Segui questo link per vedere altri tipi di pubblicazioni sul tema: Hydrogeology.
Tesi sul tema "Hydrogeology"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-50 saggi (tesi di laurea o di dottorato) per l'attività di ricerca sul tema "Hydrogeology".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi le tesi di molte aree scientifiche e compila una bibliografia corretta.
1
Barker, John A. "Diffusion in hydrogeology". Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-193862.
Testo completoAbstract (sommario):
The field of hydrogeology is primarily concerned with the flow of water below the ground surface and with transport, normally of solutes and heat, within that water. Many disciplines have contributed to this endeavor which requires skills from across the spectrum
of science, engineering and beyond. The diffusion equation describes not only solute transport but also the flow of water, via Darcy’s law. Of particular interest is transport in fractured rock where most of the flow is through the fractures while most of the storage is in the rock pores: a ‘double-porosity’ system. Hydrogeology remains a field that welcomes those who bring techniques from other areas
of science to address problems as varied as water supply, radioactive waste disposal and geothermal energy.
2
Barker, John A. "Diffusion in hydrogeology". Diffusion fundamentals 6 (2007) 50, S. 1-18, 2007. https://ul.qucosa.de/id/qucosa%3A14229.
Testo completoAbstract (sommario):
The field of hydrogeology is primarily concerned with the flow of water below the ground surface and with transport, normally of solutes and heat, within that water. Many disciplines have contributed to this endeavor which requires skills from across the spectrum
of science, engineering and beyond. The diffusion equation describes not only solute transport but also the flow of water, via Darcy’s law. Of particular interest is transport in fractured rock where most of the flow is through the fractures while most of the storage is in the rock pores: a ‘double-porosity’ system. Hydrogeology remains a field that welcomes those who bring techniques from other areas
of science to address problems as varied as water supply, radioactive waste disposal and geothermal energy.
3
Cooksey, Kirsty. "Hydrogeology of the Mackenzie Basin". Thesis, University of Canterbury. Geological Sciences, 2008. http://hdl.handle.net/10092/1983.
Testo completoAbstract (sommario):
The intermontane Mackenzie Basin is located within the central South Island of New Zealand. The glacial basin contains three glacial lakes which are used for hydroelectric power generation via a canal system that links the lakes. The basin is an area of climate extremes, low rainfall, high summer temperatures, and snowy winters. The area is predominantly used for pastoral farming, however farming practices are changing and, combined with an increasing population, there is a need to define the groundwater resources to enable sustainable resource management. Little is currently known about the hydrogeological system within the Mackenzie Basin, and what is known is from investigations carried out during the construction of the canal system from 1935 to 1985. There are four glacial formations that overlie Tertiary sequences and Torlesse bedrock. However, due to the glacial processes that have been ongoing over at least the last 300 ka, determining the occurrence and extent of groundwater within the outwash gravels is difficult. It is suggested that the permeability of the formations decreases with depth, therefore horizontal and vertical hydraulic conductivity decrease with depth. A shallow groundwater table is present within the Post Glacial Alluvial Gravels which is recharged directly from fast flowing streams and rivers as well as rainfall. It appears that this shallow system moves rapidly through the system and it is unlikely that the water infiltrates downwards to recharge the deeper groundwater system. It is thought that a deep groundwater system flows preferentially through the Mt John Outwash Gravels, being the second youngest glacial formation. Water chemistry and age dating tracer analysis indicate that the deeper groundwater is over 80 years old and that the groundwater system is recharging slowly. The shallow groundwater in the Post Glacial Alluvial Gravels and within the major fans to the east of the basin is 10 to 20 years in age. Baseline data such as water chemistry, groundwater levels, and surface water gaugings have been collected which can be used for future investigations. More data needs to be collected to create a long term record to further define the hydrogeological system and to determine the best way to manage the resource for long term sustainable use in the future.
4
Vincent, Craig Nicholas. "Hydrogeology of the Upper Selwyn Catchment". Thesis, University of Canterbury. Geological Sciences, 2005. http://hdl.handle.net/10092/1137.
Testo completoAbstract (sommario):
Farming practices within the upper Selwyn plains have significantly expanded, and are becoming more dependent on groundwater as a reliable source of irrigation. This expansion has resulted in the rapid development of the groundwater resource and water levels in many wells have reached record low levels. Groundwater resources can be found within at least three aquifers within the glacial gravel deposits of the upper Selwyn plains. Aquifer 1 occurs between approximately 0-30 m, aquifer 2 between 40-85 m and aquifer 3 greater than 100 m below the surface. Aquifers 1 and 2 occur within close proximity to the Selwyn River and its tributaries. Aquifer 1 is unconfined, aquifer 2 semi-confined and aquifer 3 semi-confined to confined. Significant leakage of groundwater occurs between the different aquifers. Recharge sources to the aquifers include rainfall infiltration and river seepage. Water levels and groundwater chemistry suggest that the Selwyn River provides the dominant source of recharge to aquifers 1 and 2 in areas immediately surrounding the river and to the south of the current course of the river between Greendale and Dunsandel.
5
Loris, Phoebe. "Hydrogeology of the Waipara alluvial basin". Thesis, University of Canterbury. Geology, 2000. http://hdl.handle.net/10092/7655.
Testo completoAbstract (sommario):
The Waipara alluvial basin, located 50 kilometres north of Christchurch on the South Island of New Zealand is experiencing rapid transformation in land use from pastoral farming to horticulture. In the last five years the use of the groundwater resources has increased significantly. Knowledge is lacking about the availability and sustainability of the groundwater resources.
Groundwater resources can be found throughout the basin in the Quaternary Canterbury and Teviotdale Gravels, and the late Pliocene/Early Pleistocene Kowai Formation. The hydrogeological system can be described as a complex network of discrete, lithologically and hydraulically heterogeneous and aniosotropic semipermeable to permeable channels. The physical and hydraulic nature of the aquifers (or water-bearing units) makes identification and characterisation of the resources difficult. However, the resources can be distinguished in terms of the observed hydrogeologic properties (i.e. lithology, yield, transmissivity, and chemistry).
Chemical and isotope sampling indicate that recharge to the basin aquifers is occurring through the uplifted and fractured Tertiary sequences formed along the eastern and western margins of the basin, and through infiltration of local rainfall in the unconfined and semi-confined portions of the aquifer. Groundwater residence times are long (20- 40+ years). Long residence times, slow recharge, and low hydraulic conductivity suggests that if the groundwater resources are not properly monitored and managed, there is great potential for 'mining' the resource(s), or in other words for depleting the resource faster than it can be recharged.
Long term monitoring and management strategies have been recommended for future work to help gain more knowledge and understanding of the Waipara hydrogeological system, and ensure sustain ability for future development.
6
Carpenter, Stan H. "Hydrogeology of northern Daviess County, Indiana". Virtual Press, 1992. http://liblink.bsu.edu/uhtbin/catkey/865949.
Testo completoAbstract (sommario):
In 1988, ninety ground-water samples were collected in northern Daviess County, Indiana. Sampled wells were completed in the Pennsylvanian Age Racoon Creek Group and underlying Mississippian units. Twenty-one inorganic parameters were targeted for laboratory analysis.The computer program DATAGEN4 was utilized to generate saturation indices for target mineral species. Thirteen, thirty-six, twenty-four, eighty-six, and thirteen samples were saturated with barite, calcite, dolomite, hematite, and siderite, respectively. All samples were undersaturated with respect to gypsum and fluorite.Trilinear diagrams were plotted, and the prevalent chemical characters of the samples were determined. Generally, samples collected from depths of less than 225 feet were characterized as Ca-HCO3 waters. Deeper wells yielded Na-HCO3 and Na-HCO3-Cl type waters.The naturally-occurring chemical processes that result in the water types (decomposition of organic material, carbonate dissolution, and cation exchange) are described. The influence of coal units and upwelling brines on ground-water chemistry is also discussed.Department of Geology
7
Stanger, Gordon. "The hydrogeology of the Oman Mountains". Thesis, Open University, 1986. http://oro.open.ac.uk/57011/.
Testo completoAbstract (sommario):
Northern Oman is an arid area almost entirely dependent upon groundwater recharged by highly sporadic rainfall. Precipitation estimates are hampered by a lack of any reliable altitude-rainfall relationship. Below 700 m there is no statistically significant relationship. The isotopic composition of groundwater is strongly influenced by the rainfall amount (related to storm frequency), and not just by altitude/temperature. Storm events with long return periods are of disproportionate importance to recharge. Despite the huge volume of carbonate formations, holokarstic development is generally immature, and groundwater storage is greatest in alluvial piedmont surrounding main limestone massifs. Isotopes, chemistry and hydrologic measurements show that post-storm evaporative losses are very large. The origin of limestone springs and their chemical and physical anomalies are described. Structure rather than petrology controls groundwater flow in the limestones, hence regional differences in structural style produce contrasting hydrologic regimes between the various massifs. The Semail nappe mantle sequence is the only other hard-rock formation of groundwater significance. Though much less productive than the carbonates, these ultramafics display extraordinary chemical activity, yielding bicarbonate waters from the weathered zone, whilst more deeply circulating groundwaters produce hyperalkaline springs by low-temperature serpentinisation. Associated processes include solute reduction, hydrogen evolution, hydroxide and carbonate precipitation, hydroxide-basic rock reaction, salt enrichment and water-rock isotopic exchange. Throughout the interior catchments, groundwater mostly flows into narrow buried alluvial channels which are often constricted at hard-rock nodal points, thus facilitating very efficient interception and recovery by the "falaj" system. Traditional agriculture has evolved to cope with fluctuating groundwater supply but is sensitive to increased abstraction. On the Batinah plain, greatly increased coastal abstraction has locally induced moderate to severe salinisation. Existing process studies are insufficiently quantified to provide the resolution necessary to manage groundwater resources, especially in high-risk coastal areas.
8
Smart, Michael Charles. "Hydrogeology of the Queenstown 1:500 000 map region (Sheet 3126)". Thesis, Rhodes University, 1999. http://hdl.handle.net/10962/d1005583.
Testo completoAbstract (sommario):
The Groundwater characteristics of a portion of the Eastern Cape are depicted on a General Hydrogeological Map (Queenstown 3126) at 1 :500 000 scale. The purpose of the map and accompanying text is to provide a synoptic overview of the hydrogeology of the area. The "fractured and intergranular" aquifer type predominates in the more humid eastern part of the study area where the lithologies are more highly weathered whereas the fractured type predominates in the drier west. For the bulk of the area borehole yields are in the 0.5 - 2.0 ℓ/sec range. Higher yields (in the 2.0 - 5.0 ℓ/sec range) are common only in a small area in the south-west of the map. Lowest yields (0.1 - 0.5 ℓ/sec) are obtained in an area immediately north of East London and in the Dwyka Group near the NE coast. It is important to note that these yield ranges are merely a measure of the central tendency, and that higher yields - in excess of 3 ℓ/sec - could well be obtainable at optimal hydrogeological target features within these areas. Highest borehole yields are obtained in folded areas (restricted to the southern edge of the study area) followed by rocks with dolerite intrusions (common over the bulk of the study area). Other targets include fractured sedimentary and volcanic rock and unconsolidated deposits. Yields obtained from dolerite contact zones vary across the area; differences correspond to spatial variations in the style of intrusion. Highest success rates are obtained in areas intruded by a combination of dykes, ring-shaped sheets and irregular sheets while poor results are obtained in areas intruded by thick massive sills. Air photo and satellite image interpretation, geological mapping, magnetic, electrical resistivity and electromagnetic geophysical methods can be used to locate drilling target features. Groundwater quality is good since electrical conductivities over much of the area are lower than 70 mS/m and rarely exceed the South African Water quality guideline limit for human consumption of 300 mS/m. The volume of groundwater abstractable ranges between approximately 2 000 m³/km²/annum and 80 000 m³/km²/annum and is limited by either volumes of recharge or subsurface storage.
9
Davis, Stanley N., e Augusta G. Davis. "Hydrogeology in the United States 1780-1950". Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2005. http://hdl.handle.net/10150/615795.
Testo completoAbstract (sommario):
Most modern textbooks that deal with subsurface water, or hydrogeology, include a brief
summary of the historical development of the science. In our book, we have expanded on this
general theme without introducing the more technical aspects of the topic. We have, however,
emphasized two important points that are commonly overlooked. First, most of the fundamental
contributions made during the 1800's were not American but were primarily European. Second,
1885 was the date of the first ground -water publication of the United States Geological Survey, but
it did not mark the birth of hydrogeology in the United States. Some American contributions were
made about 80 years earlier.
The authors are grateful for the assistance of many individuals. T. N. Narasimhan, M. P.
Anderson, F. M. Phillips, D. B. Stephens, J. V. Brahana, C. W. Fetter, D. Deming, and D. I. Siegel
were given the initial version of our book and provided numerous useful comments.
10
Pool, Donald Robert 1955. "Hydrogeology of McMullen Valley, west-central Arizona". Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/191959.
Testo completoAbstract (sommario):
The hydrogeology of McMullen Valley, west-central Arizona, was investigated using geologic, geophysical, and hydrologic data and a numerical model of the ground-water system. Geologic information and gravity modeling indicate that the main structure of McMullen Valley is a syncline. Basin fill that accumulated in the structural depression is the main aquifer and is divided into upper and lower units. A fine-grained facies in separates the aquifer into shallow and deep systems. A numerical model was used to analyze the ground-water system for both steady-state and transient conditions. The steady-state model aided in evaluating the distribution of hydraulic properties. The transient model was used to analyze system response to pumping stress. Water-level declines are controlled by the distribution of pumpage, specific-yield, and the fine-grained facies of lower basin fill. Significant water-level declines may extend to aquifer boundaries in most of the basin.
11
Nicol, Ryan Charles Smith. "Hydrogeology of the Cromwell Terrace Aquifer, Central Otago". Thesis, University of Canterbury. Geological Sciences, 2011. http://hdl.handle.net/10092/6431.
Testo completoAbstract (sommario):
A hydrogeologic model, groundwater chemistry and stable isotopic analysis were used to establish recharge resources and outflows so a water balance could be developed for the Cromwell Terrace Aquifer (CTA) in Central Otago, New Zealand. Increased popularity of the Central Otago region for viticulture, orcharding and tourism, has resulted in an increased demand for water. Groundwater is a viable option to meet this demand for water.
The CTA is a single unconfined aquifer contained within a thin veneer of permeable Quaternary glacial outwash gravels that range in thickness between 10 and 50m. These gravels rest unconformably on less permeable folded Tertiary sediments. The buried surface of the Tertiary sediments is irregular and provides the main hydrogeologic control in the CTA. Buried topographic highs in the Tertiary sediments impede groundwater flow, while the buried paleochannels at the southern end of the Cromwell Flat allow groundwater to flow unrestricted. The saturated thickness of the aquifer varies between 10 and 30 m.
The direction of groundwater flow is in south easterly and south westerly directions toward both Lake Dunstan and the Kawarau Arm respectively. This indicates that recharge is from the Pisa Range. Annual fluctuations in groundwater levels show that there is a seasonal effect on the groundwater table. Annual fluctuations in groundwater level are in the range of 0.4 – 0.5 m, with lowest levels in winter and highest groundwater levels in late summer. The higher groundwater levels in summer correlate with when higher rainfall occurs, but could also be due to artificial recharge from irrigation during summer, and/or seepage from the Ripponvale Irrigation Scheme canals and storage ponds.
Groundwater chemical analysis showed the dominant facies to be calcium bicarbonate waters. The source of the calcium bicarbonate is considered to be calcite in the Otago Schist, with concentrations of calcium bicarbonate being higher closer to the bedrock schist of the Pisa Range. Concentrations decreased toward Lake Dunstan, where calcium bicarbonate concentrations were lowest. The trend of calcium bicarbonate concentrations decreasing toward Lake Dunstan produces a similar pattern to the direction of groundwater flow. This would suggest that calcium bicarbonate concentrations are being diluted by rainwater infiltrating into the aquifer. However stable isotopic analysis showed that lake water infiltrates into the aquifer around the lake margin, and would also dilute calcium bicarbonate concentrations.
Stable isotopic analysis found that groundwater was more depleted in both δ¹⁸O and δ²H than water from Lake Dunstan. The average δ¹⁸O for groundwater was -9.5‰, whereas the average δ¹⁸O for samples from Lake Dunstan was -8.1‰. The average δ¹⁸O value of Pisa Range snow, Pisa Range streams and Cromwell Flat precipitation gave values of -9.2‰ +/- 1.4‰, which is very similar to groundwater. This suggests recharge to the CTA is from a combination of snow melt and surface stream flow from the Pisa Range, and some direct rainfall infiltration on the Cromwell Flat.
A water balance was calculated for the CTA groundwater system using the information from this study, and from a limited Otago Regional Council (O.R.C.) database. The main inputs to the CTA were found to be recharge precipitation and subsurface flows from the Pisa Range. The main outputs were identified as surface evaporation and discharge from the CTA to Lake Dunstan. The water balance showed that the total flow of water through the CTA is 93 Million cubic metres per year (Mm³/yr).
At present the CTA has limited groundwater allocation measures in place. Using the information from the water balance, a volume of groundwater that could be abstracted sustainably was estimated. This volume was estimated using the O.R.C. method of allocating 50% of the mean annual precipitation that recharges the aquifer for groundwater abstraction. The total mean annual precipitation for the Cromwell Flat and Pisa Range is 20 Mm³/yr. Using the 50% of mean annual precipitation method, 10 Mm³/yr can be allocated for groundwater abstraction. The total volume of groundwater currently abstracted is 3 Mm³/yr, leaving 7 Mm³/yr of unallocated groundwater. Due to the small land area, types of land use, low population density of Cromwell Flat and availability of surface water (i.e. Lake Dunstan), it is unlikely that the total volume of 10 Mm³/yr will be fully allocated.
12
Bako, Mazadu Dader. "Hydrogeology of three hard rock catchments in Britain". Thesis, Loughborough University, 1988. https://dspace.lboro.ac.uk/2134/11712.
Testo completoAbstract (sommario):
The ground water regimes of three small, undisturbed (natural) and accessible hard rock catchments representing the South, Midlands and the North of Great Britain have been hydrogeologically investigated and compared. There is a dearth of hydro geological information on hard rock areas in Britain. This is because the general availability of surface water and extensive sedimentary aquifers has not encouraged ground water prospecting in hard rock areas. In view of this, low flow study was considered essential since geology exerts a great influence on its characteristics. This was carried out using baseflow recession analysis. From a combination of practical, empirical and theoretical considerations aided by statistical analysis on a computer, baseflow recession constants which dynamically reflect the physiographic and geologic controls within a catchment were derived for the catchments investigated. These were used to characterise the behaviour of the low flows. A new method which is free of random selection of data for baseflow recession analysis is presented and a model for the curve fitting both by computer and manual methods are fully discussed and its application is also presented. Water balance computations for each of the three catchments is presented in chapter 2. Lithological units were identified by a detailed geological study. These were further investigated using resistivity and electromagnetic methods of geophysical survey. Hydrogeological properties of the aquifers were investigated by pumping test analysis and subsequent comparison of hydraulic conductivities from soils and baseflow studies. A water chemistry investigation of spring, river and rain waters has been carried out to try and defme flow paths of the ground water and this is presented in chapter 7. From these investigations, this research concludes that large community water supplies through boreholes can be economical only in one of the catchments (East Dart catchment). In the other two catchments (Blackbrook and Calder catchments), small community and household supplies are possible through boreholes (in some areas) and large diameter wells.
13
Klock, Heike. "Hydrogeology of the Kalahari in north-eastern Namibia". Doctoral thesis, [S.l.] : [s.n.], 2001. https://nbn-resolving.org/urn:nbn:de:bvb:20-1181287.
Testo completoAbstract (sommario):
This study has focused on hydrogeological and hydrochemical settings of the Northern Namibian Kalahari Catchment which is the Namibian part of the Makgadikgadi-Kalahari-Catchment. Recharge has been the subject of process-understanding, quantification and regionalisation. Within the semiarid study area a bimodal surface constitution is prominent: hardrocks areas allow for fast infiltration along karsts and joints, whereas areas covered by unconsolidated sediments receive minor diffuse recharge and locally some preferred flow path recharge develops along shrinkage cracks and rootlets. Five substratum classes have been soil physically studied: Pans and vleis, brown to red soils, dune sand, soil with an aeolian influence, and calcrete. Aeolian sands are most promising for the development of direct diffuse recharge. Recharge by preferred flow might occur in all soil classes either due to joints in calcrete or structures and rootlets in soils. All soil classes contribute to indirect recharge because even the dune sand allows, albeit very locally, the generation of runoff. The occurrences of recharge through the unconsolidated soil and the hardrocks have been confirmed by hydrograph interpretation and by a study of hydrochemical data which identified groundwater of flood water and flood water after soil passage composition. Other prominent hydrochemical processes in the Kalahari are associated with the carbonate-equilibrium-system, mixing with highly mineralised water that is either sulphate (central area) or chloride dominated (fringe area) and development of sodium hydrogencarbonate water types. The latter is mostly generated by feldspar weathering. Variations of the hydrochemical compositions were observed for shallow groundwaters. They do not only reflect the recharge amount but also the recharge conditions, e.g. a wetter year is allowing more vegetation which increases the hydrogencarbonate content. Inverse determination of recharge by the chloride mass balance method gives recharge amounts between 0.2 and locally more than 100 mm/a. The least favoured recharge conditions are found for Kalahari covered areas, the largest amount occurs in the Otavi area. The distribution of recharge areas within the catchment is rather complex and regionalisation of recharge for the entire catchment was done by a forward approach using satellite images and by an inverse approach using hydrochemical data. From the inverse hydrochemical approach a basin-wide balanced recharge amount of 1.39 mm/a is achieved. The forward approach gave a basin-wide figure of 0.88 (minimum assumption) to 4.53 mm/a (maximum assumption). A simplistic groundwater flow model confirmed the results from the minimum recharge regionalisation by satellite images and the result from the hydrochemical approach. Altogether a mutually verified basin-wide recharge figure of ca. 1 mm/a turns outDiese Studie hat sich mit den hydrogeologischen und hydrochemischen Gegebenheiten im nordnamibischen Kalahari-Einzugsgebiet befaßt. Dabei sind Prozeßverständnis, Quantifizierung und Regionalisierung für die Grundwassserneubildung erarbeitet worden. Das semiaride Arbeitsgebiets ist durch eine bimodale Oberflächenbeschaffenheiten gekennzeichnet: Festgesteinsgebiete erlauben schnelle Infiltration entlang von Klüften und Karsthohlräumen, während Gebiete die mit Lockersedimenten überdeckt sind, wenig Neubildung über die Matrix erfahren und Makroporen nur lokal eine schnellere Neubildung erlauben. Fünf Bodenklassen sind bodenphysikalisch untersucht worden: Pfannen und Vleis, Rote und Braune Böden, Dünensande, Böden mit äolischem Einfluß und Kalkkrusten. Äolische Sand sind am vielversprechendsten für die Entwicklung von direkter Neubildung über die Matrix. Alle Bodenklassen tragen zur indirekten Neubildung bei, da sie -lokal allerdings sehr begrenzt- zum oberflächlichen Abfluß beitragen. Durch die Interpretation von Grundwasserganglinien und hydrochemischer Daten ist die Neubildungserscheinung bestätigt worden. Die dominanten hydrochemischen Prozesse in der Kalahari stehen im Zusammenhang mit dem Kalk-Kohlensäure-Gleichgewicht, der Mischung mit stärker mineralisierten Wässern (im zentralen Einzugsgebiet sulfatreich, am Rand eher chloridreich) und der Entwicklung von Natriumhydrogenkarbonatwässern (häufig durch Feldspatverwitterung). Die zeitlichen Variationen der hydrochemischen Parameter in flachen Grundwasser spiegeln nicht nur die Neubildungsmenge, sondern auch die Neubildungsbedingungen wider; in relative niederschlagsreichen Jahren steigt der Hydrogenkarbonatgehalt deutlich an in folge der üppigeren Vegetation. Die inverse Bestimmung der Grundwasserneubildung mit der Chloridbilanzmethode ergibt Neubildungswerte zwischen 0,2 und 100 mm/a. Die geringsten Werte treten dabei in Kalahari-Lockersedminet bedeckten Bereichen auf, die größten Werte treten im Otavi-Gebiet auf. Die Verteilung der Neubildung innerhalb des Arbeitsgebiets ist sehr komplex. Die Regionalisierung erfolgte mit einem fernerkundlichen und einem hydrochemischen Ansatz. Die Ergebnisse liegen für den hydrochemischen Ansatz bei 1,39 m/a und der fernerkundliche Ansatz gibt eine einzugsgebietsweite Neubildung von 0,89 (Minimumansatz) bis 4,53 mm/a (Maximumansatz). Ein vereinfachtes Grundwasserströmungsmodell bestätigt die Ergebnisse der hydrochemischen Regionalisierung und des minimalen fernerkundlichen Ansatzes. Daraus ergibt sich abschließend eine Gebietsneubildung von ca. 1 mm/a für das Arbeitsgebiet
14
Onyskow, Lawrence Paul 1948. "Hydrogeology of the Catalina area, near Tucson, Arizona". Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/192027.
Testo completoAbstract (sommario):
This thesis sets forth aquifer conditions in the Catalina Basin, north of Tucson, Arizona. Historically, this area has not experienced significant urban development and no serious attempt has been made to determine either the extent of local groundwater reserves or the potential yield of the Catalina aquifer system. To address these issues, the geology of the basin fill units was defined through the construction and lithologic logging of two test holes, each 1200-feet deep. In addition, test data from three local wells were analyzed to determine that the local aquifer has a transmissivity averaging 50,000 gpd/ft and a specific yield of 15 percent. With this information, the USGS computer program MODFLOW was used to construct a transient state model of the Catalina aquifer system. The model was then employed to compute the expected drawdown throughout the area which would result from full urbanization.
15
Krug, Kristen. "THE GEOCHEMISTRY AND HYDROGEOLOGY OF ABANDONED HOMESTEAD RESERVOIRS". OpenSIUC, 2008. https://opensiuc.lib.siu.edu/theses/471.
Testo completoAbstract (sommario):
The main purpose of this study was to determine if geology controls the water quality and hydrology of abandoned, hand-dug, homestead reservoirs scattered throughout the Shawnee National Forest. Field, laboratory, and statistical methods were used to identify the hydrologic and gTwo main groups emerged; one comprised of reservoirs with large diameter casings and shallow water depth, while the other consisted of reservoirs with small diameter casings and deep water depth.eochemical nature of the reservoirs in the SNF.
16
Hackett, Joshua Andrew. "Hydrogeology of the McKinney Butte Area: Sisters, Oregon". PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/371.
Testo completoAbstract (sommario):
McKinney Butte, a late Tertiary andesite vent and flow complex, is located near the town of Sisters, Oregon, in the upper Deschutes Basin, and is situated along the structural trend that forms the eastern margin of the High Cascades graben (Sisters fault zone and Green Ridge). Rapid development and over appropriated surface water resources in this area have led to an increased dependence upon groundwater resources. A primary concern of resource managers is the potential impact of expanding groundwater use on stream flows and spring discharge. Two sets of springs (McKinney Butte Springs and Camp Polk Springs) discharge to Whychus Creek along the east flank of McKinney Butte, and during low-flow conditions supply a substantial component of the total flow in the creek. Despite their contribution to Whychus Creek, the springs along McKinney Butte are small-scale features and have received less attention than larger volume (> 2 m³/s) springs that occur in the basin (i.e., Metolius Spring and Lower Opal Springs). This study used discharge measurements in Whychus Creek upstream and downstream of the springs, and mixing models using measurements of electrical conductivity and temperature in the springs and Whychus Creek to determine the contribution of the springs to the creek. Isotopic, thermal, and geochemical signatures for the McKinney Butte and Camp Polk Springs, and local streams (Whychus Creek and Indian Ford Creek) and springs (Metolius Spring, Paulina Spring, Alder Springs, and Lower Opal Spring) were assessed to determine the source(s) of the McKinney Butte and Camp Polk Springs. The discharge and hydrochemical data along with hydraulic head data from local wells were used in the development of a conceptual model of groundwater flow for the McKinney Butte area. Discharge from the McKinney Butte Springs supplies the majority of water to Whychus Creek on the east flank of McKinney Butte (~0.20 m³/s), provides up to 46% of the flow in the creek, and is relatively stable throughout the year. Discharge from the Camp Polk Springs is less than 0.05 m³/s. Isotopic, thermal, and geochemical signatures indicate distinct sources for the McKinney Butte and Camp Polk Springs. Groundwater discharged at the McKinney Butte Springs is depleted in heavy stable isotopes (δD and δ¹⁸O) relative to the Camp Polk Springs. Recharge elevations inferred from stable isotope concentrations are 1800-1900 m for the McKinney Butte Springs and 950-1300 m for the Camp Polk Springs. Elevated water temperature in the McKinney Butte Springs relative to the average air temperature at the inferred recharge elevation indicates the presence of geothermal heat and implies deep circulation in the flow system. The temperature in the Camp Polk Springs is not elevated. The Camp Polk Springs, though not the McKinney Butte Springs, contain elevated concentrations of ions Cl, SO₄, and NO₃ that are indicative of contamination. The study results indicate the source of the Camp Polk Springs is shallow groundwater whereas the McKinney Butte Springs discharge water that has circulated deep in the groundwater flow system. Additionally, the hydrochemical traits of the McKinney Butte Springs are similar to Metolius Spring, suggesting discharge from the McKinney Butte Springs is controlled by the structural trend that forms the eastern margin of the High Cascades graben. The significant difference in discharge between the McKinney Butte Springs and Metolius spring may be related to the size of faults that occur locally.
17
Roessel, Raymond J. "Hydrogeology of the Chinle Wash Watershed, Navajo Nation Arizona, Utah and New Mexico". Thesis, The University of Arizona, 1994. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0243_sip1_w.pdf&type=application/pdf.
Testo completo
18
Sibley, Samuel D. Jr. "The Impact of Salt Marsh Hydrogeology on Dissolved Uranium". Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/7262.
Testo completoAbstract (sommario):
We quantified U removal and investigated the efficacy of uranium as a quantitative tracer of groundwater discharge in a headwater salt marsh of the Okatee River, Bluffton, SC. Determining the magnitude of U removal is important for advancing U as a tracer of paleo-oceanic conditions. Since salt marsh groundwater is typically enriched in nutrients and other biologically and chemically reactive species, quantifying groundwater discharge from marshes is critical for understanding the ability of salt marshes to modify the chemistry of important species in surface waters.
We hypothesized that water-column U(VI) was removed by tidally-induced advection of surface water into permeable, anoxic salt marsh sediments, a process resulting in bacterially-mediated precipitation of insoluble U(IV)O2 and/or sorption of uranium to iron-oxides at the oxic/anoxic sediment interface. Furthermore, we suggested that hydraulic pressure gradients established by marsh-surface tidal inundation and seasonally-variable rainfall promote the discharge of salt-marsh-processed, uranium-depleted groundwater to tidal creeks, producing the surface-water U-removal signal.
Groundwater and surface water data revealed non-conservative uranium behavior. We documented extensive uranium removal from shallow marsh groundwater and seasonally variable uranium removal from surface waters. These observations allowed for the calculation of seasonally-dependent salt marsh uranium removal rates. On a yearly basis, our removal rate (58 to 104 mol m-2 year-1) reemphasized the importance of anoxic coastal environments for U removal.
High uranium removal, high barium concentration water observed seeping from creek banks at low tide supported our hypothesis that groundwater discharge must contribute to uranium removal documented in tidal surface waters. Average site groundwater provided an analytically reasonable endmember for explaining uranium depletion in surface water. Therefore, we used three endmember mixing models for estimating the fraction of surface water with presumed a groundwater signature. Our discharge estimates of 8 to 37 L m-2 day-1 agreed closely with previously published salt marsh values. Seasonality in discharge rates can be rationalized with appeal to seasonal patterns in observed rainfall, tidal forcing, and marsh surface bioturbation. Although more work is needed, the results of this portion of the study suggest that U may be an effective quantitative tracer of groundwater discharge from salt marshes.
19
Tripathi, Ajay. "Developing a Modular Hydrogeology Ontology Extending the Sweet Ontologies". Digital Archive @ GSU, 2005. http://digitalarchive.gsu.edu/geosciences_theses/3.
Testo completoAbstract (sommario):
Application of ontologies in the environmental science will allow experts in this field to model their domain knowledge for more efficient exchange and reuse. This thesis presents a modular approach in reengineering existing upper-level ontologies to conceptualize specific domain knowledge. The aim of extending these upper-level ontologies is to tailor and transform the existing conceptual models into new ones designed for the use in a specific domain in the earth sciences. This thesis extends the upper-level Semantic Web for Earth and Environmental Terminology (SWEET)ontologies to develop ontologies for part of the hydrogeology domain. The existing SWEET ontologies are developed by NASA’s Jet Propulsion lab for Earth system science (http://sweet.jpl.nasa.gov/ontology/). In the new model, presented in this thesis, the architecture and orthogonal design of the SWEET ontologies is not disturbed but restructured at certain levels. New concepts are added to the old structure and the consistency is maintained for use by other domains. This thesis discusses the useful steps,necessary tools and other procedures involved in ontological reengineering of existing upper-level ontologies. The hydrogeology domain modeled in this thesis by means of reengineering, exemplifies the reusability methodology for the Earth system science knowledge base.
20
Arpin, Sarah Marie. "Karst Hydrogeology of the Haney Limestone, South-Central Kentucky". TopSCHOLAR®, 2013. http://digitalcommons.wku.edu/theses/1253.
Testo completoAbstract (sommario):
South-central Kentucky has one of the world’s most intensively studied karstareas, with most work focusing on the Mammoth Cave System and related caves and aquifers. However, slightly higher in the stratigraphic section than Mammoth Cave, the Haney Limestone is a locally important but less well studied carbonate aquifer. This research provides the most comprehensive synthesis to date of the karst hydrogeology of the Haney Limestone of south-central Kentucky, focusing on the distribution and controls on cave and karst features developed within. In contrast to drainage systems within the major limestones below, joints are the most dominant control on passage development in the Haney Limestone within the study area and the orientation of these joints is consistent with that of regional joint sets. Bedding planes and the presence of insoluble rock at the base of the Haney also exert control on conduit development in the Haney Limestone. Most of the caves of the study area developed in the Haney Limestone are singleconduit caves that receive water through direct, allogenic sources. Cave entrances are frequently perennial spring resurgences and the presence of active streams suggests that the caves function within the contemporary landscape, acting as drains for localized recharge areas. The hydrology of the Haney Limestone plays an important, if localized, role in the regional hydrology of south-central Kentucky, integrated into the current system of surface and subsurface drainage of the regional karst landscape. Evidence supports the idea that caves of the Haney Limestone are, geologically, relatively recent phenomena. A majority of the cave passages in the study area are hydrologically active, the water resurging from the sampled springs is typically undersaturated with respect to limestone, and the caves in some case appear to be developed along potential stress release fractures associated with small, apparently young valleys. This suggests that caves in the Haney Limestone were not directly influenced by the incision of the Green River over vast periods, like Mammoth Cave, but that cave development is a largely contemporary process.
21
Parker, S. K. "The hydrogeology of the Diamond Harbour region, Banks Peninsula". Thesis, University of Canterbury. Geology, 1989. http://hdl.handle.net/10092/5501.
Testo completoAbstract (sommario):
The study area comprises an area of about 40 km2 and includes the township of Diamond Harbour located on the sourthern side of Lyttelton Harbour. The area is broken up into two valley systems (Orton Bradley and Purau Valleys) separated by a gently northward dipping slope known as the Diamond Harbour ‘Dip-slope’. Pressure on a water reticulation pipeline due for repair or replacement, combined with an increasing population) formed the basis for this investigation. It was hoped that local groundwater resources could at least supplement the domestic supply coming from Lyttelton.
Drill hole and geophysical information confirmed that the sediments that fill the lower Purau and Orton Bradley Valleys consist of river clays and silts, marine/estuarine muds and a number of gravel units. In the case of the Purau Valley two aquifers were located, a first probably representing an infilled river channel or channels immediately overlying volcanic bedrock (Lower Purau Aquifer), and a second river gravel unit which is saturated only within 200m of the coast (Upper Purau Aquifer). While no borehold data was available to confirm geophysical data interpretations for the Orton Bradley Valley, the indications are that a single river gravel unit exists, and that it is saturated near the coast.
Pump test results for the Lower Purau Aquifer show that this aquifer has a transmissivity of 11.92m2/day and a storage coefficient of 3.87 x 10-4. Computer modelling indicated the Lower Purau Aquifer possesses two hydraulic boundaries 14 and 50m from the pumped bore I and this is consistent with the interpretation of the aquifer being an infilled river channel of approximately 64m width.
Evidence suggests that the alluvial aquifers of both valleys are recharged from deep circulating groundwaters present in fractured bedrock aquifers located within the volcanic formations found in the area. Isotope and chemical evidence suggests that the alluvial and deep circulating groundwaters are similar in their relative concentrations of most ions, and have similar residence times of about 50 years. The deep and alluvial groundwaters are fit for domestic supply provided treatment is carried out for excessive concentrations of iron and manganese, and aeration to bring low pH values to within acceptable limits.
An experiment on a known perennial High Altitude Spring indicates that the increased discharge seen following a rain event is composed almost entirely of 'old' stored water, and the increased flow is due to increa.sed pressure head following recharge of the aquifer system by meteoric waters. Superimposed on this event variability is a seasonal discharge variability related to seasonal rainfall patterns. An infiltration- 'head' /storage model is proposed to explain the behaviour of the High Altitude Springs of Diamond Harbour. Isotopic evidence suggests an exponential-piston flow model is consistent with observed results and this indicates the spring groundwaters have residence times of 10 to 25 years.
An estimate of the safe yield from all available water resources in the Diamond Harbour area ranges from 660 to 1300m3/day, allowing for sufficient water to maintain acceptable river baseflows.
22
Smith, Matthew B. "The hydrogeology and hydraulics of artesian springs in Canterbury". Thesis, University of Canterbury. Geology, 2003. http://hdl.handle.net/10092/7890.
Testo completoAbstract (sommario):
The increasing demand for water in the Canterbury region, and the realisation that spring flow plays an important role in many wetland and river systems, requires methods for predicting changes in spring behaviour as Canterbury's groundwater resources are utilised. This study into the flow of groundwater through artesian spring systems provides a better understanding of the impacts of changes in artesian aquifer pressure.
The aquifer system of the central coastal Canterbury Plains consists of gravels separated by successive layers of fine sediment. The fine sediment acts as a confining aquitard, creating artesian pressures in the gravel aquifers where the piezometric surface is above ground level. Artesian springs occur in the confining aquitard through localised zones of weakness.
Piezometric levels associated with artesian springs in gravel aquifers are not well documented and have never been observed in Canterbury. Examination of near-spring groundwater flow patterns should confirm the shallow artesian aquifer as the main source of water to artesian springs.
Little information is available on the relationship between artesian aquifer pressure and artesian spring discharge. Groundwater flow equations indicate that turbulence occurs in the high velocity flow encountered in artesian spring systems. Energy losses should thus be proportional to velocity squared and the pressure - flow relationship is expected to be non-linear. A non-linear relationship would buffer spring discharge against changes in aquifer pressure induced by groundwater abstraction.
Field investigations were carried out at two spring sites near Christchurch. Near-spring water levels were observed in the aquifer directly below the spring to confirm it as the principal source of water to the spring. Variations in artesian pressure were then induced via groundwater abstraction from nearby wells in the source aquifer, and changes in spring discharge measured.
The upper confined aquifer was confirmed to be the primary source of water for Christchurch's artesian spring systems. The relationship between artesian aquifer pressure and artesian spring discharge was found to be entirely linear for the range of pressures and flows observed. Although theoretical analysis indicates that turbulent flow is occurring at, and close to, the spring vent, the distance over which it occurs is small enough that energy losses due to rapid flow in the groundwater system are negligible. The results imply that any reduction in artesian pressure due to groundwater abstraction will have a direct, linear impact on artesian spring flow.
23
Kuma, Jerry S. "Environmental hydrogeology of the Tarkwa gold mining district, Ghana". Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394569.
Testo completo
24
Marazuela, Calvo Miguel Ángel. "Hydrogeology of salt flats : the Salar de Atacama example". Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/673063.
Testo completoAbstract (sommario):
This thesis aims to advance the knowledge of the hydrogeological functioning of salt flats in order to achieve a sustainable management of their mineral resources and ecosystems. Salt flats are a major source of Li, B, I, K, Mg and NaCl, and they host some of the most outstanding ecosystems on earth. Around 25 % of Li world reserves are located in the Salar de Atacama (NE of Chile). The exploitation of this raw material, highly valued in the technological and pharmaceutical industries, is carried out by brine pumping. Brine pumping can affect the natural hydrogeological regime of salt flats and, in many cases, the possible impact on their ecosystems is unknown.
This thesis contributes to (1) explain the geometry and groundwater flow of the mixing zone (saline interface) located around salt flats, (2) define the water balance and hydrodynamics of the Salar de Atacama under the natural regime, (3) analyse and quantify the impacts caused by brine pumping, (4) improve the design of the brine exploitations in salt flats and (5) question the traditional ideas on the origin of the Li-enrichment in the Salar de Atacama.
The groundwater recharged in the mountains is forced to flow upward when it reaches the mixing zone around the salt flat due to its lower density, feeding the lake and wetland ecosystems. The first 3D mapping of a salt flat mixing zone has been carried out in the Salar de Atacama and it has shown a slope of the mixing zone much lower than previous assumptions. The 2D modelling of the mixing zone demonstrated as the permeability of the upper aquifer increases, the slope of the mixing zone decreases, resulting in a shallower mixing zone. Thus, the permeability of the upper aquifer, mostly constituted of very permeable karstified evaporites and alluvial deposits, is critical to the geometry of the mixing zone.
The hydrogeological conceptual model of the Salar de Atacama, prior to brine pumping (natural regime), has been defined and validated using a 3D steady-state groundwater flow model. The asymmetric distribution of the recharge by infiltration of rainwater and, above all, the evaporation discharge results in a water table whose minimum hydraulic head is located in the easternmost nucleus, close to the eastern mixing zone.
The 3D transient-state modelling of the Salar de Atacama basin from 1986 to 2018 has allowed to explain the hydrodynamics and water balance impacts caused by brine exploitation. From 1994 to 2015, under the mining regime, the brine pumping caused an additional drawdown of the water table that triggered a decrease of the phreatic evaporation. This effect has been defined as "damping capacity" and it allows to counteract the disturbances occasioned by natural or anthropogenic events on the water table and balance of salt flat basins. The damping capacity compensated, at least in part, the decrease of the evaporation discharge, but nowadays it is already amortized in the nucleus and the mixing zone begins to be impacted.
The 3D modelling of a hypothetical salt flat under brine exploitation has contributed to optimize the spatial distribution of the pumping wells in terms of impact on the water balance. Brine exploitations should consider to distribute the pumping outflow in the greatest extent possible to take full advantage of the damping capacity.
The results of the hydro-thermo-haline modelling of the Salar de Atacama basin has suggested the Salar Fault System as the main contributor for the extreme Li-enrichment, either through the rise of Li-rich brines from a deep hydrothermal reservoir or remobilization of ancient layers of Li-enriched salts and/or clays by non-evaporated recharge waters coming from the W. The persistence of the mixing zones in depth also dismissed previous ideas of (1) leaking of brines from the present salt flats or (2) leaching of hypothetical salt flats buried by volcanic eruptions in the Altiplano-Puna as sources for the extreme Li-enrichment of the Salar de Atacama brines.Esta tesis contribuye a avanzar en el conocimiento del funcionamiento hidrogeológico de los salares con el fin de mejorar la gestión de sus recursos minerales y ecosistemas. Los salares son una fuente principal de Li, B, I, K, Mg y NaCl, y albergan algunos de los ecosistemas más excepcionales de la tierra. Alrededor del 25 % de las reservas mundiales de Li se localizan en el Salar de Atacama (NE de Chile). La explotación de esta materia prima, altamente valorada en las industrias tecnológica y farmacéutica, se realiza mediante bombeo de salmuera. El bombeo de salmuera puede afectar al régimen hídrico natural de los salares y, en muchos casos, se desconoce el posible impacto sobre sus ecosistemas. Esta tesis ayuda a (1) explicar la geometría y el flujo subterráneo de la zona de mezcla (interfaz salina) ubicada alrededor de los salares, (2) definir el balance hídrico y la hidrodinámica del Salar de Atacama en su régimen natural, (3) analizar y cuantificar los impactos causados por el bombeo de salmuera, (4) mejorar el diseño de las explotaciones de salmuera en salares y (5) cuestionar las ideas tradicionales que explican el origen del enriquecimiento en Li del Salar de Atacama. El agua subterránea recargada en las montañas es forzada a fluir hacia la superficie cuando alcanza la zona de mezcla que rodea al salar debido a su menor densidad, alimentando los ecosistemas lagunares y humedales. La primera cartografía 3D de la zona de mezcla de un salar se ha llevado a cabo en el Salar de Atacama, evidenciando una pendiente mucho menor que las predicciones anteriores. El modelado 2D de la zona de mezcla ha demostrado que cuanto mayor es la permeabilidad del acuífero superior, más baja es la pendiente y más superficial se vuelve la zona de mezcla. Por lo tanto, la permeabilidad del acuífero superior, principalmente constituido por evaporitas karstificadas y depósitos aluviales muy permeables, es crítica para la geometría de la zona de mezcla. El modelo hidrogeológico conceptual del Salar de Atacama, previo al bombeo de salmuera (régimen natural), se ha definido y validado utilizando un modelo estacionario 3D del flujo subterráneo. La distribución asimétrica de la recarga por infiltración del agua de lluvia y, sobre todo, de la descarga por evaporación da como resultado una superficie freática cuyo mínimo nivel hidráulico se localiza en el sector más oriental del núcleo, cerca de la zona de mezcla oriental. El modelado transitorio 3D de la cuenca del Salar de Atacama desde 1986 hasta 2018 ha permitido explicar los impactos causados por la explotación de salmuera sobre la hidrodinámica y el balance hídrico. Desde 1994 hasta 2015, el bombeo de salmuera causó una profundización de la superficie freática que desencadenó una reducción de la evaporación freática. Este efecto ha sido definido como la "capacidad de autorregulación" y permite a los salares contrarrestar las perturbaciones ocasionadas por eventos naturales o antropogénicos sobre la superficie freática y el balance hídrico. La capacidad de autorregulación compensó, al menos en parte, la disminución de la descarga por evaporación, pero hoy en día ya está amortizada en el núcleo y la zona de mezcla comienza a verse afectada. El modelado 3D de un hipotético salar bajo explotación de salmuera ha contribuido a optimizar la distribución espacial de los pozos de bombeo en términos de impacto sobre el balance hídrico. Para aprovechar al máximo la capacidad de autorregulación, las explotaciones de salmuera deben considerar distribuir el caudal bombeado en la mayor área posible. Los resultados del modelado hidro-termo-halino de una sección vertical Este-Oeste de la cuenca del Salar de Atacama han señalado al Sistema de Fallas Salar (SFS), localizado en el sector central del núcleo, como el principal contribuyente para explicar el enriquecimiento extremo en Li, ya sea por el ascenso de salmueras ricas en Li desde un reservorio hidrotermal profundo o por removilización de antiguas capas de sales y/o arcillas ricas en Li por aguas de recarga no evaporadas provenientes del Oeste. La localización del mínimo nivel hidráulico regional en el lado oriental del núcleo descarta considerar la evaporación avanzada como un mecanismo actual para alcanzar el alto contenido de Li de las salmueras ubicadas sobre el SFS. Además, la persistencia de las zonas de mezcla en profundidad también permite descartar las hipótesis previas de 1) infiltración de salmueras desde los salares actuales del Altiplano-Puna y 2) lixiviado de hipotéticos salares enterrados por erupciones volcánicas en el Altiplano-Puna como origen del enriquecimiento excepcional en Li de las salmueras de Salar de Atacama.
25
Tsiftsis, E. V. "Geology and hydrogeology of the Megalopolis Basin, Peloponnese, Greece". Thesis, University of Bristol, 1987. http://hdl.handle.net/1983/df43eab5-19cd-42e5-a740-e850188d2474.
Testo completo
26
Dzirasah, Bernard. "Hydrogeology of a Modified Wetland, Liberty Park, Twinsburg, Ohio". University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1216924052.
Testo completo
27
Carr, Cynthia Hewson Carleton University Dissertation Geology. "Hydrogeology of Zio and Yoto prefectures, Togo, West Africa". Ottawa, 1988.
Cerca il testo completo
28
Wilson, Heather C. (Heather Carol) Carleton University Dissertation Geology. "The hydrogeology of the Carleton University campus, Ottawa, Ontario". Ottawa, 1990.
Cerca il testo completo
29
Fang, Yao-chuen. "Scientific research impact and data mining applications in hydrogeology". Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1092774125.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xiii, 122 p.; also includes graphics (some col.). Includes bibliographical references (p. 118-122). Available online via OhioLINK's ETD Center
30
Feldman, Peter Roy 1957. "Hydrogeology of a contaminated industrial site on filled land". Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/192025.
Testo completoAbstract (sommario):
A detailed hydrologic investigation was conducted at a wood preservative treatment plant to determine the extent of soil and groundwater contamination and to define the rate at which preservative compounds (polycyclic aromatic hydrocarbons and phenols) are migrating to an adjacent saltwater body. Contamination appears restricted to the uppermost aquifer, which occurs in a sequence of fill deposits comprising the land surface at the site. Groundwater flow and contaminant distribution are likely controlled by heterogeneities within the fill deposits, which are a result of placement history and other factors such as buried shorelines, bulkheads, and filled channels. Calculations of total contaminant flux from the groundwater system to the adjacent saltwater body range from 143 to 191 pounds per year.
31
Johnson, Timothy Chad. "Fresnel volume ground penetrating radar attenuation difference tomography and incorporating geostatistical constraints in nonlinear inverse problems /". ProQuest subscription required:, 2006. http://proquest.umi.com/pqdweb?did=1411340331&sid=5&Fmt=2&clientId=8813&RQT=309&VName=PQD.
Testo completo
32
Corder, Lacoa L. "Hydrogeochemical characterization of springs and wells in the Cacapon Mountain Aquifer". Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5719.
Testo completoAbstract (sommario):
Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains vii, 80 p. : ill., col. maps. Includes abstract. Includes bibliographical references (p. 62-64).
33
Dennis, Frank. "The evolution of London chalk groundwater". Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283633.
Testo completoAbstract (sommario):
The chemical and isotopic composition of groundwater from 53 sites in the London area was determined as part of a project aimed at assessing the spatial variation in age of Chalk groundwater, and determining the relationship between fracture and matrix groundwater in this dual porosity system. Systematic changes in groundwater chemistry take place in the downgradient direction in response to several chemical processes. These processes include early concentration by evaporation and congruent dissolution of calcite, and widespread incongruent dissolution and ion exchange in addition to local oxidation-reduction reactions, gypsum dissolution and saline intrusion. As a result of the above processes, Chalk groundwater follows an evolutionary path from calcium bicarbonate type to sodium sulphate bicarbonate or sodium chloride bicarbonate type groundwaters. The age of Chalk groundwater was modelled using 4He, 14C and tritium concentrations. This work indicated that there is a general increase in groundwater age in a downgradient direction with the oldest water found in the Hammersmith area. Groundwater in the unconfined zones and in an area south of the Greenwich fault is almost entirely of unevolved, modern composition. With the exception of several sites adjacent to the axis of the Basin, Chalk groundwater in the south Basin is generally less than 10,000 years old. Groundwater in the north Basin is generally between 10,000 and 25,000 years old. This implies that while Chalk groundwater in the south of the Basin is Holocene in age, groundwater in the north is mainly of late Pleistocene age. The above conclusion is confirmed by the palaeorecharge temperatures which were calculated from noble gas contents. These calculations indicate that southern groundwaters yield typical Holocene temperatures of 9-12 °c, whereas those in the north are characterized by average recharge temperatures of 5-8 °C. The results of age modelling imply that average linear groundwater velocities in the Basin are equivalent to those related to matrix flow. These values are several orders of magnitude lower than those related to well test analysis and imply that there is a significant interplay between matrix and fracture groundwater. This conclusion is confirmed by analysis of stable chlorine isotopes which indicates that diffusion processes are active in the Chalk groundwater system. A model of the development of the Chalk recognises that it is a classic dual porosity aquifer in which groundwater flow occurs predominantly in the fracture system. The upper 50 m of the aquifer was flushed with fresh water during the 2-3 million years of the Pleistocene and therefore meteoric water largely replaced the Tertiary and Cretaceous marine water that previously saturated the system. Most processes which control the chemistry of the groundwater occur in the matrix where the surface area is exceptionally high. Although fracture flow dominates the flow regime, diffusion from the matrix into the fracture porosity controls the chemistry of Chalk groundwater.
34
Cronin, Aidan A. "Groundwater flow and isotope geochemical modelling of the Triassic sandstone aquifer, Northern Ireland". Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247400.
Testo completo
35
Makubalo, Sisanda Sesethu. "Hydrogeochemistry of the groundwater in the Namaqualand region, South Africa : implications for surficial uranium mineralization". Diss., University of Pretoria, 2020. http://hdl.handle.net/2263/73255.
Testo completoAbstract (sommario):
Since the discovery of the Yeelirrie deposit in Australia in 1972, exploration for surficial uranium deposits has been supported through hydrogeochemical studies of groundwater and the calculation of the carnotite solubility index (CSI). This study aims to evaluate groundwater quality and delineate potential areas where surficial uranium mineralization (i.e. carnotite) may take place in the Namaqualand region. Surficial uranium deposits are unconsolidated soils or sediments, usually of Tertiary to Recent age. The most common surficial uranium mineral is carnotite. The study area in Namaqualand is located in the arid to semi-arid Northern Cape Province of South Africa, which comprises a variety of metamorphic rocks of the Namaqua Metamorphic Province, overlain by Cenozoic sediments. A total of 85 water samples were collected from existing boreholes. Physicochemical properties (EC, TDS, pH, DO and Eh) were measured on site and samples were analysed for major ions and trace elements at the Council for Geoscience laboratory in Pretoria. The CSI was calculated using hydrochemical data, and interpolated using inverse distance weighting (IDW) and kriging to produce maps of potential carnotite mineralization. The groundwater of the area is alkaline, with elevated concentrations of EC, TDS, Na+, Cl-, F-and U. The predominant water types are Na-Cl, Na-HCO3 and Mg-HCO3. Most groundwater samples have uranium values that range from 1.2–5 120 ppb, which are above the World Health Organization drinking water quality guideline of 15 ppb. Analysis shows that, in the presence of carbonates, uranium mostly occurs in solution as UO2(CO3)22- and UO2(CO3)34-. The CSI values ranged from -6.71 to -2.99 and those that ranged from 2.99 to -4 were in close proximity to known surficial uranium occurrences. The use of IDW and kriging interpolation methods revealed areas with potential for carnotite mineralization. The existence of suitable uranium source rocks, palaeochannels, climate and geomorphology makes the Namaqualand region prospective for calcrete-hosted uranium deposits. The CSI, used to delineate areas with a potential for surficial uranium mineralization in the Northern Cape, can be extrapolated to other areas with similar geological environments and climatic conditions. More sampling of groundwater is recommended to conduct a medical geology study to ascertain the impacts of uranium and other elements on the people, animals and plants of the area.Dissertation (MSc)--University of Pretoria, 2020.
Council for Geoscience
Geology
MSc
Unrestricted
36
Phillips, Robert John. "Isotope hydrogeology and aqueous geochemistry of selected British Columbia hotsprings". Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/10156.
Testo completoAbstract (sommario):
Hydrogeochemical analyses of the thermal waters at Hotsprings Cove, west coast Vancouver Island, reveal the presence of a stable geothermal reservoir. Temperature (50.5$\sp\circ$C), and aqueous geochemical data are nearly identical to those dating back to 1898. $\delta\sp $O-D plots indicate local recharge for these thermal waters, whereas radiocarbon isotopes suggest mean residence times of several thousand years and modification by sulphate-reducing bacteria. Bromide/chloride ratios, when considered with tritium and $\sp{34}$S data, are indicative of minor seawater mixing near the discharge zone. Binary mixing models, with local recharge waters and local seawater as end-member components, point to maximum local seawater contributions of about 1% and 4% for Hotsprings Cove and associated Mate Island thermal waters, respectively. Most chemical and isotopic geothermometer estimates are 90$\sp\circ$C. The Ahouset hotspring, located 12 km south of Hotsprings Cove has low total dissolved solids, a pH of 10.05, and a different geochemistry. Data from the Selkirk Range show a consistent sodium-sulphate geochemistry among the three hotsprings sampled in the Kuskanax Batholith. All waters have low bicarbonate content. $\sp $C values in excess of 100 pmc at the Nakusp hotspring imply incorporation of $\sp $C-active DIC from soil zone organics entrained during recharge, with possible additional $\sp $C contributions occurring due to sulphate reduction and incorporation of soil zone organics during mixing with non-thermal groundwaters near discharge. $\sp $C-derived mean residence times for the sulphide-rich waters of Halcyon hotspring are also short; possibly ${\sim}$1000 years. Geothermometer estimates for all three springs are consistent and fall into two groups, one group near ${\sim}$90$\sp\circ$C and the other between 115$\sp\circ$C and 155$\sp\circ$C. (Abstract shortened by UMI.)
37
Wischusen, John David Henry School of Biological Earth & Environmental Sciences UNSW. "Hydrogeology, hydrochemistry and isotope hydrology of Palm Valley, Central Australia". Awarded by:University of New South Wales. School of Biological, Earth and Environmental Sciences, 2005. http://handle.unsw.edu.au/1959.4/32925.
Testo completoAbstract (sommario):
The Palm Valley oasis in arid central Australia is characterised by stands of palm trees (Livistona mariae). How these unique plants, separated by nearly a 1000 kilometres of arid country from their nearest relatives persist, has long fascinated visitors. Defining the hydrogeology of the Hermannsburg Sandstone, a regionally extensive and thick Devonian sequence of the Amadeus Basin that underlies Palm Valley, is the major thrust of investigation. Appraisal of drilling data shows this aquifer to be a dual porosity fractured rock aquifer which, on a regional scale, behaves as a low permeability, hydraulically continuous resource. Groundwater is low salinity (TDS <1000 mg/L) and bicarbonate rich. Slight variations in cation chemistry indicate different flow paths with separate geochemical histories have been sampled. Stable isotope (????H, ???????O) results from Palm Valley show groundwater to have a uniform composition that plots on or near a local meteoric water line. Radiocarbon results are observed to vary from effectively dead (< 4%) to 87 % modern carbon. To resolve groundwater age beyond the radiocarbon window the long lived radioisotope 36Cl was also used. Ratios of 36Cl/Cl range from 130 to 290 x 10-15. In this region atmospheric 36Cl/Cl ratio is around 300 x 10-15. Thus an age range of around 300 ka is indicated if, as is apparent, radioactive decay is the only significant cause of 36Cl/Cl variation within the aquifer. A review of previous, often controversial, 36Cl decay studies shows results are usually ambiguous due to lack of certainty when factoring subsurface Cl- addition into decay calculations. Apparently, due to the thickness of the Hermannsburg Sandstone, no subsurface sources of Cl- such as aquitards or halites, are encountered along groundwater flow paths, hence the clear 36Cl decay trend seen. The classic homogenous aquifer with varying surface topography, the "Toth" flow model, is the simplest conceptual model that need be invoked to explain these isotope data. Complexities, associated with local topography flow cells superimposed on the regional gradient, signify groundwater with markedly different flow path lengths has been sampled. The long travel times (> 100 ka) indicate groundwater discharge would endure through arid phases associated with Quaternary climate oscillations. Such a flow system can explain the persistence of this arid zone groundwater-dependent ecosystem and highlight the possibility that Palm Valley has acted as a flora refuge since at least the mid- Pleistocene.
38
Bush, Angela L. "Physical and chemical hydrogeology of the Otway Basin, southeast Australia". Connect to thesis, 2009. http://repository.unimelb.edu.au/10187/8523.
Testo completoAbstract (sommario):
The Otway Basin of southeast Australia is the subject of this thesis, which incorporates pre-existing geological, hydraulic and major element hydrogeological data with new isotope hydrogeochemical investigations. The region is an Upper Cretaceous–Tertiary basin, filled with siliciclastic and calcareous aquifers and aquitards and characterised by late volcanic activity, pervasive faulting and karstification. (For complete abstract open document.)
39
Loco, Ratu Aminisitai. "Hydrogeology of the Middle Sigatoka Valley, Southwest Viti Levu, Fiji". Thesis, University of Canterbury. Geological Sciences, 2011. http://hdl.handle.net/10092/5997.
Testo completoAbstract (sommario):
Bedrock geology of the middle Sigatoka valley, located ~ 20 km inland of the township of
Sigatoka, southwest of Viti Levu, Fiji, includes the steeply inclined Tari Fomation and uplifted
Qalimare Limestone of the Wainimala Group of Oligocene to Middle Miocene age. These units
are juxtaposed against the steeply inclined and moderately-highly fractured Cici Sandstone and
Takaro Conglomerate/Rudite of the Tuva Sedimentary Group of Late Miocene age, northwest of
the study area. Surface geology is largely expressed by the sinistral Nasovatava Fault, and its
associated faults splays, and unconsolidated Quaternary to Recent Alluvium that fills the incised
valley. The valley includes a ~40 km² rural area, from Bilalevu to Dubalevu, characterized by
semi-commercial agricultural land-use practices. This area is subject to high water resource
demand and utilisation, particularly from groundwater sources. Geophysical surveys, through
electromagnetic and electrical resistivity methods, at Dubalevu, Tubakeli and Bila Rd, permitted
the estimation of depth to bedrock, thickness and extent of alluvial materials and the presence of
fractured systems within the mapped units. Groundwater drilling, through mud-rotary
circulation, permitted the characterization of the major hydrogeological units, namely surficial
confining unit, alluvial aquifer system, and intermediate confining unit and fractured aquifer
systems. The hydrogeological framework is capped by low permeability surficial confining unit
comprising sandy silt and silty loam with 7.8x10⁻⁸ m/s at Dubalevu, 2.2x10⁻⁷ m/s at Tubakeli and
4.3x10⁻⁸ m/s at Bila Rd. The alluvial aquifer system, comprising unconsolidated coarse-medium
gravels with some fine-medium sand in Dubalevu and Bilalevu have an estimated transmissivity
and conductivity of 600 m²/d⁻¹ and 30 m/d⁻¹ and 1644 m²/d⁻¹ and 274.8 m/d⁻¹, respectively. The
intermediate confining unit is composed of the fresh and unweathered sedimentary rock mass.
Groundwater bore pump tests showed the fractured sedimentary system has an average
transmissivity, storativity and conductivity of 10.9 m²/d⁻¹, 3.7x10⁻⁴, 1.16 m/d⁻¹ for the fractured
Cici Sandstone at Dubalevu, 26.2 m²/d⁻¹, 6.1x10⁻⁴, 6.1 m/d⁻¹ for the fractured Takaro
Conglomerate/Rudite at Tubakeli and 48.7 m²/d⁻¹, 1.7x10⁻³, 9.1 m/d⁻¹ for the fractured Tari
Formation at Bila Rd. Hydrogeochemical classification of groundwaters, springs and surface
sources, showed the dominance of Ca(HCO₃)₂ type water suggesting the dissolution of calcite in
the sedimentary units with variable sources of Na⁺ and Mg⁺². Stable hydrogen and oxygen
isotope analyses of groundwater, surface water and precipitation show a local meteoric water line
slope of 4.3, suggesting that water resources in the middle Sigatoka Valley are meteoric in origin
with variable modifications via evaporation and mixing with older residual evaporated and
connate groundwater. Chloride concentrations confirm the dominance of meteoric rechargeinduced
dilution. Groundwater recharge estimation, through physical and chemical mass balance
models, yielded different results of 0.08 m/month (physical) and 0.2-0.6 m/month (chemical) in
the wet season and -0.01 m/month (physical) and 0.1-0.2 m/month (chemical) during the dry
season. Groundwater recharge mechanisms in the Sigatoka Valley, include moderate-rapidly
dispersing meteoric-derived waters along fractured flow paths and seasonally variable leakage,
from surface sources, dispersing along alluvial macro-poses. Groundwater protection and
sustainable management in the study area is likely to be threatened by unregulated groundwater
drilling, excess groundwater abstraction, absence of groundwater legislation and growing
concerns of climatic variability. This thesis concludes by presenting several recommendations
for groundwater protection and sustainable management, including sound groundwater
exploration and evaluation of geological units, establishing an effective and sustainable legal
frameworks, and increasing awareness of inherent groundwater issues such as climatic
seasonality, climate change, vulnerability to contamination and unsustainable abstraction.
40
Lawler, Mark E. "The hydrogeology of the Cheviot Region, North Canterbury, New Zealand". Thesis, University of Canterbury. Geology, 1988. http://hdl.handle.net/10092/9363.
Testo completoAbstract (sommario):
In 1967 a pump station was installed on a bore in the north west portion of the Spotswood Plains, and although it has provided an adequate supply to the farms and main township of the region, Cheviot, the water supply has on a number of occasions failed to meet demand. Consequently this study was initiated to examine the geology of aquifer systems, to quantify by hydrological gaugings and pump tests the groundwater system of Spotswood and to determine the groundwater resources of the other major plains area of Mina. The Spotswood Plains cover 28.5 km² and are transgressed by the Waiau River and Leamington Stream which for the 1986-87 period had mean yearly flows of 98676 and 456 ls-¹ respectively. The Mina Plains cover only 16.0 km² and contain three streams, Mina, Swamp and Crystal Brook which do not maintain surface flow from November to March and whose flow rates in the other months range in 1986-87 from 8 to 196 ls-¹. The average number of days where rainfall was recorded for each month during the period November to January 1987 was only five, illustrating the dependence of the areas aquifers on recharge from surface streams.
Geological investigations have shown that the aquifer in Spotswood consist of at least four stratigraphic units which in general terms, represent successive aggradational and degradational periods during cyclic climatic variations throughout the Quaternary Period. Geophysical investigations have targeted all of these units apart from the oldest unit, SO in Spotswood and MO in Mina which are not water bearing. Electrical resistivity soundings showed that the aquifer in Spotswood ranges from 10 to 80 metres, on average 40 metres thick, and consists of unconsolidated gravel within a sandy matrix (average resistivity of unit, 422 ohm-m), underlain by a relatively impermeable silty mudstone (average resistivity of 30 ohm-m). The lithologically equivalent unit in Mina was shown to be approximately 10 metres thick ranging from 7 to 16 metres, and consists of unconsolidated alluvium within a silty-clay matrix (average resistivity value of 140 ohms) again resting on silty mudstone, identified as Greta Formation by investigative drilling.
Borehole water level monitoring produced potentiometric surveys and flow nets which for the 14th August 1987 showed that 47.23 m³/min was recharged to the aquifer system of Spotswood by the Waiau River and Leamington Stream (38.34 and 8.89 m³/min respectively) and that 28.81 m³/min was discharged back to the Waiau River through subsurface flow. Surface flow gaugings determined that for that same day in August 18.4 m³/min was discharged to the Waiau River. In the Mina Plains 0.815 m³/min was recharged to the aquifer system, 0.047 m³/min was discharged by subsurface flow and 2.00 m3/min was estimated as discharging from surface streams and artesian bores.
Pumping tests showed that the alluvial material in Spotswood has a Transmissivity value averaging 5.2 m²/min whilst the best transmissivity value obtained at Mina was 0.04 m²/min. A step drawdown test determined that the suggested maximum drawdown in bore 19, an irrigation water supply bore would occur at 20 weeks based on a calculated long term pumping rate of 0.928 m³/min.
A water quality survey showed that the groundwater in Mina is greater than 25 years old and contains concentrations of nitrate, chloride and sodium 2 to 4 times the desirable level set by New Zealand Health Standards. The contaminants originated as a consequence of agricultural practices such as the drilling of offal holes and the application of fertilizer. The groundwater of the Spotswood Plains was dated as less than 5 years old, and contained acceptable concentrations of contaminants primarily due to the dilution effect from recharge waters of Waiau River.
The groundwater system of the Mina Plains was proven to be an inadequate substitute to the water supply operation presently in operation in the Spotswood Plains. Further the Spotswood Plains aquifer system is under utilized and remains as an excellent source and potential source of quality groundwater.
41
Shultz, Kelly N. "The hydrogeology and geochemistry of Liberty Park, a baseline study". University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1131552574.
Testo completo
42
Alderks, David O. "Unresolved Problems Involving the Hydrogeology and Sequence Stratigraphy of the Wasatch Plateau based on Mapping of the Wattis 7.5 Minute Quadrangle, Carbon and Emery Counties, Utah: Insights Gained from a New Geologic Map". Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1199.pdf.
Testo completo
43
Halihan, Todd. "Permeability structure in fractured aquifers /". Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
Testo completo
44
Almasi, Istvan. "Petroleum hydrogeology of the Great Hungarian Plain, Eastern Pannonian Basin, Hungary". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ60365.pdf.
Testo completo
45
Younger, Paul L. "Stream-aquifer systems of the Thames Basin : hydrogeology, geochemistry and modelling". Thesis, University of Newcastle Upon Tyne, 1990. http://hdl.handle.net/10443/354.
Testo completoAbstract (sommario):
The vulnerability of riverside wells in the Thames Basin to pollution by contaminated river water has been assessed by a programme of field characterisation and modelling. The Chalk, Quaternary river gravels and the modern streambed sediments control groundwater flow and solute transport in these stream-aquifer systems. The Chalk is a fissured aquifer, In which matrix diffusion is an important cause of pollutant retardation. On the basis of new field evidence, it is proposed that the distribution of permeability within the Chalk reflects the configuration of Quaternary permafrost. Flow in the highly permeable Quaternary river gravels is intergranular, and adsorption by organic matter and hydroxides may cause retardation of reactive contaminants. The streambed sediments comprise lowly permeable carbonaceous muddy silts and peats. Slow advection and sorption of contaminants makes the sediments an effective barrier to pollution. A mathematical model for flow and solute transport in stream - aquifer systems has been developed. Groundwater velocities are obtained by the solution of coupled flow equations (written in finite difference form) for up to three superposed aquifer layers. Vertical velocities are approximated using an interpolation scheme based upon the transmlssivity of the constituent horizons of each layer. A 3-D particle tracking formulation (including a simple representation of matrix diffusion) is used for solute transport. Hypothetical river spills of various duration were modelled for two sites (Dorney and Gatehampton). It was predicted that no wells would experience pollutant concentrations In excess of EC limits after 20 - minute spills, although the Gatehampton wells would probably succumb after a 7—day event. Well water at both sites would breach EC limits after a 28—day event. Travel times to wells varied from 12 hours (chloride at Gatehampton) to many years (lindane at Dorney). Model performance was more sensitive to streambed paraieters (permeability and sorption coefficient) than to aquifer parameters.
46
Burrows, Mark Robert. "Landfill hydrogeology and the hydraulic properties of in situ landfilled material". Thesis, Royal Holloway, University of London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286066.
Testo completo
47
Groat, Lucas Matthew. "The Physical Hydrogeology of the Broader Historical Irwin Prairie Wetland System". University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1470251155.
Testo completo
48
Banks, Vanessa Jane. "Karst hydrogeology of the southern catchment of the River Wye, Derbyshire". Thesis, University of Huddersfield, 2007. http://eprints.hud.ac.uk/id/eprint/2008/.
Testo completoAbstract (sommario):
A conceptual model of the regional hydrogeology of the White Peak, considered fundamental to the understanding of the local (Wye) catchment has been presented. Specific to the local catchment, an investigation of the karst hydrogeology has been carried out in the context of its geological setting using results from: tracer experiments, chemical analyses of spring water, and hydrograph analyses; alongside detailed consideration of speleogenetic processes and terrain evaluation. Derived from these studies, a conceptual model has been developed, which represents the catchment hydrogeology in a number of hydrogeological units. Their attribution reflects the lithological differences and material responses to both stress and mineralization that have exerted significant influence on speleogenetic processes in the catchment. The units exhibit different recharge, through-flow and resurgence characteristics. Speleogenetic processes in some of the bedrock units support the inception horizon hypothesis. Flow paths typically pass through more than one hydrogeological unit. Lead-zinc-fluorite-baryte mineralization is associated with the dominant hydrogeological unit on the eastern side of the catchment. The mineral deposits were subject to several phases of exploitation facilitated by dewatering via drainage adits (soughs). Records pertaining to the soughs have been used to contribute to an understanding of the changes in groundwater levels as a consequence of mineral exploitation. A case study focused on Lathkill Dale has been used to test the catchment model and further explore human impacts on the hydrogeology. The major contribution of this work is in furthering the understanding of the hydrogeology and speleogenetic processes operating in the catchment. This is supplemented by additional contributions to the understanding of the distribution of superficial deposits within the catchment. Speculation regarding mineralizing processes; geomorphology; functioning of karst aquifers; seasonality of the groundwater chemistry; climate change, and the engineering properties of the bedrock may encourage further research in these areas.
49
Pérez, Pérez Odalís 1950. "Hydrogeology and groundwater modeling study of the Azua Valley, Dominican Republic". Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277062.
Testo completoAbstract (sommario):
The results of the model can be used for enhancing the integrated management of the water resources of the Azua Valley. The model shows the effects of an extensive drainage network on the high ground-water levels which prevailed from 1983 to 1988. A sensitivity analysis also shows the zones of the aquifer which require development of new pumpage in order to overcome the drainage problem in areas still flooded by uncontrolled artesian flow. The results of the model can be used for enhancing the integrated management of the water resources of the Azua Valley.
50
Woodbury, Allan David. "Simultaneous inversion of thermal and hydrogeologic data". Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/27652.
Testo completoAbstract (sommario):
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