da origem e o entendimento do comportamento geoquímico do nitrato no Aqüífero Adamantina, em Urânia, noroeste do Estado de São Paulo. As principais atividades desenvolvidas foram a elaboração de um cadastro de poços e de fontes potenciais de contaminação e a realização de análises físico-químicas (no campo e em laboratório) e isotópicas (nitrogênio) das águas subterrâneas. O Aqüífero Adamantina, na área urbana do município de Urânia, encontra-se extensivamente contaminado por nitrato e poluído por cloreto e amônio. A fonte de contaminação é do tipo antrópica, multipontual, proveniente de sistema de saneamento in situ do tipo fossas negras. As maiores concentrações de nitrato foram identificadas na zona rasa (ZR) do aqüífero (até 21 m de profundidade). Estas distribuem-se na forma de \"ilhas\" circulares. Foram observadas variações temporais destas concentrações quando comparadas às estações seca e úmida. Na ZR distinguem-se águas bicarbonatadas nitratadas cálcicas, secundariamente bicarbonatadas nitratadas sódicas e cloro-nitratadas cálcicas. As águas de profundidade intermediária (ZI), de 57 a 104 m de profundidade, são bicarbonatadas cálcicas e bicarbonatadas nitratadas cálcicas. Na zona profunda (ZP), até 160 m de profundidade, as águas são bicarbonatadas sódicas. Estas evoluem, da ZR para ZI, acompanhando o fluxo subterrâneo, da recarga para a descarga, junto às principais drenagens que cortam a área, com diminuição das concentrações de nitrato, cloreto e sódio. Predomina nas zonas rasa e intermediária um ambiente hidroquímico oxidante / This study has been conducted with a view to determining the origin and understanding the geochemical behavior of nitrate in the Adamantina Aquifer in Urânia, located in the northwest of the state of São Paulo. The main activities developed included a survey of wells and potential sources of contamination, as well as physical-chemical analyses (in the field and the laboratory) and isotopic (nitrogen) analyses of groundwater. In the urban area of the municipality of Urânia, the Adamantina Aquifer is found to be extensively contaminated by nitrate and pollued with chloride and ammonia. The source of this contamination is anthropic and multi-point in nature, caused by the in-situ sanitation system(cesspit). The highest concentrations of nitrate were detected in the shallow zone (ZR) of the aquifer (until 21 m depth). These concentrations are distributed in the form of circular \"islands\". Seasonal variations in these concentrations were observed when making a comparison between the rainy and dry seasons of the year. In the ZR, there are found to be calcium-nitrate-bicarbonate waters and, to a lesser extent, sodium-nitrate-bicarbonate and calcium-chloride-nitrate waters. Groundwater of intermediate depth (ZI), from 57 to 104 m depth, is calcium-bicarbonate and calcium-nitrate-bicarbonate. In the deep zone (ZP), until 160 m depth, sodium-bicarbonate waters are to be found. These waters evolve from the ZR to the ZI, in a manner that accompanies froundwater flow, from the recharge zone to the discharge zone, joined to the main drains that cross the area, with a fall in concentrations of nitrate, chloride and sodium. An oxidizing hydrochemical environment predominates in the shallow and intermediate zones.

Thesis advisor: Rudolph Hon / Road de-icing salts (predominantly NaCl, CaCl2, and MgCl2) are applied each winter in the northern US, northern Europe, and Canada to maintain safe driving conditions. It is widely recognized that road salt enters the environment through runoff and infiltration (Williams et al., 2000; Ostendorf, et al., 2001; J. Marsalek, 2003), resulting in salinization of freshwater (Godwin et al., 2003; Kaushal et al., 2005; Kelly et al., 2012). The chloride concentration (a proxy for deicers) has doubled in the last 20 years in the groundwater Norwell, MA, the primary public water supply for the town’s residents, and often exceeds the EPA secondary drinking water standard for chloride. The annual budget TDLCl¬ of Third Herring Brook in Norwell, MA is estimated using specific conductance and discharge datasets to determine the retention of dissolved deicers in the watershed during the study period. The estimated retention rate is between 59% and 78%. / Thesis (MS) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.

Por muito tempo acreditou-se que o solo atuaria como um filtro protegendo os grandes reservatórios de água subterrânea. Porém estes reservatórios possuem áreas onde existe uma maior sensibilidade à contaminação da água, devido características específicas do solo e não confinamento da rocha porosa. Estes locais são conhecidos também como áreas de recarga. O Sistema Aquífero Guarani (SAG) é atualmente a reserva de água subterrânea mais importante do Brasil. Transfronteiriço, ocupa 8 estados nacionais e 3 países da América do Sul, e recebe constante impacto pelo uso da água e de suas áreas de recarga por atividades industriais e agrícolas. No estado de São Paulo, Brasil, existe uma faixa contínua e estreita de afloramento do SAG que abrange a porção central, com ocorrência de solos arenosos, baixa profundidade da rocha sedimentar e ocupação do solo com atividades agrícolas intensivas (em especial citros, café, cana-de-açúcar e silvicultura). As características edafoclimáticas influenciam diretamente a vulnerabilidade dos aquíferos, e esta pode ser medida com ajuda de ferramentas de modelagem digital associadas a Sistemas de Informações Georreferenciadas (SIG). Sendo a atividade agrícola a mais recorrente neste sistema de recarga do SAG, este projeto objetivou estudar os impactos da agricultura neste sistema em três frentes. Primeiro pela determinação da vulnerabilidade do aquífero pelo modelo DRASTIC-SIG de uma área de recarga do Aquífero Guarani ocupada com a cultura de citros e com solo arenoso. Segundo pela avaliação da ocorrência de contaminação por agrotóxicos de águas superficiais, subterrâneas e sedimento por HPLC-UV/DAD e CG-µECD. E por final, avaliando o comportamento do herbicida Diuron em solo da área de estudo. Os resultados do modelo DRASTIC apontaram alta vulnerabilidade do aquífero para a região estudada. Foi identificada contaminação pontual por Heptacloro em duas amostras de água superficial analisadas. Quanto ao comportamento do Diuron em solo, este apresentou baixo risco de lixiviação e baixa adsorção em solo arenoso. Estes resultados indicam que estas áreas devem ser mais estudadas quanto à vulnerabilidade, visando o direcionamento de políticas públicas para orientar a melhores práticas nas lavouras objetivando a proteção desta importante reserva natural de água, que está atualmente exposta às atividades antrópicas e pode ter a sua qualidade comprometida no longo tempo / For a long time it was believed that watersheds would be free of environmental contamination due protection exerted by soil and rock layers. However, aquifers may have confined areas where it is covered by one or more layers of solid rock, and not confined areas where the sedimentary rock, which retains water, is outcropping. In the non-confined areas, the aquifer is recharged usually by direct infiltration of rainwater or indirectly from other water bodies. Thus, the recharge areas have higher sensitivity and vulnerability to contamination because they are more exposed to anthropogenic activities. The Guarani Aquifer System (GAS) is currently the most important groundwater reserve in Brazil. Transboundary, it occupies 8 national states and 3 countries in South America, and receives constant impact of it is uses and soil occupation for industrial and agricultural activities. In São Paulo State, Brazil, there is a continuous narrow strip of outcrop of GAS covering the inner portion of the central part of the State, with the occurrence of sandy soils, shallow sedimentary rock and soil occupation with intensive agricultural activities (especially citrus, coffee, sugarcane and planted forestry). Soil and climatic characteristics directly influence the vulnerability of aquifers, and this can be measured with the help of digital modeling tools associated with Geo-referenced Information Systems (GIS). Due the agricultural activity being the most practiced activity in the GAS recharge system, this project aimed to study the specific impact of agriculture in the system by three fronts. First was to determine the vulnerability by DRASTIC-GIS model of a recharge area of the Guarani Aquifer occupied with the cultivation of citrus and sandy soil. Second, was the evaluation of the occurrence of pesticides contamination in surface water, groundwater and sediment by HPLC-UV/DAD and GC-µECD for the period of one year. And last, studying the Diuron behavior in the soil of the study area. The results of the DRASTIC model showed a high vulnerability of the aquifer to the region studied. Spot contamination was identified by Heptachlor in two field samples of surface water. The Diuron behavior in soil showed lowrisk of leaching and low sorption coefficient. These results indicates that these areas should be more studied for vulnerability, targeting the direction of public policies to guide best practices in the fields aiming to protect this important natural water reserve, which is currently exposed to human activities and may have their quality compromised in the long time

A importância do estudo de aqüíferos livres e rasos se evidencia quando se leva em conta que tais aqüíferos são altamente vulneráveis a contaminação e que em geral se encontram em regiões densamente povoadas. Com o objetivo de melhor compreender a dinâmica do fluxo de água subterrânea na zona saturada destas formações aqüíferas, foi construído e calibrado um detalhado modelo tridimensional e transiente para representar o fluxo subterrâneo em uma porção de um aqüífero livre e raso que ocorre no Parque Ecológico do Tietê, no Município de São Paulo. Este modelo, baseado em dados de cargas hidráulicas de 81 poços de monitoramento instalados em uma área de 320m2 medidas diariamente, em valores diários de precipitação na área e em 75 determinações de condutividades hidráulicas, foi construído e executado através do software Visual MODFLOW e calibrado por meio do software PEST, através de um método de regressão não linear. Os resultados gerados por este modelo para um evento de recarga rápida indicam que a distribuição de cargas hidráulicas na área de estudo é governada pela recarga regional, pela distribuição das condutividades hidráulicas horizontais e pelas vazões específicas das camadas superiores da formação, mas é praticamente independente da intensidade e distribuição temporal da recarga local, que influencia apenas os níveis mais rasos da formação. Além disso, verifica-se o caráter extremamente dinâmico do fluxo, que responde rapidamente ao evento de recarga regional, apresentando alterações significativas de intensidade e direção no intervalo de apenas alguns dias. Tais resultados, verificados apenas por meio de um modelo tão detalhado como o produzido neste trabalho, sugerem que estratégias comuns de avaliação podem não ser capazes de avaliar suficientemente bem o comportamento deste tipo de aqüífero. / The importance of studying unconfined and shallow aquifers is verified when taking into account that these aquifers are highly vulnerable to contamination and that they are often located under heavily populated regions. A detailed three-dimensional and transient model, which represents the groundwater flow in an area of an unconfined and shallow aquifer at the Parque Ecológico do Tietê, in the Municipality of São Paulo, Brazil, was created and calibrated with the objective of enhancing the comprehension of the dynamics of the groundwater flow in the saturated zone of these formations. This model was based on hydraulic head data of 81 monitoring wells, which were installed in an area of 320 m2 and measured on a daily basis, on daily values of precipitation occurring in the area and 75 determinations of hydraulic conductivities. The model was created and run using the software Visual MODFLOW and calibrated using the software PEST, based on a non-linear regression method. The results generated by this method for an event of rapid recharge indicate that the distribution of the horizontal hydraulic conductivities and by the specific yield of the upper layers of the formation, but it is mostly disconnected from the intensity and temporal distribution of the local recharge, that only influences the shallowest levels of the formation. Furthermore, the extremely dynamic character of the flow can be verified, which responds rapidly to the regional recharge event, presenting significant changes of intensity and direction within only a few days. These results, which were only observable through a very detailed model such as the one produced and presented in this study, suggest that commonly employed evaluation strategies may not be capable of evaluating this kind of aquifer in a satisfactory way.

Typescript (photocopy). / Digitized by Kansas Correctional Industries / Department: Economics.