Dissertations / Theses on the topic 'Coastal aquifers'
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Park, Chan-Hee. "Saltwater Intrusion in Coastal Aquifers." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4857.
Full textTeo, Hhih-Ting, and h. teo@griffith edu au. "Tidal Dynamics in Coastal Aquifers." Griffith University. School of Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030729.155028.
Full textTeo, Hhih-Ting. "Tidal Dynamics in Coastal Aquifers." Thesis, Griffith University, 2003. http://hdl.handle.net/10072/365678.
Full textThesis (Masters)
Master of Philosophy (MPhil)
School of Engineering
Full Text
Costall, Alexander Ross. "Hydro-geophysics in High-Quality Coastal Aquifers." Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/82107.
Full textDemirbas, Korkut. "Optimal Management Of Coastal Aquifers Using Heuristic Algorithms." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613135/index.pdf.
Full textAlternating Constraints Method&rdquo
is introduced to improve the solution for the cases with variable location. The results show that both proposed method and the regular solution with GA or SA prove to be successful methods for the optimal management of coastal aquifers.
Karam, Hanan Nadim. "Seawater circulation in coastal aquifers : processes and impacts." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78141.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 150-154).
This thesis explores the subterranean domain of chemical cycling in coastal oceans abutting permeable aquifers, where transport through sediments is dominated by advection, rather than diffusion. We investigate the mechanisms by which seawater circulates in the subsurface over a range of spatio-temporal scales, and the chemical reactions to which this circulation is coupled. Seawater circulation in coastal aquifers is driven by salinity variations in pore water as well as by the effects of temporally variable forcings at both terrestrial (variable recharge) and marine (tides, waves and secular sea level changes) boundaries. It is coupled to the transport of biogeochemically reactive species through the subsurface and their exchange between the sediments and the water column. Our understanding of how different forcing mechanisms interact to determine spatial scales and residence times of subsurface seawater circulation, as well as temporal patterns and rates of aquifer-surface water exchange has thus far been very limited. The large range in the spatial and temporal scales of flow dynamics associated with different forcings challenges our ability to comprehensively observe and monitor their associated seafloor fluxes. In this thesis, we present a novel, homemade instrument for high-resolution, long-term monitoring of seafloor fluxes, designed to address this challenge. Two-year deployments of several such instruments at Waquoit Bay, MA, produced the most comprehensive datasets on seafloor fluxes available to date, multiplying the length of published time series by tenfold. The length and integrity of the datasets permit the use of spectral analysis to investigate distinct frequency components of seafloor fluxes and quantify their relationship to various forcing mechanisms. The temporal and areal coverage of the datasets allow us to distinguish the contributions of different forcings to observed fluxes, as a function of distance from shore and season. Furthermore, we discuss new insight derived from the data into the physics underlying observed seafloor fluxes and their associated subsurface circulation processes. Additionally, we describe results from an independent but related project to characterize chemical dynamics associated with seawater circulation in beach sand at Waquoit Bay. We present evidence for the important contribution of this circulation to the nitrogen budget of the Bay.
by Hanan Nadim Karam.
Ph.D.
Mary, Makokha. "Seawater intrusion and contaminant transport in coastal aquifers." Kyoto University, 2008. http://hdl.handle.net/2433/136601.
Full text0048
新制・課程博士
博士(農学)
甲第13874号
農博第1689号
新制||農||953(附属図書館)
学位論文||H20||N4341(農学部図書室)
UT51-2008-C790
京都大学大学院農学研究科地域環境科学専攻
(主査)准教授 小林 晃, 教授 河地 利彦, 教授 川島茂人
学位規則第4条第1項該当
Sun, Dongmin. "Aquitard control of stream-aquifer interaction and flow to a horizontal well in coastal aquifers." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/4740.
Full textAyutthaya, Sarinya Sanitwong-Na. "Impacts of climate change on groundwater levels in coastal aquifers." Thesis, University of Dundee, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505624.
Full textCumming, Benjamin Donald. "Modelling sea water intrusion in coastal aquifers using heterogeneous computing." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/61038/1/Benjamin_Cumming_Thesis.pdf.
Full textFelisa, Giada <1983>. "Dynamics of coastal aquifers: data-driven forecasting and risk analysis." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7177/1/felisa_giada_tesi.pdf.
Full textFelisa, Giada <1983>. "Dynamics of coastal aquifers: data-driven forecasting and risk analysis." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7177/.
Full textBatista, Filho Job Jesus. "A dinamica das aguas subterraneas no estuario do Rio Itanhaem, litoral sul do Estado de São Paulo." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287665.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias
Made available in DSpace on 2018-08-07T09:50:38Z (GMT). No. of bitstreams: 1 BatistaFilho_JobJesus_M.pdf: 4294081 bytes, checksum: 28f487525ec460febd41ef1f05e36218 (MD5) Previous issue date: 2006
Resumo: O presente trabalho estuda a interferência da maré nos aqüíferos costeiros, identificando alterações hidrodinâmicas e químicas em suas águas. A pesquisa foi realizada no estuário do rio Itanhaém, em duas localidades: no Sitio de Pesquisa, com 7 poços instalados, situados às margens do rio Acima, a 3,5 km do oceano, e no CePeRio - Centro de Pesquisa do Estuário do rio Itanhaém, com 1 poço, localizado a aproximadamente 1 km do oceano. O estudo foi executado em 3 etapas, buscando-se conhecer: a geologia dos aqüíferos, suas características físicas, químicas e geométricas. Para os aspectos hidrodinâmicos, englobaram-se o monitoramento do nível d'água superficial e subterrâneo e os cálculos dos parâmetros hidrodinâmicos, como: condutividade hidráulica, velocidade média linear e transmissividade. Para a hidroquímíca foram executadas coletas periódicas, a cada 45 minutos, análise dos parâmetros físicoquímicos: temperatura, pR, Eh, condutividade elétrica (CE), sólidos totais dissolvidos (STD) e salinidade. Foram coletadas amostras em cada etapa para se an$l.lisar a composição química das águas estudadas, quantificando-se os seguintes íons: Na, K, Si, Mg, Ca, Sr, Co, Mn, Cu, P, Zn, Pb, AI, Ba, Cd, N~, Fe, Cr, RC03-, F- ,cr ,Br- ,N ,S042- e PO/- . Os aqüíferos estudados, um livre e um confmado, são compostos de sedimentos arenosos de granulometria fina. O aqüífero confinado é composto de areia com lente df. conchas calcáreas, à profundidade de 20 metros. As águas superficiais monitoradas foram: as dos rios Acima, Itanhaém e do ribeirão Campininha, que margeiam as áreas estudadas. O aqüífero livre, formado por areia fina, e o rio Acima apresentam águas sulfatadas ou cloretadas sódicas. No aqüífero, o STD varia de 40 a 70 mg/L e o pH é ácido (entre 4 e 5); no rio, o STD varia de 90 a 5.900 mgIL e o pH de 6 a 7. O aqüífero confinado, com argila siltosa na sua base e conchas calcáreas na sua estrutura, apresenta águas bicarbonatadas sódicas, com STD variando de 310 a 2.000 mg/L e pH neutro (entre 6 e 7,5). O aqüífero livre, com condutividade hidráulica (10 de 10-4 m/s, possui influência direta das oscilações da maré, com uma variação de amplitude do nível d'água (NA) 5 vezes menor que a da maré; o aqüífero confinado, com K igual a 10-6 m/s, oscila 11 vezes menos que a maré, com maior variação de 1,4 m. A direção do fluxo hidrodinâmico no aqüífero livre é para NW e a do confinado é para WSW, ambos com descarga no rio Acima. O aqüífero livre tem velocidade média linear da ordem de 10-6 m/s e transmissividade de 205 m2/dia, e o confinado 10-8 m/s e 13 m2/dia. Apenas no aqüífero livre, durante subidas fortes da maré, o fluxo hidrodinâmico se altera, derivando para o norte. Hidroquimicamente, as águas subterrâneas variam pouco com a intrusão salina. No inverno, as águas superficiais são mais salobras que em outras épocas do ano, o que está associado a fatores como: a maré mafs alta e a pluviometria reduzida
Abstract: The present work studied the influence of the tide in the coastal aquifers by identifying hydrodynamic and chemical alterations in the aquifiers. The research was carried out in the Itanhaém river estuary in two localities: in the Sitio de Pesquisa with 7 installed wells situated on the banks of the Acima river, 3,5 km from the ocean, and in the CePeRio - Center of Research ofthe ltanhaém river estuary with 1 well located approximately 1 km from the oceano The study was executed in 3 stages that studied the geologic formations of the aquifers and their physical, chemical and geometric characteristics. The hydrodynamic aspects were studied by monitoring of the superficial and underground water leveI, and hydrodynamic parameters such as hydraulical condutivity, linear average velocity and transmissivity were determined. The hydrochemical part of the research was executed with periodic collections of samples every 45 minutes and analyzed for the physical chemical parameters of temperature, pH, Eh, electric condutivity (EC), total dissolved solids (TDS) and salinity. AIso, samples were collected for each stage of the study and analyzed for the following íons: Na, K; Si, Mg, Ca, Sr, Co, Mo, Cu, P, Zn, Pb, AI, Ba, Cd, Ni, Fe, Cr, HC03-, F- ,cr ,Br- ,N ,sot e P043- . The aquifers, one phreatic and one confined,rare both composites of fine sand sediments. The confined one is a sand layer with presences of limestone shells and has a depth of 20 meters. The surface waters were also monitored in the Acima river, the Campininha brook and the Itanhaém river, which border the study area. The phreatic aquifer is formed of fine sand and with the Acima river has sodium sulfated or chlorinated and sodium bicarbonated water. In the aquifer, the TDS varied between 40 and 70 mg/L and pH was acidic (between 4 and 5). In the river, the TDS varied from 90 to 5,900 mg/L and pH was 6 to 7. The confined aquifer, with silt clay and limestone shell, had sodic bicarbonated waters with the TDS varying from 310 to 2,000 mg/L and pH neutral (between 6 and 7,5). The phreatic aquifer with hydraulical condutivity (K) 10-4 m/s had a direct influence from tidal oscillations with a variation of phreatic leveI amplitude 5 times lesser than that of the tide. The confined aquifer with K of 10-6 m/s, oscillated 11 times less than the tide for variations of larger than 1,4 m. The hydrodynamic flow direction for the phreatic aquifer was to NW and for the confined one it was for WSW, both with discharges in the Acima river. The phreatic aquifer had linear average velocity of the order of 10-6 m/s with a transmissivity of 205 m2/day and for the confined the values were 10-8 m/s and 13 m2/day. In the phreatic aquifer the hydrodynamic flow was modified during strong flows of the tide northward. Hydrochemically, the groundwater varied slightly with saline intrusion. In the winter, the river had the biggest ionic concentrations in comparison to the other seasons which were associated with factors such as the tide being higher in and the low precipitation at that time of year
Mestrado
Geologia e Recursos Naturais
Mestre em Geociências
Hussain, Mohammed Salih. "Numerical simulation and effective management of saltwater intrusion in coastal aquifers." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/19239.
Full textSchultz, Gregory Michael. "Hydrologic and geophysical characterization of spatial and temporal variations in coastal aquifer systems." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/27071.
Full textMatengu, Brian Munihango. "Groundwater assessment and sustainable management of the coastal alluvial aquifers in Namib Desert, Namibia: Omdel Aquifer as case study." University of Western Cape, 2020. http://hdl.handle.net/11394/7852.
Full textThe study addressed the groundwater assessment and sustainable management of the coastal alluvial aquifers in Namib Desert, the Omaruru River Delta Aquifer (Omdel Aquifer) was used as a case study. Sustainable utilization of groundwater in parts of hyper-arid Sub-Saharan Africa, like the Namib Desert, is always a challenge due to lack of resources and data. Understanding of hydrogeological characteristics of the Omaruru Delta Aquifer System is a pre-requisite for the management of groundwater supply in the Central Namib area (Namib Desert). For the Omdel Aquifer in the Omaruru catchment, Namibia, issues to investigate include the lack of information on the geology and hydrogeological setting, the hydraulic properties and geometry of the aquifer at the inflow and outflow sections, groundwater recharge conditions upstream of the aquifer, and the impact of artificial recharge.
Basdurak, Berkay Nuvit. "Analysis Of Saltwater Intrusion And Investigations On Prevention Techniques In Coastal Aquifers." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604734/index.pdf.
Full textRAMLI, MUHAMMAD. "NUMERICAL MODELING OF GROUNDWATER FLOW IN MULTI-LAYER AQUIFERS AT COASTAL ENVIRONMENT." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/77971.
Full text0048
新制・課程博士
博士(工学)
甲第14599号
工博第3067号
新制||工||1456(附属図書館)
26951
UT51-2009-D311
京都大学大学院工学研究科都市環境工学専攻
(主査)教授 大西 有三, 教授 間瀬 肇, 准教授 西山 哲
学位規則第4条第1項該当
Manyama, Kinsley. "Hydrogeophysical characterisation of shallow coastal aquifers in the Western Cape, South Africa." University of the Western Cape, 2017. http://hdl.handle.net/11394/5972.
Full textCoastal aquifers present a key groundwater resource for freshwater supply in many coastal zones of Africa, and its availability is largely driven by the physical hydrogeological properties. An understanding of the aquifer properties in coastal areas is fundamental in that these aquifers present unique resource largely controlled to a very large extent by its geological and hydrological features and process. This study thus analysed information of resistivity variation of formations, drilling samples, water levels and slug test data, in an attempt to characterise aquifers in the coastal region of the Heuningnes Catchment, Western Cape. This was in an effort to address the issue of limited knowledge on key hydrogeological properties of aquifers in coastal regions. Resistivity survey results indicated that the shallow aquifers in the study area were limited in extent, had a poor potential, with resistant layers occurring below shallow, high conductive formations. The long profile of the wellpoints revealed that the area is underlain by various layers of material of consolidated to unconsolidated form. The hard rocks formations are overlain by sandy materials of fluvial origin, and clay material with marine deposits (mollusc shells). This findings were in agreement with the results of the resistivity models. In addition, the findings indicated that the saturation thickness of the aquifers was also small. The findings of the study on aquifer properties indicated that, hydraulic conductivity (K), transmissivity (T) and borehole yields were generally poor and small. Estimates of K and T ranged from 0.0030 to 0.2856 m/day and from 0.0008 to10.993 m2/day accordingly, while average borehole yields were at 0.55 l/s, with productivity of the aquifers classified as low to moderate. These were indicative of a low permeability environment, with low yielding formations. An updated conceptual groundwater flow model developed in this study, revealed a rather compacted groundwater flow systems, in which local and intermediate flows were dominant. These findings in this study support the view that aquifers in coastal regions were predominantly characterised by shallow depth, patchy distribution and low potential.
2019-04-30
Ryan, Joseph Nolte. "Groundwater colloids in two Atlantic coastal plain aquifers : colloid formation and stability." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14560.
Full textKriyo, Sambodho. "The Dynamics of Groundwater Flow and Salinity Transport in Unconfined Coastal Aquifers." 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/97967.
Full textNguyen, Bach Thao. "Coupling geophysical and isotopic approaches to better simulate saltwater intrusion into coastal aquifers : a case study in the Crau aquifer." Thesis, Avignon, 2016. http://www.theses.fr/2016AVIG0052/document.
Full textThe research has focused on the constraints related to the modeling of groundwater in coastal aquifer. In these aquifers, the concomitant presence of freshwater and saltwater alters the flow patterns typically represented by the Darcy equation. The influence of salinity on density and permeability complex the mathematical resolution of flow equations. Moreover, the influence of heterogeneities of aquifer makes it more difficult and risky the model parameterization and its calibration. We propose to use fort that the results of both geophysical and isotopic investigations. Thus, we hypothesize that the description of the subsurface and the imaging of the freshwater/saltwater can help to setup and validate the simulation of groundwater in coastal aquifers. Also we have shown that geochemical measurements such as radon may help to validate the simulated flow. Our approach was applied on the downstream part of the Crau aquifer. The comparison of simulated results to data resulting from monitoring has shown the usefulness and applicability of our approach
Ezzy, Timothy Robert. "Integrated Approach to Characterisation of Coastal Plain Aquifers and Groundwater Flow Processes: Bells Creek Catchment, Southeast Queensland." Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/16166/1/Tim_Ezzy_Thesis.pdf.
Full textEzzy, Timothy Robert. "Integrated Approach to Characterisation of Coastal Plain Aquifers and Groundwater Flow Processes: Bells Creek Catchment, Southeast Queensland." Queensland University of Technology, 2005. http://eprints.qut.edu.au/16166/.
Full textSanz, Escudé Esteban. "Brackish springs in coastal aquifers and the role of calcite dissolution by mixing waters." Doctoral thesis, Universitat Politècnica de Catalunya, 2007. http://hdl.handle.net/10803/6251.
Full textThese mechanisms have been studied for many years but some controversy still remains. It is clear that they are related to deep well developed karst systems. Under these conditions, groundwater flows in a turbulent mode through a network of interconnected conduits immersed in a porous matrix with slow Darcyan flow velocities. Surprisingly, different models to explain the functioning of the system, although based on different conceptual and methodological approaches lead to similar results. This sugests that a global study on the salinitzation mechanisms of brackish springs should be undertaken. Here, we first derive the equations governing turbulent flow for density-dependent fluids and describe different mechanisms of salinization of inland brackish springs, in order to compare with the spring discharge and concentration response for those mechanisms of salinization.
The insights gained in this analysis are applied to the study of S'Almadrava spring (Mallorca, Spain). This spring discharges up to 2 m3/s with salinities of 20 mS/cm at an elevation of 8 m.a.s.l. It generally displays an inverse relation between discharge rate and concentration (i.e., discharging higher salinity waters for low flow rates, and vice versa). A hypothetical but geologically feasible dual permeability model is proposed to reproduce observed salinity variations for both the dry and wet seasons but also to explain the secondary salinity peaks observed after every rainfall event. Model results agree with observations, but the lack of geological information at depth impedes model validation. Therefore, a second validation of the conceptual model is undertaken based on high-frequency geochemical observations. Due to the highly dynamic conditions of the system, the geochemical data was analyzed using fully coupled reactive transport modelling. The interpretation of geochemical data not only helps on validating conceptual models but also yields information on the water-rock interaction processes occurring at deep carbonate systems. In fact, one of the processes initially proposed to explain the occurrence of well-developed karst systems at depth, is the enlargement of tectonic fissures by carbonate dissolution due to the mixing of fresh and seawater.
The theory of dissolution by mixing waters is based on the fact that when two solutions are mixed, concentrations in the mixture are volume weighted averages of the two end-members, but the thermodynamic activities of the species controlling the water-mineral reactions are non linear functions of the mixing ratio. Therefore, two end-member solutions in equilibrium with a solid phase could lead to an undersaturated mixture depending on several factors, most notably CO2 content and ionic strength. Observation of mixing and carbonate dissolution at depth has not been possible because of technical difficulties. More accessible to observation is the seawater mixing zone in coastal aquifers where calcite undersaturation and/or calcite dissolution have been reported numerous times. Yet, dissolution in coastal environments is not always clear and oversaturation or lack of dissolution in mixing zones have also been described. This apparent inconsistency on field observations around the world prompted the studies of the second part of the thesis. Flow-through laboratory experiments were performed in CO2-controlled atmosphere in order to quantify the dependence of the dissolution of calcite with the mixing ratio, and the role that CO2 variations may have on enhancing the dissolution capacity of the mixture. Results show that, although dissolution occurs, the major carbonate dissolution in aquifers must be considered only in a geological time scale. Sanford and Konikow (1989) predicted the location and magnitude of long term porosity development of coastal aquifers, based on a two step method. We compare their results with a reactive transport model approach in 1D and 2D, showing that reactive transport is required to properly understand the phenomenon because it is found that dissolution is controlled not only by geochemical factors but also by the rate at which fresh and salt water mix (i.e., by dispersion).
Kennedy, Casey David. "Pilot project on groundwater dating in confined aquifers of the North Carolina Coastal Plain." NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-04162004-145829/.
Full textHogan, Matthew Brooks Clement Thangadurai Prabhakar. "Understanding the flow and mixing dynamics of saline water discharged into coastal freshwater aquifers." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Fall/Theses/HOGAN_MATTHEW_43.pdf.
Full textAbd-Elhamid, Hany Farhat. "A simulation-optimization model to study the control of seawater intrusion in coastal aquifers." Thesis, University of Exeter, 2010. http://hdl.handle.net/10036/3054.
Full textVan, Der Schyff Malikah. "Using hydrogeochemistry and geophysical techniques to determine the extent of connectivity between Langerban road and Elandsfontein aquifer system, West Coast, South Africa." University of Western Cape, 2020. http://hdl.handle.net/11394/7308.
Full textThe heterogeneity in groundwater systems suggest that not all aquifers are connected in groundwater systems. This study is about the interaction between aquifers within groundwater system. Langebaan Road and Elandsfontein aquifers in the West Coast groundwater aquifer system were chosen as case studies. These units were chosen because the previous studies on groundwater excluded the aspect of connectivity between aquifers from methods perspective which is the focus on the current study. The second reason for the study area was the present of human activities and ecosystems which are proved to be groundwater dependents. Aquifer-aquifer interaction refers to hydraulic connection between two aquifers. The interaction is influenced by hydraulic pressure and lithology of geological strata, their integrity and spatial continuity. While factors for such connectivity are well known, appropriate techniques to establish the extent of connectivity remain poorly understood and hence the need to employ various techniques so that the extent of connectivity between the two aquifers is established. Understanding the connectivity between aquifers is important because such connectivity explains the pathways for the availability of groundwater in each aquifer unit and the associated groundwater quality in each unit that supports human activities and sustain ecological systems.
Kalisperi, Despina. "Assessment of groundwater resources in the north-central coast of Crete, Greece using geophysical and geochemical methods." Thesis, Brunel University, 2009. http://bura.brunel.ac.uk/handle/2438/4241.
Full textChen, Kouping. "Impact of land reclamation on hydrogeochemical processes in coastal aquifer systems : a case study in Shenzhen, China /." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/HKUTO/record/B39558940.
Full textGuo, Haipeng, and 郭海朋. "Groundwater movement and subsurface air flow induced by land reclamation and tidal fluctuation in coastal aquifers." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40987735.
Full textGuo, Haipeng. "Groundwater movement and subsurface air flow induced by land reclamation and tidal fluctuation in coastal aquifers." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B40987735.
Full text李海龍 and Hailong Li. "Tide-induced periodic groundwater and air flows in coastal aquifer systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31244452.
Full textMartínez, Pérez Laura. "Characterization of seawater intrusion and submarine groundwater discharge in al luvial coastal aquifers: field and laboratory approach." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/671052.
Full textLa intrusión de agua de mar causa no solo la salinización de los acuíferos costeros, sino también una reducción en la descarga submarina de agua subterránea y en los flujos de nutrientes a los ecosistemas marinos. Para poder entender los efectos que provoca la coexistencia de ambos procesos en acuíferos costeros aluviales, hemos desarrollado un campo experimental a pequeña escala. La zona de campo está ubicada en la desembocadura de una riera efímera en la costa del Maresme (Barcelona, España), en un acuífero aluvial costero. En la presente tesis, se describen los intentos de caracterización detallada del sitio, basada en los cuatro pilares de la hidrogeología: geología (descripción litológica y análisis geoquímico de sedimentos), geofísica (registros de pozos, tomografía de resistividad eléctrica y monitoreo térmico), hidráulica (bombeo y pruebas de respuesta de marea) e hidroquímica (elementos mayores y menores, isótopos estables e isótopos de radio para la evaluación de la descarga de agua submarina). La implementación de los diferentes tipos de técnicas supuso la reconsideración de algunas de las preconcepciones establecidas a priori: la parte del acuífero analizada está constituida por sedimentos aluviales, en lugar de depósitos de llanura costera. A pesar de que el acuífero es libre, parece que la respuesta del acuífero a las mareas está causada por la carga mecánica impuesta por el mar, en lugar de evidenciar la conexión hidráulica con el mismo. La hidroquímica sugiere una capa inusualmente reactiva, con todos los cationes que reflejan algún proceso de disolución mineral, más allá del intercambio catiónico esperado. El radio aumenta con la salinidad, pero no de una manera evidente, debido a que el pH es expecialmente ácido en la zona más profunda del acuífero considerado. La integración de las diferentes técnicas permitió caracterizar la distribución diferentes masas de agua subterránea salada y dulce, que de hecho presentaban una disposición inversa a lo que se espera en zonas costeras. Tanto los registros de pozo como la tomografía eléctrica de resistividad realizada entre los pozos, ayudaron a identificar capas de limo, frecuentes en los depósitos aluviales, pero que demostraron desempeñar un papel fundamental aquí. Para mejorar la cuantificación de los flujos de SGD, también se caracterizó el comportamiento del radio dentro del acuífero. El sedimento recuperado durante la perforación de los pozos se utilizó para realizar experimentos batch y en columna en el laboratorio. Para ello, realizamos lavados consecutivos a salinidad constante, pero también variando la salinidad (simulando eventos de SWI y SGD), para inferir el Ra adsorbido a partir de su movilización. Posteriormente se modelaron los experimentos de columna utilizando un modelo 0D para interpretar los resultados. En las columnas hemos observado flujo heterogéneo a través de caminos preferentes. Las variaciones en estos caminos podrían explicar las fluctuaciones observadas en los experimentos realizados a salinidad constante. Dichas variaciones tambi én pueden ocurrir durante los experimentos de descarga de agua dulce y salinización, pero los cambios en la sorción del radio con la salinidad son tan dominantes que superan el impacto de los cambios en la estructura de la porosidad.
Del, Val Alonso Laura. "Advancing in the characterization of coastal aquifers : a multimethodological approach based on fiber optics distributed temperature sensing." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/672709.
Full textUna caracterización detallada de los acuíferos costeros es esencial para la gestión de los recursos hídricos costeros, y en general de las zonas costeras. A pesar de su importancia, en general no existe un monitoreo sistemático de la zona de intrusión salina (SWI). Parte de esta carencia se debe a limitaciones en las herramientas y metodologías tradicionalmente empleadas. El objetivo de esta tesis es proporcionar nuevos enfoques y herramientas para la caracterización de los acuíferos costeros, y en particular de la SWI. Inicialmente, tres sistemas de monitoreo fueron testados en campo para caracterizar la SWI: Cross-Hole Electric Resistivity Tomography (CHERT), Time Laps Induction Logging (TLIL) and Fiber Optics Distribute Temperature Sensing (FO-DTS). Para poder operar las tres herramientas en paralelo, el cable de fibra óptica y los electrodos de la CHERT se instalaron entre el entubado y el sedimento. De este modo redujimos costes de instalación y mejoramos el proceso de caracterización con la combinación de información complementarias. De hecho, la combinación de las tres permitió´ detectar diferentes niveles y dinámicas de la SWI. De estas tres técnicas, nos hemos querido concentrar en explorar el uso de la FO-DTS para el monitoreo de acuíferos costeros. Sin embargo, antes de todo tuvimos que estudiar el uso de la temperatura como trazador de la SWI. A pesar de que los fundamentos del transporte de calor en agua subterránea están establecidos, el uso de la temperatura como trazador natural de la SWI es limitado. Para estudiar la SWI se han hecho dos modelos numéricos. De los resultados obtenidos surge un posible marco teórico para la interpretación de datos térmicos de la SWI. Usando la distribución vertical de temperaturas podríamos diferenciar niveles de SWI, la dirección de flujo, e incluso aproximar la velocidad del mismo. Con estos resultados llegamos a la conclusión de que el uso de la temperatura para el seguimiento de la SWI tiene todavía un gran potencial sin explorar. Basándonos en estos resultados testamos la FO-DTS para el monitoreo de la SWI en nuestro emplazamiento experimental durante un año y medio. Los datos obtenidos con la FO_DTS permitieron identificar la respuesta de la SWI a eventos a distintas escala temporales. De este modo, los datos confirmaron las conclusiones obtenidas con los modelos numéricos. La FO-DTS puede ser usada también de forma activa, es decir, calentando el cable de fibra óptica y midiendo el calentamiento y posterior enfriamiento. En la tesis proponemos una metodología activa de la FO-DTS para medir la velocidad del flujo de agua subterránea y estimar las propiedades térmicas del medio teniendo en cuenta el efecto del almacenamiento de calor en el cable. Los valores obtenidos concuerdan con estimaciones independientes. El método puede ser aplicado tanto para la caracterización del flujo de descarga al mar en acuíferos costeros, como en cualquier medio poroso saturado. Finalmente, se revisa la interpretación de los tradicionales ensayos de bombeo. De esta revisión surge proponer una alternativa para separar los descensos de los niveles medidos durante el bombeo, y filtrar el ruido. Esta metodología facilita y refuerza el uso de este tipo de ensayos en acuíferos costeros. La FO-DTS proporciona diferentes tipos de información sobre la SWI, lo que bien justifica profundizar en su estudio para poder generalizar su uso. Por otro lado, la revisión de métodos tradicionales, como los ensayos de bombeo, o de metodologías establecidas, como el uso de la temperatura como trazador, podrían beneficiarse de cierta revisión para adaptarlas a las condiciones especificas de los acuíferos costeros. En cualquier caso, el conjunto de métodos presentados en este documento expande las herramientas y resolución disponibles para la caracterización de la SWI en acuíferos costeros.
Mokoena, Portia Leah. "Novel approach of using Hydrogeochemistry, Hydrogeologic and Hydrostratigraphic techniques in evaluating coastal aquifers in Heuningnes catchment, South Africa." University of the Western Cape, 2019. http://hdl.handle.net/11394/7960.
Full textThe increasing population in search for better social and economic development in coastal areas puts groundwater resources under pressure because of the high fresh water demand for domestic and agriculture use. Seawater intrusion is widely recognised as major concern in coastal aquifers across the globe and is influenced by multiple factors, being climate variation which is projected to adjust recharge of groundwater because of decreased precipitation patterns and to increase sea level variations and over-abstraction due to high freshwater demand as a result of increased population and agricultural practices, thereby inducing salinization in groundwater. The coastal aquifer in Heuningnes Catchment is not exempted from these issues and salinization is a major concern in the area affecting groundwater quality. In Heuningnes Catchment and South Africa in general there is limited knowledge on the application of integrated approach for assessing groundwater quality especially salinization mechanism in coastal aquifers. The main goal of this research is to test and demonstrate the viability of using joint interpretation approach of geophysics, geochemical and geological information to investigate groundwater quality in coastal aquifers thus improving on the understanding of using such approach. This work offers the initial thorough assessment of groundwater quality and understanding of the salinity sources and hydro-geochemical processes governing the chemical composition of groundwater in the region. Thus provide advice on the fitness of this water for consumption and irrigation purposes. Thirty-two groundwater samples were collected and analysed for (Mg2+), (Ca2+), (Na+), (K+), (Cl-), (SO42), (HCO3-), (pH, TDS and EC). To estimate fitness of groundwater quality for consumption purposes WHO (2011) and SANS241 guideline were used and for irrigation utilization the water quality indices (EC), (Na+%), (SAR), (RSC), (KR) and (MR) were used. Statistics approaches were employed to ascertain the primary geochemical processes governing the chemical composition of groundwater in the research region. Lastly, the spatial distribution maps were created by means of ArcGIS. Electrical resistivity method was used to map the extent of saline distribution within the subsurface. The findings of this study revealed that groundwater in the region is alkaline type and TDS, EC, Na+, Cl- exceeded WHO and SANS241 guidelines for consumption water. The geophysical investigation revealed that the sandy clay/clayey sand, fine sand and fractured sandstone units make up the coastal aquifer systems within the area. Further, revealed that these aquifers were saturated with fresh, saline or brackish water depending on the subsurface layer. The presence of saline and brackish was confirmed by the chemical results which indicated a Na+-Cl- type as a dominant water type. Also classifying groundwater based on EC and TDS supports these findings. The foremost hydro-geochemical processes that controls the salinity and quality of groundwater in the study region as indicated by Gibbs plot are water-rock interaction followed by evaporation process. Furthermore, analysis of hydrochemical data also proposes that weathering of silicate minerals, ion-exchange and dissolution of carbonate minerals amended ion concentration in groundwater thus influencing salinisation in certain parts of the study region. Also assessment of ionic-ratios displays influences of marine sprays as well as seawater, on the chemical structure of groundwater within the Heuningnes Catchment aquifer. Valuation of groundwater quality and its fitness for ingestion and irrigation purposes, the results indicated that shallow groundwater in the area is not suitable for any use; however, groundwater from deeper boreholes was found fresh and appropriate for irrigation and household purposes. Findings of this study indicated that salinity is the major groundwater quality issue for this area and that monitoring of groundwater quality in Heuningnes Catchment is limited. The absence of consistent monitoring program on groundwater quality makes it difficult to ascertain long term trends on groundwater quality parameters. Therefore, this study emphasizes the need for regular groundwater quality monitoring to assess the trends of these parameters in order to make an informed decision as to what can be done for mitigation purposes.
O???Shea, Bethany Megan School of Biological Earth & Environmental Science UNSW. "Delineating the source, geochemical sinks and aqueous mobilisation processes of naturally occurring arsenic in a coastal sandy aquifer." Awarded by:University of New South Wales. School of Biological, Earth and Environmental Science, 2006. http://handle.unsw.edu.au/1959.4/25179.
Full textPope, Jason Philip. "Characterization and modeling of land subsidence due to groundwater withdrawals from the confined aquifers of the Virginia Coastal Plain." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/42812.
Full textMaster of Science
Gámez, Torrent Desiré. "Sequence Stratigraphy as a tool for water resources management in alluvial coastal aquifers: application to the Llobregat delta (Barcelona, Spain)." Doctoral thesis, Universitat Politècnica de Catalunya, 2007. http://hdl.handle.net/10803/6255.
Full textThis thesis is focused on sequence stratigraphy, which is necessary to understand the onshore-offshore aquifer connection, thus modifying the classical hydrogeological conceptual models. The methodology of sequence stratigraphy offers a perspective of delta architecture based on geological controls and processes. Sequence stratigraphic concepts are used in Western Mediterranean deltas in addition to local factors, such as subsidence, uplift and the rate of sediment supply to account for differences in Pleistocene stratigraphic patterns and aquifer preservation. These local factors exert an influence over the shape, slope and thickness of aquifers. Together with the width of the continental shelf, the presence of submarine canyons, faults and thin prodelta layers conditions vulnerability to seawater intrusion.
The Quaternary Mediterranean shelf is characterized by high-frequency depositional sequences mainly composed of large-scale regressive wedges with poor or poorly preserved transgressive to highstand intervals. Although the Llobregat delta is an anomaly, it serves as a paradigm of deltaic architecture because of its well preserved transgressive and highstand intervals. The well preserved coarse transgressive deposits are important from hydrogeological point of view. They act as aquifers with high lateral continuity from onshore to offshore providing paths for seawater intrusion.
The excellent preservation in the Llobregat delta may be a consequence of Quaternary growth faults, which caused high accommodation space, limiting the action of wave and storm events. The identification of different seismic units and deformation features along the coast makes it possible to distinguish two main morpho-structural sectors. These sectors can be influenced by tectonic movements, which may be intensified by sediment supply changes.
Detailed sedimentological, age and paleontological (foraminifera and ostracods) data display a cyclic vertical pattern of facies, including a high degree of reworked sediments. Available ages together with high sediment preservation due to constant subsidence and sediment supply during sea level rises allow us to establish a chronostratigraphic framework. The most significant and widespread erosion were interpreted as occurring during gradual sea-level falls with a frequency of 100 Kyr. glacial-interglacial cycles. However, most of the regressive deposits display complex internal architectures, which suggest the imprint of higher-frequency cycles.
The stacking pattern of the modern Holocene delta is controlled by changes in the relative sea-level and in the sediment supply. Paleofloods frequencies controlled by climatic changes and intensified by anthropic activity caused an important progradational pulses in the Llobregat delta and the channel switching with the rapid abandonment of the delta lobes.
Mizuno, Jun. "Numerical Analyses of Potential Losses of Freshwater Resources in Coastal Aquifers Caused by Global Climate Change Using an Appropriate Boundary Condition." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1213328150.
Full textPechstein, Armin [Verfasser], Sabine [Gutachter] Attinger, and Nadim K. [Gutachter] Copty. "Innovative techniques for the characterization and interpretation of coastal aquifers : pumping test interpretation by means of the drawdown derivative to estimate aquifer heterogeneity / Armin Pechstein ; Gutachter: Sabine Attinger, Nadim K. Copty." Jena : Friedrich-Schiller-Universität Jena, 2017. http://d-nb.info/1177603160/34.
Full textKowlesser, Akshay. "Sustainable Aquifer Management in Small Island Developing States : A case study of Mauritius." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-227316.
Full textSmall Island Developing States (SIDS), små önationer under utveckling, är bland de mest sårbara staterna i världen. De är utsatta för ett antal stressfaktorer inklusive ekonomiska, klimatrelaterade och rumsliga restriktioner. Detta examensarbete undersöker effekterna av några kritiska stressfaktorer på grundvattenreserverna i dessa önationer. Mauritius valdes som fallstudie för detta projekt på grund av tre huvudsakliga orsaker. Dessa var att öar i Indiska Oceanen är de minst studerade jämfört med atlantiska och karibiska öar, att det inte finns någon riktig grundvattenmodell för akvifererna på Mauritius och slutligen att information och bakgrundskunskap var mer lättåtkomligt för författaren. Två kritiska akviferer på Mauritius valdes utifrån deras respektive sårbarheter (uttagshastighet av grundvatten, geologiska egenskaper och nederbördsmönster). Baserat på detta valdes Akvifer II och Akvifer V. Akvifererna kalibrerades med hjälp av data publicerat av mauritiska lokala myndigheter och genom en omfattande litteraturstudie. Akvifer II och Akvifer V modellerades i programmet ModelMUSE och en steady state-modell (med en tidsserie på 100 år) användes för att kalibrera modellerna med hjälp av begränsad data som erhölls under litteraturstudien. Inmatningsvärdena erhölls från vattenresursenheten på Mauritius, från vilka genomsnittliga värden över en tidsperiod om 15 år togs fram och användes som begynnelsevillkor för steady state-modellen. Akvifer V kalibrerades med framgång medan Akvifer II gav inkonsekventa resultat. Detta hänfördes till de stora skillnaderna i topografin i Akvifer II, vilka bidrog till att fel uppstod under uträkningen. En tidsberoende modell med fyra scenarios inspirerade av FN:s klimatpanels scenarioanalys användes för att undersöka saltvatteninträngningen samt grundvattennivån i båda akvifererna. Scenarierna (körda över en period om 100 år, d.v.s. till 2100) var av varierande viktighetsgrad och inkluderade de främsta drivkrafterna som ansågs påverka Mauritius grundvattenförbrukning. De attribut som fokuserades på i denna avhandling var: ekonomi, demografi, teknik och klimat. Dessa omvandlades sedan till indata som användes i modellen för att bedöma migrationen av saltvatten/sötvattengränsen i akvifererna. Scenario 4 som innebar liten grundvattenbildning i akviferen, hög havsnivåstigning, låg BNP-tillväxt och ökande befolkning utsatte akviferen för en reducerad vattennivå, och påföljande havsvatteninträngning av ordningen 1,5 km över den analyserade tvärsektionen. Scenario 3 gav å andra sidan mer optimistiska resultat då saltvatten/sötvattengränsen rörde sig mot havet. Scenario 4 medförde att ungefär 50 % av brunnarna i akviferen blev oanvändbara. Åtgärder såsom hållbara stadsdräneringssystem, kontrollerad grundvattenbildning och Seepcat (en metod som innebär att man placerar en serie rör runt kustområden för att förhindra saltvattenintrång) rekommenderas för att minska saltvatteninträngningen och så småningom öka öns färskvattenlins på olika rumsliga och tidsrelaterade skalor. Det föreslås att den grova grundvattenmodellen som utvecklats för Akvifer V i Mauritius förfinas och appliceras på olika akviferer på ön. Därtill rekommenderas att diskontinuiteter i geologin integreras i grundvattenmodellen i framtida arbete. Genom att applicera modellen kan viktig information användas för en hållbar vattenförvaltning på Mauritius i framtiden.
Smith, James V. S. School of Biological Earth & Environmental Sciences UNSW. "Inorganic hydrogeochemistry, hydrogeology and geology of the Stuarts Point aquifer system : a process analysis of the natural occurrences of enriched As(III) and As(V) in an Australian coastal groundwater system." Awarded by:University of New South Wales. School of Biological, Earth and Environmental Sciences, 2005. http://handle.unsw.edu.au/1959.4/22349.
Full textvon, Bahr Maximilian, and Bergström Ida Gomez. "Investigation of the origin of salt in coastal aquifers and assessment of metals in the aquatic environment : River Drin and River Vjosa, Albania." Thesis, KTH, Vatten- och miljöteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235421.
Full textGrundvatten är en av de viktigaste naturresurserna vilket innebär att för att säkerställa en långvarig försörjning krävs en god förvaltning av befintliga akvifärer. I kustnära områden kan intrång av saltvatten från havet till grundvattnet påverka sötvattenkvaliteten negativt. Ett sådant riskområde är den Adriatiska kustlinjen i Albanien, ett land som är övervägande rikt på sötvattenresurser tack vare de många floder som rinner från bergen i öst mot havet i väst. Kustområdena används huvudsakligen för jordbruksverksamhet, där grundvatten är en viktig resurs vid bevattning. Denna studie genomfördes därför delvis i Albanien där prov av grundvatten och flodvatten hämtades från Drins och Vjosas floddeltan för att undersöka saltets ursprung och för att bedöma de biotillgängliga metalkoncentrationerna av nickel och zink. Vattenprover togs på ett urval av platser och testades direkt för omgivningsberoende parametrar samt analyserades vidare i laboratorier. I laboratoriet analyserades proverna med avseende på fördelning av syre- och deuteriumisotoper. Resultaten användes för att bedöma syreinnehållets ursprung, eftersom metoden för att undersöka saltets ursprung använder syreisotopen som spårämne. Anjon- och katjonkoncentrationer analyserades såväl som koncentrationerna av metaller. Dessa användes som inmatningsdata till Visual Minteq, en modell som används för att beräkna metallsammansättningen i vatten och en Biotic ligand model som användes för att beräkna de biotillgängliga koncentrationerna samt HC5-koncentrationerna. Isotopanalysen gav resultat som liknar tidigare studier utförda i det närliggande området vilket indikerar att saltet inte har oceaniskt ursprung utan meteorologiskt. De biotillgängliga koncentrationerna av nickel och zink var i de flesta fall lägre än de beräknade HC5-koncentrationerna, vilket indikerar att det finns ett buffertsystem, trots att gruvaktiviteter uppströms provplatserna skulle kunna ha påverkat vattenkvaliteten negativt. Studien slutsats är att saltet i grundvattnet och flodvattnet är av meteoriskt ursprung och inte ett resultat av saltvatteninträngning från det Adriatiska havet. De biotillgängliga halterna av nickel och zink understiger HC5 halterna i samtliga fall utom ett. För att fördjupa förståelsen och kunskapen om vattenkvaliteten i dessa områden bör framtida studier fokusera på en kontinuerlig mätperiod som till exempel sträcker sig över hela året vilket skulle minimera eventuella säsongsvariationer av insamlad data. Andra metoder så som geofysiska mätningar kan också bidra till en bredare analys av tillståndet i grundvattnet.
陳扣平 and Kouping Chen. "Impact of land reclamation on hydrogeochemical processes in coastal aquifer systems: a case study in Shenzhen,China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B39558940.
Full textFatema, Suraiya [Verfasser], Christoph [Akademischer Betreuer] Schüth, Anwar Akademischer Betreuer] Zahid, Matthias [Akademischer Betreuer] [Hinderer, and Wilhelm [Akademischer Betreuer] Urban. "Vulnerability assessment of the coastal aquifers in the Cox’s Bazar area, Bangladesh using hydrochemical tools and the GALDIT model / Suraiya Fatema ; Christoph Schüth, Anwar Zahid, Matthias Hinderer, Wilhelm Urban." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2020. http://d-nb.info/1211088529/34.
Full textFatema, Suraiya [Verfasser], Christoph [Akademischer Betreuer] Schüth, Anwar [Akademischer Betreuer] Zahid, Matthias [Akademischer Betreuer] Hinderer, and Wilhelm [Akademischer Betreuer] Urban. "Vulnerability assessment of the coastal aquifers in the Cox’s Bazar area, Bangladesh using hydrochemical tools and the GALDIT model / Suraiya Fatema ; Christoph Schüth, Anwar Zahid, Matthias Hinderer, Wilhelm Urban." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2020. http://d-nb.info/1211088529/34.
Full textLu, Chunhui. "Mixing in complex coastal hydrogeologic systems." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39600.
Full textBeddows, Patricia Anne. "Groundwater hydrology of a coastal conduit carbonate aquifer : Caribbean coast of the YucataÌn Peninsula, MeÌxico." Thesis, University of Bristol, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398776.
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