To see the other types of publications on this topic, follow the link: Ground water-surface water interface.
Dissertations / Theses on the topic 'Ground water-surface water interface'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Ground water-surface water interface.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Cho, Jae-Pil. "A comprehensive modeling approach for BMP impact assessment considering surface and ground water interaction." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/27890.
Full textAbstract:
The overall goal of this study was to develop a comprehensive tool for assessing the effectiveness of selected BMPs on both hydrology and water quality and to demonstrate the applicability of the system by considering 1) temporally and spatially changing land use management practice in an agricultural watershed and 2) interaction between surface and ground water over the entire system. A user interface and Dynamic Agricultural Non-point Source Assessment Tool (DANSAT) were developed to achieve this goal. DANSAT is the only distributed-parameter, physically-base, continuous-simulation, and multi-soil layer model for simulating impacts of agricultural BMPs on hydrology and water qulality in small agricultural watersheds. DANSAT was applied to QNB plot (18m à 27m) and two agricultural watersheds in Virginia, including Owl Run watershed (1140 ha) and QN2 in the Nomini Creek watershed (216 ha), to evaluate the model components and its performance in predicting runoff, sediment yield, and pesticide load. DANSAT performed well in predicting total runoff and temporal variations in surface runoff for both field-scale and watershed-scale applications. Total percent errors between the measured and predicted results were less than 10% except for one case (39.8% within a subwatershed of Owl Run watershed), while the daily Nash-Sutcliffe model efficiencies were greater than 0.5 in all applications. Predicted total sediment yields were within ±35% of observed values in all applications. However, the performance of DANSAT in predicting temporal trend and spatial distribution of sediment loads was acceptable only within Owl Run watershed, where high correlations between flow rates and sediment loads exist. The predicted total pesticide loads were within ±100% of observed values. DANSAT failed to simulate the temporal occurrence of pesticide loads with a 0.42 daily Nash-Sutcliffe efficiency value. The Dual-Simulation (DS) was developed within the linked ground water approach to resolve problems encountered due to the existence of different temporal scales between DANSAT and the existing ground water models such as MODFLOW and MT3D. The linked approach performed better in predicting the seasonal trend of total runoff compared to the integrated approach by showing an increase in monthly Nash-Sutcliffe efficiency value from 0.53 to 0.60. Surface and subsurface output variables were sensitive to the changes in spatially distributed soil parameters such as total porosity and field capacity. A maximum grid size of 100 m was recommended to be appropriate for representing spatial distribution of topographic, land use, and soil characteristics based on accuracy analysis during the GIS manipulation processes. Larger time-step based on predefined acceptable maximum grid size, decreased the computational time dramatically. Overall sensitivity to different grid sizes and time-steps was smallest for hydrology components followed by sediment and pesticide components. Dynamic crop rotation was considered by DANSAT, and the model successfully simulated the impacts of temporal and spatial changes in crop rotations on hydrology and water quality for both surface and subsurface areas. DANSAT could prove to be a useful tool for non-point source pollution managers to assess the relative effectiveness of temporally and spatially changing BMPs on both surface and ground water quantity and quality.<br>Ph. D.
2
Simpson, Matthew. "An analysis of unconfined ground water flow characteristics near a seepage-face boundary." University of Western Australia. Centre for Water Research, 2003. http://theses.library.uwa.edu.au/adt-WU2004.0025.
Full textAbstract:
A quantitative understanding of ground water flow characteristics in unconfined aquifers is important because of the prevalence of abstraction from, and pollution of these systems. The current understanding of ground water flow in unconfined aquifers is limited because of the dominance of horizontal flow modelling strategies used to represent unconfined flow processes. The application of horizontal flow principles leads to an ignorance of seepage-face formation and can not predict the complicated three-dimensional nature of the ground water flow that dominates at the ground water-surface water interface. This study aims to address some of these deficiencies by exploring the true three-dimensional nature of ground water flow including the formation of seepage faces at the ground water-surface water interface using numerical and laboratory techniques. A finite element model for simulating two-dimensional (vertical) variably saturated flow is developed and benchmarked against standard laboratory and field-scale solutions. The numerical features of the finite element model are explored and compared to a simple finite difference formulation. The comparison demonstrates how finite element formulations lead to a broader spatial averaging of material properties and a different method for the representation of specified flux boundaries. A detailed comparison analysis indicates that these differences in the finite element solution lead to an improved approximation to the partial differential equation governing two-dimensional (vertical) variably saturated flow. A laboratory analysis of unconfined ground water flow and associated solute transport characteristics was performed. The analysis focused upon unconfined flow towards a pumping well. The laboratory observations were reliably reproduced using a three-dimensional (axi-symmetric), variably saturated ground water flow model. The model was benchmarked against the ground water flow characteristics such as the seepage-face height and total flow rate. In addition, the model was shown to reliably reproduce the solute transport features such as travel times and streamline distributions. This is the first time that a numerical model has been used to reliably reproduce the solute transport characteristics near a seepage-face boundary where the three-dimensional flow effects are prevalent. The ability to reliably predict solute transport patterns in the seepage-face zone is important since this region is known to support vital microbially facilitated reactions that control nutrient cycling and contaminant attenuation. The three-dimensional travel time distribution near the seepage-face was compared to that predicted using a horizontal flow modelling approach derived from the basic Dupuit-Forchheimer equations. The Dupuit-Forchheimer based model indicated that horizontal flow modelling would under-estimate the total residence time near a seepage-face boundary, thereby introducing a considerable source of error in a solute transport analysis. For this analysis, a new analytical solution for the steady travel time distribution in an unconfined aquifer subject to a single pumping well was derived. The analytical model has identified, for the first time in the hydrogeology literature, the use of the imaginary error function. The imaginary error function is a standard transcendental function and an infinite series approach to evaluate the function was successfully proposed. The two-dimensional (vertical) ground water flow model was extended to handle the case where the flow is driven by density gradients near the ground water-surface water interface. The unsteady, two-dimensional, Galerkin finite element model of density-dependent ground water flow in variably saturated porous media is rigorously presented and partially benchmarked under fully saturated (confined) conditions. The partial benchmarking involved reproducing solutions to the standard Henry salt-water intrusion and the Elder salt-convection problems. The model was used in a standard density-coupled and a new density-uncoupled mode to elucidate the worthiness of the Henry and Elder problems as benchmark standards. A comparison of the coupled and uncoupled solutions indicates that the Henry salt-water intrusion problem has limited worthiness as a benchmark as the patterns of ground water flow are relatively insensitive to density-coupled effects. Alternatively, the Elder problem is completely dependent upon a correct representation of the density-coupled flow and solute transport processes. The coupled versus uncoupled comparison is proposed as a new test of the worthiness of benchmark standards. The Henry salt-water intrusion problem was further analysed in an attempt to alleviate some of the difficulties associated with this benchmark problem. The numerical model was tested against a re-evaluated version of Henry's semi-analytical solution for the coupled solute concentration distribution. The numerical model was used to propose a modified version of the Henry problem where the importance of density-coupled processes was increased. The modified problem was shown to have an improved worthiness as compared to the standard solution. The numerical model results were benchmarked against a new set of semi-analytical results for the modified problem. Certain advantages in using the modified problem as a test case for benchmarking the results of a numerical model of density-dependent ground water flow are identified. A numerical investigation of the patterns of density-driven ground water flow at the ground water-surface water interface was undertaken. The numerical model is shown to produce grid-independent results for a finely discretised domain. The pattern of discharge is controlled, in part, by two parameters. One describes the recharge applied to the aquifer, and the second describes the magnitude of the density differences between the fresh recharging fluid and the saline receiving fluid. The influence of dense intrusions upon the formation of seepage-face boundaries at the ground water-surface water interface under steady-state conditions was also investigated. Dense intrusions are shown to dominate the pattern of ground water flow only under mild recharge conditions, while seepage faces dominate the outflow pattern under strong recharge conditions. Therefore, the formation of seepage-face boundaries and dense intrusions are unlikely to coincide under the conditions examined in this study.
3
Vionnet, Leticia Beatriz 1960. "Modeling of ground-water flow and surface water/ground-water interactions of the San Pedro River Basin, Cochise County, Arizona." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278134.
Full textAbstract:
Ground-water exploitation in the Upper San Pedro Basin has produced the formation of a cone of depression around the Sierra Vista-Fort Huachuca area. A portion of the mountain front recharge that otherwise would reach the San Pedro River is being intercepted by pumping, and portions of baseflow are being captured by pumping. The purpose of this study is to construct a simulation model capable of simulating the ground-water system as well as the ground-water-surface water interactions. The flow simulation was done by a three-dimensional, finite-difference ground-water flow model (MODFLOW) that incorporates a new stream-aquifer interaction package. Steady state simulations were performed to represent mean annual conditions. Transient simulations cover a 48 year period, starting in 1940 and ending in 1988. A sensitivity analysis of the steady state model was also performed.
4
McCary, John. "Incorporating surficial aquifer ground-water fluxes into surface-water resource management studies." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001095.
Full text
5
Rosenberry, Donald O. "Influence of fluvial processes on exchange between ground water and surface water." Connect to online resource, 2007. 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:3284456.
Full text
6
Anderson, Jacob. "Geochemical Tracers of Surface Water and Ground Water Contamination from Road Salt." Thesis, Boston College, 2013. http://hdl.handle.net/2345/3313.
Full textAbstract:
Thesis advisor: Rudolph Hon<br>The application of road de-icers has lead to increasing solute concentrations in surface and ground water across the northern US, Canada, and northern Europe. In a public water supply well field in southeastern Massachusetts, USA, chloride concentrations in ground water from an unconfined aquifer have steadily risen for the past twenty years. The objectives of this study are to understand spatial and temporal trends in road salt concentrations in order to identify contamination sources and fate. To this end, the methods of this project include field and lab work. Water samples were collected from surface, near-surface, and ground water from March 2012 to March 2013. The other major field data are specific conductance measurements from probes located in three piezometers. In the lab, all samples were analyzed for major ions with ion chromatography analysis. Additionally, trace elements were measured by inductively coupled plasma analysis on a subset of samples. The results of these hydrogeochemical procedures showed several important trends. First, the highest concentrations of sodium and chloride from near-surface samples were located near to roadways. Second, ground water samples taken from glacial sediments contained relatively high concentrations throughout the water column, whereas ground water samples from wetlands had high concentrations only near the surface. Third, there was no clear relationship between pH and cation concentrations. Finally, specific conductance data showed strong seasonal trends near to the surface, whereas values taken from deeper in the aquifer were steadily increasing. Based on these results, it is highly probable that road salt application is the dominate contamination source. The pathways of road salt in the watershed include runoff into surface water and infiltration into the vadose zone and ground water. Road salt appears to preferentially travel through glacial features rather than floodplain features. It is possible that sodium from road salt is sorbed to aquifer sediment and displaces other cations. However, the low values of trace metals suggest that cation exchange is not mobilizing heavy metals. Finally, the increasing specific conductance values deep in the aquifer suggest that road salt is retained within the aquifer and concentrations will likely increase in the future if the current road salt application procedures are continued<br>Thesis (MS) — Boston College, 2013<br>Submitted to: Boston College. Graduate School of Arts and Sciences<br>Discipline: Earth and Environmental Sciences
7
Smith, Jonathan William Neil. "Pollutant retardation at the groundwater- Surface water interface." Thesis, University of Sheffield, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500234.
Full text
8
Colgan, Gary A. "Estimating surface/ground-water mixing using stable environmental isotopes." Thesis, The University of Arizona, 1989. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0042_m_sip1_w.pdf&type=application/pdf.
Full text
9
Zwierschke, Kerry Hughes. "IMPACT OF TURFGRASS SYSTEMS ON THE NUTRIENT STATUS OF SURFACE WATER, AND GROUND WATER." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1235150457.
Full text
10
Grundy, Ian H. "Air flow near a water surface /." Title page, table of contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phg889.pdf.
Full text
11
Coes, Alissa L., and Alissa L. Coes. "A GEOCHEMICAL APPROACH TO DETERMINE GROUND-WATER FLOW PATTERNS IN THE SIERRA VISTA BASIN, ARIZONA, WITH SPECIAL EMPHASIS ON GROUND-WATER/SURFACE-WATER INTERACTION." Thesis, The University of Arizona, 1997. http://hdl.handle.net/10150/622969.
Full textAbstract:
Water quality in the Sierra Vista Ground-Water Basin is of extreme importance due to the basin's unique ecosystem and predicted future population growth. Portions of the Upper San Pedro River, flowing through the Sierra Vista Basin, contain some of the few remaining perennial streamflows in the southwest. Baseflow in the perennial reaches of the river are maintained almost entirely by the regional and floodplain aquifer systems. A population increase is predicted for the Sierra Vista Basin, and an impact on groundwater quality and availability can be expected. Due to the closely linked hydrologic systems within the basin, contamination or depletion of the regional aquifer could have direct implications for the San Pedro River. Water samples were collected within the study area from the regional and floodplain aquifers, the San Pedro River, and a bedrock spring in the Huachuca
Mountains. Samples were analyzed for field parameters, major-ions, and stable isotopes to describe the main chemical characteristics of the hydrologic systems within the basin. Analysis of regional aquifer geochemistry indicates a ground-water system strongly controlled by calcite precipitation. Specific conductance, deuterium and oxygen-18 values indicate a mixing of regional-aquifer ground water and San Pedro River surface water within the floodplain aquifer. Estimates of inflow to perennial reaches of the floodplain aquifer from the regional aquifer vary from 50 to 80%, depending on location. Inflow to the San Pedro River at Charleston from the regional aquifer is estimated to be about 50 to 70% of the stream discharge.
12
Kikuchi, Colin. "Spatially Telescoping Measurements for Characterization of Ground Water - Surface Water Interactions along Lucile Creek, Alaska." Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/202976.
Full textAbstract:
A new spatially telescoping approach was proposed to improve measurement flexibility and account for hydrologic scale in field studies of groundwater-surface water (GW-SW) interaction. We applied this spatially telescoping approach in a study GW-SW interactions along Lucile Creek, Alaska. Catchment-scale data were used to screen areas of potentially significant GW-SW exchange, indicating groundwater contribution from a deeper regional aquifer along the middle to lower reaches of the stream. This initial assessment was tested using reach-scale estimates of groundwater contribution during base flow conditions. The reach-scale measurements indicated a large increase in discharge along the middle reaches of the stream accompanied by a shift in chemical composition towards a regional groundwater end member. Point measurements of vertical water fluxes were used to evaluate spatial and temporal variability of GW-SW exchange within representative reaches. The spatially telescoping approach identified locations of GW-SW exchange and improved interpretation of reach-scale and point-scale measurements.
13
Robinson, J. Mike. "Chemical and Hydrostratigraphic Characterization of Ground Water and Surface Water Interactions in Cache Valley, Utah." DigitalCommons@USU, 1999. https://digitalcommons.usu.edu/etd/6717.
Full textAbstract:
A series of five east-west and two north-south hydrostratigraphic cross sections were drawn from drillers' logs of water wells within the southern half of Cache Valley, Utah. These cross-sections demonstrate that ground water flow to streams is restricted by a continuous low- II permeability layer, nearly 100-feet thick. This layer was correlated to the lake-bottom deposits of the Bonneville (30,000 -13,000 years ago) and Little Valley (140,000 - 90,000 years ago) cycles of the ancient Lake Bonneville.
The most productive aquifers in the valley, collectively termed the principal aquifer , are in the southeast corner , approximately between Smithfield and Hyrum, and between the eastern valley margin and the valley center. Sands and gravels of the principal aquifer were deposited as alluvial fans and deltas by streams draining the Bear River Range.
Ground water chemistry in the principal aquifer system is of the calcium-magnesium bicarbonate type with total dissolved solids (TDS) averaging about 300 ± 100 mg/L. TDS and the relative proportions of sodium, potassium, and chloride increase down flowpath, from recharge areas in the east to discharge areas in the west.
Oxygen-18 (18O) and deuterium (D) analyses were performed on precipitation samples at three locations on the east valley benches, four surface water samples from streams entering the valley, and fourteen ground water samples from either wells or springs. Precipitation and surface water values generally plotted along the Global Meteoric Water Line (GMWL), although the precipitation values plotted significantly lower on the GMWL than the surface water values. Of the ground water samples, twelve from the principal aquifer generally clustered near the surface water data points, suggesting that water from streams, rather than infiltrating precipitation, recharges the principal aquifer.
Twelve ground water samples were analyzed for tritium. The tritium values of eight samples from wells or springs in the principal aquifer suggest recharge after 1952. Two samples with tritium values dating prior to 1952 are from wells in the principal aquifer, and two are from wells west of the principal aquifer.
Four samples were analyzed for 14C. Two of these wells were completed in the principal aquifer and two west of it. Correcting for partial carbon dilution, the age difference between the different areas is on the order of tens of thousands of years.
14
Vionnet, Leticia Beatriz, Thomas III Maddock, and David C. Goodrich. "Investigations of stream-aquifer interactions using a coupled surface-water and ground-water flow model." Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/615700.
Full textAbstract:
A finite element numerical model is developed for the modeling of coupled
surface-water flow and ground-water flow. The mathematical treatment of subsurface
flows follows the confined aquifer theory or the classical Dupuit approximation for
unconfined aquifers whereas surface-water flows are treated with the kinematic wave
approximation for open channel flow. A detailed discussion of the standard approaches to
represent the coupling term is provided. In this work, a mathematical expression similar
to Ohm's law is used to simulate the interacting term between the two major hydrological
components. Contrary to the standard approach, the coupling term is incorporated
through a boundary flux integral that arises naturally in the weak form of the governing
equations rather than through a source term. It is found that in some cases, a branch cut
needs to be introduced along the internal boundary representing the stream in order to
define a simply connected domain, which is an essential requirement in the derivation of
the weak form of the ground-water flow equation. The fast time scale characteristic of
surface-water flows and the slow time scale characteristic of ground-water flows are
clearly established, leading to the definition of three dimensionless parameters, namely, a
Peclet number that inherits the disparity between both time scales, a flow number that
relates the pumping rate and the streamflow, and a Biot number that relates the
conductance at the river-aquifer interface to the aquifer conductance.
The model, implemented in the Bill Williams River Basin, reproduces the observed
streamflow patterns and the ground-water flow patterns. Fairly good results are obtained
using multiple time steps in the simulation process.
15
Van, Metre Peter Chapman 1956, and Metre Peter Chapman 1956 Van. "Flow and water quality relations between surface water and ground water in the Puerco River basin near Chambers, Arizona." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277926.
Full textAbstract:
The Puerco River is an ephemeral stream that received effluent from uranium-mine dewatering operations from the 1950's until 1962 and from 1968 until mining ceased in 1986. Flow and water-quality relations between the Puerco River and the alluvial aquifer underlying it were investigated at a site near Chambers. Data collection included installing and sampling nine monitor wells and two drive points; monitoring stage and sampling surface water; and slug testing wells. The stream recharges the alluvial aquifer during periods of flow and the streambed is a location of ground-water discharge by evapotranspiration during periods of no flow. Discharge by evapotranspiration may exceed recharge thus reducing the potential for contaminant movement away from the river by advective transport. Geochemical modeling indicates that uranium minerals are undersaturated in the range in Eh observed. A +0.84 correlation was calculated relating dissolved uranium concentration to depth in monitor wells suggesting the stream is a source of uranium to the alluvial aquifer. (Abstract shortened with permission of author.)
16
Hadley, Heidi K. "Hydrochemical Definition of Ground Water and Surface Water, with an Emphasis on the Origin of the Ground-Water Salinity in Southern Juab Valley, Juab County, Utah." DigitalCommons@USU, 1996. https://digitalcommons.usu.edu/etd/6706.
Full textAbstract:
As part of a U.S. Geological Survey study in Juab Valley in central Utah from 1991 to 1994, the chemistry of ground - and surface -water samples was determined. Total dissolved solids in the ground water of southern Juab Valley have historically been higher , in general, than ground water in other areas of Utah . Total dissolved solids for ground-water samples from this study ranged from 623 to 3,980 milligrams/liter. High-sulfate chemical data of previous studies suggested that the major source of ground-water salinity is the dissolution of gypsum (hydrous calcium sulfate ) from the Arapien Shale. Sulfur-34 to sulfur- 32 isotopic ratio data have confirmed that dissolved Arapien Shale is the major source of salinity in southern Juab Valley water.
This thesis study of southern Juab Valley had four main objectives: 1) define the present chemistry of the ground and surface water; 2) qualitatively determine the mineralogy of the Middle Jurassic Arapien Shale; 3) determine the major sources of salinity; and 4) determine the main flow path in the ground-water system. Chemical data show that the water in southern Juab Valley is predominantly of a calcium-magnesium-sulfate-bicarbonate composition. X-ray diffraction determined the mineralogy of the Arapien Shale as primarily calcite and quartz. Mineralogy of the acid-insoluble residue is illite, chlorite, quartz, and a trace of feldspar. Based on chemical, isotopic, and simple salt weight percent data, dissolution of gypsum is the major source of salinity in southern Juab Valley water. Using the chemical and isotopic data as input , a mass balance computer software program (NETPATH) helped to determine that the gypsum is derived from the Arapien Shale . NETPATH and the potentiometric surface map helped to define the main ground-water flow path as southwest across southern Juab Valley, from Chicken Creek in the San Pitch Mountains on the east side of the valley toward Chick Creek Reservoir in the southwest part of the valley.
17
Fleming, Brandon J. "Effects of anthropogenic stage fluctuations on surface water/ground water interactions along the Deerfield River, Massachusetts." Amherst, Mass. : University of Massachusetts Amherst, 2009. http://scholarworks.umass.edu/theses/226/.
Full text
18
Wang, Xiaolu. "Janus Colloids Surfing at the Surface of Water." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS272/document.
Full textAbstract:
Considérant une particule isolée, la différence principale entre un colloïde actif et un colloïde passif réside dans le temps de persistance du régime balistique. La transition du régime balistique vers le régime diffusif est déterminée dans les deux cas par des coefficients de friction ou de manière équivalente par des coefficients de diffusion. Le mouvement d’une particule colloïdale passive micrométrique est diffusif lorsqu’il est observé sur des intervalles de temps d’au moins une microseconde, suffisamment longs pour que la direction de la quantité de mouvement soit rendue aléatoire par des collisions avec les molécules de solvant. A l’échelle macroscopique ces collisions se traduisent par un coefficient de friction de translation. Pour une particule colloïdale active, un mouvement diffusif est observé pour des intervalles de temps de plusieurs secondes, suffisamment longs pour que la direction d’auto-propulsion soit rendue aléatoire par la diffusion rotationnelle de la particule.Dans cette thèse, nous étudions le mouvement d’une particule colloïdale active déposée à la surface de l’eau. Des particules Janus aux propriétés catalytiques ont été préparées par dépôt de platine métal à la surface de particules de silice. La profondeur d’immersion des particules ainsi que leur orientation par rapport à la surface de l’eau ont été caractérisées et discutées en tenant compte des propriétés de mouillage non-uniformes de la surface des particules Janus. Le mouvement de particules isolées en présence de quantités variables d’eau oxygénée utilisée comme source d’énergie, a été enregistré par vidéo-microscopie optique et les trajectoires analysées en termes de déplacement carré moyen et de fonction d’auto-corrélation des vitesses. L’observation de deux types de trajectoires, rectilignes et circulaires, révèle la force effective ainsi que le couple induit par la décomposition catalytique de l’eau oxygénée à la surface de la particule Janus. Le résultat principal de ce travail est que le mouvement des particules actives confinées à l’interface persiste plus longtemps dans le régime balistique que celui de particules actives totalement immergées en solution. Ceci est dû au confinement qui réduit le nombre de degrés de liberté de rotation mais aussi aux conditions de mouillage partiel qui font apparaître des contributions supplémentaires à la friction de rotation<br>At the single-particle level, the main difference between active colloids and passive ones is the time scale over which the motion crosses over from ballistic to diffusive regime. In both cases, friction coefficients or equivalently diffusion coefficients determine this time scale. For instance, the motion of a passive colloid of 1m radius is diffusive when observed over lag times longer than a microsecond, once the direction of its momentum has been randomized by collisions with solvent molecules. At the macroscopic scale these collisions are accounted for by the translational friction coefficient. For an active colloid the effective diffusive behavior observed over lag times larger than few seconds results from the randomization of the direction of self-propulsion by rotational diffusion. In this thesis we investigated the motion of an active Janus colloid trapped at air-water interface. Spherical catalytic Janus colloids have been prepared through the deposition of platinum metal at the surface of silica particles. Immersion depth of the Janus colloid as well as their orientation with respect to the water surface, has been characterized and interpreted in terms of the non-uniform wetting properties of the Janus particles. The motion of the active Janus colloids in the presence of various concentration of hydrogen peroxide H2O2 as fuel was characterized by video microscopy and the trajectories analyzed through the mean square displacement and the velocity autocorrelation function. The types of trajectories, directional and circular ones that we observed in our experiments, revealed the effective force and torque induced by the catalytic decomposition of H2O2. At the water surface, active colloids perform more persistent directional motions as compared to the motions performed in the bulk. This has been interpreted as due to the loss of degrees of freedom resulting from the confinement at interface and also to the partial wetting conditions that possibly bring new contributions to the rotational friction at interface
19
Zhang, Ju. "Poly(N-isopropylacrylamide) at the air/water interface /." *McMaster only, 1998.
Find full text
20
Neaville, Chris C. "Hydrogeology and simulation of ground-water and surface-water flow in Pinal Creek Basin, Gila County, Arizona." Thesis, The University of Arizona, 1991. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1991_400_sip1_w.pdf&type=application/pdf.
Full text
21
Cairampoma, Arroyo Alberto, and Vega Paul Villegas. "Legal regime ground water in Peru." THĒMIS-Revista de Derecho, 2017. http://repositorio.pucp.edu.pe/index/handle/123456789/108913.
Full textAbstract:
This article studies the legal regime of groundwater by analyzing the context of integrated water resources management and recognizing its definition and characteristics.Furthermore, it analyses the ownership of ground water, the planning regime applicable, the exploration and exploitation activities, their authorization certificates, the activity of supervision over them, and finally the article describes the special schemes for management and limitation recognized in Peruvian law.<br>En el presente artículo se estudia el régimen jurídico de las aguas subterráneas, analizando el marco de la gestión integrada de recursos hídricos y reconociendo su definición y particularidades.Asimismo, se analiza la titularidad de las aguas subterráneas, el régimen de planificación aplicable, las actividades de exploración y explotación, sus títulos habilitantes, la actividad de supervisión que sobre ellas recae, para finalmente, dejar anotados los regímenes especiales de gestión y limitación reconocidos en el ordenamiento jurídico peruano.
22
Da, Rocha Sandro Roberto Possatti. "CO₂-water interface : interfacial tension, emulsions, microemulsions, and computer simulations /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004246.
Full text
23
Vionnet, Leticia Beatriz, and Thomas Maddock. "Modeling of Ground-Water Flow and Surface/Ground-Water Interaction for the San Pedro River Basin Part I Mexican Border to Fairbank, Arizona." Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 1992. http://hdl.handle.net/10150/614152.
Full textAbstract:
Many hydrologic basins in the southwest have seen their perennial streamflows
turn to ephemeral, their riparian communities disappear or be jeopardized, and their
aquifers suffer from severe overdrafts. Under -management of ground -water exploitation
and of conjunctive use of surface and ground waters are the main reasons for these
events.
24
Davis, Laura Agnes. "Ground-Water Flow and Interaction with Surface Water in San Bernardino Valley, Cochise County, Arizona and Sonora Mexico." Thesis, The University of Arizona, 1997. http://hdl.handle.net/10150/191298.
Full textAbstract:
In the center of San Bernardino Valley in southeastern Arizona, San Bernardino National Wildlife Refuge provides unique wetlands habitat for endangered fish and wildlife. Confined conditions exist within the refuge, producing springs, artesian wells, and perennial pools along Black Draw, the main surface-water drainage. A numerical flow model was constructed in order to understand the hydrogeologic system of the basin. Annual inflows to the basin include 50,171 acre-feet of mountain-front recharge, 4,360 acft of underflow, and 7,074 ac-ft of river leakage. Annual outflows consist of 57,704 ac-ft of underflow, 3,010 ac-ft of river leakage, 537 ac-ft of evapotranspiration, 346 ac-ft of spring discharge, and 5 ac-ft of stream leakage. Further investigations are needed to refine the annual steady-state model, develop a seasonal (oscillatory) model, and construct transient simulations predicting responses of the hydrologic system to climatic and/or anthropogenic stresses. Extremely large mountain-front recharge and subsurface outflow estimates should be improved by conducting pump tests, geophysical studies, and isotope dating and chemistry analyses of ground water, and by collecting more water levels in Sonora. These studies will also provide information on the role of basalt flows in mountain-front recharge distribution and ground-water flow patterns. The study concludes with a recommended monitoring program for the refuge.
25
Davis, Laura Agnes, Thomas III Maddock, and Robert Mac Nish. "Ground-water flow and interaction with surface water in San Bernardino valley, Cochise county, Arizona and Sonora, Mexico." Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/615699.
Full textAbstract:
In the center of San Bernardino Valley in southeastern Arizona, San Bernardino
National Wildlife Refuge provides unique wetlands habitat for endangered fish and
wildlife. Confined conditions exist within the refuge, producing springs, artesian wells,
and perennial pools along Black Draw, the main surface-water drainage. A numerical
flow model was constructed in order to understand the hydrogeologic system of the basin.
Annual inflows to the basin include 50,171 acre-feet of mountain-front recharge, 4,360 acft
of underflow, and 7,074 ac-ft of river leakage. Annual outflows consist of 57,704 ac-ft
of underflow, 3,010 ac-ft of river leakage, 537 ac-ft of evapotranspiration, 346 ac-ft of
spring discharge, and 5 ac-ft of stream leakage. Further investigations are needed to refine
the annual steady-state model, develop a seasonal (oscillatory) model, and construct
transient simulations predicting responses of the hydrologic system to climatic and/or
anthropogenic stresses. Extremely large mountain-front recharge and subsurface outflow
estimates should be improved by conducting pump tests, geophysical studies, and isotope
dating and chemistry analyses of ground water, and by collecting more water levels in
Sonora. These studies will also provide information on the role of basalt flows in
mountain-front recharge distribution and ground-water flow patterns. The study
concludes with a recommended monitoring program for the refuge.
26
Li, Bingbing. "Surface Characterization of Poly (epsilon-caprolactone) at the Air/Water Interface." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/10125.
Full textAbstract:
Surface behavior of poly (epsilon-caprolactone) (PCL) have been studied at the air/water interface (A/W). PCL is a hydrophobic and crystalline polyester with a glass transition temperature around -60 degrees centigrade, a melting point around 55 degrees centigrade, excellent biocompatibility, and low toxicity. In the past decade, PCL based systems have attracted considerable interest for controlled-release drug delivery and as scaffolds for tissue engineering, that require a fundamental understanding of PCL's degradation mechanisms and crystallization properties. PCL spherulites were commonly observed in previous bulk studies. This thesis focuses on PCL crystallization in Langmuir monolayers. Brewster angle microscopy (BAM) studies show that square, distorted rectangular, and dendritic crystals form at the A/W interface. While dendritic structures have been observed in poly (ethylene oxide) (PEO) thin film on solid substrates, this study of PCL is the first time that dendritic morphologies have been observed at the A/W interface for a linear flexible-coil polymer. As far as we know, the crystallization of flexible-coil polymers at the A/W interface is a brand new area of research. These findings may provide an interesting model system for studying crystallization in confined geometries and the effect of crystallinity on enzyme catalyzed hydrolysis of this important biodegradable polymer at the A/W interface.
The main objectives of this thesis were to investigate the phase behavior of PCL at the A/W interface, gain a deeper understanding of the nucleation and growth mechanism of PCL crystallization at the A/W interface through surface pressure-area isotherms and isobaric area relaxation analyses, and interpret the effects of molecular weight on the nucleation and growth mechanism, and morphologies of semicrystalline PCL crystallized in Langmuir monolayers at the A/W interface.<br>Master of Science
27
Timson, Andrew John. "Second harmonic generation of molecules located at the air/water interface." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326716.
Full text
28
Schmid, Wolfgang. "A farm package for MODFLOW-2000 simulation of irrigation demand and conjunctively managed surface-water and ground-water supply /." Diss., The University of Arizona, 2004. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_2004_287_sip1_w.pdf&type=application/pdf.
Full text
29
Schmid, Wolfgang, and Wolfgang Schmid. "A farm package for modflow-2000: Simulation of irrigation demand and conjunctively managed surface-water and ground-water supply." Thesis, The University of Arizona, 2004. http://hdl.handle.net/10150/626888.
Full textAbstract:
A new Farm Package (FMP) was developed for using the U.S. Geological Survey's
groundwater modeling program, MODFLOW-2000 (MF2K), to estimate irrigation water
allocations to irrigation settings. The FMP dynamically integrates irrigation water
demand, surface-water & groundwater supply, and return flow from excess irrigation.
Routed surface-water delivery is optional, and can be simulated by coupling FMP with
the Streamflow Routing Package (SFRl ).
MF2K with FMP and SFRl allows estimating the allocation of surface-water and
groundwater to farms for the following applications: (1) historic and future simulations,
(2) water rights issues and operational decisions, (3) non-drought and drought situations.
Irrigation demand, supply, and return flow are partly subject to head-dependent sinks
and sources such as transpiration uptake from groundwater (formulated by FMP) and
leakage between the conveyance system and the aquifer (formulated by SFRl).
A steady state transpiration uptake, varying with changing water level, is stepwise
linearly approximated by FMP. This was validated by ensembles of variably saturated
soil column models using HYDRUS2D for different soil types, values of potential
transpiration, and root zone depths. A restriction of transpiration uptake is proportional to
a reduction of the active root zone. It is approximated in FMP by an analytical solution,
which determines inactive ranges of the root zone with pressure heads typical for
conditions of anoxia or wilting. At steady state, the transpiration uptake equaled the flux across the water table (plus
the irrigation flux, if applied). Therefore, changes in soil water storage are assumed
negligible. Based on this assumption, the irrigation flux required is determined in FMP
by subtracting transpiratory components from natural sources (groundwater,
precipitation) from a maximum transpiration uptake. This transpiratory irrigation
requirement is calculated for each finite difference cell, and increased sufficiently to
compensate for evaporative losses and for inefficient use. Accumulating the resulting cell
delivery requirement over all cells in a farm yields the total farm delivery requirement,
which is to be satisfied with surface- or groundwater.
Five economic and non-economic drought response policies can be applied, if the
potential supply of surface- and groundwater is insufficient to meet the crop demand.
The code was verified by a hypothetical example problem run in 55 scenarios (5
drought policy scenarios x 11 parameter-group scenarios). Among all sources and sinks
in a cumulative volumetric budget, 'farm well discharge,' and particularly 'farm net
recharge,' were most sensitive to changes in drought policies or changes of parameters.
30
Mathipa, Morongwa Mary. "Analysis of the bio-physicochemical quality of surface and ground water in the Tubatse Municipality." Thesis, University of Limpopo, 2016. http://hdl.handle.net/10386/1663.
Full textAbstract:
Thesis (M. Sc. (Microbiology)) -- University of limpopo, 2016<br>Human activities are known to be the major contributors to contamination of natural water sources. This becomes a serious health risk when the communities rely on the same water sources for their household water needs. The current study investigated the bio-physicochemical quality of surface and ground waters found in a mining area in the Tubatse locality, for their suitability for drinking and other household use. The bacteriological analyses of surface waters showed dominance by genera of the phylum Proteobacteria, followed by Actinobacteria and Firmicutes. The isolates included the genera Aeromonas, Pseudomonas, Cronobacter, Acinetobacter, Enterobacter, Pantoea, Serratia, Bordetella, Kocuria and Streptococcus. This dominance pattern is proportionately similar to the pattern reported on human skin and of gut biota. Enterobacter spp. were the predominant species in the surface waters, followed by Bordetella spp. With regard to ground water, one sample was laden with coliforms whereas the other sample was free of coliforms. Physical quality parameters such as turbidity, colour and (total suspended solids) TSS of the surface and ground water samples were compliant with the set standards for drinking water according to South African water quality guidelines (2005). The concentrations of Zn, [SCN-], Cr, Co, Fe, Ni, Cu, H2O2, Cl2 were determined in the surface and ground waters in dry and wet seasons as well. A non-significant decrease in the levels of Cl2 and [SCN-] and an increase in TDS and Cr were observed in the wet season. All metal and chemical levels in surface and ground water, except Cr, were lower than permitted concentration for drinking water. However the concentrations of Zn, Fe and Co exceeded the normal expected concentrations of < 3.5 μg/L, 0.5 mg/L, < 0.01 mg/L and < 5 μg/L respectively. The sediments and soil samples were digested with aqua regia for Cu, Cr, Fe, Co and Zn analyses. An increase in the levels of Zn, Cr and Co in the wet season was observed. The concentrations of the heavy metals such as Co, Cu and Cr were higher in sediments at the sampling points closer to the mining sites. Cytotoxicity assay was performed with different concentrations, as detected in the water and sediment samples, of Zn, [SCN-], Cr, Co, and Fe on C2C12 (mammalian) cells. An increase in viable cells was observed after treatment with Cr (0.2, 0.45 and 0.9 mg/L), Zn and Fe (1.0 and 2 mg/L), Co (2, 5 and 10 mg/L). Only cells treated with SCN- (3.3, 5.4 and 7.2 mg/L) exhibited a significant decrease in viability. These results demonstrate that the water in the Tubatse municipality is not suitable for drinking and other household purposes without prior treatment which will remove contaminating microorganisms and chemicals and heavy metals.
31
Longford, Francis G. J. "Modelling surface thermodynamics and intrinsic optical properties of the air-water interface." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/419052/.
Full textAbstract:
Intrinsic surface sampling techniques are used to analyse MD simulations of the air-water interface in order to investigate reports of anomalous optical behaviour recently uncovered by ellipsometry. In doing so, a new approach to calculating surface thermodynamic properties has been described and an overlooked finite size e↵ect a↵ecting surface tension measurements has been uncovered. A correction has also been developed to reduce a fitting bias in the intrinsic sampling method (ISM), which leads to a non-Gaussian distribution of mean curvature at interfacial molecular coordinates on a parametrised intrinsic surface. Consequently, it is now possible to reduce artefacts that prevent successful mapping back of the intrinsic density to the global density at high resolutions via convolution along the axis normal to the interface. A further method has been developed to estimate the local linear optical properties of interface regions, with application to the prediction of ellipsometry experiments. The e↵ective medium approximation for the dielectric permittivity of a system possessing a non-homogeneous polarisation density distribution is combined with an intrinsic surface technique describing the structure of the interface region as a Fourier series. It is concluded that employing the this description allows for optical properties of the air-water interface to be revealed from classical molecular dynamics simulations that are distinct from other polar solvents (methanol), and lie in agreement with new experimental data. This investigation also provides new pathways to determine a more robust description of the intrinsic surface and explores new simulation tools using extended capillary wave theories.
32
Noerpel, Matthew Robet. "Surface Complexes Of Lead And Organic Acids At The Hematite / Water Interface." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1439904226.
Full text
33
Oztas, Nur Banu. "Pesticide Pollution In Surface And Ground Water Of An Agricultural Area, Kumluca, Turkey." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12609445/index.pdf.
Full textAbstract:
Concentrations of 17 organochlorine and 14 organophosphorus pesticides were measured in 27 ground and 11 surface water samples collected from a heavily agricultural area, Kumluca, in spring and fall seasons of 2005. The samples were preconcentrated by Solid Phase Extraction. GC-ECD and GC-NPD systems were used for quantitative determination of organochlorine and organophosphorus pesticides respectively.
The quality check/quality assurance tests were performed by the analysis of field and laboratory blanks, standard reference materials, spiked control and sample matrices, surrogate standards, sampling and analysis replicates. It is observed that, sample matrix lowers average percent recoveries from 89% to 76%.
The uncertainties of measurements were calculated to determine major factors affecting the analysis results. It was observed that uncertainty arising from extraction procedure was generally the highest.
The most commonly observed pesticide was endosulfan (70%) and chlorpyriphos (53%) for organophosphorus and organochlorine pesticides. The highest average concentration was observed for heptachlor (26 ng/L) and fenamiphos (184 ng/L).
Generally pesticides were detected more often in surface waters, where the concentrations were also higher. The concentrations of organophosphorus pesticides in spring, and organochlorine pesticides in fall season were higher.
The high occurrences and detection of degradation products of chlorinated pesticides clearly indicate their intense use before 1980s. It is shown that, in Kumluca environment, degradation of these pesticides mostly occurs in surface waters.
It is observed that agricultural activities affect water quality in the region. The total concentration limit (500ng/L) was exceeded for 27% of surface and 14% of ground water samples, at least once in both seasons. The legal limit for a single pesticide (100ng/L) was exceeded by 32 % of surface, 24 % of ground water samples.
34
Lauwo, Simon Yesse. "A modeling investigation of ground and surface water fluxes for Konza Tallgrass Prairie." Thesis, Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/470.
Full text
35
Bruant, Robert Gilbert. "Adsorption of volatile hydrophobic organic compounds at the vapor/water interface." Diss., The University of Arizona, 2000. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_2000_292_sip1_w.pdf&type=application/pdf.
Full text
36
Ramstedt, Madeleine. "Chemical Processes at the Water-Manganite (γ-MnOOH) Interface". Doctoral thesis, Umeå universitet, Kemi, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-253.
Full textAbstract:
The chemistry of mineral surfaces is of great importance in many different areas including natural processes occurring in oceans, rivers, lakes and soils. Manganese (hydr)oxides are one important group to these natural processes, and the thermodynamically most stable trivalent manganese (hydr)oxide, manganit (γ-MnOOH), is studied in this thesis. This thesis summarises six papers in which the surface chemistry of synthetic manganite has been investigated with respect to surface acid-base properties, dissolution, and adsorption of Cd(II) and the herbicide N-(phosphonomethyl)glycine (glyphosate, PMG). In these papers, a wide range of analysis techniques were used, including X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS) spectroscopy, Fourier transform infra-red (FTIR) spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), potentiometry, electrophoretic mobility measurements and wet chemical techniques, in order to obtain a more complete understanding of the different processes occurring at the manganite-water interface. From the combined use of these techniques, a 1-pKa acid-base model was established that is valid at pH>6. The model includes a Na+ interaction with the surface: =MnOH2+½ --> =MnOH-½ + H+ log β0 (intr.) = -8.20 = -pHiep =MnOH2+½ + Na+ --> =MnOHNa+½ + H+ log β0 (intr.) = -9.64 At pH<6 the manganite crystals dissolve and disproportionate into pyrolusite (β-MnO2) and Mn(II)-ions in solution according to: 2 γ-MnOOH + 2H+ --> β-MnO2 + Mn2+ + 2H2O log K0 = 7.61 ± 0.10 The adsorption and co-adsorption of Cd(II) and glyphosate at the manganite surface was studied at pH>6. Cd(II) adsorption displays an adsorption edge at pH~8.5. Glyphosate adsorbs over the entire pH range, but the adsorption decreases with increasing pH. When the two substances are co-adsorbed, the adsorption of Cd(II) is increased at low pH but decreased at high pH. The adsorption of glyphosate is increased in the entire pH range in the presence of Cd(II). From XPS, FTIR and EXAFS it was found that glyphosate and Cd(II) form inner sphere complexes. The binary Cd(II)-surface complex is bonded by edge sharing of Mn and Cd octahedra on the (010) plane of manganite. Glyphosate forms inner-sphere complexes through an interaction between the phosphonate group and the manganite surface. The largest fraction of this binary glyphosate complex is protonated throughout the pH range. A ternary surface complex is also present, and its structure is explained as type B ternary surface complex (surface-glyphosate-Cd(II)). The chelating rings between the Cd(II) and glyphosate, found in aqueous complexes, are maintained at the surface, and the ternary complex is bound to the surface through the phosphonate group of the ligand.
37
Norén, Katarina. "Coordination Chemistry of Monocarboxylate and Aminocarboxylate Complexes at the Water/Goethite Interface." Doctoral thesis, Umeå University, Chemistry, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1337.
Full textAbstract:
<p>This thesis is a summary of five papers with focus on adsorption processes of various monocarboxylates and aminocarboxylates at the water/goethite interface. Interaction of organic acids at the water/mineral interfaces are of importance in biogeochemical processes, since such processes have potential to alter mobility and bioavailability of the acids and metal ions.</p><p>In order to determine the coordination chemistry of acetate, benzoate, cyclohexanecarboxylate, sarcosine, MIDA (methyliminediacetic acid), EDDA (ethylenediamine-N,N’-diacetic acid) and EDTA (ethylenediamine-N,N’-tetraacetic acid) upon adsorption to the goethite (alpha-FeOOH) surface, a combination of quantitative measurements with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was utilized.</p><p>Over the pH range studied here (pH 3- 9) all ligands, except for sarcosine, have been found to form surface complexes with goethite. In general, theses were characterized as outer sphere surface complexes i.e. with no direct interaction with surface Fe(III) metal ions. Furthermore, two types of different outer-sphere complexes were identified, the solvent-surface hydration-separated ion pair, and hydration-shared ion pair. For the monocarboxylate surface complexes distinction between these two could be made. At high pH values the solvent-surface hydration-separated ion pair was the predominating complex, while at low pH the surface complex is stabilized through the formation of strong hydrogen bonds with the goethite surface. However, it was not possible to clearly separate between the two outer-sphere complexes for coordination of the aminocarboxylates with the surface of goethite. Additionally, EDDA also formed an inner-sphere surface complex at high pH values. The EDDA molecule was suggested to coordinate to the surface by forming a five membered ring with an iron at the goethite surface, through the amine and carboxylate groups.</p><p>Contrary to the other ligands studied, EDTA significantly induced dissolution of goethite. Some of the dissolved iron, in the form of the highly stable FeEDTA- solution complex, was indicated to re-adsorb to the mineral surface as a ternary complex. Similar ternary surface complexes were also found in the Ga(III)EDTA/goethite system, and quantitative and spectroscopic studies on adsorption of Ga(III) in presence and absence of EDTA showed that EDTA considerably effects speciation of gallium at goethite surface.</p><p>The collective results in this thesis show that the affinity of these ligands for the surface of goethite is primarily governed by their chemical composition and structure, and especially important are the types, numbers and relative position of functional groups within the molecular structure.</p>
38
Nalesso, Mauro. "Integrated Surface-Ground Water Modeling in Wetlands With Improved Methods to Simulate Vegetative Resistance to Flow." FIU Digital Commons, 2009. http://digitalcommons.fiu.edu/etd/122.
Full textAbstract:
This dissertation focused on developing an integrated surface – subsurface hydrologic simulation numerical model by programming and testing the coupling of the USGS MODFLOW-2005 Groundwater Flow Process (GWF) package (USGS, 2005) with the 2D surface water routing model: FLO-2D (O’Brien et al., 1993). The coupling included the necessary procedures to numerically integrate and verify both models as a single computational software system that will heretofore be referred to as WHIMFLO-2D (Wetlands Hydrology Integrated Model). An improved physical formulation of flow resistance through vegetation in shallow waters based on the concept of drag force was also implemented for the simulations of floodplains, while the use of the classical methods (e.g., Manning, Chezy, Darcy-Weisbach) to calculate flow resistance has been maintained for the canals and deeper waters. A preliminary demonstration exercise WHIMFLO-2D in an existing field site was developed for the Loxahatchee Impoundment Landscape Assessment (LILA), an 80 acre area, located at the Arthur R. Marshall Loxahatchee National Wild Life Refuge in Boynton Beach, Florida. After applying a number of simplifying assumptions, results have illustrated the ability of the model to simulate the hydrology of a wetland. In this illustrative case, a comparison between measured and simulated stages level showed an average error of 0.31% with a maximum error of 2.8%. Comparison of measured and simulated groundwater head levels showed an average error of 0.18% with a maximum of 2.9%.
39
Knock, Mona Marie. "Monolayers of cationic surfactants at the air-water and oil-water interfaces." Thesis, University of Oxford, 2003. http://ora.ox.ac.uk/objects/uuid:c0cdaf66-716a-4b48-b22c-659d1fe2a342.
Full textAbstract:
Monolayers of the cationic surfactant hexadecyltrimethylammonium halide (CTAX, where X = F¯, Cl¯, Br¯, and I¯) have been studied at the air-water and oilwater interfaces. At the air-water interface, the effects of the halide counterion and the addition of counterion were investigated. Sum-frequency spectroscopy (SFS), ellipsometry, and surface tensiometry indicated that the counterion changed the efficiency and effectiveness of the surfactant, both decreasing in the order of Br¯> Cl¯>F¯. The addition of salt in the form of 0.1 M KX was found to reduce the cmc but had little effect on the limiting area per molecule attained at the cmc, which increased from 44 Å<sup>2</sup> for CTAB to 65 Å<sup>2</sup> for CTAC and ca. 94 Å<sup>2</sup> for CTAF. Neither SFS nor ellipsometry provided any firm evidence for specific effects of the halide ions on the structure of the surfactant monolayers. For CTAB monolayers in the absence of excess electrolyte, the effect of area per molecule on the sum-frequency (SF) spectra was studied. Mixed monolayers of CTAB and tetradecane at the air-water interface exhibit a first-order phase transition from a conformationally disordered to a conformationally ordered state as the temperature is lowered. The phase transition occurs ca. 11 °C above the bulk melting point of tetradecane. A new experimental arrangement is described for acquiring SF spectra from surfactants at the oil-water interface. The key features of this approach are the stabilisation of a thin oil film between a sapphire prism and an aqueous phase, and the use of total internal reflection to enhance the total signal and discriminate against signals from other interfaces in the system. With this new methodology, the first SF vibrational spectra of surfactant monolayers at an alkane-water interface were obtained. Surface tensiometry was used to characterise the monolayers further. The structure of CTAB monolayers at the hexadecane-water interface was determined by SFS and compared with monolayers of CTAB at the air-water interface. At low concentrations, CTAB/hexadecane showed the expected features in the C-H stretching region, characteristic of a conformationally disordered monolayer. As the bulk concentration approached the critical micelle concentration, the spectra changed to one characteristic of a more ordered, upright conformation. Ellipsometric measurements supported this conclusion. This qualitative structural change is not observed in analogous monolayers at the air-water interface or CCl<sub>4</sub>-water interface, or in surfactant solutions in contact with a hydrophobic solid surface.
40
Liberti, Caroline Elizabeth. "Self-Alignment of Silicon Microparts on a Hexadecane-Water Interface by Surface Tension." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3207.
Full textAbstract:
Mechanical assembly of systems and structures on the micro-scale can be inefficient as pthesiss of sub-millimeter dimensions are difficult to manipulate. Cutting edge manufacturing methods implement self-assembly as an approach to ordering micro and nano-sized parts into a desired arrangement. This thesis studies a technique utilizing surface tension as a method of actuating microparts on a liquid-liquid interface via lateral capillary interactions. Preliminary experimentation is conducted to investigate the feasibility of developing a new method for self-alignment of microparts by observing the influence of interfacial geometry on the movement of silicon tiles along a hexadecane-water interface. Different surface geometries are created by implementing vertical rods of different wetting properties that alter the curvature of the interface. Results demonstrate that the microparts attain an equilibrium separation distance from the vertical rods. It is indicated that this equilibrium distance is determined by the dimensions of the micropart and the curvature of the interface. With further investigation, these results may be used to cultivate a method for self-alignment of microparts into rings of a desired radius.
41
Logan, Jennifer. "Polystyrene-block-poly(ethylene oxide) stars surface films at the air/water interface /." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0009470.
Full text
42
Syaukat, Yusman. "Economics of integrated surface and ground water use management in the Jakarta region, Indonesia." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0028/NQ51048.pdf.
Full text
43
Zhu, Danyun. "Determination of Residential-Use Turf Pesticides in Surface and Ground Water by HPLC/DAD." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/ZhuD2003.pdf.
Full text
44
Pullan, Stephanie. "Modelling of pesticide exposure in ground and surface waters used for public water supply." Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/8605.
Full textAbstract:
Diffuse transfers of pesticides from agricultural land to ground and surface waters can lead to significant drinking water quality issues. This thesis describes the development and application of a parameter-efficient, numerical model to predict pesticide concentrations in raw water sources within an integrated hydrological framework. As such, it fills an unoccupied niche that exists in pesticide fate modelling for a computationally undemanding model that contains enough process complexity to be applicable in a wide range of catchments and hydrogeological settings in the UK and beyond. The model represents the key processes involved in pesticide fate (linear sorption and first-order degradation) and transport (surface runoff, lateral throughflow, drain flow, percolation to the unsaturated zone, calculated using a soil water balance) in the soil at a daily time step. Soil properties are derived from the national soil database for England and Wales and are used to define the boundary conditions at the interface between the subsoil and the unsaturated zone. This is the basis of the integrated hydrological framework which enables the application of the model to both surface water catchments and groundwater resources. The unsaturated zone model accounts for solute transport through two flow domains (accounting for fracture flow and intergranular matrix flow) in three hydrogeological settings (considering the presence and permeability of superficial deposits). The model was first applied to a small headwater sub-catchment in the upper Cherwell. Performance was good for drainflow predictions (Nash Sutcliffe Efficiency > 0.61) and performed better than the MACRO model and as well as the modified MACRO model. Surface water model performance was evaluated for eight pesticides in five different catchments. Performance was generally good for flow prediction (Nash Sutcliffe Efficiency > 0.59 and percentage bias below 10 %, in the validation period for all but two catchments). The 90th percentile measured concentration was captured by the model in 62 % of catchment-pesticide combinations. In theremaining cases predictions were within, at most, a factor of four of measured 90th percentile concentrations. The rank order of the frequency of pesticides detected over 0.1 μg L-1 was also predicted reasonably well (Spearman’s rank coefficient > 0.75; p < 0.05 in three catchments). Pesticide transport in the unsaturated zone model was explored at the point scale in three aquifers (chalk, limestone and sandstone). The results demonstrate that representing the unsaturated zone processes can have a major effect on the timing and magnitude of pesticide transfers to the water table. In comparison with the other catchment scale pesticide fate models that predict pesticide exposure at a daily time-step, the model developed stands out requiring only a small number of parameters for calibration and quick simulation times. The benefit of this is that the model can be used to predict pesticide exposure in multiple surface and groundwater resources relatively quickly which makes it a useful tool for water company risk assessment. The broad-scale approach to pesticide fate and transport modelling presented here can help to identify and prioritise pesticide monitoring strategies, to compare catchments in order to target catchment management and to highlight potential problems that could arise under different future scenarios.
45
Clay, Christopher M. "Structure, composition and stability of water and mixed OH/Water films at the single crystal interface : a surface science study." Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486096.
Full textAbstract:
Pure water and mixed OH/H20 overlayers have been studied using a combination of TPD, TPRS, LEED and RAIRS and compared to DFT and kinetic Monte Carlo simulations carried out by collaborations with Georg Held, Gustav Garlberg and George Darling. On Pt(1l1) a mixed OH/H20 overlayer forms as an intermediate in the water oxygen reaction, with a (V3 x V3)R30° periodicity. T~e stability of the overlayer is dependent on the degree of hydrogen bonding, and reaches a maximum at an OH/H20 ratio of one. The optimal structure is found to be a mixed (OH+H20) phase containing a hexagonal lattice of alternating OH and H20 with a (3x3) superstructure, caused by ordering of the hydrogen bonds. The mixed overlayer can accommodate a range of H20/OH compositions, but becomes less stable as the water content is reduced. A LEED I-V analysis indicates that the (3x3)-3(OH+H20) overlayer is coplanar and the periodicity results from a lateral distortion of the 0 atoms away from the atop adsorption site. TPD of water from a (3x3)-3(OH+H20) overlayer on Pt(111) shows pseudo zero order desorption kinetics. However, leading edge and Polanyi-Wigner analysis of various mixed OH/water overlayers find an activation barrier to desorption that depends on the composition, coverage and heating rate of the film, indicating complex desorption kinetics. To understand these kinetics a new model based on direct H20 desorption, proton transfer, and OH recombination is proposed, and is compared and contrasted with kinetic Monte Carlo simulations. Water and oxygen also react on Pd(111) at low temperatures to form a mixed OH/H20 layer with a (V3 x V3)R30° registry. As on Pt(1l1), the most stable structure is formed when the OH/H20 ratio reaches unity. The (OH+H20) phase cannot be formed by O/H reaction and is distinct from the (V3 x V3)R30° structure formed by O/H coadsorption below 200 K. Mixed OH/water structures do not react with coadsorbed H below 190 K on Pd(l11), preventing this phase catalysing the low temperature H2/02 reaction. Adsorption of H20 and D20 on Ru(OOOl) shows a unique isotope effect. Above 150 K H20 dissociates to form a mixed (OH/H20/H) overlayer, whereas D20 desorbs intact. Dissociation of H20 to form the mixed overlayer competes with H20 desorption and this branching can be enhanced or suppressed by preadsorbing 0 or H. D20, and below 150 K H20, adsorbs intact on Ru(OOOl) with a diffuse (V3 x y'3)R30° tEED pattern visible at low coverage, which sharpens as the coverage reaches 0.6 ML, becoming diffuse again as the coverage exceeds 0.67 ML. Water initially adsorbs flat at Ru(OOOl), forming small clusters, which buckle as the coverage increases to accommodate an extended, hydrogen bonded overlayer at saturation. Only as the overlayer starts to complete does the free OH/OD stretch appear in RAIRS, indicating that water is embedded either flat or in a H-down geometry, up to 0.67 ML. DFT calculations find that water favours formation of flat lying small hexamer clusters at low coverage, adsorbed atop the metal. At 0.67 ML, calculations find stable water structures containing flat lying chains, linked by upright waters bonded H-down, with a hexagonal backbone of oxygen atoms. This structure is found to be more than 20% more stable than the conventional H-up or H-down bilayer and is expected to wet Ru(OOOl)
46
Holmes, Stuart W. "Investigation of Spatial and Temporal Groundwater Thermal Anomalies at Zanesville Municipal Well Field, Ohio: Implications for Determination of River-Aquifer Connectivity Using Temperature Data." Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1462026430.
Full text
47
Miller, Aline Fiona. "Organisation and dynamics of well-defined graft copolymers at the air-water interface." Thesis, Durham University, 2000. http://etheses.dur.ac.uk/4226/.
Full textAbstract:
Novel amphiphilic graft copolymers with a backbone of poly(norbornene) (PNB) with poly(ethylene oxide) (PEO) grafts have been synthesised by a combination of ring opening metathesis and anionic polymerisation methods. The polymer has been prepared with hydrogenous and deuterated grafts and with grafts of different degrees of polymerisation. These graft copolymers spread at the air-water and air-PEO solution interface forming thin films and their organisation and dynamic behaviour is discussed. Monolayer behaviour was characterised from surface pressure isotherms and it was demonstrated that the shape of the isotherm is dependent on graft length and on the concentration of PEO in the subphase. Using neutron reflectometry the organisation of such spread films at the air-water interface have been obtained over a range of surface concentrations for each length of PEO graft. Data were analysed by both exact calculation methods and the partial kinematic approximation and the models adopted were verified by applying the model independent Bayesian analysis. All yield the same description i.e. the hydrophobic backbone remains at the uppermost surface while the PEO grafts penetrate the subphase. The PEO layer increases in thickness with increased surface concentration and graft length. In each case the rate of increase with surface concentration was initially rapid but above a critical concentration, a slower rate was observed. In this latter regime the variation of the tethered layer height scales with surface density (ơ) and degree of polymerisation of the graft (N) as, r(_s) = N(^1.06)ơ(^0.33),which agrees well with scaling and self consistent field theory of polymer brushes. The dynamic behaviour of each copolymer film spread on water has been studied using surface quasi-elastic light scattering. A resonance between the capillary and dilational waves is observed at identical surface concentrations for each copolymer film. The viscoelastic behaviour of the dilational mode is reminiscent of Kramers-Kronig relations. The phenomenon of resistive mode mixing was observed in frequency dependency studies.
48
Schock, Kevin A. "Predicting Seepage of Leachate from the St. Johns Landfill to Ground and Surface Water Systems." PDXScholar, 1993. https://pdxscholar.library.pdx.edu/open_access_etds/4648.
Full textAbstract:
Determination of the vertical and horizontal groundwater hydraulic gradient within a landfill is the first step in determining the potential of groundwater contamination from the landfill leachate. The length of a study and the frequency at which measurements are recorded can greatly affect the description of the local groundwater environment. A more comprehensive analysis can be preformed for longer periods of study and greater measurement frequency. The intent of this study was to install a continuous groundwater level monitoring system around the st. Johns Landfill for a minimum study length of one year. This would allow a more thorough study of the seasonal character and behavior of the groundwater system beneath the landfill than in previous studies. Particular interest was paid to groundwater level changes resulting from seasonal weather changes. Additional attention was paid to other forcing mechanisms which could be perturbing groundwater levels, and variations in the geochemical groundwater constituents. Included throughout this report is a literature review of various studies pertinent to the analysis of groundwater level variations. Seasonal variations in vertical groundwater hydraulic gradients were reviewed and time averaged vertical seepage rates were estimated. Areal plots of groundwater levels were used to view expected horizontal groundwater hydraulic gradients during seasonal maximum and minimum groundwater levels. A computer model was developed to study the effects temporal variations in slough water levels had on groundwater seepage rates through the perimeter dike separating the landfill from the sloughs. The modeling provided an estimate of the average horizontal leachate seepage rate into the sloughs. Comparison plots of monitoring well groundwater levels were used to analyze potential swash zones beneath the landfill and potential effects of lowered water levels in Bybee Lake. Spectral analysis techniques were imployed to determine the dominant frequencies observed in the groundwater levels, allowing determination of the type of forcing mechanism driving the fluctuations. Geochemical groundwater constituents were statistically analyzed to determine the significance of observed trends in the data: areal plots of chloride concentrations and electrical conductivity were made to view constituent distributions within the underlying aquifers. Estimated vertical and horizontal groundwater seepage rates into the local waters showed that horizontal leachate seepage is insignificant compared to vertical leachate seepage. Groundwater level comparison plots indicated no significant swashing beneath the landfill occurred. The statistical studies on groundwater forcing mechanisms indicated that either the slough or the Columbia River water levels could be perturbing groundwater levels. Trend analyses on the geochemical groundwater constituents indicated significant, positive trends in chloride concentrations, and undeterminable trends in electrical conductivity.
49
Pearce, Meryl Winsome. "Assessment of factors influencing the quality of surface and ground water in the Hout Bay river catchment." Thesis, Rhodes University, 1989. http://hdl.handle.net/10962/d1001900.
Full textAbstract:
An investigation into the quality of surface water and ground water was conducted during 1988 in the 38,8 km² Hout Bay River catchment near Cape Town. The main objective of the study was to determine those areas and activities which constitute a pollution source and to ascertain the relative proportion which each contributes to the pollution problem and health risk of the surf zone of the beach at Hout Ba . The objective was achieved by monitoring the chemical and microbiological attributes of the Hout Bay River, its tributaries and stormdrains in wet and dry conditions on a routine basis and during storm events. Hout Bay is a rapidly developing residential area in which sewage disposal occurs by means of septic tank soakaway systems. Ground water quality was monitored to investigate the contribution to contamination by septic tank effluent. Results showed that stormdrain effluent in dry and wet conditions and surface runoff during rainfall were the main vectors of pollution. Although the pollution concentration was high during dry conditions the greatest pollution discharge to the surf zone of Hout Bay occurred during storm events. In view of the proposed residential development it is imperative that pollution control measures be undertaken so as to secure the future recreational and aesthetic value of Hout Bay
50
Paul, Kristian W. "Molecular modeling study of sulfate and phosphate adsorption at the mineral-water interface." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 223 p, 2009. http://proquest.umi.com/pqdweb?did=1654487581&sid=3&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Full text