Made available in DSpace on 2015-05-14T12:09:03Z (GMT). No. of bitstreams: 1 parte1.pdf: 2222495 bytes, checksum: 927bf1cf555b1b2fb857b8aee36f0d0d (MD5) Previous issue date: 2011-03-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This study aimed at assessing the direct recharge of the river Gramame basin aquifer, located in the south region of Paraiba state, through the application of the method WTF (water table fluctuation). Moreover, the study aimed at understanding the behavior of static level variation of the unconfined aquifer, in terms of space and time. For that, a monitoring program was carried out in the unconfined aquifer. Static levels of 27 wells were measured as well as rainfall data. During the period of static level monitoring, three different types of behavior were detected. Investigations have sought to correlate these variations with different behaviors, including: rainfall, thickness of the unsaturated soil, digital terrain model, land use, geology and hydraulic conductivity. This last property was obtained using Beerkan methodology. Most of the factors have influence on the fluctuation of static level, except the geology, most likely due to the low level of detail of this information. The direct calculated recharge for the monitored hydrological year (2009/2010) ranged between 53 and 105 mm, which represents between 5 and 10% of average rainfall in the basin during the study. These values were lower than expected for a humid region, probably due to the low values of rainfall during the survey, which was about 42% lower than average annual basin. According to the results, a systematic monitoring of the aquifer for a longer period is recommended, in order to provide better input data to decision making regarding the use of the groundwater basin. / Este trabalho teve como objetivo a determinação da recarga direta na bacia hidrográfica do rio Gramame, porção sul do Estado da Paraíba, através da aplicação do método WTF (water table fluctuation). Para tanto, foi realizado o monitoramento do aqüífero livre da bacia, através de freqüentes medições do nível estático de 27 poços e tratamento de dados de precipitação. Durante o período do monitoramento do nível do lençol freático dos poços, três tipos diferentes de variação foram detectados. Investigações realizadas buscaram correlacionar as variações com alguns fatores, entre eles: precipitação, espessura da camada não-saturada do solo, elevação do terreno, uso do solo, geologia e condutividade hidráulica, que foi obtida a partir da utilização da metodologia Beerkan. A maioria dos fatores exerceu grande influência no comportamento do aqüífero, com exceção da geologia, provavelmente pelo baixo nível de detalhes destas informações. A recarga direta calculada para o ano hidrológico do monitoramento (2009/2010) variou entre 53 e 105 mm, o que representa entre 5 e 10% da precipitação média na bacia durante o estudo. Estes valores ficaram abaixo do esperado para uma região úmida, muito provavelmente pelos baixos índices pluviométricos registrados durante a pesquisa, que foi cerca de 42% menor do que média anual da bacia. Recomenda-se o monitoramento sistemático do aqüífero por um período mais longo, a fim de dar subsídios na tomada de decisões quanto à utilização da água subterrânea da bacia.

O objetivo principal deste trabalho é estimar a recarga direta e profunda do Sistema Aqüífero Guarani (SAG) na bacia representativa do Ribeirão da Onça. Paralelamente são analisados os comportamentos do aqüífero e da evapotranspiração na bacia. A bacia do Ribeirão da Onça apresenta características representativas típicas da região de afloramento do Sistema Aqüífero Guarani (SAG) no Estado de São Paulo. A bacia do Ribeirão da Onça tem a vantagem de ser uma bacia amplamente estudada em vários aspectos referentes à sua hidrologia e hidrogeologia. Obtiveram-se dados suficientes para fazer um balanço hídrico da bacia monitorada por um ano hidrológico e extrair uma estimativa da recarga direta e profunda nesta zona de afloramento do Sistema Aqüífero Guarani. Utilizaram-se dados da flutuação do nível do aqüífero para estimar a recarga direta e a variação do armazenamento subterrâneo. Os poços de monitoramento foram distribuídos em diversas culturas, possibilitando uma análise do comportamento do aqüífero por cultura. Estimou-se que a recarga direta do sistema, na bacia, está em torno de 400 mm anuais. A estimativa da recarga profunda indica um valor entre zero e 40 mm. A análise do comportamento do aqüífero mostra que a recarga direta é menor em solos cultivados com eucalipto e maior em áreas cultivadas com pastagem. A variação do nível do aqüífero apresenta forte correlação entre as culturas, exceto a de eucaliptos. A posição dos poços é fator fundamental para a estimativa da recarga direta. Terrenos mais planos tendem a produzir uma maior recarga direta do aqüífero. Avaliaram-se métodos de estimativa de evapotranspiração. A avaliação foi realizada entre alguns métodos empíricos e a evapotranspiração obtida através do balanço hídrico. Estimou-se uma evapotranspiração em torno de 900 mm anuais a partir do balanço hídrico. Todos os métodos empíricos e semi- empiríco, com exceção do de Thornthwaite, superestimaram a evapotranspiração quando comparados ao valor estimado pelo balanço hídrico. O método de Hargreaves-Samani foi o que mais se distanciou, com 1894 mm anuais. O método de Thornthwaite foi o que mais se aproximou, com 936 mm anuais, com discrepância de apenas entre 3% e -6% do valor estimado pelo balanço hídrico. A utilização dos métodos empíricos e semi- empíricos de estimativa da evapotranspiração, para estudos da recarga de aqüíferos na região da zona de afloramento do Sistema Aqüífero Guarani no estado de São Paulo, deve ser vista com cautela. Só uma avaliação prolongada poderá indicar quais os métodos mais se aproximam da realidade. Pelos resultados obtidos, recomenda-se a revisão das estimativas de disponibilidade hídrica sustentável do Sistema Aqüífero Guarani e a utilização com cautela dos métodos empíricos e semi-empíricos de estimativa da evapotranspiração, para estudos hidrológicos no estado de São Paulo. A análise do monitoramento da bacia do Ribeirão da Onça só vem a confirmar a representatividade dos estudos feitos nessa região e a grande relevância que esses estudos terão para o gerenciamento desse importante reservatório que é o Sistema Aqüífero Guarani / The main objective of this work is to esteem the recharge direct and deep in the Guarani Aquifer System (GAS) at the representative basin of Ribeirão da Onça. At the same time, the behavior and the evapotranspiration at the water basin have been studied. The Ribeirão da Onça water basin has typical representative characteristics on the outcrop region in the Guarani Aquifer System (GAS) in the São Paulo State. Its hydrology and hydrogeology have been widely studied under several aspects, what consists of an advantage. It had been gotten enough data to make a water balance of the monitored water basin for one hydrological year and get out the direct and deep recharge estimate at this outcrop region of the Guarani Aquifer System. It had been used data of the aquifer level fluctuation in order to estimate the direct recharge and the subterranean storage. The monitoring wells are distributed in several crops, making the behavior in the aquifer per crop analysis possible. The estimated direct recharge of the system, at the water basin, is about 400 mm. The estimated deep recharge is between zero and 40 mm. The aquifer behavior analysis shows that the direct recharge is smaller in soils with eucalyptus cultivated than it is in other crops. The wells position is also an important aspect to the direct recharge. Plainer and higher lands tend to produce a greater direct recharge of the aquifer. Evapotranspiration esteem methods had been also evaluated. The evaluation was made with some empirical methods and the evapotranspiration gotten through to the water balance. The evapotranspiration estimated through the water balance was about 900 mm per year. All the empirical and semi-empirical methods, excepting Thornthwaite, overestimated the evapotranspiration if compared to the water balance estimated value. The Hargreaves-Samani´s method was the most far-away, with 1894 mm per year. The Thornthwaite method was the closest, with 936 mm per year, only between -6% and 3% of the estimated value through the water balance. The use of empirical and semi-empirical methods to esteem the evapotranspiration, in order to study the aquifers recharge in the region of the outcrop zone of the Guarani Aquifer System at São Paulo State, must be used with caution. Only a long-term evaluation could say which methods get closer to the reality. Through the analysis of the gotten results, it is recommended a revision of the estimated sustained water accessibility of the Guarani Aquifer System and the cautious use of the empirical and semi- empirical methods to esteem the evapotranspiration, to hydrological studies at São Paulo State. The analysis of the monitoring of the Ribeirão da Onça water basin comes to prove the active role of the studies in this region and the importance that this studies will have to the management of this great reservoir that is the Guarani Aquifer System

Philosophiae Doctor - PhD / The focus of this study was on recharge mechanisms and recharge estimation within the Table Mountain Group area. The study evaluated recharge processes and recharge estimation methods in the Table Mountain Group aquifer systems. / South Africa

Magister Scientiae - MSc / The Western Klein Karoo-Montagu area is located in the mid-eastern of the Western Cape Province , South Africa. In most of the study areas within semi-arid climatic zone , groundwater plays an important role in meeting both agricultural and urban water requirements. Developments of agriculture depend on more and more groundwater supply from Table Mountain Group (TMG) sandstone aquifer system in the study area. Groundwater recharge is considered as one of the most important factors governing the sustainable yield of groundw ater exploitation. There have been few studies on the recharge estimation of the TMG aquifer system in the Montagu area. Thus accurate and reliable recharge estimation of the TMG aquifer system in the Montagu area is important. The TMG aquifer in the Montagu area comprises approximate 4,000m thick sequence of sandstone with an outcrop area of 3,124 km2, which is recharge area. The outcrops are characterized by mountainous topography with sparse to dense vegetation, shallow and intermittent diverse soils and mean annual rainfall of 350-450 mm/yr. Based on detail analysis and interpretation of factors influencing recharge, water balance method is used to estimate recharge rates by using readily available data (rainfall, runoff, temperatures). Other estimate methods are difficult to be applied due to the limited information available in the study area. In this study, the water balance approach based on empirical evapotranspiration and runoff model is employed to determine and analyse long-term average water recharge. The long-term average recharge is modelled as a function of the regional interaction of the site conditions: climate, soil, geology and topography. Modelling is performed according to the outlined procedure using long-term climatic and physical data from the different rainfall period of different gauge stations. As results, actual evapotranspiration, direct runoff and recharge have been quantified. The recharge ranges vary from 0.1 mm/yr to 38.0 mm/yr in the study area, and the values less than 20.0 mm/yr are predominant. Relatively low recharge rates coincide with low precipitation in most regions. Recharge is less than 5.0 mm/yr if mean annual precipitation (MAP) is less than 400 mm/yr. The ranges of 10.0-20.0 mm/yr of recharge occur in precipitation ranging from 600 mm/yr to 1,200 mm/yr. The recharge rates exceeding 20.0 mm/yr are more related to the precipitation with 800 mm/yr or more. The low recharge rates less than 2.0 mm/yr are related to single high rainfall event in the study area. The total recharge volume of the outcrop of the TMG in the study area is approximately 54.2× 106m3/yr . Approximately 29.3% of the stream flow may be contributed by recharge in terms of baseflow. The recharge in the study area increases with increasing precipitation, but recharge percentage is non-linear relationship with the precipitation. Separate high rainfall events mainly contribute recharge if annual precipitation is extremely low in the study area. Spatial distribution of recharge is associated with the variations in precipitation, geological and geomorphologic settings in the study area. The method used yields a point estimate and then ext rapolate s to the whole study area. The ranges of recharge may be exaggerated or underestimated due to the finite number of the rainfall stations in the outcrop of the TMG of the study area. After comparison to other recharge estimates from early studies in the area, the estimates are considered as reasonable and reliable. The feasibility of the water balance approach in semi-arid area is confirmed as well. The estimates based on the water balance model should be crosschecked before they are applied for management of groundwater resources. / South Africa

Magister Scientiae - MSc / This study focuses on the development of a Direct Aqueous Injection Gas Chromatographic method with Flame Ionization Detection (DAI-GC/FID) for the analysis of MTBE and TBA. The analytical method was then applied in a site specific study where MTBE contamination was evident. The method achieved detection limits of 1 ppm for MTBE and 0.1 ppm for TBA. The method showed good precision, accuracy and selectivity. The method was selected primarily for its ability to simultaneously analyze MTBE and TBA. The result of the site specific study showed the persistence of high concentrations of MTBE and TBA at the source of contamination, whilst concentrations at the adjacent primary school dropped to below detection limits as a result of rapid natural attenuation. It was found that an overall decrease in MTBE concentrations was met with an increase in TBA concentrations; which is a direct indication of MTBE degradation. Despite the fact that problematic MTBE concentrations persist at the source of contamination, limited evidence of the persistence of MTBE contamination was identified at the adjacent primary school. As such, MTBE health risks from existing pathways were found to be irrelevant for receptors at the adjacent school. / South Africa

The Bahamas is a small island nation that is dealing with the problem of freshwater shortage. All of the country’s freshwater is contained in shallow lens aquifers that are recharged solely by rainfall. The country has been struggling to meet the water demands by employing a combination of over-pumping of aquifers, transport of water by barge between islands, and desalination of sea water. In recent decades, new development on New Providence, where the capital city of Nassau is located, has created a large area of impervious surfaces and thereby a substantial amount of runoff with the result that several of the aquifers are not being recharged. A geodatabase was assembled to assess and estimate the quantity of runoff from these impervious surfaces and potential recharge locations were identified using a combination of Geographic Information Systems (GIS) and remote sensing. This study showed that runoff from impervious surfaces in New Providence represents a large freshwater resource that could potentially be used to recharge the lens aquifers on New Providence.

The Swedish Nuclear Fuel and Waste Management Company, SKB, is planning to construct a deep geological repository for spent nuclear fuel in Forsmark, Sweden. Leakage of groundwater into the repository during the construction and operational phases might cause a groundwater drawdown that in turn may affect the hydrological conditions in sensitive habitats in the area. The sensitive habitats in question are wetlands, home to several protected species. SKB has planned to take mitigation measures in the case variations of the surface-water elevation are identified for the concerned wetlands. The mitigations measures consists in infiltrating water in the ground in the direct vicinity to the wetland to create a higher groundwater pressure that then will propagate to the surface-water. This study describes the modelling of a pilot-study of such a measure and aims at serving as one of the background materials for the planning and design of the pilot study. The aims of the pilot study are to show that the surface-water level in a wetland can be controlled and to gain knowledge and experiences regarding artificial groundwater recharge for this purpose. The pilot study would take place before the construction of the repository so the undisturbed case is considered. The results show that an infiltration facility can control the surface-water level in a wetland. It is also shown that an infiltration rate of 0.5 L/s is enough to manipulate the surface-water level in the undisturbed condition.

This master’s project was conducted under the direction of the Central Coast Regional Water Quality Control Board (Water Board) to assist with augmenting their Basin Plan. An investigation of the current practices for identifying and managing groundwater recharge areas was conducted, and strategies for protecting water quality by managing land uses in groundwater recharge areas were developed. Data sources included a review of agency documents, websites, and maps; interviews with stakeholders, and literature research. Data from these sources provided the foundation on which to base strategies for maintaining and improving groundwater quality in the Central Coast Hydrologic Region. This project recommends standard language for groundwater recharge areas, minimum criteria for identifying and mapping these areas, and protection strategies. The Water Board must establish minimum standards to protect groundwater recharge areas, and collaborate with local agencies to protect the quality of groundwater throughout their jurisdiction.

A groundwater model of a 126.2-acre ranch in Cambria, California was expanded upon to analyze the effects of artificial recharge and a subsurface barrier. The ranch lies within the 48mi2 Santa Rosa Creek Watershed along the Central Coast of California. The mainly agricultural watershed outfalls to the Pacific Ocean to its west. Creek Lands Conservation, a non-profit that aims to conserve and restore habitat along the Central Coast, plans to identify projects to restore stream flow during dry seasons in the creek that runs through the Santa Rosa Creek Watershed and to increase artificial groundwater recharge. This study focuses on two of those projects. One project is an existing recharge basin and the other is a subsurface barrier. The objective of this numerical model is to improve upon an existing model by using a longer duration of data to calibrate the model, calibrating the model to hydraulic properties of soil samples that were obtained from the site at various depths, refining elevations of layers through integration of new borehole exploration data, and adding updated and new data such as mountain front recharge and pumping rates. The modeling program used was GMS which allows calculation and determination of heads and flow directions. Within the model, there are three separate layers based on hydrogeological characterization from previous studies. There is an upper unconfined zone, a confining clay layer, and a confined zone. A package within GMS (Groundwater Modeling System) called PEST (i.e., Parameter ESTimation) was used to calibrate the model to known water surface elevations throughout the site. Data such as elevations, head boundaries, stream flow, pumping rates, recharge, evapotranspiration, well locations, and hydraulic properties of the subsurface was processed and incorporated into the overall model in GMS. Recharge rates from the basin were estimated to be 0.1 m/day roughly starting in February and ending in May for each year. The model showed that the confining layer slows down the flow of water from the recharge basin, but it does eventually percolate into the underlying groundwater aquifer before reaching Santa Rosa Creek after a time period of 5 years. The proposed subsurface barrier does reduce travel times of groundwater by roughly a year and helps percolation of water into the confined layer. With the subsurface barrier it was seen that the water held within the confined aquifer increased on average 5,200 m3 each year.

No description available.