The purpose of this study is the characterization and modeling of Ulubey aquifer system which serves as an important water supply for USak province located in inner parts of the Aegean Region in Turkey. In recent years, growing population, accelarating industrial activities and on the contrary decreasing rainfall and contamination of the surface water resources made groundwater indispensable to meet domestic, agricultural and industrial water demands of USak province. All these facts necessitate the development of a groundwater management plan, which this study aims to end up with. For this purpose, every single component of the recharge/discharge mechanisms of the groundwater budget of the aquifer system should conceptually be comprehended. However, due to lack of data, all of the components can not be precisely determined. Hence, a mathematical groundwater flow model successfully calibrated under steady state conditions, is utilized to calculate the missing components of the groundwater budget and also to test the effects of increased pumping rates for irrigational and domestic uses to supply the increasing demand in the future. For this purpose, three management scenarios are set up under transient conditions over a planning period of 20 years. Drawdown maps, groundwater budgets and groundwater level hydrographs are utilized to observe the effects. The results of these simulations proved that neither of the tested management scenarios creates significant drawdowns or change in groundwater reserve of the Ulubey aquifer system.

Groundwater and surface water in the Edwards Plateau region exhibits spatial variability arising from mineral differences in aquifers and mixing of groundwaters with diverse flow paths and ages. Integration of basic hydrochemical and isotope data (⁸⁷Sr/⁸⁶Sr, [delta]¹⁸O, [delta]D, ¹⁴C, ³H) document that groundwaters in the Lower Cretaceous Edwards-Trinity (Plateau) aquifer system reflect intermixing of modern and Pleistocene recharge. Pleistocene recharge occurred under cooler paleo-climatic conditions, based on [delta]¹⁸O variance of 4.59%, and flow traversed sub-cropping Permian evaporite and Triassic strata under hydraulic conditions that promoted upward flow into the Plateau system. Recharge areas may have been in topographically elevated areas in New Mexico that no longer are connected with the Plateau. Present distribution of groundwaters with higher SO₄/Cl values occurring beneath topographic divides on the Plateau suggests that modern recharge occurs preferentially in losing-stream networks and is inhibited on divides by low-permeability soils. Relationships between ¹⁴C, tritium, [delta]¹³C, and Mg/Ca values confirm that effectively younger groundwaters occur beneath the upper parts of drainage networks, but down slope of divides. Thus, groundwater-age and hydrochemical data suggest that recharge preferentially occurs in the upper parts of drainage networks. Correlations between groundwater relative age and Mg/Ca enable estimation of the proportion of modern recharge at specific well locations based on Mg/Ca values and enables estimating local absolute recharge rates from regional-scale recharge estimates obtained from regional flow models. The Upper Colorado River bounds the northern and northeastern margin of the Plateau system and shows systematic chemical evolution along its flow path, including decreasing salinity and increasing SO₄/Cl values. The stream can be conceptually divided into three segments that each reflect groundwater inputs from five hydrochemically distinct intervals: 1) deep Permian and Pennsylvanian reservoirs similar to those that produce hydrocarbons in the region; 2) Upper Permian halite (Salado Formation); 3) the Triassic siliciclastic aquifer (Dockum Group); 4) the sulfate-evaporite-bearing Permian system (Ochoan, Guadalupian, and Leonardian Series); and 5) the Plateau aquifer system. Conservative mixing models suggest that any aquifer that the river is traversing at a specific location contributes a distinct hydrochemical signature, but the dominant contribution is from the Plateau system. / text

The study focuses on an alluvial plain situated within a large meander of the Logan River at Josephville near Beaudesert which supports a factory that processes gelatine. The plant draws water from on site bores, as well as the Logan River, for its production processes and produces approximately 1.5 ML per day (Douglas Partners, 2004) of waste water containing high levels of dissolved ions. At present a series of treatment ponds are used to aerate the waste water reducing the level of organic matter; the water is then used to irrigate grazing land around the site. Within the study the hydrogeology is investigated, a conceptual groundwater model is produced and a numerical groundwater flow model is developed from this. On the site are several bores that access groundwater, plus a network of monitoring bores. Assessment of drilling logs shows the area is formed from a mixture of poorly sorted Quaternary alluvial sediments with a laterally continuous aquifer comprised of coarse sands and fine gravels that is in contact with the river. This aquifer occurs at a depth of between 11 and 15 metres and is overlain by a heterogeneous mixture of silts, sands and clays. The study investigates the degree of interaction between the river and the groundwater within the fluvially derived sediments for reasons of both environmental monitoring and sustainability of the potential local groundwater resource. A conceptual hydrogeological model of the site proposes two hydrostratigraphic units, a basal aquifer of coarse-grained materials overlain by a thick semi-confining unit of finer materials. From this, a two-layer groundwater flow model and hydraulic conductivity distribution was developed based on bore monitoring and rainfall data using MODFLOW (McDonald and Harbaugh, 1988) and PEST (Doherty, 2004) based on GMS 6.5 software (EMSI, 2008). A second model was also considered with the alluvium represented as a single hydrogeological unit. Both models were calibrated to steady state conditions and sensitivity analyses of the parameters has demonstrated that both models are very stable for changes in the range of ± 10% for all parameters and still reasonably stable for changes up to ± 20% with RMS errors in the model always less that 10%. The preferred two-layer model was found to give the more realistic representation of the site, where water level variations and the numerical modeling showed that the basal layer of coarse sands and fine gravels is hydraulically connected to the river and the upper layer comprising a poorly sorted mixture of silt-rich clays and sands of very low permeability limits infiltration from the surface to the lower layer. The paucity of historical data has limited the numerical modelling to a steady state one based on groundwater levels during a drought period and forecasts for varying hydrological conditions (e.g. short term as well as prolonged dry and wet conditions) cannot reasonably be made from such a model. If future modelling is to be undertaken it is necessary to establish a regular program of groundwater monitoring and maintain a long term database of water levels to enable a transient model to be developed at a later stage. This will require a valid monitoring network to be designed with additional bores required for adequate coverage of the hydrogeological conditions at the Josephville site. Further investigations would also be enhanced by undertaking pump testing to investigate hydrogeological properties in the aquifer.

Submitted by Anderson Luiz dos Santos Safre (andersonsafre@hotmail.com) on 2018-07-23T19:43:45Z No. of bitstreams: 1 ALSS_dissertacao.pdf: 7462772 bytes, checksum: b07ec4a1d1d0d003c7c73a59116539ce (MD5) / Approved for entry into archive by Ana Lucia de Grava Kempinas (algkempinas@fca.unesp.br) on 2018-07-24T12:07:25Z (GMT) No. of bitstreams: 1 safre_als_me_botfca.pdf: 7462772 bytes, checksum: b07ec4a1d1d0d003c7c73a59116539ce (MD5) / Made available in DSpace on 2018-07-24T12:07:25Z (GMT). No. of bitstreams: 1 safre_als_me_botfca.pdf: 7462772 bytes, checksum: b07ec4a1d1d0d003c7c73a59116539ce (MD5) Previous issue date: 2018-05-11 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os usos de técnicas de modelagem em águas subterrâneas vêm sendo amplamente utilizado para entender a variabilidade e as incertezas associadas às condições hidrodinâmicas dos aquíferos. Os modelos numéricos de fluxo das águas subterrâneas são utilizados para representar a distribuição da carga hidráulica, bem como a velocidade e volume de escoamento da água no aquífero. O Estado de São Paulo possui algumas unidades de conservação de proteção integral, chamadas de Estações Ecológicas. Na região hidrográfica do Médio Paranapanema (UGRHI-17), destaca-se a Estação Ecológica de Santa Barbara (EEcSB), localizada sob uma transição do Sistema Aquífero Bauru (SAB) e o Sistema Aquífero Serra Geral (SASG). A principal atividade econômica na região é a agricultura, onde as águas subterrâneas e superficial são captadas para a irrigação. A demanda excessiva pode ameaçar os recursos hídricos e os ecossistemas da região. Desse modo, foi analisado nesse estudo qual o papel da EEcSB como área de garantia de recarga, utilizando a modelagem do fluxo das águas subterrâneas a partir da plataforma FREEWAT, que utiliza o código MODFLOW de diferenças finitas para simulação numérica. Gerou-se uma camada de espessura variada, representado o SAB. A discretização horizontal foi de 7.789 células ativas, com extensões de 100 m x 100 m. Foram utilizados 23 poços de observação, distribuídos por entre as microbacias da EEcSB, para calibração do modelo. A recarga foi dívida em duas zonas para representar a EEcSB ou outros usos da terra no entorno. Os valores variaram entre 15% de recarga da precipitação média. As duas formações do SAB contidas na EEcSB (Adamantina e Marilia) foram representadas por zonas com diferentes condutividades hidráulicas, a primeira com 1,75 m/d e a segunda com 0,9 m/d. A análise de sensibilidade foi realizada automaticamente pelo módulo UCODE_2014 e demonstrou que os parâmetros com maior sensibilidade foram a condutividade hidráulica na zona 1 e a recarga. A calibração teve um erro médio quadrático residual de 0,52 m. O valor total de afluxo simulado pelo modelo em regime permanente é de 66.893,882 m³/d, onde 59.079 m³/d correspondem ao volume escoado pelos drenos, e 7.813 m³/d ao valor de saída pela evapotranspiração. Foram observados três padrões principais de fluxo, com um divisor de águas subterrâneas no centro do domínio simulado. Um padrão de fluxo possui sentido Oeste em direção ao Rio Capivari, apresentando segmentações nas direções de fluxo próximas aos córregos afluentes (Divisa, Santana, Guarantã e Boi). Foram simulados dois cenários, o primeiro com a remoção de 50% da área e o segundo com remoção total da EEcSB. O primeiro cenário apresentou redução de 53,6% no volume da recarga e 47,5% no volume das drenagens, com quedas de até 11m no nível freático. O segundo cenário apresentou uma redução de 61,68% na recarga e de 77,79% na vazão das drenagens com rebaixamentos de até 14m no nível freático. / The uses of groundwater modeling techniques have been widely applied to understand the variability and uncertainties associated with the hydrodynamic conditions of aquifers. Numerical groundwater models are used to represent the hydraulic head distribution, as well as the velocity and volumetric flow. The São Paulo State has some Conservation Units of integral protection, called Ecological Stations. In the Médio Paranapanema Hydrographic region (UGRHI-17), stands out the Santa Bárbara Ecological Station (EEcSB), located under a transition from the Bauru Aquifer System (BAS) and the Serra Geral Aquifer System (SGAS). The main economic activity in the region is agriculture, where the groundwater and surface water are extracted for irrigation. The excessive demand of water threatens the region’s water resources and ecosystems. Thus, in this study, the role of EEcSB as a recharge guarantee area, was analyzed through groundwater flow modeling through the FREEWAT platform, that uses the MODFLOW finite difference code for numerical approximation. One layer of varied thickness, representing the BAS was generated. The horizontal discretization was made of 7,789 active cells, with 100 m x 100 m extension. Twenty three observation wells were used, distributed among EEcSB micro-basins for calibration. The recharge was divided in two zones, to represent the EEcSB and the other land uses in the environment. Recharge values varied around 15% of average rainfall. The two BAS formations (Adamantina and Marillia) at EEcSB were represented by two zones with different hydraulic conductivity, the first with 1.75 m.d-1, and the second with 0.9 m.d-1. The sensitivity analysis was performed automatically by UCODE_2014 module and showed that the parameters with the highest sensitivity were the hydraulic conductivity at zone 1 and the recharge. The calibration had a mean square residual error of 0.52 m. The total value of simulated inflow by the steady state model is 66,893,882 m³.d-1 where outflow was 59,079 m³.d-1 by the leakage into the drains, and 7,813 m³.d-1 by evapotranspiration. Three main flow patterns were observed, with a groundwater divide at the center of the simulated domain. A flow pattern runs westward toward the Capivari Rver, showing segmentations in the flow directions near the tributaries (Divisa, Santana, Guarantã and Boi). Two scenarios were simulated, the first with the removal of 50% of the area and the second one with total removal of the EEcSB. The first scenario presented a reduction of 53.6% in the recharge volume and 47.5% in the drainage volume, with decreases up to 11 m in the water table. The second scenario presented a reduction of 61.685 in recharge and 77.79% n drainage flow with decreases up to 14 m in the water table.

Made available in DSpace on 2014-06-11T19:26:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-05-03Bitstream added on 2014-06-13T18:29:38Z : No. of bitstreams: 1 franzini_as_me_rcla.pdf: 5288174 bytes, checksum: dd9a681c43d63366f35542e58bdfa93e (MD5) / A interpretação de perfis geofísicos e dados de poços constituiu importante ferramenta para o entendimento do arcabouço hidrogeológico da área do assentamento Margarida Alves, região oeste do Estado de São Paulo. Foram reconhecidas as formações Santo Anastácio e Caiuá, separadas por superfície de discordância regional evidenciada nos perfis geofísicos. As referidas formações constituem unidades aquíferas homônimas que representam o Sistema Aquífero Bauru, caracterizado na área como livre e multi-camadas. Essas unidades litoestratigráficas são constituídas por intercalações de camadas arenosas interdigitadas a camadas areno-siltosas e silto-arenosas, compondo corpos lenticulares de espessuras métrica a decamétrica de pequenas extensões laterais. Esses corpos estão arranjados em padrão de fining upward, sugerindo um ambiente deposicional fluvial. O fluxo regional é em direção SW e tem o ribeirão Nhancá como área de descarga. Na porção ocidental da área, foi identificado um aquífero freático suspenso com águas pouco mineralizadas e baixos teores de sólidos totais dissolvidos. As águas do Sistema Aquífero Bauru apresentam constituição química distintas. No Aquífero Santo Anastácio foram classificadas como bicarbonatadas magnesianas e no Aquífero Caiuá classificadas como bicarbonatadas cálcicas / Geophysical logs and water well data constitute important tool for understanding the hydrogeologic framework of the Margarida Alves settlement, located in western Sao Paulo State. Two lithostratigraphic formations - Santo Anastácio and Caiuá - were recognized and they are separed by an unconformity surface. These formations are water-bearing units of the multi-layered Bauru Aquifer System (SAB). These lithostratigraphic units are composed of sandy layers intercalated with sandy-silty and silty-sand layers, forming lenticular bodies of metric to decametric thickeness with small lateral continuity. These bodies, as evidenced in well logs, are arranged in fining upward pattern, typical of fluvial depositional environment. The regional flow is directed SW and it discharge in the ribeirão Nhancá. In the western portion of the area a perched aquifer has been identified, bearing waters with low levels of total dissolved solids. Two distinct type of groundwater have been identified in the SAB, the Santo Anastácio aquifer is classified as bicarbonated-magnesian water and that of Caiuá Aquifer as bicarbonated-calcium rich waters

O município de São José do Rio Preto (SJRP), localizado na porção noroeste do estado de São Paulo, é extremamente dependente da água subterrânea, tanto para abastecimento público quanto privado, justificando-se o grande número de poços existentes, que excede a mais de dois mil, sobretudo no Sistema Aquífero Bauru (SAB). Embora este recurso seja fundamental para o abastecimento da cidade, 79% dos poços não possuem outorga. O aumento do número de poços, sem o devido controle, explotando o aquífero, pode justificar e intensificar os problemas de forte abatimento da superfície potenciométrica na região central da área urbana do município. Nesse sentido, esta pesquisa objetivou desenvolver um aplicativo computacional, na forma de modelagem numérica de simulação de fluxos subterrâneos, para subsidiar a explotação sustentável do SAB. Para o sucesso do modelo numérico, foi realizada toda a caracterização hidrogeológica e definido o modelo conceitual de fluxo das águas subterrâneas. O modelo numérico foi calibrado em regime estacionário para duas situações: pré-explotação e bombeamento atual; e, posteriormente, foram gerados três diferentes cenários futuros de bombeamento: a) explotação duas vezes maior do que a atual (Q = 133.206 m³/dia); b) explotação três vezes maior do que a atual (Q = 199.809 m³/dia); c) explotação apenas dos poços públicos (Q = 39.662 m³/dia). Houve médias de rebaixamento na área urbana de 15 m, 42 m e 8 m, respectivamente. Rebaixamentos mais proeminentes do nível freático ocorrem na área central do município, onde se concentra 80% dos poços. Dessa forma, recomendam-se algumas ações direcionadas ao poço, à proteção do aquífero e ao usuário. / The city of São José do Rio Preto (SJRP), located in the northwestern portion of the state of São Paulo, is highly dependent of groundwater for both public and private supply, that justifies the large number of existing wells, which exceeds more than 2000, especially in the Bauru Aquifer System (BAS). Although this resource is essential for the city supply, 79% of the wells do not have grants. The increase of wells, without the correct control, exploring the aquifer can justify and intensify the problems of strong relief in the central region of the urban area by city. Then, this research aimed to develop a computational application how numerical simulation modeling of groundwater flow, to support the rational exploitation of the BAS. For the success of the numerical model, the entire hydrogeological characterization was performed and defined the conceptual model of groundwater flow. The numerical model was calibrated in steady state for two situations: pre-exploitation and current pumping, and then were generated three different future scenarios of pumping: a) exploitation twice larger than the current (Q = 133,206 m³/day); b) exploitation three times larger than the current (Q = 199 809 m³/day); and c) exploitation of only public wells (Q = 39,662 m³/day). There were averages of debasement in the urban area of 15 m, 42 m and 8 m, respectively. Most prominent debasements of groundwater level occurred in the central area of the city, which the concentrates is 80 % of the wells. Therefore, some actions are recommended directed to the well, to protect the aquifer and the user.

Na última década foram encontradas concentrações anômalas de bário em poços de abastecimento do Sistema Aquífero Bauru (SAB), com casos de ocorrências de teores acima do limite de potabilidade (0,7 mg/L). Estas concentrações foram encontradas pelo monitoramento da CETESB e por estudos anteriores. Tavares (2013) e Crespi (2013) indicam que a contaminação nesta área tem origem natural, advinda da lixiviação da cimentação carbonática da Formação Marília. Utilizando dados bibliográficos e expandindo o estudo para toda a região do Espigão de Marília, este trabalho visou aprofundar o conhecimento sobre esta anomalia e tentar compreender o seu comportamento com auxílio de dados isotópicos (O e H) de chuva e água subterrânea. Para o entendimento da anomalia foi construído um banco de dados com os Autos de Outorga de poços do DAAEE, CETESB e CPRM. Após o cadastro destes dados, foram confeccionadas as seções geológicas, o modelo conceitual de fluxo da área, e um modelo hidrogeológico. Após esta etapa foram selecionados 21 poços para as duas primeiras campanhas de amostragem ao longo do ano hidrológico e 8 poços para uma terceira campanha de amostragens ao longo do ano hidrológico. Simultaneamente foi instalado no DAAEE de Marília um coletor de chuva para coletar amostras desde junho de 2014 até dezembro de 2015 para a confecção da reta meteórica local. Os resultados analíticos dos poços foram tratados agrupando-os de acordo com sua geologia, observando-se padrões de distribuição dos parâmetros químicos analisados, bem como dos isótopos. Foi possível notar que há contaminação por cloreto e nitrato em alguns poços. A contaminação de bário ocorre em diferentes pontos, não estando restrita a apenas uma formação. Sem nenhuma relação com os demais componentes antrópicos, esta anomalia se confirma natural. Os altos teores de bário também aparecem em locais com uma maior variedade geológica. A análise dos isótopos de hidrogênio e oxigênio das amostras mostrou que as águas amostradas são mais empobrecidas que as de chuva, até mesmo as mais rasas. Em teste de bombeamento foi possível acompanhar a evolução da assinatura com a profundidade. O que pode ser concluído é que a anomalia de bário ocorre em todo o Espigão, em geral em poços com filtros nas Formações Marília e Adamantina, que possuam um teor mais elevado de magnésio, não necessariamente tendo uma influência antrópica. / In the last decade, anomalous concentrations of barium were found in supply wells of Bauru Aquifer System (BAS), with occurrences of levels above the drinking limit (0.7 mg/L). These concentrations were found by CETESB monitoring and some previous studies. Tavares (2013) and Crespi (2013) indicate that contamination in this area has natural origin, from the leaching of carbonate cementation of Marília Formation. Using bibliographic data and expanding the study to the entire region of the Espigão de Marília this study aimed to increase knowledge about this anomaly and try to understand their behavior with aid of isotopic data (O and H) of rain and groundwater. For the understanding of the anomaly, a database was built with information from DAAEE, CETESB and CPRM wells. After the register of this database, some geological sections were made, the groundwater flow conceptual model for the area, and a geological model. After this step, 22 wells were selected for the three sampling campaigns. At the same time was installed in DAAEE of Marília a rain collector that operated from middle of 2014 by the end of 2015, to construct a Local Meteoric Water Line. The wells have been grouped according to the geology, and some patterns were discovered. It was possible to notice that there is a problem about chloride and nitrate contamination. Barium contamination appeared at various points, not being restricted to just one Formation. Without any relation with man-made components, according to the bibliography, this anomaly confirms natural. High levels of barium also appear in places with greater geological variety. The analysis of the isotopes of hydrogen and oxygen of the samples showed that the waters sampled are isotopic depleted compared to the rain. In pumping test was possible to monitor the evolution of the signature with the depth. It is possible to conclude that the barium anomaly is spread all over the Espigão de Marília, in general in wells with filters in Marília and Adamantina Formations, which have a higher content of magnesium, not necessarily having a human influence.

A gestão das águas subterrâneas transfronteiriças surge como um novo paradigma. Nos dias atuais fala-se muito em mudanças, principalmente na área ambiental, porém, muito pouco tem sido feito a respeito. O grande desafio para a sociedade no século XXI será o modo como pensamos a gestão dos recursos hídricos. Historicamente a gestão dos recursos hídricos tem sido direcionada a expansão da oferta de água, sendo que a única solução encontrada para enfrentarmos a escassez são as grandes obras. Atualmente não existe uma regulamentação internacional especifica para as águas subterrâneas transfronteiriças, esse cenário nos traz uma questão, como o Brasil está preparado? A legislação e os instrumentos de gestão nacionais são fundamentais para o país exercer a sua soberania e não ficar vulnerável a ação de outros Estados. É nesse sentido que, os esforços cooperativos na busca da sustentabilidade e da segurança ambiental internacional concorrem com a concepção clássica de soberania. Hoje o Sistema Aquífero Guarani (SAG) se encontra em um cenário de abundância de água em geral, porém existe um aumento gradual no uso da água, e também, problemas quantitativos por concentração de usos e problemas de contaminação local, ambos em áreas transfronteiriças e nacionais. Existe também uma possível contaminação difusa em áreas de recarga. As políticas para o SAG terão que apontar soluções e alternativas para esses problemas pontuais, a realidade vivida em todos os países com os profundos desequilíbrios sociais, econômicos e ecológicos será posta em questão. Se a Gestão integrada não tiver como objetivo fundamental a superação desses desequilíbrios, seguramente teremos ações políticas meramente ilustrativas. Essa idéia leva a um questionamento fundamental: Os Países estão dispostos a ceder parte de seus possíveis benefícios na procura de um bem comum? / The transboundary groundwater management emerges as a new paradigm. Nowadays there is talk in much change, especially in the environmental area, but very little has been done about it. The great challenge for society in the XXI century will be how we think the water resources management. Historically the water resources management has been directed to expanding the supply of water, and the only solution to tackle the shortage are the major works. Currently there is no specific international regulations for transboundary groundwater, this scenario brings us a question, as Brazil is ready? The legislation and the instruments of nationals management are fundamental to the country exercising its sovereignty and not be vulnerable to actions of other states. That is why the cooperative efforts in the pursuit of sustainability and international environmental safety competition with the classical conception of sovereignty. Today the Guarani Aquifer System (known as the SAG in Spanish and Portuguese) is in a scenario of water abundance in general, but there is a gradual increase in water use, and also quantitative problems for concentration of uses and problems of local contamination, both in transboundary areas and national. There is also a possible diffuse contamination in recharge areas. Policies for the SAG will have to point out solutions and alternatives to these problems, the reality experienced in all countries with deep social, economic and ecological imbalances will be called into question. If the integrated management has not aimed to overcoming these imbalances, we certainly have political action merely illustrative. This idea leads to a fundamental question: The countries are willing to cede part of its possible benefits in seeking a common good?

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22421号 / 工博第4682号 / 新制||工||1731(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 大津 宏康, 教授 三村 衛, 准教授 PIPATPONGSA Thirapong / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The Coastal Plain in the southern Chesapeake Bay area is becoming increasingly susceptible to nuisance flooding as a result of the combination of sea-level rise and land subsidence associated with aquifer compaction from excessive groundwater pumping. Detailed time-series of cumulative compaction data (land subsidence) from the three U.S. Geological Survey deployed extensometers in the regions, along with cyclical piezometer data, reflect the nature of the complex multi-aquifer/aquitard system in the Coastal Plain. Franklin, Virginia and Suffolk, Virginia extensometers were deactivated in 1995 and were reactivated in 2016 along with the addition of a high-sensitivity borehole extensometer in Nansemond, Virginia in collaboration with the Hampton Roads Sanitation District as a part of the Sustainable Water Initiative for Tomorrow (SWIFT). Yearly compaction rates estimated from the reactivated extensometers are -3.3 mm/year, 15.6 mm/year, and -20.7 mm/year in Franklin, Suffolk, and Nansemond, Virginia respectively. One-dimensional vertical compaction modeling is utilized to estimate the total compaction and differentiate which fine-grained confining units or aquifer interbeds are contributing most to total compaction historically and presently. Additionally, properties of the system can be estimated including the elastic specific storage of the aquitards and aquifers and the inelastic storage of the aquitards. The total cumulative change in aquifer system thickness estimated by the MODFLOW subsidence package can be compared to the observed total cumulative change in aquifer system thickness at each site for validation of hypothesis about the dynamics of the aquifer system to known changes in stress. Subsidence rates and aquifer/aquitard properties can be useful for managing and modeling the groundwater in the Coastal Plain of Virginia. / Master of Science / The Coastal Plain in the southern Chesapeake Bay area is becoming increasingly susceptible to flooding at high tides in low lying areas as a result of the combination of sea-level rise and sinking of the land surface (land subsidence) associated with aquifer compaction from excessive groundwater pumping from buried aquifers. Detailed time-series of land subsidence data from the three U.S. Geological Survey deployed extensometers in the region, along with water level data from nearby wells, reflect the nature of the complex multi-aquifer/aquitard system in the Coastal Plain. Franklin, Virginia and Suffolk, Virginia extensometers were deactivated in 1995 and were reactivated in 2016 along with the addition of a high-sensitivity borehole extensometer in Nansemond, Virginia in collaboration with the Hampton Roads Sanitation District as a part of the Sustainable Water Initiative for Tomorrow (SWIFT). Yearly land subsidence rates estimated from the reactivated extensometers are -3.3 mm/year, 15.6 mm/year, and -20.7 mm/year in Franklin, Suffolk, and Nansemond, Virginia respectively. One-dimensional vertical compaction modeling is utilized to estimate the total sinking of the land surface as well as to differentiate which fine-grained confining units or aquifer interbeds are contributing most to total subsidence historically and presently. Additionally, properties of the system can be estimated including the elastic specific storage of the aquitards and aquifers and the inelastic storage of the aquitards. The total cumulative change in aquifer system thickness estimated by the MODFLOW subsidence package can be compared to the observed total cumulative change in aquifer system thickness at each site for validation of hypothesis about the dynamic changes of the aquifer system with known changes in stress. Subsidence rates, understanding the dynamics of the aquifer system, and aquifer/aquitard properties can be useful for managing groundwater and modeling the aquifer system in the Coastal Plain of Virginia.