Thèses sur le sujet « Hydrogeological data »

The conceptualisation of a groundwater system involves continuous monitoring and evaluation of a large number of parameters (e.g., hydraulic parameters). Regarding hydraulic properties of the aquifers, their quantification is one of the most common problems in groundwater resources and it is recognised that all methods to obtain them have their limitations and are scale dependants. Therefore, it is necessary to have methods and tools to estimate them within a spatial context and to validate their uncertainty when they are applied in an upper scale. All these datasets collected and generated to perform a groundwater conceptual model are often stored in different scales and formats (e.g., maps, spreadsheets or databases). This continuous growing volume of data entails further improving on how it is compiled, stored and integrated for their analysis. This thesis contributes to: (i) provide dynamic and scalable methodologies for migrating and integrating multiple data infrastructures (data warehouses, spatial data infrastructures, ICT tools); (ii) to gain higher performance of their analysis within their spatial context; (iii) to provide specific tools to analyse hydrogeological processes and to obtain hydraulic parameters that have a key role in groundwater studies; and (iv) to share open-source and user-friendly software that allows standardisation, management, analysis, interpretation and sharing of hydrogeological data with a numerical model within a unique geographical platform (GIS platform). A dynamic and scalable methodology has been designed to harmonise and standardise multiple datasets and third-party databases from different origins, or to connect them with ICT tools. This methodology can be widely applied in any kind of data migration and integration (DMI) process, to develop Data warehouses, Spatial Data Infrastructures or to implement ICT tools on existing data infrastructures for further analyses, improving data governance. A higher performance to obtain hydraulic parameters of the aquifer has been addressed from the development of a GIS-based tool. The interpretation of pumping tests within its spatial context can reduce the uncertainty of its analysis with an accurate knowledge of the aquifer geometry and boundaries. This software designed to collect, manage, visualise and analyse pumping tests in a GIS environment supports the hydraulic parameterization of groundwater flow and transport models. To enhance the hydraulic parameters quantification, a compilation, revision and analysis of the hydraulic conductivity based on grain size methodologies have been performed. Afterwards, the uncertainty of applying these methods on a larger scale has been addressed and discussed by comparison of the upscaling results with pumping tests. Finally, a sharing, open-source and user-friendly GIS-based tool is presented. This new generation of GIS-based tool aims at simplifying the characterisation of groundwater bodies for the purpose of building rigorous and data-based environmental conceptual models. It allows to standardise, manage, analyse and interpret hydrogeological and hydrochemical data. Due to its free and open-source architecture, it can be updated and extended depending on the tailored applications.
La conceptualització d’un sistema hidrogeològic implica una continua monitorització i avaluació d’una gran quantitat de paràmetres (e.g., paràmetres hidràulics). Pel que fa als paràmetres hidràulics de l’aqüífer, la seva quantificació és un dels problemes més comuns als estudis hidrogeològics. És àmpliament reconegut que els mètodes per obtenir aquest tipus de paràmetres tenen les seves limitacions i són dependents de l’escala d’anàlisi. Per aquest motiu, cal disposar de mètodes i eines per estimar-los dins del seu context espacial i validar la seva incertesa quan s’apliquen en una escala superior d’anàlisi. Les dades recopilades i generades per realitzar un model conceptual hidrogeològic sovint s'emmagatzemen en diferents escales i formats (e.g., mapes, fulls de càlcul o bases de dades). Aquest volum de dades en continu creixement requereix d'eines i metodologies que millorin la seva compilació i gestió per al seu posterior anàlisi. Les contribucions realitzades en aquesta tesi son: (i) proporcionar metodologies dinàmiques i escalables per migrar i integrar múltiples infraestructures de dades (infraestructures de dades espacials i no espacials, o la implementació d'eines TIC); (ii) obtenir un major rendiment de l'anàlisi hidrogeològic tenint en compte el seu context espacial; (iii) proporcionar eines específiques per analitzar processos hidrogeològics i obtenir paràmetres hidràulics que tenen un paper clau en els estudis d'aigües subterrànies; i (iv) difondre software de codi lliure i de fàcil accés que permeti l'estandardització, gestió, anàlisi, interpretació i intercanvi de dades hidrogeològiques amb un model numèric dins d'una única plataforma de informació geogràfica (SIG). S'ha dissenyat una metodologia dinàmica i escalable per harmonitzar i estandarditzar múltiples conjunts de dades de diferents orígens, o bé per connectar aquestes infraestructures de dades amb eines TIC. Aquesta metodologia pot ser implementada en qualsevol tipus de procés de migració i integració de dades (DMI), per a desenvolupar infraestructures de dades espacials i no espacials, o bé per implementar eines TIC a les infraestructures de dades existents per a anàlisi addicionals; millorant així la governança de les dades. Un major rendiment per obtenir els paràmetres hidràulics de l'aqüífer s'adreça des del desenvolupament d'una eina SIG. La interpretació dels assaigs de bombament dins del seu context espacial, pot reduir la incertesa del seu anàlisi amb un coneixement precís de la geometria i els límits de l'aqüífer. Aquest software dissenyat per recopilar, administrar, visualitzar i analitzar els assaigs de bombament en un entorn GIS, dóna suport a la parametrització hidràulica dels models de flux i transport d'aigües subterrànies. Per millorar la quantificació dels paràmetres hidràulics, es va realitzar una compilació, revisió i anàlisi de la conductivitat hidràulica basada en metodologies de mida de gra. Posteriorment, s'ha considerat i discutit la incertesa d'aplicar aquests mètodes en una escala major comparant els resultats de la millora d'escala amb les proves de bombament. Finalment, es presenta una eina SIG lliure, de codi obert i de fàcil aplicació. Aquesta nova generació d'eines SIG pretenen simplificar la caracterització de les masses d'aigua subterrània amb el propòsit de construir models conceptuals ambientals rigorosos. A més, aquesta eina permet estandarditzar, gestionar, analitzar i interpretar dades hidrogeològiques i hidroquímiques. Donat que la seva arquitectura és de codi lliure i obert, es pot actualitzar i ampliar segons les aplicacions personalitzades que cada usuari requereixi.
La conceptualización de un sistema hidrogeológico implica el continuo monitoreo y evaluación de una gran cantidad de parámetros (e.g., parámetros hidráulicos). Con respecto a los parámetros hidráulicos, su cuantificación es uno de los problemas más comunes en los estudios hidrogeológicos. Es ampliamente reconocido que los métodos para obtener este tipo de parámetros tienen sus limitaciones y son dependientes de la escala de análisis. En este sentido, es necesario disponer de métodos y herramientas para estimarlos dentro de su contexto espacial y validar su incertidumbre cuando se aplican en una escala superior de análisis. Los datos recopilados y generados para realizar un modelo conceptual hidrogeológico a menudo se almacenan en diferentes escalas y formatos (e.g., mapas, hojas de cálculo o bases de datos). Este volumen de datos en continuo crecimiento requiere de herramientas y metodologías que mejoren su compilación y gestión para su posterior análisis. Las contribuciones realizadas son: (i) proporcionar metodologías dinámicas y escalables para migrar e integrar múltiples infraestructuras de datos (ya sean infraestructuras de datos espaciales y no espaciales, o la implementación de herramientas TIC); (ii) obtener un mayor rendimiento del análisis hidrogeológico teniendo en cuenta su contexto espacial; (iii) proporcionar herramientas específicas para analizar procesos hidrogeológicos y obtener parámetros hidráulicos que desempeñan un papel clave en los estudios de aguas subterráneas; y (iv) difundir software de código abierto y de fácil acceso que permita la estandarización, gestión, análisis, interpretación e intercambio de datos hidrogeológicos con un modelo numérico dentro de una única plataforma de información geográfica (SIG). Se ha diseñado una metodología dinámica y escalable para armonizar y estandarizar múltiples conjuntos de datos de diferentes orígenes, o bien para conectar éstas infraestructuras de datos con herramientas TIC. Esta metodología puede ser implementada en cualquier tipo de proceso de migración e integración de datos (DMI), para desarrollar infraestructuras de datos espaciales y no espaciales, o para implementar herramientas TIC en las infraestructuras de datos existentes para análisis adicionales; mejorando así la gobernanza de los datos. Un mayor rendimiento para obtener los parámetros hidráulicos del acuífero se ha abordado desde el desarrollo de una herramienta SIG. La interpretación de ensayos de bombeo dentro de su contexto espacial, puede reducir la incertidumbre de su análisis con un conocimiento preciso de la geometría y los límites del acuífero. Este software diseñado para recopilar, administrar, visualizar y analizar las pruebas de bombeo en un entorno SIG, apoya la parametrización hidráulica de los modelos de flujo y transporte de aguas subterráneas. Para mejorar la cuantificación de los parámetros hidráulicos, se ha realizado una compilación, revisión y análisis de la conductividad hidráulica basada en metodologías de tamaño de grano. Posteriormente, se ha considerado y discutido la incertidumbre de aplicar estos métodos en una escala mayor comparando los resultados de la mejora de escala con los obtenidos en ensayos de bombeo. Finalmente, se presenta una herramienta SIG libre, de código abierto y de fácil aplicación. Esta nueva generación de herramienta SIG pretende simplificar la caracterización de los cuerpos de agua subterránea con el propósito de construir modelos conceptuales ambientales rigurosos. Además, esta herramienta permite estandarizar, gestionar, analizar e interpretar datos hidrogeológicos e hidroquímicos. Gracias a su arquitectura de código libre y abierto, se puede actualizar y ampliar según las aplicaciones personalizadas que cada usuario requiera

A causa del crescente interesse per la protezione dell’ambiente, sta aumentando la quantità di dati disponibili relativi al monitoraggio ambientale. Man mano che le dimensioni e la complessità dei data set ambientali continuano a crescere, si apre un sempre più ampio ventaglio di possibilità per l'implementazione di data science nel campo delle scienze ambientali. Il focus del presente progetto di dottorato è la risoluzione di diverse problematiche idrogeologiche tramite tecniche data-driven. Più specificatamente, il presente progetto di dottorato mira a identificare e applicare tecniche data-driven adatte a dataset idrogeologici, in base alla struttura del problema e dei dati disponibili e alle condizioni sito specifiche. Nell'ambito del presente progetto di dottorato due problemi idrologici principali sono stati affrontati parallelamente, riguardanti i due aspetti principali della gestione delle risorse sotterranee: a) la qualità delle acque sotterranee e b) la quantità delle acque sotterranee. Ognuno di questi due task è stato affrontato in due fasi successive. La prima fase consiste in un'analisi esplorativa dei dati disponibili, volta a raggiungere una migliore comprensione del sistema, del problema e delle informazioni disponibili. La seconda fase consiste nell’uso di tecniche data - driven per indagare sulla loro efficacia in campo idrogeologico. L'analisi dei dati sulla qualità delle acque sotterranee comporta l'applicazione di tecniche di analisi statistica multivariata, normalmente utilizzate per l’identificazione delle sorgenti, a un dataset relativo ai dati chimici di acque superficiali e sotterranee. Lo scopo di questo task è determinare l’efficacia di queste tecniche nell'identificare i fenomeni che contribuiscono alla concentrazione di diversi composti in un campione. Nell’ambito di questo task sono state implementate Factor Analysis, Cluster Analysis e Positive Matrix Factorization. Per quanto riguarda la quantità delle risorse idriche sotterranee, l'analisi delle serie temporali di livelli piezometrici si basa su modelli in grado di ricostruire dati storici ed elaborare scenari futuri; in questo task sono state utilizzate autocorrelazione, autocorrelazione parziale e impulse response e sono stati sviluppati modelli lineari e non lineari (reti neurali). Questo lavoro ha evidenziato che le tecniche data-driven possono essere considerate uno strumento utile a supporto della gestione delle risorse idriche sotterranee.
Due to the constantly growing interest toward environment protection, the amount of available data concerning environmental monitoring is increasing. As the size and complexity of environmental datasets continue to grow, there is a wide variety of possibility for implementation of data science in the environmental sciences field. The focus of the present PhD work is the resolution different hydrogeological issues by means of data science. More specifically, the present PhD project aims at identifying and applying data-driven techniques suitable for hydrogeological datasets, based on the structure of the problem and the available data and on site-specific conditions. In the scope of this PhD work two main hydrological problems were addressed parallelly, concerning the two main aspects of groundwater resource management: a) groundwater quality and b) groundwater quantity. Each task was tackled in two successive phases. The first phase consisted in an exploratory analysis of the available data, aimed at reaching a better understanding of the system, the problem and the available information. The second phase involved the application of specific data driven techniques to investigate their effectiveness in the hydrogeological field. The groundwater quality data analysis involves the application of multivariate techniques, normally used for the source apportionment, to a dataset concerning chemical data of surface water and groundwater aiming at determining their effectiveness in identifying the phenomena that contribute to the concentration of several compounds in a sample. In this task Factor Analysis, Cluster Analysis and Positive Matrix Factorization were implemented. As regards the groundwater quantity, the analysis of groundwater level time series uses models able to reconstruct historical data and applicable to forecast scenarios; in this task autocorrelation, partial autocorrelation and impulse response were used and linear and nonlinear neural networks models

Several countries have acquired, over the past decades, large amounts of area covering Airborne Electromagnetic data. Contribution of airborne geophysics has dramatically increased for both groundwater resource mapping and management proving how those systems are appropriate for large-scale and efficient groundwater surveying. We start with processing and inversion of two AEM dataset from two different systems collected over the Spiritwood Valley Aquifer area, Manitoba, Canada respectively, the AeroTEM III (commissioned by the Geological Survey of Canada in 2010) and the “Full waveform VTEM” dataset, collected and tested over the same survey area, during the fall 2011. We demonstrate that in the presence of multiple datasets, either AEM and ground data, due processing, inversion, post-processing, data integration and data calibration is the proper approach capable of providing reliable and consistent resistivity models. Our approach can be of interest to many end users, ranging from Geological Surveys, Universities to Private Companies, which are often proprietary of large geophysical databases to be interpreted for geological and\or hydrogeological purposes. In this study we deeply investigate the role of integration of several complimentary types of geophysical data collected over the same survey area. We show that data integration can improve inversions, reduce ambiguity and deliver high resolution results. We further attempt to use the final, most reliable output resistivity models as a solid basis for building a knowledge-driven 3D geological voxel-based model. A voxel approach allows a quantitative understanding of the hydrogeological setting of the area, and it can be further used to estimate the aquifers volumes (i.e. potential amount of groundwater resources) as well as hydrogeological flow model prediction. In addition, we investigated the impact of an AEM dataset towards hydrogeological mapping and 3D hydrogeological modeling, comparing it to having only a ground based TEM dataset and\or to having only boreholes data.

Several countries have acquired, over the past decades, large amounts of area covering Airborne Electromagnetic data. Contribution of airborne geophysics has dramatically increased for both groundwater resource mapping and management proving how those systems are appropriate for large-scale and efficient groundwater surveying. We start with processing and inversion of two AEM dataset from two different systems collected over the Spiritwood Valley Aquifer area, Manitoba, Canada respectively, the AeroTEM III (commissioned by the Geological Survey of Canada in 2010) and the “Full waveform VTEM” dataset, collected and tested over the same survey area, during the fall 2011. We demonstrate that in the presence of multiple datasets, either AEM and ground data, due processing, inversion, post-processing, data integration and data calibration is the proper approach capable of providing reliable and consistent resistivity models. Our approach can be of interest to many end users, ranging from Geological Surveys, Universities to Private Companies, which are often proprietary of large geophysical databases to be interpreted for geological and\or hydrogeological purposes. In this study we deeply investigate the role of integration of several complimentary types of geophysical data collected over the same survey area. We show that data integration can improve inversions, reduce ambiguity and deliver high resolution results. We further attempt to use the final, most reliable output resistivity models as a solid basis for building a knowledge-driven 3D geological voxel-based model. A voxel approach allows a quantitative understanding of the hydrogeological setting of the area, and it can be further used to estimate the aquifers volumes (i.e. potential amount of groundwater resources) as well as hydrogeological flow model prediction. In addition, we investigated the impact of an AEM dataset towards hydrogeological mapping and 3D hydrogeological modeling, comparing it to having only a ground based TEM dataset and\or to having only boreholes data.

Arsenic-contaminated drinking water exposes ~230 million people worldwide to increased risks of several diseases and is considered one of the greatest threats to public health. In Bangladesh, arsenic-contaminated water has been declared the largest poisoning of a population in history, where 39 million people are exposed to arsenic levels above the WHO guidelines (>10 μg/L). Drinking water is mainly provided by tube-wells installed by local drillers and the majority are located in aquifers with high arsenic levels. The major challenges of identifying arsenic-safe aquifers consist of a lack of a common tool for quality assurance of hydrogeological data, post-processing of the data, and a possibility to forward analyzed data to national and local stakeholders. Therefore, the purpose of this study was to investigate the potential of applying a digital solution for collecting and managing hydrogeological data in a quality assured platform. This study was a pilot-project in the sub-district Daudkandi, Bangladesh in collaboration with the KTH-International Groundwater Research Group. To fulfill the purpose, a method was developed for systematic and automated data capturing of hydrogeological information in GeoGIS, an advanced software that proved to be an efficient tool for visualizing hydrogeological data. The results show that collecting a few field data in a systematic and automated way is helpful for interpreting aquifer sequences and will enable better prerequisites for targeting safe aquifers and installing safe tube-wells. Conclusions are that the integration of a digital platform as a decision tool may significantly improve arsenic mitigation strategies. Furthermore, providing information to public and private sectors in Bangladesh would increase the transparency of hydrogeological conditions and may help improve safe water access to high arsenic areas of Bangladesh.
Över 230 miljoner människor världen över exponeras dagligen för arsenik-förorenat dricksvatten vilket kan ge upphov till hjärt- och kärlsjukdomar, diabetes samt olika cancersjukdomar. Arsenik (As) är en extremt giftig halvmetall som är naturligt förekommande i grundvatten och klassas som ett utav de största hoten mot allmän folkhälsa, vilket gör reducerande åtgärder till en samhällsutmaning av global karaktär. Ett land som är hårt drabbat av höga arsenikhalter är Bangladesh, där miljontals människor utsätts för arsenik-nivåer som överstiger WHO:s rekommenderade riktlinjer (>10 μg/L). Dricksvattenförsörjningen tillhandahålls framförallt genom vattenbrunnar installerade av lokala borrare och där majoriteten är placerade i akviferer med skadligt höga arsenikhalter.  Utmaningarna med att identifiera arseniksäkra akviferer är flera, bland annat saknas ett gemensamt verktyg för att hantera, kvalitetssäkra och analysera hydrogeologisk data, samt för att delge denna till olika parter på lokal, regional och nationell nivå. Syftet med den här studien var således att undersöka potentialen i att tillämpa ett digitalt verktyg för insamling och hantering av fältdata från olika databaser till en kvalitetssäkrad plattform. Studien genomfördes som ett pilotprojekt i distriktet Daudkandi, Bangladesh i samarbete med forskningsgruppen KTH-International Groundwater Research Group. För att uppfylla syftet utvecklades en metod för systematisk och automatiserad datainsamling av hydrogeologisk information i GeoGIS, en avancerad mjukvara som visade sig vara ett effektivt verktyg för visualiseringar av hydrogeologiska data. Resultaten visar att insamling av en liten mängd fältdata är till stor hjälp för att tolka akvifersekvenser samt för att urskilja arseniksäkra akviferer, vilket skapar bättre förutsättningar för installation av säkra vattenbrunnar. En slutsats som dras är att integreringen av en digital plattform för datainsamling avsevärt kan förbättra beslutsfattandet för arsenikreducerande strategier samt underlättar ett transparent informationsflöde. Genom att tillhandahålla transparent hydrogeologisk information till privat och offentlig sektor i Bangladesh kan även tillgången på säkert dricksvatten förbättras.

Geothermal reservoirs have become very popular in the last decades due to their renewable energy contents. Turkey has a high geothermal energy potential
especially Western Anatolia is a promising region in terms of its highest energy. Bü
yü
k Menderes Graben system is a tectonically active extensional region and is undergoing a N&ndash
S extension leading to form geothermal fields in the graben. In the last decade, geothermal exploration, investigations and investments have been increased rapidly through the law related to geothermal energy assigned. The aim of this study is to analyze the geothermal fields located in the graben system in order to investigate their geological, hydrogeological and geochemical features and reservoir characteristics. A data set is compiled from the accessible archives, published papers and documents and several variables have been searched at every field in the graben. The variables include the fluid temperature, the distance to sea, the depth to the reservoir, the reservoir lithology, the chemical constituents, etc. In view of these variables the fields are compared and constrasted and their common characterisrics have been noted. Interpretation of the data set reveals that the fields have some common features and characters however some fields have got notable differences.

The question that is addressed in this thesis is: can a simultaneous inverse scheme involving thermal and hydrologic data resolve hydrologic model parameters to a better degree than hydrologic data alone? The first chapter sets the framework for this question by first reviewing linear and non-linear inverse problems and then illustrating the advantages of a simultaneous inverse of two different data sets through the use of a simple example. It is the goal of Chapter 2 to examine current methodologies for stating and solving the inverse problem. A review of the maximum likelihood approach is presented, and a construction formalism is adopted by introducing a series of objective functionals (norms) which are minimized to yield a variety of possible models. The inverse is carried out using a modification of a constrained simplex procedure. The algorithm requires no derivative computations and can be used to minimize an arbitrarily complicated non-linear functional, subject to non-linear inequality constraints. The algorithm produces a wide variety of acceptable models clustered about a global minimum, each of which generates data that match observed values. The inverse technique is demonstrated on a series of one and two-dimensional synthetic data sets, and on a hydraulic head data set from Downie Slide, British Columbia, Canada. At this site, four parameters are determined; the free-surface position of the water table and three boundary conditions for the domain. Further simulations using a theoretical data set with assumed properties similar to that of Downie Slide show that with noise free data, and an adequate spacing between points it is possible to interpolate an unbiased estimate of hydraulic head data at all nodes in the equivalent discretized domain. When the inverse technique is applied, the domain's conductivity structure is correctly identified when enough prior log-conductivity information is available. The implications for Downie Slide are that in order to construct anything but a simple hydrogeologic model, accurate field measurements of hydraulic head are required, as well as well-defined estimates of hydraulic conductivity, a better spacing between measurements, and adequate knowledge of the boundary conditions. Chapter 3 is devoted to developing the idea of a joint inversion scheme involving both thermal and hydrologic data. One way of overcoming data limitations (sparse hydraulic head or few hydraulic conductivity estimates) in an inverse problem is to introduce an independently collected data set and apply simultaneous or joint inversion. The joint inversion method uses data from a number of different measurements to improve the resolution of parameters which are in common to one or more functional relationships. One such data set is subsurface temperature, which is sensitive to variations in hydraulic conductivity. In Chapter 3, the basic concepts of heat and fluid transfer in porous media with emphasis on forced convective effects are reviewed, followed by inversion of theoretical data and a re-investigation of the hydrogeology of Downie Slide, augmented with thermal data and a simultaneous inverse. Additional runs on a heterogenous medium presented in Chapter 2 are carried out. With a good temperature data base, thermal properties can be properly resolved. However, in this stochastic problem the addition of thermal data did not condition .the inverse to a greater degree than accomplished with the addition of prior information on log-conductivity. The benefits of including thermal data and applying a joint inversion can be substantial when considering the more realistic problem of uncertain boundary conditions. The simultaneous inverse is also applied to the Downie Slide data set examined in Chapter 2. Unfortunately, with a homogeneous hydraulic conductivity, all that can be determined from a hydraulic head inverse are ratios of flux to hydraulic conductivity. By including thermal data, the value of hydraulic conductivity can be determined at this site. Some of the model parameters (basal heat flux, thermal conductivity, specified head boundaries) are not resolved well by the joint scheme. None theless the constructed models do offer valuable insight into the hydrogeology of the field site. The constructed models persistently show a hydraulic conductivity value of about 1 x 10⁻⁷ m/sec, which is consistent with previous estimates of hydraulic conductivity at the site. A further comparison with the inverse results in Chapter 2 show good agreement between the two inverses for the hydraulic properties.
Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate

During the 1950's and 1960's a railroad yard located in Oneida, Tennessee, was used as a creosote treatment facility for railroad ties. After the cross-ties were treated with creosote, the excess creosote was stored in an holding pond located about 100 feet north of Pine Creek (Fetterolf 1998). In 1990, during a creek modification project, creosote was discovered seeping through the banks of Pine Creek. The creosote had leached through the bottom of the pond and migrated towards the creek. In 1997, the Tennessee Department of Environment and Conservation authorized a remedial strategy prepared by Geraghty & Miller, Inc (Fetterolf 1998). The strategy involved the use of phytoremediation and a previously installed interception trench system. The primary goals of the phytoremediation plan are to stimulate biodegradation and to decrease groundwater flow, thus minimizing the migration of the contaminant into Pine Creek. Poplar trees were selected for the phytoremediation plan and were planted in two sections. The objectives of this report involved analyzing the hydrogeology of the Oneida, Tennessee site and organizing the collected data for the purpose of evaluating the impact of the phytoremediation and interception trench systems on the aquifer. The water level data was used to evaluate water level and hydraulic gradient changes due to evapotranspiration, rainfall, and groundwater extraction. It was obvious from the water level and rainfall comparison plots that the rainfall has a measurable effect on the water table elevation (i.e. groundwater flow). Some areas may be less affected because the coal layer has a tendency to decrease recharge. Meanwhile, the interception trench lowers the water level around the trench. The decrease in head occurs before and after the trench, thus the water level forms a "v-shape" at the trench. This "v-shape" lends to the notion that the hydraulic gradient also slopes towards the trench in both directions. As for the phytoremediation, there was not sufficient evidence to suggest that the water levels were being lowered by evapotranspiration. This was expected since the poplar trees were had only completed their second growing season. GMS MODFLOW was used to predict the effects on the water table due to the phytoremediation and the interception trench systems. The calibrated model did an adequate job in simulating the site when the interception trench was not in operation and the trees were not in their growing season. By using variable recharge in some areas, the results are expected to improve. For example, it is important to know the location of the coal layer so this area can be given a lower recharge value than the other areas in the model. As for the trench model, the simulated heads were much lower than the observed heads, which emphasizes that using wells is not the best method to simulate the interception trench. In the future, a transient model should be used to simulate the site with the trench operation, and the drain package could be used to model the trench itself. Meanwhile, the ET model was a valuable simulation, because it illustrates how effective the poplar trees can be even under conservative conditions. With an assumed root zone of just 3 feet and a maximum potential evapotranspiration rate of 4.6 gallons per day per tree, the majority of the site will experience the dry conditions expected.
Master of Science

碩士
國立成功大學
資源工程學系
105
Because of the heterogeneity of geological materials and scarcity of in-situ data, the geological model is usually uncertainty embedded. In this study, the statistical moment differential equation (ME) based on the small perturbation method is applied to assess predictive uncertainty. The models were conditional on geological data such as hydraulic conductivity, hydraulic head or/and lithofacies jointly or separately. The meshless generalized finite difference method (GFDM) is adopted to obtain the first and second moment solutions advantageously and conveniently by virtue of its arbitrarily-distributed computational nodes. The conditioning data were randomly sampled from a hypothetical field with spatially correlated data, which was generated by Sequential Gaussian simulation (SGSIM). This study quantifies how different types of measurements act jointly or separately to reduce the predictive uncertainty of conditional models. The results show that, conditioning different types of measurements yields improved estimates of head.

博士
國立中央大學
地球物理研究所
97
Resistivity Image Profiling (RIP), a mature technique and that provides stable quality data, can acquire a continuous subsurface image. Moreover, it is sensitive to water and fine content. In general, the significant results can be produced at landslide due to high contrast of resistivity between colluvium and bedrock. Combining RIP, groundwater mobility obtained from E-Logging, geological and groundwater level data, the mechanism and hydrogeological model of landslide can be further determined. The southeastern part of Lishan and Gangxianxiang landslide areas of central Taiwan were chosen as study sites. The following conclusions can be drawn: 1. The southeastern part of Lishan landslide area: Based on RIP and rock samples collected from boreholes results, three electrical strata are recognized; colluvium, the shear zone composed of shear gouges and shattered slate, and the undisturbed slate formation. The steep shear zone serves as aquitard, it forms a natural barrier which blocks and retains groundwater flowing down the slope. Groundwater will brim over the barrier when the water level is high. Sufficient supply of groundwater from Fushoushan Farm creates a dynamic balance of groundwater with a stable water level where is higher than shear zone. A series of curved basal surface of the colluvium associated with the main slope failure shown from resistivity variation indicated that the slope migrated upwards, this may be caused by the uplift of the tectonic movement. 2. Gangxianxiang landslide area: The trend of iso-resistivity line in bedrock is similar to the bedding plane, it indicates that lithological characters dominate resistivity. The low permeable bedrock with poor developed joint and fracture can be further inferred. The groundwater within the bedrock lowers the negative effect on slope stability. When a large quantity of groundwater accumulates in the colluvium; this increases the downward force of the slope and decreases the resistance of surface between colluvium and bedrock. The sliding surface occurred from colluvium down to shallower bedrock. The open release joint of rock slope, highly weathered, near upslope Huoshaoping Terrace is well developed. The rock body, cut by joints, collapse easily, it must be related to groundwater flow with higher gradient from Huoshaoping Terrace.

碩士
國立中央大學
土木工程學系
106
To face the likelihood and severity of water shortage, understanding the hydrogeological conditions and groundwater flow are important. Hydrogeological parameters of aquifer such as hydraulic conductivity (K) and storage coefficient (S) are the essential and crucial basic data in the groundwater modeling and resource assessment. However, traditionally, the estimation of hydrogeological parameters is inefficient in spatial resolution, time consuming and expensive from pumping test. In this study, a data mining framework based on Extended Empirical Orthogonal Function (EEOF) combing with Machine Learning models were applied to estimate the hydraulic conductivity and storage coefficient. We extract the major spatial-temporal patterns of groundwater level variation from EEOF and use them to build a spatial machine learning model to estimate the hydrogeological parameters in Pingtung plain. The EEOF results have shown that this analysis framework can provide the information of main variation of spatial temporal feature between rainfall and groundwater, and it can provide crucial information for the machine learning model. The model results have shown that the model precision is quite high. This framework could also apply to other aquifers and provide as a very useful information for groundwater modeling and management through the pure data-driven techniques proposed by this study.

Field data and a density-dependent groundwater flow model were used to understand the processes affecting saltwater intrusion and saline water distribution at a field site located adjacent to the Fraser River Estuary in Richmond, BC. At the field site saline water from the Fraser River intrudes a confined sand aquifer forming a saline wedge which extends laterally approximately 500 m into the aquifer. Chemical analysis of groundwater samples from three multi-level sampling wells (installed to obtain groundwater samples at closely spaced depth intervals), zone-specific piezometers, a West Bay well, and cone penetrometer tests was completed. The groundwater chemical data were used to delineate salinity contours defining the saline wedge. The chemical data were also analyzed using trilinear diagrams. Four chemically different groundwater facies were identified; shallow fresh groundwater above the saline wedge, brackish groundwater at the transition zone, saline water within the core of the saline wedge, and deep fresh groundwater beneath the saline wedge. Water level data from the zone-specific piezometers at the site were analyzed using a tidal filtering technique to determine average groundwater levels. The average water levels were then converted to equivalent freshwater head and compared for wells screened at the same elevation. The results indicated non-uniform flow conditions within the aquifer. Field data were not sufficient to thoroughly define the flow system. The numerical density-dependent groundwater flow and solute transport model Fracdens (Shikaze et al., 1996) was used simulate site conditions. The model was calibrated to field salinity data and a good match was obtained. The results indicated that the average groundwater flow regime at the site is typical for an area influenced by saltwater intrusion (circulation of dense saline water into the aquifer and then flow of saline, fresh, and mixed water toward the river under a regional freshwater gradient). Calibration of the model indicated that a shallow gradient toward the river exists and that a lower permeability zone (lower than that initially estimated based on available field data) may exist in the area of the saline wedge toe. A simulation to investigate possible effects of seasonal changes in river discharge rate on the river-side model boundary conditions indicated that the groundwater flow regime at the site likely varies due to transient conditions at the river. Seasonal influences caused the dilution of the groundwater salinity near the river-side model boundary due to the migration of fresh river water into the aquifer during high river discharge conditions. The regional groundwater flow regime for the Fraser River delta, developed by Ricketts (1998), was modified to account for the effects of saltwater intrusion from the Fraser River and Georgia Strait. A review of available geochemical data and electrical conductivity measurements indicated that saltwater intrusion into the sand aquifer from the Fraser River and Georgia Strait occurs across the delta. Identification of the different groundwater geochemical facies at the field site and comparison to other groundwater data from the Fraser delta supports the conceptual model for regional groundwater flow. There has been significant industrial development adjacent to the Fraser River Estuary and there is some potential for contamination of soil or groundwater at these industrial sites. For sites influenced by saltwater intrusion, this thesis indicates that a unique densitydependent groundwater flow regime develops that could affect the migration of contaminants. Inadequate site characterization plans, inaccurate contaminant transport predictions, and/or ineffective groundwater remediation designs could result if the effects of saltwater intrusion on the groundwater flow regime are not considered. Characterization of the groundwater flow regime in areas adjacent to the Fraser River is complicated by shallow gradients, tidal effects, and the variable density system. Densitydependent groundwater flow modelling can provide a valuable tool to assess the flow regime.

Over the course of the past several decades the benefits of redeveloping brownfields have been widely recognized. Actions have been taken to foster sustainable redevelopment of brownfields by government, policy makers and stakeholders across the world. However, redevelopments encounter great challenges and risks related to environmental and non-environmental issues. In this work, we intend to build a comprehensive and practical framework to evaluate the hydrogeological and financial risks involved during redevelopment and to ensure developers reserve sufficient capital to cover unexpected future costs within the guarantee period. Punitive damages, which contribute to these costs, are in this thesis solely associated with the cost of repossessing a house within a development should the indoor air concentration of TCE exceed the regulatory limit at a later time. The uncertainties associated with brownfield remediation have been among the barriers to brownfield redevelopment. This is mainly caused by the lack of knowledge about a site’s environmental condition. In order to alleviate uncertainties and to better understand the contaminant transport process in the subsurface, numerical simulations have been conducted to investigate the role of controlling parameters in determining the fate and transport of volatile organic compounds originating from a NAPL source zone located below the water table in the subsurface. In the first part of this thesis, the numerical model CompFlow Bio is used on a hypothesized three-dimensional problem geometry where multiple residential dwellings are built. The simulations indicate that uncertainty in the simulated indoor air concentration is sensitive to heterogeneity in the permeability structure of a stratigraphically continuous aquifer with uncertainty defined as the probability of exceeding a regulatory limit. Houses which are laterally offset from the groundwater plume are less affected by vapour intrusion due to limited transverse horizontal flux of TCE within the groundwater plume in agreement with the ASTM (2008) guidance. Within this uncertainty framework, we show that the Johnson and Ettinger (1991) model generates overly-conservative results and contributes to the exclusion zone being much further away from the groundwater plume relative to either CompFlow Bio or ASTM (2008). The probability of failure (or the probability of exceedence of the regulatory limit) is defined and calculated for further study. Due to uncertainties resulting from parameter estimation and model prediction, a methodology is introduced to incorporate field measurements into the initial estimates from the numerical model in order to improve prediction accuracy. The principle idea of this methodology is to combine the geostatistical tool kriging with the statistical data assimilation method Kalman filter to evaluate the worth and effectiveness of data in a quantitative way in order to select an optimal sampling scenario. This methodology is also used to infer whether one of the houses located adjacent to affected houses has indoor air problems based on the measurements subject to the observation that the affected house is monitored and has problems and developers have liability if a problem occurs. In this part of the study, different sampling scenarios are set up in terms of permeability (1 – 80 boreholes) and soil gas concentration (2, 4 and 7 samples) and three metrics are defined and computed as a criterion for comparison. Financing brownfield redevelopment is often viewed as a major barrier to the development process mainly due to risks and liabilities associated with brownfields. The common way of managing the risk is to transfer it to insurers by purchasing insurance coverage. This work provides two different strategies to price the risk, which is equivalent to an insurance premium. It is intended to give an instructive insight into project planning and feasibility studies during the decision-making process of a brownfield project. The two strategies of risk capital valuation are an actuarial premium calculation principle and a martingale premium calculation principle accounting for the hydrogeological and financial uncertainties faced in a project. The data used for valuation are the posterior estimates of data assimilation obtained from the results of different sampling scenarios. The cost-benefit-risk analysis is employed as a basis to construct the objective function in order to find the least cost among sampling scenarios for the project. As a result, it shows that drilling seven boreholes to extract permeability data and taking soil gas samplings in four locations or seven locations alternatively give the minimum total cost. Sensitivity analysis of some influential parameters (the safety loading factors and the possible methods to calculate the probability of failure) is performed to determine their roles of importance in the risk capital valuation. This framework can be applied to provide guidance for other risk-based environmental projects.

A raingauge network made of six stations was installed in the Hyblean region. Stations were located at different altitudes (from 5 m to 986 m a.s.l.) and along two directions (E-W and SW-NE). Rainwater samples were monthly collected for stable isotope measurements. Spatial distribution of rainwater isotope composition has confirmed the wet air masses move from South-East/South-West toward North. Water balance has highlighted that the annual volume of infiltrating waters is in the range of 1-1.5 *105 m3 Km-2. 82 well waters and 12 spring waters located within the Hyblean Plateau (South-Estern Sicily), were also collected from 1999 to 2001 during several surveys for chemical (major,minor and trace elements) analyses. Water chemistry allowed to identify two main aquifers: the first aquifer hosted within sedimentary rocks is characterized by earthalkaline bicarbonate waters, while the second aquifer, located within the volcanic deposits (mainly towards North- North-East) is characterized by groundwaters evolving from earthalkaline bicarbonate water-type towards a Na-HCO3-type. A slightly anomaly in water temperature (24-28°C) have been identified along the northern margin, while the lower Eh values have been recorded along the M.Lauro-Scicli and the Hyblean Malta Escarpment fault systems. Isotope composition of groundwaters has suggested the occurrence of evaporative processes during soil infiltration having a dD/d18O slope close to 4.5. Chemical and isotope composition of dissolved gases (d13CTDIC, d13CCH4, 3He/4He) have revealed, as expected, that deeply-derived gases rise along the main tectonic discontinuities. Chemical and isotope analyses of dissolved carbon have revealed the existence of two sampling sites (NA and FE samples) attesting the interaction between groundwaters and a consistent amount of deep inorganic carbon dioxide. He isotope ratios (from 0.81Ra to 6.19 Ra) have revealed the occurrence of mixing process, in different proportions, between crustal and mantle components. On the base of the obtained results, a clear picture of the groundwaters circulation within the Hyblean aquifers has been drawn. In framework of projecting of a geochemical network for the continuous monitoring of the local seismic activity the most suitable geochemical parameters and the sites of great interest have been identified.
- Unione Europea Fondo Sociale Europeo; - Ministero dell’Università e della Ricerca Scientifica e Tecnologica; - Università degli studi di Palermo
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