Dissertations / Theses on the topic 'Site hydrology'
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1
Graham, Aaron Robert. "In Situ Characterization of Unsaturated Soil Hydraulic Properties at the Maricopa Environmental Monitoring Site." Thesis, The University of Arizona, 2004. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0005_m_sip1_w.pdf&type=application/pdf.
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Hebert, Kevin D. "Site Investigation of Underground Storage Tank Contamination." Arizona-Nevada Academy of Science, 1990. http://hdl.handle.net/10150/296431.
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From the Proceedings of the 1990 Meetings of the Arizona Section - American Water Resources Association and the Hydrology Section - Arizona-Nevada Academy of Science - April 21, 1990, Arizona State University, Tempe, ArizonaNew regulations concerning the management of underground storage tanks (USTs) have resulted in increased awareness of environmental contamination resulting from leaking USTs. The objective of the typical underground storage tank investigation is to determine if any subsurface contamination has occurred as a result of tank or product line leakage, fuel spills or overfills. Soil contamination at underground storage tank sites is usually discovered during the removal and replacement of USTs. Techniques that can be used to detect the presence of soil contamination adjacent to existing USTs include soil vapor analysis, exploratory boring, and soil and ground water sampling. The lateral and vertical extent of contamination must be determined at any site which contains detectable quantities of contamination. Two common methods for determining the extent of contamination are over-excavation and borehole drilling and sampling. Boring design and location considerations include number of borings, borehole depth and spacing, and site sub -surface conditions. Differentiation between perched sub -surface water and aquifers is critical. Once an appropriate boring plan has been established, then a sampling and analysis plan must be adopted that meets the needs of the particular investigation. The determination of the extent of contamination at an underground storage tank site is the first step leading to site closure and remediation.
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Journell, Scot. "Site Remediation of Underground Storage Tank Contamination." Arizona-Nevada Academy of Science, 1990. http://hdl.handle.net/10150/296432.
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From the Proceedings of the 1990 Meetings of the Arizona Section - American Water Resources Association and the Hydrology Section - Arizona-Nevada Academy of Science - April 21, 1990, Arizona State University, Tempe, ArizonaRemedial techniques for sub-surface soil and water contamination are dependent on the lateral and vertical extent of petroleum hydrocarbon contamination and the type of petroleum hydrocarbons which have been released into the sub-surface. Specific remedial technologies are required for diesel fuel and heavy oils compared to the more volatile gasoline compounds. Available remedial technologies for vadose zone contamination include excavation and treatment; soil vapor extraction and possible vapor burning; bioremediation; and chemical treatment. Remedial technologies for ground-water contamination include water recovery, contaminant volatilization, carbon adsorption, bioremediation and water reinjection. Specialized apparatuses are utilized when petroleum hydrocarbon product floating on the water table surface must be separated from the ground water. A number of hydrologic considerations must be evaluated prior to any remediation scenario. These considerations include geologic characterization of the sub-surface soil matrix, and aquifer.
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Camp, Stephen E. "Soil Vapor Surveys for Cost Cutting Site Characterization." Arizona-Nevada Academy of Science, 1991. http://hdl.handle.net/10150/296438.
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From the Proceedings of the 1991 Meetings of the Arizona Section - American Water Resources Association and the Hydrology Section - Arizona-Nevada Academy of Science - April 20, 1991, Northern Arizona University, Flagstaff, ArizonaNew technical approaches and cost cutting alternatives are being utilized in the environmental engineering field. These unique methods are used in the mapping, delineation and remediation of contaminated sites. One development which has seen a sudden increase in the recent past is the utilization of soil vapor surveys to map contamination plumes in the vadose zone. Using the soil vapor method, industrial sites and sites containing potential buried drums or underground storage tanks can be quickly evaluated for the presence of volatile contaminants. This information can be especially important in property transactions where buyers desire to protect themselves from potential costly clean-ups. The soil vapor survey consists of sampling volatile vapors in the vadose zone and analysis of the vapors on analytical instruments. The survey targets those contaminants which have volatilized from residues in soils or shallow ground water. One method of sampling soil vapors is penetrating five to ten feet into the sub-surface with a sampling probe. Upon collection of the vapors, concentrations may be measured. The analytical instruments can range from simple Drager Tubes to a laboratory gas chromatograph. The methodology for selecting sampling locations depends on the site. An underground storage tank facility may be approached by completing sampling locations at the tank pit and near the product lines. A grid sampling location map may be used to sample a property with an unknown organic content. Soil vapor surveys have limitations in regards to soil types, sampling depths and constituents being analyzed. However, given the proper conditions, soil vapor surveys can provide qualitative data at lower costs than alternative methods.
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Ouellette, Karli J. "Hydrologic applications of GPS site-position observations in the Western U.S." Thesis, University of California, Irvine, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3605189.
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Permanent Global Positioning System (GPS) networks have been established around the globe for a variety of uses, most notably to monitor the activity of fault lines and tectonic plate motion. A model for utilizing GPS as a tool for hydrologic monitoring is also developed.
First, observations of the recent movement of the land surface throughout California by the Scripps Orbit and Permanent Array Center (SOPAC) GPS network are explored. Significant seasonal cycles and long term trends are related to historical observations of land subsidence. The pattern of deformation throughout the state appears to be caused by the occurrence of poroelastic deformation of the aquifer in the Central Valley, and elastic crustal loading by surface water and the winter snowpack in the Sierra Nevada Mountains. The result is a sort of teeter-totter motion between the Valley and the mountains where the Valley sinks in the dry season while the mountains lift, and the mountains sink in the wet season while the Valley lifts.
Next, the elastic crustal deformation caused by the winter snowpack is explored more thoroughly at 6 high elevations throughout the Western United States. Expected annual deformation as a result of thermoelastic and snow water equivalent are calculated using SNOTEL observations and an elastic half-space model. The results demonstrate the dominance of snow loading on the seasonal vertical land surface deformation at all 6 GPS stations. The model is then reversed and applied to the GPS vertical site-position observations in order to predict snow water equivalent. The results are compared to SNOTEL observations of snow water equivalent and soil moisture. The study concludes that GPS site-position observations are able to predict variations in snow water equivalent and soil moisture with good accuracy.
Then a model which incorporates both elastic crustal loading and poroelastic deformation was used to predict groundwater storage variations at 54 GPS stations throughout the Central Valley, CA. The results are compared to USGS water table observations from 43 wells. The predictions and observations show a similar magnitude and spatial pattern of groundwater depletion on both a seasonal and long term timescales. Depletion is focused on the southernmost part of the Valley where GPS reveals seasonal fluctuation of the water table around 2 m and 8 m/yr of water table decline during the study period. GPS also appears to respond to deformation from peat soils and changing reservoir storage in the northern parts of the Valley.
Finally, preliminary work exploring the potential for using GPS as a tool for monitoring snowmelt runoff and infiltration is explored at one station in Eastern Idaho. Taking the difference between the change in GPS water storage estimates with time and the change in SNOTEL observed snow water equivalent with time produces a time series of infiltration, or the amount of water added to storage in the geologic profile. Then subtracting the estimated infiltration and snow water equivalent from the total precipitation observed by SNOTEL produces a time series of runoff. The estimated runoff at the GPS site was compared to observations from a nearby stream gauge and the foundation for a more extensive comparison is laid out.
The overall impact of this work is to introduce the unique hydrologic information and monitoring capabilities which can be accessed through monitoring of the land surface position using GPS. As GPS networks grow and expand worldwide, the available data should be harnessed by the hydrologic community for the benefit of local water management as well as improvements to data assimilated models. The work presented here represents only a small fraction of the wealth of knowledge that could result from a budding field of GPS hydrologic remote sensing. (Abstract shortened by UMI.)
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Burger, Mark Allen. "A wetland trafficability hazard index based on soil physical properties and site hydrology evaluations." Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/42629.
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Harvesting of forested wetlands in the Atlantic and Gulf lower coastal plains has the potential to cause intense site disturbance. Often, as a result of poor pre-harvest planning, silvicultural activities are performed on wetland soils highly susceptible to rutting and puddling. Potential decreases in pine productivity have been connected with increased soil strength and decreased aeration that are commonly remnants of site disturbances associated with wet-weather harvesting. A simple and economical rating system is needed to identify soils susceptible to disturbance by various types of equipment. The use of such a system could lower the impact on wetland soils and lower the cost of extensive site preparation methods. Logging efficiency and operational productivity could also be increased by identifying equipment types compatible with site conditions.
The purpose of this study was to characterize and model soil strength as a function of soil physical properties and site characteristics. The soil strength model was subsequently used to develop a trafficability hazard index. Forested wetland sites in the South Carolina coastal plain were characterized to develop the trafficability hazard index. The study site consisted of three blocks located on poorly drained loblolly pine plantations. Five sequences of measurements were taken consisting of soil moisture, water table depth, and soil strength. The five sequences of measurements were taken over a wide range of soil moisture contents and water table depths to characterize the effects on soil strength. Bulk density, porosity, texture, organic matter, and hydraulic conductivity were also determined to characterize the blocks and identify effects on soil strength.
Evaluating the effects of these properties on soil strength identified two relatively easily determined soil properties that could be used for the trafficability index. Volumetric moisture content and penetration resistance of the A horizon were used due to their relationships with trafficability and ease of determination. Estimates of pressure applied to the soil by harvesting equipment were used to find the limits of the sandy loam A horizon to support various types of equipment. Equipment pressures were compared to soil penetration resistance pressures estimated by soil moisture. The trafficability hazard index presented used general ground pressures for various harvesting equipment, but use of specific equipment pressures would provide the best results. Using the trafficability hazard index, sites with less than optimal conditions for traffic can be avoided or special harvesting equipment can be identified to limit site disturbance.Master of Science
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Lakel, William A. "Slash Mulching and Incorporation as Mechanical Site Preparation for Pine Plantation Establishment and Subsequent Effects on Soil Moisture and Site Hydrology." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/9874.
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Over one million hectares of pocosins and wet flats in the southeastern coastal plain are intensively managed for the production of loblolly pine (Pinus taeda) plantations. These management activities may have adverse effects on soil physical properties, site hydrology, and overall site productivity. Substantial quantities of wood residues are often left on these sites by timber harvesting operations, and it was hypothesized that the incorporation of this slash into the soil could improve the soil physical properties and site hydrology. One organic pocosin site and one mineral wet flat site were chosen post-harvest for treatment. The wet flat study was organized as an incomplete block design having four blocks and six treatments: (i) conventional bedding, (ii) strip surface mulching with bedding, (iii) strip surface mulching with tillage and bedding, (iv) broadcast mulch without bedding, (v) broadcast mulch with bedding, and (vi) flat planted control. The pocosin study was organized as a randomized complete block design with four blocks and four treatments. The treatments are identical to those of the wet flat site without the broadcast mulch treatments (iv and v). Soil physical property data was analyzed pre- and post-treatment, while post-treatment site hydrology and soil water chemistry data was analyzed periodically for one year. Seedling survival and height data were analyzed after one growing season.
The treatments had little effect on soil physical properties, site hydrology, soil water nutrients, or seedling survival on the wet flat study site. Bedding in general significantly increased tree height growth, but mulching had no significant effects. The treatments had little effect on soil physical properties on the pocosin study site except for soil macroporosity, which was significantly increased by bedding. Site hydrology and soil water nutrients were not significantly affected by the treatments, but seedling survival and height growth were significantly increased by bedding. Mulching had no significant effects on any of the parameters studied.Master of Science
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Stein, David Martin. "A 3-dimensional numerical flow analysis of a superfund site in Ohio /." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61079.
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The closed Chem-Dyne Site is located in southwestern Butler County, Ohio. It operated from 1974 to 1980 as a waste recycling operation. Over the six year period of operation, the corporation built a clientele comprised of over 200 chemical and manufacturing companies throughout the United States. Due to inappropriate controls, numerous hazardous waste spills occurred during the period of operation. These spills resulted in severe contamination to the surface soils and underlying aquifer. Beginning in 1980, engineering consultants were contracted by federal and state environmental agencies to study the site and submit recommendations for remediating the environmental contamination. Since the start-up of the Remedial Investigation/Feasibility Study in 1980, approximately 5 professional consulting firms have been contracted to study the Chem-Dyne site. The site is currently in a cleanup phase.The objective of the present thesis study is to determine the effectiveness of the site remediation program since the commencement operations in January 1987. To accomplish this task, an analytical and 3-dimensional numerical flow analysis was performed. (Abstract shortened by UMI.)
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Ringler, Joseph William. "MONITORING THE HYDROLOGY OF SOILS FOR ON-SITE WASTEWATER TREATMENT SYSTEMS USING MATRIC POTENTIAL SENSORS." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243013245.
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Liu, Shuyun. "A sequential inverse approach for hydraulic tomography and electrical resistivity tomography: An effective method for site characterization." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279846.
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Hydraulic tomography (i.e., a sequential aquifer test) has recently been proposed as a method for characterizing aquifer heterogeneity. In this study a sequential inverse approach is developed to interpret results of hydraulic tomography. The approach uses an iterative geostatistical inverse method to yield the effective hydraulic conductivity of an aquifer, conditioned on each set of head/discharge data. To efficiently include all the head/discharge data sets, a sequential conditioning method is employed. Two-dimensional numerical experiments were conducted to investigate the optimal sampling scheme for the hydraulic tomography. The effects of measurement errors and uncertainties in statistical parameters required by the inverse model were also investigated. The robustness of this inverse approach was demonstrated through its application to a hypothetical, three-dimensional, heterogeneous aquifer. Two sandbox experiments were conducted to evaluate the performance of the sequential geostatistical inverse approach under realistic conditions. One sandbox was packed with layered sands to represent a stratified aquifer while the other with discontinuous sand bodies of different shapes and sizes to represent a more complex and realistic heterogeneous aquifer. The tomography was found ineffective if abundant head measurements were collected at closely spaced intervals in a highly stratified aquifer. While it was found beneficial when head measurements were limited and the geological structure was discontinuous. The sequential inverse approach for hydraulic tomography was extended for electrical resistivity tomography. Numerical experiments were conducted to demonstrate the robustness of this approach for delineating the resistivity distribution in the subsurface and to investigate effectiveness of different sampling arrays of the ERT: the surface, the down-hole, and the combination of the surface and down-hole array. Orientation of bedding was found to dictate the effectiveness of the ERT layout. Samples were collected to quantify spatial variability of the resistivity-moisture relationship in the field. Numerical experiments then illustrated how the spatially varying relationship exacerbated the level of uncertainty in the interpretation of change of moisture content based on the estimated change in resistivity. A sequential inverse approach was then developed to estimate water content with less uncertainty by considering the spatial variability of the resistivity-moisture relationship and incorporating point moisture measurements and ERT data sets.
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Hallard, M. "The effects of agricultural drainage on the hydrology of a grassland site in South-West England." Thesis, University of Exeter, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384728.
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Hawkins, Adam J. "Measurement of the spacial distribution of heat exchange in a geothermal analog bedrock site using fiber-otic distributed temperature sensing." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1527320.
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Mas-Pla, Josep. "Modeling the transport of natural organic matter in heterogeneous porous media: Analysis of a field-scale experiment at the Georgetown site, South Carolina." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186412.
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Observations that colloidal natural organic matter (NOM) enhances the migration of pollutants in groundwater have focused scientific interest towards the transport of NOM and its adsorptive properties. A small-scale tracer test was performed at a field site in Georgetown, SC, to investigate the movement of NOM under field conditions. Special emphasis was given to the hydrological heterogeneity of the site,with the idea that the flow field must be accurately known in order to distinguish adsorption from the effects of the hydrological processes. 308 slug tests were performed to characterize the spatial variability of hydraulic conductivity at the site. Using the hydraulic conductivity dataset, a three-dimensional transport model successfully reproduced the migration of a chloride plume. In this way, the uncertainties due to hydrological factors were minimized. NOM was then injected in a second tracer test. A two-site adsorption model was used to describe NOM transport. Adsorption on the first site of the model was described by a linear equilibrium isotherm, with adsorption on the second site being described by a linear time-dependent (first order kinetic) reaction. Modeling results indicated that the time-dependent process dominated the adsorption of NOM, with a fast attachment and slow detachment rates. An approximate retardation factor of 77 was estimated for NOM. Because of the high velocities created by the forced gradient, chemical equilibria was not reached during the test. Spatial variability of the chemical properties of the aquifer was identified at two different depths of aquifer. Furthermore, differences at late times between the observed and simulated NOM breakthrough curves suggested possible changes on the adsorption properties of the soil caused by continuous NOM adsorption.
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McQuade, Theresa Lynn. "Hydrogeochemical Characterization of Acid-Mine Drainage, Ohio Valley Mushroom Farm Site in North Lima, Ohio." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1353785356.
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Hodgkins, Julia Elizabeth. "The effects of whole tree harvesting on site hydrology and soil structure at Beddgelert Forest, N. Wales, UK." Thesis, University of Plymouth, 1996. http://hdl.handle.net/10026.1/1904.
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The ITE biogeochemistry group monitoring solute movement at Beddgelert Forest provided an opportunity to study the hydrology of a steep section of hillslope in a high rainfall environment. The aim of the experiment was to characterise and compare the hillslope hydrologies of one forested and one whole tree harvested site. Particular attention was paid to the influence of trees both directly on soil water pathways and indirectly on soil characteristics. Atmospheric inputs were monitored for the slope and individual plots for one year. In spite of high rainfall volumes, the slope was not waterlogged indicating a soil with high conductivity. However, frequent macropore flow was not observed at the site. Tensiometer results showed that the mineral soil remained unsaturated. Therefore, a type of preferential flow dominates at both sites. A one dimensional modelling approach to soil water movement confirmed that mesopores within the soil could conduct a large volume of water rapidly. Modelling demonstrated the importance of soil structure especially a large pore size distribution. Analyses of active soil water pathways based on tensiometer results were inconclusive. Downslope moisture gradient combined with high conductivity suggested that large quantities of water could be transmitted. Similarly, the well structured surface soil and marked horizon development also indicate lateral flow may be dominant. The study showed that saturated hydraulic conductivity was highly variable at both the forest and whole tree harvested sites. Analysis of semi-variograms indicated that most of the variance occurred at a sampling distance of 50 cm (i.e. individual tree roots and slate fragments were causing variations in Kg). Investigations of soil structure found more vertical cracks in the forest soil compared to the whole tree harvested site. At the more detailed ped scale, fractal dimensions of both sites were similar. Based on these results combined with temporal moisture content data the research has demonstrated that first, the hydrologicai regime at both sites were similar. Second, the direct impact of trees was limited. Third, the large cracks at the forest site were not significant. The major result of this research was that at both sites vertical flow in the Ah/Ea horizon dominates and a significant amount of water moved laterally within the Eag, Bs and C horizons. This result has major implications for the solute chemistry and movement of acid deposition in that soil water born solutes will tend to enter water courses more rapidly than if vertical flow predominated.
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Koestner, Peter E., Karen A. Koestner, and Daniel G. Neary. "Monitoring the Effects of Air-Quality on Forests: An Overview of the Sierra Ancha Experimental Forest ICP-Level II Site." Arizona-Nevada Academy of Science, 2012. http://hdl.handle.net/10150/301341.
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From the Proceedings of the 2012 Meetings of the Hydrology Section - Arizona-Nevada Academy of Science - April 14,2012, Glendale Community College, Glendale, ArizonaThe Sierra Ancha International Cooperative Program on Assessment and Monitoring of Air Pollution Effects on Forests study site or (SAEF-ICP II) is part of an international network of cooperative forest monitoring sites spread throughout Europe and the United States. The United Nations Economic Commission for Europe established the ICP II network in 1985 to monitor long-term effects of transboundary air pollution. The Sierra Ancha Experimental Forest was chosen to be a part the U.S.’s network because it is the southernmost Experimental Forest in the contiguous U.S., and because it is downwind from a major metropolitan area, Phoenix, Arizona. The site monitoring includes forest overstory growth, crown condition, foliar chemistry, understory vegetation, litterfall, soil chemistry meteorology, ozone, and deposition. This paper provides an overview of the ICP forest network, and discusses the research currently underway at the Sierra Ancha ICP II site. An overview of the challenges encountered while implementing ICP Level II monitoring will also be included.
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Illman, Walter A. "Single- and cross-hole pneumatic injection tests in unsaturated fractured tuffs at the Apache Leap Research Site near Superior, Arizona." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284217.
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This dissertation documents research results from a series of field experiments and analyses used to test interpretive models for investigating the role of fractures in fluid flow through unsaturated, fractured tuffs. It summarizes the experimental design of single- and cross-hole pneumatic injection tests, including borehole configuration and testing schedules, data collection system, interpretive models developed and tested, data, and conclusions. Single-hole tests were interpreted by Guzman et al. (1996) by means of steady-state analysis to obtain permeability values based solely on late pressure data. This dissertation and Illman et al. (1998) employ pressure and pressure-derivative type-curves to analyze transient data. Air permeabilities determined from transient analyses agree well with those derived from steady-state analyses. Cross-hole pneumatic tests were analyzed by means of a graphical matching procedure using newly-developed pressure and pressure-derivative type-curves. Analyses of pressure data from individual monitoring intervals using these new type-curves, under the assumption that the rock acts as a uniform and isotropic fractured porous continuum, yield results that are comparable with parameters obtained from a numerical inverse procedure described in Illman et al. (1998). The results include information about pneumatic connections between the injection and monitoring intervals, corresponding directional air permeabilities, and air-filled porosities. Together with the results of earlier site investigations, single- and cross-hole test analyses reveal that at the Apache Leap Research Site in central Arizona: (1) the pneumatic pressure behavior of fractured tuff is amenable to analysis by methods that treat the rock as a continuum on scales ranging from meters to tens of meters; (2) this continuum is representative primarily, but not exclusively, of interconnected fractures; (3) its pneumatic properties vary strongly with location, direction and scale, in particular, the mean of pneumatic permeabilities increases, and their variance decreases with scale; (4) this scale effect is most probably due to the presence in the rock of various size fractures that are interconnected on a variety of scales; and (5) given a sufficiently large sample of spatially varying pneumatic rock properties on a given scale of measurement, these properties are amenable to analysis by geostatistical methods, which treat them as correlated random fields defined over a continuum.
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Humes, Karen Sue, and Soroosh Sorooshian. "THE ESTIMATION AND SCALING OF LAND-SURFACE FLUXES OF LATENT AND SENSIBLE-HEAT WITH REMOTELY SENSED DATA OVER A GRASSLAND SITE." Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 1993. http://hdl.handle.net/10150/617639.
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The overall topic of the research described in this dissertation was the
partitioning of available energy at the Earth's surface into sensible and latent heat
flux, with an emphasis on the development of techniques which utilize remotely
sensed data. One of the major objectives was to investigate the modification of
existing techniques, developed over agricultural surfaces, to "natural" ecosystems (i.e.,
non -agricultural vegetation types with variable and incomplete canopy cover).
Ground -based measurements of surface fluxes, vegetation cover, and surface
and root -zone soil moisture from the First ISLSCP (International Land Surface
Climatology Program) Field Experiment (FIFE) were used to examine the factors
controlling the partitioning of energy at ground stations with contrasting surface
characteristics.
Utilizing helicopter -based and satellite -based data acquired directly over
ground -based flux stations at the FINE experimental area, relatively simple
algorithms were developed for estimating the soil heat flux and sensible heat flux
from remotely sensed data. The root mean square error (RMSE) between the
sensible heat flux computed with the remotely sensed data and the sensible heat flux
measured at the ground stations was 33 Wm 2. These algorithms were then applied
on a pixel -by -pixel basis to data from a Landsat -TM (Thematic Mapper) scene
acquired over the FIFE site on August 15, 1987 to produce spatially distributed
surface energy- balance components for the FIFE site.
A methodology for quantifying the effect of spatial scaling on parameters
derived from remotely sensed data was presented. As an example of the utility of this approach, NDVI values for the 1,IFE experimental area were computed with
input data of variable spatial resolution. The differences in the values of NDVI
computed at different spatial resolutions were accurately predicted by an equation
which quantified those differences in terms of variability in input observations.
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Humes, Karen Sue. "The estimation and scaling of land-surface fluxes of latent and sensible heat with remotely sensed data over a grassland site." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/186059.
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The overall topic of the research described 10 this dissertation was the partitioning of available energy at the Earth's surface into sensible and latent heat flux, with an emphasis on the development of techniques which utilize remotely sensed data. One of the major objectives was; to investigate the modification of existing techniques, developed over agricultural surfaces, to "natural" ecosystems (i.e., non-agricultural vegetation types with variable and incomplete canopy cover). Ground-based measurements of surface fluxes, vegetation cover, and surface and root-zone soil moisture from the First ISLSCP (International Land Surface Climatology Program) Field Experiment (FIFE) were used to examine the factors controlling the partitioning of energy at ground stations with contrasting surface characteristics. Utilizing helicopter-based and satellite-based data acquired directly over ground-based flux stations at the FIFE experimental area, relatively simple algorithms were developed for estimating the soil heat flux and sensible heat flux from remotely sensed data. The root mean square error (RMSE) between the sensible heat flux computed with the remotely sensed data and the sensible heat flux measured at the ground stations was 33 Wm⁻². These algorithms were then applied on a pixel-by-pixel basis to data from a Landsat-TM (Thematic Mapper) scene acquired over the FIFE site on August 15, 1987 to produce spatially distributed surface energy-balance components for the FIFE site. A methodology for quantifying the effect of spatial scaling on parameters derived from remotely sensed data was presented. As an example of the utility of this approach, NDVI values for the FIFE experimental area were computed with input data of variable spatial resolution. The differences in the values of NDVI computed at different spatial resolutions were accurately predicted by an equation which quantified those differences in terms of variability in input observations.
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Pedersen, Jonas. "Site Application of a Channel Network Model for Groundwater Flow and Transport in Crystalline Rock." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-354486.
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Groundwater flow and transport in deep crystalline rock is an important area of research. This is partly due to its relevance for constructing a long term repository for storing radioactive spent nuclear fuel in deep bedrock. Understanding the behavior of flow and transport processes in deep crystalline rock is crucial in developing a sustainable solution to this problem. This study aims to increase the understanding of how channel network models (CNM) can be applied to represent groundwater flow and solute transport in sparsely fractured crystalline rock under site specific conditions. A main objective was to determine how to incorporate structural and hydrogeological site characterization data in the construction of the CNMs. In addition to this, the associated key parameters of the CNMs were investigated to gain further understanding of model site application. To that end, a scripting approach with the python scripting library Pychan3d was used to create alternative channel network representations of a field site. A conceptual discrete fracture network (DFN) model was constructed using field site data obtained from a structural model of the fractures present at the site of the Tracer Retention Understanding Experiments (TRUE) - Block Scale at the Äspö Hard Rock Laboratory (HRL). This conceptual model was used as a base for constructing two different alternatives, denoted respectively as sparse and dense, of a CNM. The sparse CNM consisted of a limited amount of channels for each fracture, while the dense CNM acted as a DFN proxy, taking the full extent of the fracture areas into account and creating a dense, large network of flow channels for each fracture. In order to verify the performance of the generated CNMs, a reproduction of tracer tests performed at the same specific field site was attempted using a particle tracking technique. In addition to this, long term predictions of solute transport without the interference of the pumps used during the tracer tests were done in order to estimate transport time distributions. Pychan3d and the scripting approach was successfully used to create CNMs respecting specific conditions from the TRUE-Block Scale site. The sparse CNM was found to give very adequate flow and transport responses in most cases and to be relatively easier to calibrate than its dense counterpart. The long term transport predictions at the site according to the models seem to follow a channelized pattern, with only a few select paths for transport. The difficulties encountered in matching the dense CNM with the tracer tests most likely stem from difficulties in flow calibration, as well as certain key parameters being assigned too generically.
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Apipattanavis, Somkiat. "Stochastic nonparametric methods for multi-site weather generation and flood frequency estimation: Applications to construction delay, hydrology and agricultural modeling." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3303820.
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Simkover, Elizabeth Gail. "A groundwater flow model of the aquifer intercommunication area, Hanford site, Washington." PDXScholar, 1986. https://pdxscholar.library.pdx.edu/open_access_etds/3690.
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Intercommunication has been identified between the unconfined and uppermost confined aquifer systems underlying a portion of the U.S. Department of Energy's Hanford Site. Erosional thinning and fracturing of the basalt confining layer within the study area allows physical contact between the two aquifers, but the vertical hydraulic gradient (a required driving force) is small. To better conceptualize the distribution and volume of the leakage occurring between the aquifer systems, this study investigates the confined Rattlesnake Ridge Aquifer flow system, which appears to be more sensitive to the vertical leakage than the overlying unconfined aquifer.
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Margo, Michael Ray. "Restoration of resaca wetlands and associated wet prairie habitats at Palo Alto Battlefield National Historic Site." Texas A&M University, 2003. http://hdl.handle.net/1969.1/3918.
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Cultivation and drainage projects associated with livestock production have substantially
disturbed resaca wetlands and wet prairie habitats in southern Texas. As a consequence
of the anthropogenic disturbances, the area of these wetlands has been reduced and the
ecological integrity of the remaining wetlands has been compromised. The goal of this
study was to explore effective strategies for ecological restoration of coastal prairie and
resaca ecosystems in south Texas and provide restoration recommendations to the
National Park Service at Palo Alto Battlefield National Historic Site (NHS). Field
experiments were conducted to evaluate the effectiveness of different approaches for
restoring Spartina spartinae on disturbed saline flats. A resaca hydrologic study was
initiated to evaluate the groundwater hydrology in disturbed versus undisturbed resaca
wetlands and explore potential restoration strategies. Transplanting S. spartinae in the
fall season was more successful (80% survivability) than seeding (0% initial
establishment), spring transplanting (0% survival), spring and fall mechanical
transplanting (0% and 6% survivability, respectively). Soil disturbance significantly
affected (p < 0.05) survival of transplanted tillers and basal diameter of both the bare root and container-grown transplants in the fall manual treatments. The initial
hydrologic study of the resaca wetlands found that vegetation rooting zone hydrology
was likely dependent on surface water rather than groundwater. These findings suggest
that strategies that restore surface hydrologic regimes will likely restore the ecosystem
structure and function of disturbed resacas. Manually transplanting bare-root stock of S.
spartinae in the late fall season without soil disturbance will increase the likelihood of
successful saline flat restoration.
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Leyland, R. C. "Vulnerability mapping in karst terrains, exemplified in the wider Cradle of Humankind World Heritage Site." Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-02112009-171849/.
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Hauser, James W. "Effects of hydrology-altering site preparation and fertilization/release on plant diversity and productivity in pine plantations in the coastal plain of Virginia." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-05042010-020225/.
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Miao, Ziheng. "Application of Stable Isotopes and Geochemical Analysis to Characterize Sulfate, Nitrate, and Trace Element Contamination of Groundwater and Its Remediation at a Former Uranium Mining Site." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/293389.
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Sulfate, nitrate, and certain trace elements are common groundwater contaminants observed at mining sites. Their source, fate, and remediation were investigated at a former uranium mining site. First, groundwater samples collected across the site were analyzed for geochemistry, stable isotopes, and trace elements. Then, two pilot-scale ethanol injection tests were conducted for biostimulation of nitrate and sulfate reduction. Groundwater was monitored in the test area before and after the tests. The results showed a mixing of two discrete sources of sulfate. Quantification of these two sources using two methods showed that sulfide-mineral oxidation of the mine tailings served as a steady but low-discharge source while sulfuric acid (applied during ore processing in the 1960s) served as a variable, strong source. It appears that sulfuric acid served as a sustained source of sulfate for approximately 40 years. This source may be from accumulation of sulfate salts (formed from sulfuric acid) in the source zone due to the arid climate of the site. Results showing correspondence of isotopic compositions of ammonium and nitrate confirmed the generation of nitrate via nitrification. Moreover, it was observed that ammonium concentration is closely related to concentrations of uranium and a series of other trace elements including chromium, selenium, vanadium, iron, and manganese. It is hypothesized that ammonium-nitrate transformation processes influence the disposition of the trace elements through mediation of redox potential, pH, and possibly aqueous complexation and solid-phase sorption. As for the biostimulation, sulfate reduction condition has been maintained for a period of approximately 3 years after a single input. Atypical fractionation behavior of the delta34S in sulfate was hypothesized to be caused by release of sulfate from sulfate minerals associated with the sediments. Elevated hydrogen sulfide concentrations were not observed until approximately four months after the start of the test. This behavior, in concert with the observed changes in aqueous iron and manganese species, suggests that hydrogen sulfide produced from sulfate reduction was precipitated, presumably in the form of iron sulfides, until the exhaustion of readily reducible iron oxides. Hydrogen sulfide produced thereafter appears to have been in part re-oxidized.
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Miwa, Masato. "Physical and Hydrologic Responses of an Intensively Managed Loblolly Pine Plantation to Forest Harvesting and Site Preparation." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/29049.
Full textAbstract:
The Southeastern Lower Coastal Plain wet pine flats include thousands of acres of jurisdictional wetlands that are economically, socially, and environmentally important. These highly productive forests have been intensively managed as pine plantations for the past few decades. More recently, harvesting and site preparation practices have become a concern among natural resource managers because intensive forestry practices may alter soil physical properties and site hydrology. These alterations could decrease seedling survival, growth, and future site productivity. However, the effects of soil disturbance on long-term site productivity and the effects of amelioration techniques on site hydrology are uncertain. The overall objectives of this study were (1) to characterize disturbed forest soil morphology and physical properties, (2) to assess their impact on the processes that control site hydrology and site productivity, (3) to determine effects of harvesting and site preparation on site hydrology, specifically on the overall hydrological balance and on spatial and temporal patterns of surface water storage.
The study site is located in an intensively managed loblolly pine (Pinus taeda L.) plantation in the lower coastal plain of South Carolina. This study was established in winter 1991, and dry- and wet-weather harvesting treatments were installed in summer 1993 and winter 1994, respectively. Bedding and mole channel/bedding treatments were installed in both dry- and wet-harvested plots in fall 1995. Soil profiles were described for a recently disturbed, deeply-rutted area, and 2-year-old deeply-rutted and churned areas, bedded and undisturbed areas. Intact soil core samples and composite loose soil samples were collected from each morphological section for soil physical characterizations. Automated weather station and wells were used to collect continuous climatic and surface water level data since 1996. Surface water levels were monitored monthly on a 20 x 20 m grid of 1-m wells since 1992. Total groundwater heads were determined from differential piezometer measurements at high and low elevation places in each treatment plot.
Soil profile descriptions and soil physical property measurements indicated that significant amounts of organic debris were incorporated into the surface horizons, and subsurface soil horizons showed significant soil structural changes and increased redoximorphic features caused by soil disturbance. The disturbed soil layers in recently created traffic ruts consisted of exposed and severely disturbed subsurface soils, but this layer was naturally ameliorated 2 years after the disturbance. Bedding site preparation had little amelioration effects on the physical properties of surface soil horizons because the surface horizons already had some incorporation of organic debris. Overall, the main consequence of bedding in a disturbed wet site was to increase the aerated soil volume. The bedding appeared to have little effect on disturbed subsurface horizons.
Groundwater head in the study site was constantly higher than -25 cm during the study period, which caused groundwater inflow when the surface water level was low. Frequent fluctuation of the surface water level and constant water supply from the groundwater probably explain the high productivity of the study site. Results of the annual water balance showed that surface soil water storage changes were very small, and annual precipitation and potential evapotranspiration were approximately equal. Silvicultural practices and minor topography on the study site had significant effects on the water balance because they influenced surface water level.
Surface water hydraulic gradient evaluation and multivariate cluster analysis indicated that micro-site hydrology and water flow patterns were significantly altered by wet-weather harvesting and bedding site preparation, but overall site hydrology was not altered. Evaluation of predicted surface water level indicated that micro-topography and precipitation patterns had significant influences on surface water levels during the site establishment period. These results revealed that the hydrologic components of wetland delineation are complex in the wet pine flatwoods.Ph. D.
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Kjellander, Kalle. "River-Aquifer Interaction in the Uppsala Esker - a Modelling Study of a Proposed Drinking Water Production site." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355671.
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The Swedish municipalities of Gävle and Älvkarleby need new sources of drinking water as the population grows. Gästrike vatten AB has employed the consultant firm Midvatten AB to assess the possibility of a new groundwater extraction site on the Uppsala esker between Älvkarleby and Skutskär in northern Uppland county. It has been observed that the natural recharge to the aquifer in the Uppsala esker might be too low to compensate for a future groundwater extraction and that there is a risk of induced infiltration from the river Dalälven if the water table is lowered. River water might bring organic contaminants into the aquifer and negatively affect the groundwater quality.A solution proposed by Midvatten is to infiltrate the esker with river water free from organic contaminants at infiltration sites. This artificial infiltration is estimated to create new groundwater to compensate for the extraction and stop river water from reaching the extraction wells. There is however, a need to estimate the magnitude of infiltrating river water when the infiltration sites are active.The aim of this study was to estimate the flow of water between the river and a section of the Uppsala esker for a test period during 2017, specifically, the infiltration from the river. In addition to this, changes in flow depending on proposed pumping and infiltration scenarios were modelled.A MODFLOW model was developed in the graphical user interface Groundwater Modeling System (GMS) and its performance was validated against observed aquifer head. The model could accurately represent the head close to the river but was less accurate with increasing distance from the river. Average infiltration from the river varied from 3 to 25 l s-1. The calculated infiltration depended on which extraction well or artificial infiltration site was active and the rate of flow.It was concluded that the distribution of hydraulic conductivity in the aquifer was not sufficiently detailed. A solution could have been to use stratigraphic data from borehole logs instead of a general quaternary deposits map as basis for the distribution of hydraulic conductivity. Artificial infiltration close to the river prevented large volumes of induced infiltration. The accuracy of the model could have been improved if the results were compared to other methods such as particle-tracking, tracer tests and with measurements of the streambed such as seepage meters.Gävle och Älvkarlebys kommuner är i behov av nya grundvattentäkter för att kunna försörja invånarna med dricksvatten i framtiden. Ett område som är av intresse för de två kommunerna är ett grundvattenmagasin i Uppsalaåsen intill Dalälven mellan Älvkarleby och Skutskär. Vid ett dricksvattenuttag kan vattenbalansen i magasinet ändras. I magasinet uppskattas grundvattenbildningen vara för låg för att pumpa upp nog mycket vatten och bibehålla en stabil dricksvattenförsörjning. När uttaget av grundvatten är högre än grundvattenbildningen sänks grundvattenytan och vatten flödar från andra delar av magasinet eller älven för att kompensera. Älvvattnet bedöms ha en stark hydraulisk koppling med grundvattnet, vilket innebär att det finns en risk att älvvattnet infiltrerar i magasinet och sänker kvalitén på framtida dricksvatten.Konsultföretaget Midvatten AB har i uppdrag att bedöma möjligheten till ett framtida dricksvattenuttag. Midvatten har som lösning anlagt stationer med sprinklerinfiltration för att i framtiden kunna infiltrera avhumifierat älvvatten som på sikt omvandlas till grundvatten. Denna konstgjorda infiltration är också tänkt att hindra älvvatten från att ta sig in i magasinet genom att förse magasinet med den mängd vatten som går förlorad av dricksvattenuttag. Hur mycket älvvatten som tar sig in till grundvattenmagasinet och når brunnarna vid ett framtida uttag och konstgjord infiltration, är dock oklart.Syftet med denna studie var att uppskatta flödet mellan åsens grundvattenmagasin och Dalälven och specifikt infiltrationen av älvvatten. Detta gjordes genom att utveckla en digital MODFLOW-flödesmodell i programmet GMS. Modellen kunde, med hjälp av uppmätta vattennivåer i grundvattenmagasinet och älven, räkna ut hur mycket vatten som flödade in från älven (infiltrerade). Den uträknade infiltrationen låg i genomsnitt på 3-25 l s-1. Infiltrationsmängden berodde på vilken brunn som vattnet pumpades ur, hur mycket som pumpades ut och hur mycket artificiell infiltration som tillfördes i de tre infiltrationsområdena under en period av 2017. Modellen användes även till att uppskatta flödet från älven för 28 tilltänkta scenarier under 2017 med konstant pumpning och konstgjord infiltration i de olika brunnarna och infiltrationsstationerna.Resultaten visade att modellen kunde uppskatta grundvattenmagasinets vattennivåer nära älven men inte på längre avstånd ifrån älven. Detta berodde på att magasinets hydrauliska parametrar inte var korrekt fördelade. Fördelningen kunde ha förbättrats om de baserats på jordarter från borrprotokoll istället för en jordartskarta. Modellen visade att mycket lite älvvatten flödar in i akviferen om vatten artificiellt infiltreras nära älven. För att resultaten av den här studien ska bli tillförlitliga krävs det att resultaten jämförs med andra metoder som använder sig av förslagsvis partikelspårningsmodeller, spårämnesstudier eller flödesmätningar av flodbädden.
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Balocchi, Francisco, and Francisco Balocchi. "Soil Behavior during Freeze-Thaw Processes at a Snow-Dominated Forest Site Simulated with the Physically-Based Numerical Water Flow and Heat Transport Soil in Cold Regions Model (SCRM)." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/621367.
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The freeze-thaw process controls several hydrologic processes including infiltration, runoff, and soil erosion. Simulating this process is important particularly in cold and mountainous regions. The Soil and Cold Regions Model (SCRM) was used to simulate, study, and understand the behavior of 12 homogenous soils, subject to a freeze-thaw process based on meteorological data at a snow dominated forest site in Laramie, WY, from 2010 and 2012. To complete a simulation, which accounts for all three phases of water (liquid, vapor, and ice), the model requires meteorological data, canopy characteristics, soil physical properties including the van Genuchten-Mualem parameters, and the initial state of the soil profile. Different model conditions were applied included the relationship between soil pore size, soil particle contact, soil thermal conductivities, soil ice/water content, snow cover, and meteorological data. Analysis of the simulations used metrics such as soil frost depth, days with ice, and maximum ice content. The results showed a threshold in snow depth ranging from 20 to 40 cm to fully insulate the soil from the atmosphere. Additionally, the model showed that the freeze-thaw process was strongest in the period with a shallow snow pack and that particle packing within the soil profile was an important factor in this process. Soil texture and water content controlled soil thermal properties. Water movement towards the freezing front was especially important in fine textured soils, where water and ice was concentrated in the upper layers. In coarser textured soil, frost also occurs, but not to the same extent. Based on these results, future research that combines a broader set of soil conditions with an extended set of field meteorology data could elucidate how soil texture controls thermal properties related to soil frost.
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Freeman, Andrea Kelly Lee. "Middle to late holocene stream dynamics of the Santa Cruz River, Tucson, Arizona : implications for human settlement, the transition to agriculture and archaeological site preservation." Diss., The University of Arizona, 1997. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1997_349_sip1_w.pdf&type=application/pdf.
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Tang, Han, and Han Tang. "The Importance of Prior Geologic Information on Hydraulic Tomography Analysis at the North Campus Research Site (NCRS)." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/621836.
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The purpose of this study is to investigate the importance of prior information about hydraulic conductivity (K) by Kriging, using point K data and/or residual covariance, on improvements of K estimates at the North Campus Research Site (NCRS). Among many methods that can characterize the mean or detail distribution of hydraulic conductivity (K), the Cooper-Jacob straight line solution, Kriging using point K data, single-well pumping tests inversion and Hydraulic Tomography (HT) have been compared in this study, using the head data collected from 15 cross-hole pumping tests collected at NCRS, where 9 existing wells were installed with packer system and the pressure responses at different intervals in different wells were monitored with transducers. It is found that the HT method, which fuse all the available pumping test data, yields more accurate and consistent results. However, many studies have indicated that the hydraulic data combined with geologic investigation will improve the HT estimates. Thus, in this study, hard data of K obtained by permeameter (227 data points) are brought in using Kriging and combined with HT to yield better estimate K field. Moreover, the validations of unused tests indicate that the estimated K obtained using collected K information makes more accurate predictions.
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Vesselinov, Velimir Valentinov. "Numerical inverse interpretation of pneumatic tests in unsaturated fractured tuffs at the Apache Leap Research Site." Diss., The University of Arizona, 2000. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_2000_95_sip1_w.pdf&type=application/pdf.
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Baron, Dirk. "Analysis and Numerical Simulation of the Ground Water System at the Bonneville Navigation Lock Site, Oregon." PDXScholar, 1990. https://pdxscholar.library.pdx.edu/open_access_etds/4027.
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As part of the new navigation lock for Bonneville Dam a new water source for the Bonneville Fish Hatchery must be supplied. The hatchery is located on the Oregon side of the Columbia River downstream of the dam. It requires large quantities of water free from chemical and biological contamination. In addition, the water has to be in a narrow temperature range. Currently the fish hatchery receives its water from a well field that is located on the alluvial terrace downstream of Bonneville Dam. The well field lies in the proposed approach channel for the new lock and has to be abandoned during construction of the lock. For the continued water supply of the hatchery, a new well field will be developed north of the approach channel. Early in the planning phase for the new lock, concerns were raised about the potential impact of the relocation of the well field and the excavation of the new approach channel on the hatchery. To assess these concerns and to assure a continuous water supply during and after construction, a hydrogeologic investigation was initiated. Within the framework of the investigation this study focuses on the analysis of pumping test data and the development of a three-dimensional ground water flow model for the site.
In the first phase of the study, data from eight pumping tests were analyzed. Hydrogeologic properties of the sedimentary units that make up the downstream terrace were determined. The focus was the pre-slide alluvium (PSA) aquifer, the water source for the existing and the future well field. In addition, the nature and location of hydrogeologic boundaries for the ground water system were determined. The results, in conjunction with information from subsurface exploration and laboratory tests, were used to develop a conceptual understanding of the ground water system at the site. The PSA aquifer receives its recharge primarily from leakage through the overlying confining layers over a large area. A direct connection between the Columbia River and the PSA aquifer could not be detected. They appear to be separated by a continuous aquitard layer or by a layer of fine-grained sediments on the river bottom.
Based on these findings, in the second phase of the study, the ground water modeling program HST3D (Kipp, 1987) was used to develop a three-dimensional ground water model for the site. The model was calibrated with data from one of the pumping tests. The calibration was then verified with a second set of conditions including pumping from shallow and deep wells. Water levels in the deep PSA aquifer and the shallow unconfined aquifer were successfully matched. A satisfactory match of observed conditions was possible with only slight modifications of the hydrogeologic parameters determined by pumping test analysis and based on the conceptual model developed in the first phase of the study. It appears that a continuous aquitard layer separating the Columbia River and the PSA aquifer, with the aquifer receiving recharge through vertical leakage over a large area, is a valid representation of the aquifer system.
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Fourno, Andre. "Modélisation multi-échelle des transferts en milieux fracturés : application au site de Äspö (Suède)." Phd thesis, Université de Poitiers, 2005. http://tel.archives-ouvertes.fr/tel-00218275.
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Dans le cadre de la problématique de l'enfouissement des déchets nucléaires, la barrière géologique constitue la dernière zone de transfert des radio-éléments. Cette barrière pouvant être fracturée des recherches sont menées pour faire progresser la modélisation des transferts en milieu fracturé. La complexité du milieu, les contrastes existant entre les différentes zones et les incertitudes liées aux propriétés physiques rendent cette tâche complexe. De plus, après fermeture du site, les écoulements lents dans le milieu favorisent des phénomènes diffusifs dans la roche qui contribuent à augmenter le temps de transit des radio-éléments. Dans ce contexte, une approche Smeared Fractures a été développée pour un schéma en Eléments Finis Mixtes Hybrides et implémentée dans le code Cast3M. Cette approche permet une représentation explicite des fractures principales alors que la fracturation de plus petite échelle est homogénéisée. L'utilisation d'un maillage régulier permet, en outre, d'éviter un maillage explicite coûteux. La présence des fractures est prise en compte par un champ hétérogène de propriétés. Ces propriétés sont affectées de manière à respecter les critères de conservation des flux (hydraulique et massique) à l'échelle de la fracture. Pour l'écoulement, l'approche Smeared Fractures présente des performances comparables à celles obtenues avec des approches discrètes tandis que le caractère 3D de la géométrie des blocs matriciels est respecté lors de la résolution du transport. Le choix des discrétisation spatiale et temporelle doit respecter des critères qui ont été établis. Néanmoins, à l'intérieur de ces limites, et suivant la précision désirée, l'approche permet de réduire les temps de calcul. Les résultats de validation et de qualification de l'approche appliquée à des géométries 2D et 3D, synthétiques et réalistes, sont présentés pour différents jeux de paramètres physiques. Des applications de l'approche au site d'Äspö (Suède) clôturent ce travail.
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Belle, Emilien. "Évolution de l'impact environnemental de lixiviats d'ordures ménagères sur les eaux superficielles et souterraines, approche hydrobiologique et hydrogéologique. Site d'étude : décharge d'Étueffont (Territoire de Belfort – France)." Phd thesis, Université de Franche-Comté, 2008. http://tel.archives-ouvertes.fr/tel-00400680.
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L'utilisation couplée de la géophysique, de traçages d'essais, de bilan hydrique, de la géologie, de l'hydrogéologie, et d'analyse statistique sur les données physico-chimiques a permis de mettre en évidence -des infiltrations de lixiviats comprises entre 31 et 43% à travers une interface naturelle shisteuse, et > à 45% à travers une barrière artificielle géomembranaire, -et un impact localisé sur le réseau piézométrique existant. Les lixiviats récoltés sont traités par lagunage naturel. Suite à l'arrêt des dépôts, l'activité de biodégradation diminue et engendre une baisse de la nocivité des lixiviats bruts, modifiant ainsi le fonctionnement hydrobiologique des lagunes. On note une diversification de l'ensemble des composants de la boucle microbienne assurant le recyclage de la matière. La structuration de la pyramide trophique a permis d'atteindre en dernière lagune, un écosystème viable pour la faune piscicole. Les lixiviats traités subissent une seconde épuration naturelle dans le ruisseau récepteur. Une approche bactériologique des lixiviats, des lagunes et des eaux souterraines a permis d'évaluer la survie des bactéries fécales dans ces différents milieux. Cette décharge ne constitue pas une source importante de bactéries fécales. L'étude de ce site où lixiviats de décharge et apports de fosse septique se mélangent confirme le rôle d'Escherichia coli et des Entérocoques comme marqueurs de contamination fécale assez récente. L'aquifère schisteux s'apparente plus à un aquifère fracturé qu'à une zone imperméable, avec une circulation préférentielle le long de fractures qui n'assure pas une filtration et en font un aquifère vulnérable aux contaminations bactériennes.
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Moreau, Luc. "Comportement d'un glacier tempere sur son lit rocheux. Vitesses de glissement, hydrologie et hydrographie. Etude effectuee au sein du site sous-glaciaire d'emosson glacier d'argentiere, massif du mont-blanc, france." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10202.
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Le comportement d'un glacier tempere sur son lit rocheux reste pour une large part meconnu etant donne les difficultes rencontrees sur le terrain pour acceder a l'interface glace-roche, la ou se place le contact entre le glacier et son lit rocheux. L'exploitation et le captage des eaux glaciaires par les societes hydroelectriques, en developpant des sites sous-glaciaires, a facilite cet acces et l'observation de la dynamique des glaciers. A la charniere des domaines fondamental et applique, cette etude tente de repondre a plusieurs problemes majeurs en glaciologie: dynamique glaciaire et interface glace-roche, hydrologie et hydrographie sous-glaciaires, vitesses de glissement d'un glacier sur son lit rocheux. Elle concerne les glaciers temperes et plus particulierement le glacier d'argentiere, dont elle analyse vingt ans de donnees scientifiques accumulees pour les besoins des captages sous-glaciaires de la societe hydroelectrique d'emosson
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Rajaguru, Mudiyanselage Thilanki Maneesha Dahigamuwa. "Enhancement of Rainfall-Triggered Shallow Landslide Hazard Assessment at Regional and Site Scales Using Remote Sensing and Slope Stability Analysis Coupled with Infiltration Modeling." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7562.
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Landslides cause significant damage to property and human lives throughout the world. Rainfall is the most common triggering factor for the occurrence of landslides. This dissertation presents two novel methodologies for assessment of rainfall-triggered shallow landslide hazard. The first method focuses on using remotely sensed soil moisture and soil surface properties in developing a framework for real-time regional scale landslide hazard assessment while the second method is a deterministic approach to landslide hazard assessment of the specific sites identified during first assessment. In the latter approach, landslide inducing transient seepage in soil during rainfall and its effect on slope stability are modeled using numerical analysis.
Traditionally, the prediction of rainfall-triggered landslides has been performed using pre-determined rainfall intensity-duration thresholds. However, it is the infiltration of rainwater into soil slopes which leads to an increase of porewater pressure and destruction of matric suction that causes a reduction in soil shear strength and slope instability. Hence, soil moisture, pore pressure and infiltration properties of soil must be direct inputs to reliable landslide hazard assessment methods. In-situ measurement of pore pressure for real-time landslide hazard assessment is an expensive endeavor and thus, the use of more practical remote sensing of soil moisture is constantly sought. In past studies, a statistical framework for regional scale landslide hazard assessment using remotely sensed soil moisture has not been developed. Thus, the first major objective of this study is to develop a framework for using downscaled remotely sensed soil moisture available on a daily basis to monitor locations that are highly susceptible to rainfall-
triggered shallow landslides, using a well-structured assessment procedure. Downscaled soil moisture, the relevant geotechnical properties of saturated hydraulic conductivity and soil type, and the conditioning factors of elevation, slope, and distance to roads are used to develop an improved logistic regression model to predict the soil slide hazard of soil slopes using data from two geographically different regions. A soil moisture downscaling model with a proven superior prediction accuracy than the downscaling models that have been used in previous landslide studies is employed in this study. Furthermore, this model provides satisfactory classification accuracy and performs better than the alternative water drainage-based indices that are conventionally used to quantify the effect that elevated soil moisture has upon the soil sliding. Furthermore, the downscaling of soil moisture content is shown to improve the prediction accuracy. Finally, a technique that can determine the threshold probability for identifying locations with a high soil slide hazard is proposed.
On the other hand, many deterministic methods based on analytical and numerical methodologies have been developed in the past to model the effects of infiltration and subsequent transient seepage during rainfall on the stability of natural and manmade slopes. However, the effects of continuous interplay between surface and subsurface water flows on slope stability is seldom considered in the above-mentioned numerical and analytical models. Furthermore, the existing seepage models are based on the Richards equation, which is derived using Darcy’s law, under a pseudo-steady state assumption. Thus, the inertial components of flow have not been incorporated typically in modeling the flow of water through the subsurface. Hence, the second objective of this study is to develop a numerical model which has the capability to model surface, subsurface and infiltration water flows based on a unified approach, employing fundamental fluid dynamics, to assess slope stability during rainfall-induced transient seepage conditions. The developed model is based on the Navier-Stokes equations, which possess the capability to model surface, subsurface and infiltration water flows in a unified manner. The extended Mohr-Coulomb criterion is used in evaluating the shear strength reduction due to infiltration. Finally, the effect of soil hydraulic conductivity on slope stability is examined. The interplay between surface and subsurface water flows is observed to have a significant impact on slope stability, especially at low hydraulic conductivity values. The developed numerical model facilitates site-specific calibration with respect to saturated hydraulic conductivity, remotely sensed soil moisture content and rainfall intensity to predict landslide inducing subsurface pore pressure variations in real time.
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Juglea, Silvia. "Simulation de l'humidité du sol-température de brillance à partir des données in situ dans le cadre de la validation des produits SMOS : site test Valencia Anchor Station." Phd thesis, Université Paul Sabatier - Toulouse III, 2011. http://tel.archives-ouvertes.fr/tel-00697305.
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Lancée en novembre 2009, l'objectif principal de la mission SMOS (Soil Moisture and Ocean Salinity) est de fournir une cartographie globale de l'humidité du sol avec une précision supérieure à 0.04 m3/m3 et avec une résolution spatiale comprise entre 35 km au nadir et 55 km (43 km en moyenne) en utilisant la radiométrie en bande L (1.4 GHz). La résolution spatiale des satellites tels que SMOS induit de nombreuses questions scientifiques qui nécessite un minimum de mesures de terrain représentatives de la zone vue par le capteur. C'est dans cette optique que la validation des données SMOS nécessite l'acquisition de nombreuses mesures sur une vaste zone. Dans ce sens, le site VAS (Valencia Anchor Station), défini par l'université de Valence (Espagne) en décembre 2001, a pour objectif principal de caractériser une surface dédiée à l'étalonnage et la validation des missions satellites d'observation de la terre. Dans le contexte de la validation des produits SMOS au-dessus des terres émergées, l'objectif principal de cette thèse est la génération de "Match-ups" sur la zone VAS (équivalente à un pixel SMOS), qui sont à comparer avec les données réelles SMOS. Les Match-ups sont des températures de brillance micro-ondes passives simulées en utilisant les variables et les caractéristiques de surface de la zone VAS. Ainsi, pour modéliser l'humidité du sol et la température de brillance associée, nous avons couplé un modèle SVAT (Soil-Vegetation-Atmosphere-Transfer) avec un modèle de transfert radiatif. Les processus hydrologiques sont simulés avec le modèle ISBA (Interactions between Soil Biosphere Atmosphere), alors que l'émission micro-ondes est simulée avec le modèle L-MEB (L-band Microwave Emission of the Biosphere) qui est utilisé dans l'algorithme d'inversion des humidités de surface à partir des données SMOS.
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Ramboz, Claire. "Métamorphisme hydrothermal et réactions d'oxydo-réduction en contexte de marge passive et de zone de cisaillement ductile : genèse des concentrations Zn-Pb et graphite associées." Phd thesis, Institut National Polytechnique de Lorraine - INPL, 1988. http://tel.archives-ouvertes.fr/tel-00617110.
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Cette thèse rassemble 4 publications originales relatives à différents aspects de l'interaction entre fluides et minéraux dans les contextes de marge passive et de cisaillements ductiles. Une approche cristallochimique démontre la présence d'associations à grenats et de pyroxènes non stœchiométriques, formes dans des conditions hyperréductrices dans des skarns à graphite (Sidi Bou Othmane, Maroc) et met en évidence des pressions de fluides anormales dans le gisement Zn-Pb des Malines (bordure cévenole, France). Les conditions thermiques de l'alimentation hydrothermale de la fosse à saumures d'Atlantis II (Mer Rouge) sont définies par l'étude des inclusions fluides primaires dans les cristaux d'anhydrite épigénétiques, et par l'évaluation du bilan de masse et de chaleur de la fosse. Une synthèse sur les mécanismes des circulations hydrothermales dans les marges passives est réalisée
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Ramanathan, Ramya. "LINKING PLUME SPREADING TO HIERARCHICAL STRATAL ARCHITECTURE." Wright State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=wright1238547912.
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Woodhouse, Elizabeth Gail. "Perched water in fractured, welded tuff mechanisms of formation and characteristics of recharge /." Diss., The University of Arizona, 1997. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1997_87_sip1_w.pdf&type=application/pdf.
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Pandey, Ganesh Raj. "Regional estimation of floods and rainfalls for ungauged sites." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40219.
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This research deals with the estimation of rainfalls and floods for locations at which the corresponding data are unavailable (ungauged sites). The overall study can be divided into three different parts. The first part explores the validity of the distributional similarity of the rainfall time series aggregated at different time scales. Based on the theory of multiplicative cascade process, a scale independent mathematical model has been proposed to describe the probability distributions of rainfall time series aggregated at different time scales. It has been demonstrated that the multifractal formalism can be used to estimate the probability distribution of rainfalls for a wide range of space and time scales.The second part of the research deals with the estimation of floods at an ungauged site using regional physiographic and climatic variables. To this end, a detailed study was carried out to determine the best technique for estimating the parameters of the commonly used power-form flood regionalization model, and to identify the minimum number of physiographic and hydrometeorological variables which should be included in the model. The study was further elaborated by applying the linear and nonlinear covariance structural models. Results of a numerical example using hydrologic data from Quebec and Ontario have indicated the superior performance of the nonlinear optimization method. Further, it was found that the significant variables which should be considered in the estimation of floods, are the area of the basin, the basin slope and the total precipitation five days before the flood for Quebec, and the area of the basin, the area of forests, lakes, and marses and the slope of the main channel for Ontario.
The third part of the study proposed a new method of flood estimation based on the scaling of the statistical moments of the regional flood series with the basin area. Analysis of the physiographic and hydrologic data from Quebec and Ontario showed that the non-central moments of order from one to six are scaling with the basin area. This empirical evidence was used in defining the hydrologically similar basins (i.e., homogeneous flood regions), and in selecting a suitable regional distribution function for the estimation of flood quantiles. It was observed that the grouping of homogeneous basins as proposed in this study formed well-defined geographical regions with distinct climatic characteristics. Further, it was recommended that the selection of regional probability distribution and the corresponding parameter estimation method should be made such that the scaling properties of the flood series were preserved. The improved estimates of the statistical moments and flood quantiles for unguaged sites have indicated the superiority of the proposed approach as compared to those values given by existing methods.
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Odry, Jean. "Prédétermination des débits de crues extrêmes en sites non jaugés : régionalisation de la méthode par simulation SHYREG." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0424/document.
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L’estimation de l’aléa hydrologique en sites non jaugés présente un enjeu important pour la gestion des risques. La complexité du phénomène réside à la fois dans la nécessité d’avoir une approche multivariée (estimation de caractéristiques multiples des crues : durées, périodes de retour) qui propose une extrapolation raisonnable des événements. SHYREG est une méthode basée sur la simulation de scénarios de crues, qui présente ces avantages. Évaluée lors du projet ANR ExtraFlo, elle présente de bonnes performances en justesse et en stabilité lorsqu'elle est calée sur des données locales de débits. Cette méthode vise à estimer des débits de crue en tout point du territoire. Elle doit donc pouvoir être appliquée en site non jaugés.Le travail de thèse présenté ici se focalise sur le transfert de la méthode vers le non jaugé en s’intéressant aux valeurs des débits simulés mais aussi à leur cohérence. Tout d’abord, une révision du calage a permis de s’assurer de la cohérence des débits simulés le long d’un cours d’eau. Ensuite, l’application d’un large panel de méthodes de régionalisation a permis de déterminer que la régionalisation devait s’appuyer à la fois sur la structure spatiale et sur les caractéristiques physiographiques des bassins. Finalement, une méthode qui régionalise SHYREG simultanément à son calage a été retenue. Une comparaison avec d’autres approches régionalisées a mis en évidence la qualité du modèle développéFlood hazard estimation in ungauged sites presents a major challenge for risk management. The complexity of the phenomenon arises from both the need for a multivariate approach (estimation of different flood characteristics: peak flow, volume, duration ...), and for an approach which offers a reasonable extrapolation of extreme events. The SHYREG method is based on the simulation of flood scenarios and presents these benefits. It has been evaluated during the ANR ExtraFlo project. It showed good performance in both accuracy and stability when calibrated against local discharge data. However, weaknesses have been identified when implemented in ungauged sites.The objective of the present thesis is to develop the method in order to improve the SHYREG performances in ungauged sites. Two kinds of modifications were implemented. First, the calibration of the method in gauged sites was reviewed. The main idea was to integrate more data and to take more into account the coherence between simulated discharges in different sites. Then, diverse regionalisation schemes extracted from the scientific literature were considered. Their application demonstrated the necessity to exploit information from nearby sites and the physical properties of the catchments. Finally, a version which realises the regionalisation simultaneously to the calibration has been selected. Its comparison with other method showed the quality of this new version of SHYREG
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Charbonnel, Anaïs. "Influence multi-échelle des facteurs environnementaux dans la répartition du Desman des Pyrénées (Galemys pyrenaicus) en France." Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/14261/1/Charbonnel.pdf.
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L’écologie du Desman des Pyrénées (Galemys pyrenaicus), mammifère semi-aquatique endémique de la péninsule ibérique et des Pyrénées, demeure encore très peu connue. Les objectifs de cette thèse, dans le cadre d’un Plan National d’Actions, ont été d’identifier les variables environnementales agissant sur la répartition de l’espèce à différentes échelles spatiales, en considérant sa détectabilité imparfaite (i.e. fausses absences et fausses présences). Une probabilité de détection élevée, mais spatialement hétérogène à l’échelle des Pyrénées françaises, a été mise en évidence. La distribution du Desman des Pyrénées s’est également révélée spatialement structurée et majoritairement influencée par des facteurs propres aux milieux aquatiques, mais en forte régression depuis les années 80. Ces résultats ont permis de proposer des mesures de conservation pour cette espèce menacée.
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Ghorbel, Ben Abid Manel. "Contamination métallique issue des déchets de l'ancien site minier de Jebel Ressas : modélisation des mécanismes de transfert et conception de cartes d'aléa post-mine dans un contexte carbonaté et sous un climat semi-aride. Evaluation du risque pour la santé humaine." Phd thesis, Université Paul Sabatier - Toulouse III, 2012. http://tel.archives-ouvertes.fr/tel-00760685.
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Une approche pluridisciplinaire intégrée a été proposée pour étudier le transfert de la contamination métallique depuis les déchets de l'ancien site minier à Pb-Zn de Jebel Ressas, jusqu'à l'être humain. Nous avons pris en considération à la fois les caractéristiques physico-chimiques de la source, les conditions climatiques et la topographie pour hiérarchiser les vecteurs de la dispersion des métaux à partir des déchets de laverie de l'ancienne mine de Jebel Ressas. Le vecteur éolien est le principal agent capable de disperser les métaux dans toutes les directions, avec des quantités variables pouvant dépasser les normes de la qualité des l'air pour Pb et Cd sur plusieurs centaines de mètres loin de la source. Le transfert hydrique particulaire est assez limité à cause de la topographie douce au tour des terrils de déchets. Le transfert en solution est négligeable grâce à l'environnement carbonaté. L'investigation sur le risque des métaux pour la santé humaine au village de Jebel Ressas montre d'abord que, d'une part l'environnement carbonaté et d'autre part le pH neutre des fluides physiologiques dans le corps humain, limitent le passage en solution des métaux et leurs quantités bioaccessibles. Toutefois, Pb et Cd présentent un risque surtout pour les enfants en plus d'un effet cancérigène probable pour toute la population.
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Flaux, Clément. "Paléo-environnements littoraux Holocène du lac Maryut, nord-ouest du delta du Nil, Egypte." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM3011/document.
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La cité d'Alexandrie s'est développée sur un cordon littoral étroit, baigné au sud par le Maryut, lagune du delta du Nil qui s'est trouvée ainsi au coeur de l'économie industrielle et commerciale de la cité et de son arrière-pays depuis l'antiquité jusqu'à aujourd'hui. Dans ce riche contexte géo-archéologique, l'objectif de cette thèse de géomorphologie littorale a été de proposer une clef de lecture environnementale de l'histoire de l'occupation de la région du Maryut. L'analyse bio-sédimentologique des archives sédimentaires datées au radiocarbone, ainsi que la mesure du rapport isotopique du strontium dans des coquilles d'ostracode ont été utilisées pour reconstituer l'évolution hydrologique et géographique de la lagune à l'Holocène. La dépression du Maryut est transgressée par la mer vers 7,5 ka cal. BP. Les apports du Nil deviennent ensuite progressivement dominant dans le budget hydrologique, parallèlement à la progradation du littorale deltaïque. A partir de 5,5 ka cal. BP, nos données décrivent le retour progressif de conditions marines dominantes, associées à la réduction des débits du Nil, dans le contexte de la terminaison de la Période Africaine Humide. Cette lagune marine apparaît pérenne jusque 3ka cal BP, puis, dans le courant du 3ème millénaire BP, les intrants nilotiques redeviennent prépondérant. Ensuite, les archives sédimentaires et les données historiques disponibles décrivent une histoire environnementale contrastée est apparue corrélée à des phases de dynamisme et de récession agricole et met en évidence, selon nous, l'impact croissant des pratiques d'irrigation sur le fonctionnement du Maryut, situé en terminaison de la chaîne hydrauliqueThe ancient city of Alexandria was founded upon a narrow beach ridge, washed by the Maryut to the south. This Nile delta lagoon has been at the heart of the industrial and commercial economies of the city from Antiquity through to present day. Against the backdrop of this rich geoarchaeological context, the aim of this coastal geomorphology thesis is to elucidate the environmental history of the Maryut region.We have reconstructed the hydrological and geographical evolution of the lagoon during the Holocene using: (1) bio-sedimentology of radiocarbon-dated sediment archives; and (2) strontium isotopes in ostracod shells. The Maryut basin was transgressed by the sea around 7.5 ka cal. BP. Progressively, Nile inputs became dominant in the lagoon's hydrological budget, concomitant with the coastal progradation of the delta. After 5.5 ka cal. BP, our data attest to a gradual return to dominant marine conditions, which we link to a reduction in Nile flow in the context of the end of the African Humid Period. This marine lagoon seems to have been perennial until 3 ka cal. BP before Nile inflow became dominant, from the 3rd millennium BP until 0.8-0.9 ka cal. BP. The sediment archives and the historical data support an important retraction of the waterbody around 1 ka cal. BP, recorded by evaporite deposits. This was followed by a new highstand around 0.7 ka cal. BP before a retraction centred on 0.3-0.2 ka cal. BP. Since around 2000 years, this contrasting environmental history is correlated with phases of agriculture peaks and recessions and shows the increasing impact of irrigation practices on the functioning of the Maryut, located at the end of the hydrological conveyor
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Hartung, Alexander. "Konzept zur Ermittlung langfristiger hydrologischer Standortbedingungen von Fluss und Grundwasser in Auenwäldern." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2003. http://nbn-resolving.de/urn:nbn:de:swb:14-1060177479031-87945.
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Das Ziel der vorliegenden Arbeit ist die ausführliche Analyse und Beschreibung langfristiger abiotischer Standortbedingungen von Fluss und Grundwasser für das in einem Hartholzauenwald gelegene Untersuchungsgebiet im Naturschutzgebiet Saalberghau an der Mittleren Elbe bei Dessau. Hierzu erfolgt zunächst die Entwicklung eines allgemeinen Konzeptes, dass die Modellierung des Fluss- und des Grundwasserregimes sowie die statistische Auswertung dieser miteinander verbundenen Regime umfasst. Es wird davon ausgegangen, dass nur eine Synthese dieser Einzelbausteine die Grundlage für eine zusammenhängende Analyse und Beschreibung der komplexen auentypischen Dynamik dieser beiden Regime anhand objektivierbarer statistischer Parameter bilden kann. Darüberhinaus stellt die Zielsetzung auf langfristige Aussagen eine unentbehrliche Voraussetzung dar, um das Zeitspektrum der hier zu betrachtenden Altbäume typischer Hartholzauenbaumarten adäquat berücksichtigen zu könnenThe present dissertation aims at a detailed analysis and description of the long-term abiotic site conditions (river flow and groundwater) for the floodplain area under investigation, namely a hardwood forest in the nature reserve "Saalberghau" on the Middle Elbe close to the town Dessau. For this purpose, firstly a general concept which covers the modelling of the surface water and groundwater regime as well as a statistical interpretation of these two interconnected regimes is developed. It is assumed that only a synthesis of those separate modules can form a sufficient basis for a cohering analysis and description of the complex dynamics of these two regimes in floodplain forests by means of objective statistic parameters. Furthermore, only longterm statements can take into account the age spectrum of the hardwood stand
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Négrel, Jean. "Estimation du débit des fleuves à partir de mesures satellitaires des variables de surface sans mesures in situ." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20239/document.
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La question de l'eau constitue à l'heure actuelle un enjeu majeur pour nos sociétés. Bien qu'il s'agisse d'une ressource renouvelable, son cycle naturel est soumis à de fortes pressions issues tant de l'activité humaine que des modifications climatiques.Le débit des fleuves constitue une des variables clefs du cycle de l'eau. Sa quantification implique des mesures in situ lourdes. De ce fait, son suivi à l'échelle globale reste problématique, et les techniques de télédétection peuvent représenter un atout majeur. Les techniques satellitaires optiques et radar ne peuvent actuellement que mesurer les variables de surface et n'accèdent pas aux paramètres de fond des cours d'eau. Ce travail propose une méthode d'estimation de ces paramètres hydrauliques de fond à partir des seules mesures des variables de surface, en vue de l'estimation du débit. Cette méthode a été validée sur des données simulées exactes et une étude de sensibilité au bruit de mesure a été menée sur des données simulées bruitées et sur des données réelles.Le second volet de ce travail porte sur le potentiel de l'interférométrie radar temporelle à mesurer la variable de vitesse de surface des fleuves. Une campagne de mesure aéroportée a été réalisée sur le Rhône (ONERA-Cemagref) et a montré des résultats concordants avec les mesures de vitesses réalisées in situ par ADCP. En revanche, le modèle de rétrodiffusion M4S, testé dans le cadre de cette thèse, est apparu peu adapté aux scènes fluviales : il s'avère extrêmement sensible aux conditions de vent, ce qui peut s'expliquer par une faiblesse dans la modélisation des caractéristiques des surfaces de fleuves. Dans le cadre du programme SWOT (NASA-CNES), nous avons développé une méthode de mesure in situ de la rugosité des surfaces fluviales. Validée lors de mesures en laboratoire, cette méthode a été mise en œuvre sur le Rhône, et a ainsi permis de caractériser la surface et l'influence de l'intensité du vent sur les paramètres de rugositéThe water issue is currently a major challenge for our societies. Even if water is a renewable resource, its natural cycle supports great stresses, both human activity and climate change.River discharge is a key variable of the water cycle, whose quantification requires heavy field measurements. Therefore the global monitoring of river discharge remains problematic and satellite remote sensing techniques could be a major asset. Earth Observation radar techniques are currently limited to the measurement of surface variables and cannot measure river bottom hydraulic parameters. The current study proposes a method to estimate these parameters from surface variables, in order to estimate the river discharge. This method has been validated on exact simulated data and its robustness to measurement noise has been studied on noisy simulated data and on real data.The second part of this work explores the abilities of radar along-track interferometry to measure river surface velocity. Velocity measurements carried out on the Rhône river during an airborne campaign (ONERA-Cemagref) show a strong consistency with ADCP field measurements. M4S backscattering model, tested in the framework of this study, is poorly adapted to river scenes : it appears to be extremely sensitive to wind intensity which could be explained by a poor modeling of surface roughness. As part of the SWOT mission program (NASA-CNES) a method allowing in situ characterization of river surface roughness has been developed. It was validated under laboratory controlled conditions. It was implemented on the Rhône river to characterize water surface and quantify the influence of wind intensity on the water surface roughness parameters
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Yolcubal, Irfan. "In-situ monitoring of microbial activity and biodegradation during solute transport in porous media." Diss., The University of Arizona, 2001. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_2001_290_sip1_w.pdf&type=application/pdf.
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Alter, Stacie Ratcliff. "Use of Biotracer Tests to Evaluate the Impact of Enhanced-Solubilization Flushing on In-Situ Biodegradation." Thesis, The University of Arizona, 2000. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0019_m_sip1_w.pdf&type=application/pdf.
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