A Barragem de Itaipu é uma obra de engenharia de grande importância. Localizada na fronteira entre o Brasil e o Paraguai no Rio Paraná e com coordenadas geográficas aproximadas 25°24\'29\"S, 54°35\'21\"O, ela fornece energia elétrica a estes dois países e deve ser constantemente monitorada de modo a manter níveis de qualidade e segurança. Mais de dois mil instrumentos foram instalados e fornecem dados contínuos sobre diversas características da fundação e estrutura da barragem, incluindo mais de 650 piezômetros. A avaliação de níveis piezométricos em barragens é importante, pois refletem os valores de subpressão que atuam na estrutura da barragem. A utilização de novos métodos em tais análises pode permitir agilidade na tomada de decisões por parte da equipe de segurança de barragens. Dependendo do método aplicado, uma melhor compreensão do fenômeno no tempo e espaço pode ser obtida. Este estudo aplica Redes Neurais Artificiais (RNA) para simular o comportamento dos piezômetros instalados em uma descontinuidade geológica na fundação da Barragem de Itaipu. Ele considera diferentes tipos de dados de entrada em uma Rede Neural Multicamadas e determina a melhor arquitetura de RNA que mais se aproxima da situação real. / Itaipu Dam is an engineering work of high importance. Located at the border between Brazil and Paraguay in the Paraná River and with approximated geographical coordinates 25°24\'29\"S, 54°35\'21\"W, it provides electrical energy to these two countries and has to be constantly monitored in order to maintain its levels of quality and security. Over two thousand instruments have been installed and they provide continuous data about several characteristics of the dam foundation and structure, including more than 650 piezometers. The evaluation of piezometric levels in dams is important for it reflects the values of the uplift pressure that acts on the structure of the dam. The utilization of new methods in such an analysis can provide agility to decisions-taking by the security team of the dam. Depending on the method applied, a better comprehension of the phenomenon in time and space may be achieved. This study employs Artificial Neural Networks (ANN) to simulate the behavior of the piezometers installed in a geological discontinuity in the foundation of Itaipu Dam. It considers different types of entry data in a Multilayer Neural Network and determines the best ANN architecture that is closest to the real situation.

La presente tesis titulada “Instrumentación geotécnica para monitorear el nivel freático y calidad del agua con sensores eléctricos en piezómetros de tubo abierto”, planteará las nuevas propuestas y actividades que se realizan para el monitoreo de las aguas subterráneas, que tiene como objetivo principal preservar los recursos hídricos y el ecosistema. La obtención de la serie de datos del nivel freático, permitirá conocer las variaciones bruscas de los niveles de agua durante el tiempo de operación; a su vez nos permitirá determinar si existen flujos de agua que alteren el comportamiento del mismo. Además en función a la información obtenida de los resultados de los ensayos físico-químicos y de los resultados de los ensayos de determinación de metales pesados realizados en laboratorios. Estos indicadores fueron comparados y nos permitieron conocer cuál es el estado de las aguas subterráneas en el momento de su evaluación. La metodología empleada es del tipo explicativa y cuantitativa, el diseño de la investigación será descriptivo, observacional y de corte longitudinal. Por ello la presente tesis pretende establecer una metodología de monitoreo de aguas subterráneas, que permita mejorar el comportamiento ambiental de las zonas de operación de una empresa dedica a la explotación de materia prima para el sector construcción; por lo cual se procesaron parámetros asociados a los aspectos ambientales establecidos en las herramientas de gestión y la legislación ambiental aplicable. Los resultados obtenidos respecto al nivel freático permitieron establecer aquellas épocas de incremento y disminución de los niveles de agua; además se lograron identificar posibles focos de contaminación del agua subterránea, presente en el área de influencia de las unidades de operación de una empresa cementera, concluyendo con la aceptación de las hipótesis planteadas. This thesis entitled as "Geotechnical instrumentation to monitor the phreatic level and water quality sensors in electrical piezometers open tube", raise new proposals and activities undertaken for monitoring groundwater, whose main objective is to preserve the water resources and the ecosystem. Obtaining the data series of the phreatic level, will reveal the abrupt changes in water levels during the time of operation; in turn will allow us to determine if water flows that alter behavior of the same. Also, according to information obtained from the results of the physicochemical and the results of tests of heavy metal determination tests conducted in laboratories. These indicators were compared and let us know what the status of groundwater at the time of evaluation. The methodology used is the explicative and quantitative type, the research design is descriptive and longitudinal. Therefore this thesis aims to establish a methodology for groundwater monitoring, which improves environmental performance of operational areas of a company engaged in the exploitation of raw materials for construction sector; whereby parameters associated with the environmental aspects set out in the management tools and the applicable environmental legislation is processed. The results regarding the phreatic level allowed to establish those periods of rising and falling water levels, they were also able to identify potential sources of groundwater contamination present in the area of influence of the operating units of a cement company, concluding with the acceptance of the hypotheses.

This research project evaluated the overall hydroperiod and effects of monitoring well design parameters on observed levels of saturation in created wetlands with high-clay subsoils at the Cedar Run 3 mitigation bank site in Prince William County, Virginia. Three complete replications of an electronic central array and an associated surrounding array of manually monitored wells and piezometers were installed. The electronic arrays contained a U.S. Army Corps of Engineers (USACOE) standard monitoring well, as well as piezometers and tensiometers at three depths. The manually monitored well + piezometer arrays (3 per location; 9 total) consisted of 12 variants of screen types and filter pack materials, well diameter, and unlined bore holes. The site exhibited a complex seasonal hydroperiod ranging from ponded winter conditions to deep (< -50 cm) summer dry down. The site also exhibited epiaquic (perched) conditions following summer and fall precipitation events. Apparent water levels in deep (> 1 m) piezometers exhibited an unusual hydroperiod with highest levels in summer. Differences in well/piezometer diameter, design, and packing texture/fit produced surprisingly different apparent water levels that varied from ~ 4 to over 28 cm during both the winter ponded periods and summer subsoil water table flux periods. Thus, one important finding is that relatively simple differences in well designs can have dramatic effects on observed water levels. Overall, the standard USACOE appeared to be relatively accurate for predicting saturation levels during ponded periods, but nested piezometers are preferred and more accurate for the drier summer and fall. / Master of Science

Water BudgetThis chapter documents the hydrologic analysis of a watershed within the Windy Ridge mega-landslide of Central Utah to (1) create a water budget and (2) place a quantitative limit on the magnitude of climatic changes documented by Shurtliff et al. (2017) and Hudson et al. (2019). (1) A water budget was calculated over the last four years using instrumentation and weather stations both within and surrounding the watershed, In terms of precipitation input, 85% is released by the evapotranspiration of the Pinyon-Juniper forest, 4% discharges as surface water from the base of the watershed, and 11 % infiltrates the groundwater system. This infiltration rate is slightly lower than the 15% suggested by Maxey-Eakin method (Maxey and Eakin, 1949), likely due to the less permeable, clay-rich sediment. (2) Previous studies performed on Garden Basin Cattail (GBC) Fen at the base of its watershed suggest swings from pond-like to wetland environments (Shurtliff et al, 2017; Hudson et al, 2019). This study estimated precipitation values necessary to create standing water (pond) environments. Changes in annual precipitation, as well as input from North American monsoon (NAM), may cause these environmental changes. Each of these cases were examined. Trends in piezometer measurements compared to mean annual precipitation indicated that ‰¥ 644 mm of annual precipitation are required to sustain a wet (perennial standing water) environment. The change from wetland to pond conditions may depend on seasonal trends in precipitation. This study suggests an increase of 150-300 mm of precipitation in late summer (NAM) may be connected to perennially wet conditions. The higher annual precipitation values, largely accomplished by NAM fluctuations, caused a transition from wetland to pond (Hudson et al., 2019; Shurtliff et al., 2017). Chapter 2: Core AnalysisChapter 2 further documents the watershed's historical environmental and climate record by analyzing sediment and topography surrounding GBC fen, adding to the works of Shurtliff et al. (2019) and Hudson et al. (2019). A core was extracted from GBC fen at the base of the watershed and the sediment analyzed in terms of color, texture, environmental scanning electron microscope (ESEM) imaging, RockEval pyrolysis, and 14C ages. These results were then compared to pre-existing pollen and diatom proxies completed on a previous core by Shurtliff et al. (2019). This study suggests climatic variation, along with basin fill processes, was the driver of environmental change in GBC fen (Garden Basin watershed). Climate proxies show the basic trend from a particularly wet period (12-9 ka BP) of more stagnant or deeper water, to a much dryer period of much shallower water levels (9-3 ka BP), followed by a rebound in moisture levels, especially in the past few hundred years. Although climate was the driver of transitions within GBC2 core, a pollen record of sustained shallow water plants and MASW (Park et al., 1999) survey may suggest beaver activity.