Dissertations / Theses: 'Physical geography and topography'

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Bensimon, Dov Richard. "On the interaction of extratropical cyclones with topography." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ29654.pdf.

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Gagnon, Jean Sebastien. "Multiscaling and multifractality in the earth's topography." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33761.

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Topographic transects corning from four different Digital Elevation Models (DEMs) which collectively span different ranges of scales from 20000 km to 0.5 m are analyzed. Power spectra, trace moments and structure functions are used to show that continents and oceans have the same moment scaling function K(q) but different (scale by scale) nonconservation H and also that the Earth's topography is multiscaling from planetary scales down to a few meters. The results also suggest that topography can be described statistically at all scales by a global K(q). The form of K(q) shows that the statistics of topography are close to those predicted by universal multifractals. It seems that the multiscaling of topography is broken because of the presence of trees on the DEM: they introduce a characteristic length in the vertical that is approximately 9 m.

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Strick, Robert John Paul. "Floodplain geomorphology and topography in large rivers." Thesis, University of Brighton, 2016. https://research.brighton.ac.uk/en/studentTheses/a61e4805-4874-4cec-a1d8-e019aefd3053.

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Rivers are essential components of the earth surface. The world’s largest rivers have been studied much less than to smaller rivers. They are dominated by meandering channels – whether these are individual km-wide meander bends or ‘accessory’ meandering channels in an anabranching system. Large rivers, specifically ones with laterally migrating bends, can build a variety of floodplain elements that are represented by a complex surface topography, the dynamics and characteristics of which are not yet fully understood. This research brings a greater understanding to, and quantification of, the floodplain topography and geomorphology of large rivers. The project uses remote sensing imagery of the World’s largest rivers, LiDAR datasets of meandering scroll bar topography, and global coverage elevation data. Novel analytical methods are created, involving image manipulation and GIS processing, to quantify these landforms in a way that was not possible until recent technological and computational advancements. A new hierarchical classification schema of meandering floodplain deposits is presented and applied to quantify meandering deposits for two large rivers, the Amazon and the Ob. Both floodplains show similar downstream morphological changes to their floodplains despite their different sizes and locations. The new classification schema works well to describe meandering floodplain deposits. The geomorphology of scroll bars is investigated for the Mississippi River, revealing the heterogeneity of these deposits and that local meander bend conditions are important in determining scroll bar formation and preservation on the floodplain. The periodicity of scroll bars from a range of rivers is investigated and it is shown that scroll bars are intrinsically linked with the width of the adjacent river channel and respond to local planform changes. Floodplains of large rivers have complex overbank sedimentation processes that create spillage sedimentation phenomena. Spillage sedimentation was quantified down a 1700 km reach of the Amazon River and a 1400 km reach for the River Ob, revealing spatial discontinuities in spillage phenomena. Spillage dominance depends on diverse sediment loadings, hydrological sequencing, and morphological opportunity. Understanding spillage dynamics is important in quantifying overbank sedimentation rates and the spatial distribution of fine-grained deposits. The findings of this thesis highlight that despite the incredible complexity and heterogeneity of large river floodplains, order can be inferred via classification schemas and fundamental relationships identified. The thesis uses novel methods and conceptual models to bring a greater understanding and quantification to this complex floodplain geomorphology.

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Monge, Jackie Ann. "CONVERGENCE OF DUNE TOPOGRAPHY AMONG MULTIPLE BARRIER ISLAND MORPHOLOGIES." UKnowledge, 2014. http://uknowledge.uky.edu/geography_etds/19.

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Wave-dominated and mixed tidal and wave energy barrier islands are assumed to have characteristic dune topographies that link to their macroscale form. However, there has been no systematic attempt to describe the linkage between barrier island macroscale form and dune topography. The goal of this thesis was to investigate how dune topographies correspond to a number of barrier island morphologies found along the southeastern U.S. Atlantic coast. Macroscale process-form variables were used to classify 77 islands into seven morphologic clusters. Islands from each cluster were selected and sites characteristic of the range of dune topographies within islands were characterized using three methods: the frequency distribution of elevations, directional spatial autocorrelation of elevation at different distance classes, and FRAGSTATS indices summarizing the patch structure of elevations. Variables derived from each of these methods peaked in their ability to discriminate among barrier island morphologies when the islands were aggregated into three groups. An ordination of those variables revealed a two or three-fold grouping of barrier island dune types that approximated the traditional wave dominated and mixed energy barrier island morphologic classification. These findings suggest that dune topographies converge upon two to three configurations even within the heterogeneity in macroscale island morphology.

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Parker, Simon Toby. "An investigation into the effects of complex topography on particle dry deposition." Thesis, University of Birmingham, 2004. http://etheses.bham.ac.uk//id/eprint/1471/.

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There is a requirement to predict the spatial variation of particle dry deposition following a nuclear accident. The interaction of landscape features, atmospheric flow and particle dry deposition has been investigated with this in mind. Wind tunnel studies have been used with computational fluid dynamics to predict the deposition rate relative to a flat landscape. Good quantitative agreement was seen for this relative deposition rate. Landscape shapes showed significant effects on deposition rate, increasing it by more than two in some cases, over limited areas. The effect of turbulence intensity, in the absence of landscape features, was also studied and a weak relationship to dry deposition was observed. Computational fluid dynamics methods used in wind tunnel comparisons were extended to a wide range of landscape cases. Deposition rates varied spatially around the landscape features. In general, for hills and ridges, deposition was seen to increase on the windward face, decrease on the leeward face and near wake, and increase in the further wake, before returning to the flat case value. The computational results were applied to a real landscape with the use of a customised geographical information system. Good general agreement was seen when compared with a test case.

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Page, Amaris. "A topographic and photogrammetric study of rock glaciers in the southern Yukon Territory." Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28319.

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This research statistically examined the topographic characteristics of rock glacier locations in the Yukon Territory and tested the suitability of the Canadian air photo collection for photogrammetrically measuring rock glacier velocities. A database of more than 1500 rock glacier locations in the Yukon was compiled. The topographic characteristics of rock glaciers in a 12% sample were compared by classifying the sample by morphology (lobate or tongue-shaped) and activity (active, inactive or relict) and testing the difference between the class properties of elevation, slope, aspect and area. Tongue-shaped rock glaciers occurred at significantly higher mean and minimum elevations than lobate forms. Active rock glaciers were significantly larger than inactive and relict forms, and active forms were significantly more north-facing than inactive forms. The photogrammetry study found that it is possible to measure rock glacier movement rates from multi-temporal air photos of the quality and frequency available for the Canadian North. It was also found that thermokarst development could be tracked on multi-temporal air photos, though its presence hinders the measurement of movement. With the continued acquisition of high quality photos, the technique should prove useful for monitoring both rock glacier movement and thermokarst development.

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Miles, Luke G. "Global Digital Elevation Model Accuracy Assessment in the Himalaya, Nepal." TopSCHOLAR®, 2013. http://digitalcommons.wku.edu/theses/1313.

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Digital Elevation Models (DEMs) are digital representations of surface topography or terrain. Collection of DEM data can be done directly through surveying and taking ground control point (GCP) data in the field or indirectly with remote sensing using a variety of techniques. The accuracies of DEM data can be problematic, especially in rugged terrain or when differing data acquisition techniques are combined. For the present study, ground data were taken in various protected areas in the mountainous regions of Nepal. Elevation, slope, and aspect were measured at nearly 2000 locations. These ground data were imported into a Geographic Information System (GIS) and compared to DEMs created by NASA researchers using two data sources: the Shuttle Radar Topography Mission (STRM) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Slope and aspect were generated within a GIS and compared to the GCP ground reference data to evaluate the accuracy of the satellitederived DEMs, and to determine the utility of elevation and derived slope and aspect for research such as vegetation analysis and erosion management. The SRTM and ASTER DEMs each have benefits and drawbacks for various uses in environmental research, but generally the SRTM system was superior. Future research should focus on refining these methods to increase error discrimination.

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Lam, Norris. "Modeling rating curves from close-range remote sensing data : Application of laser and acoustic ranging instruments for capturing stream channel topography." Doctoral thesis, Stockholms universitet, Institutionen för naturgeografi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-142135.

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A rating curve provides a functional relationship between water height (i.e. stage) and discharge at a specified cross-section in a river. Used in combination with a time series of stage, rating curves become one of the central components for generating continuous records of streamflow. Since developing and maintaining rating curves can be time consuming, hydraulic models have shown potential to reduce the effort required for developing rating curves. A central challenge with modeling procedures, however, is the acquisition of accurate stream channel and floodplain topography. From this perspective, this thesis focuses on the real-world application of close-range remote sensing techniques such as laser-based ranging technologies (i.e. Light detection and ranging or LiDAR) or acoustic based ranging technologies (i.e. acoustic Doppler current profiler or ADCP) to capture topographic information for hydraulic modeling applications across various spatial scales. First, a review of the current LiDAR literature was carried out to identify potential ways to take full advantage of these novel data and technologies in the future. This was followed by four interconnected studies whereby: (i) a low-cost custom laser scanning system was designed to capture grain size distributions for a small stream; (ii) synthetically thinned airborne laser scanning (ALS) data was applied in a physically-based hydraulic modelling framework to develop rating curves; (iii) low-resolution national-scale ALS was coupled with ADCP bathymetry to be used in conjunction with a hydraulic model to develop rating curves; and (iv) the impact of measurement uncertainties on generating rating curves with a hydraulic model were investigated. This thesis highlights the potential of close-range remote sensing techniques for capturing accurate stream channel topography and derive from these data, the necessary parameters required for hydraulic modeling applications.
En avbördningskurva tillhandahåller ett funktionellt förhållande mellan vattendjup (dvs. vattenstånd) och flöde vid ett specifikt tvärsnitt i ett vattendrag. Avbördningskurvan blir en central komponent för generering av kontinuerliga tidsserier av vattenföring från tidsserier av vattenstånd. Eftersom det är tidskrävande att utveckla och underhålla avbördningskurvor erbjuder hydrauliska modeller attraktiva möjligheter att minska den insats som krävs för att utveckla avbördningskurvorna. En central utmaning för sådana modelleringsförfaranden är emellertid tillgången till noggrann topografidata av strömfåran och de omgivande stränderna. Den här avhandlingen fokuserar på tillämpningen av fjärranalystekniker för avståndsmätning på nära håll, såsom laserbaserade teknik (dvs. Light detection and ranging eller LiDAR) och akustisk baserat teknik (dvs. acoustic Doppler current profiler eller ADCP), för att fånga topografisk information för hydraulisk modellering av vattendrag i olika rumsliga skalor. Först presenteras en litteraturstudie av den nuvarande LiDAR-litteratur för att identifiera potentiella sätt att dra full nytta av dessa nya data och tekniker i framtiden. Detta följs av fyra sammanlänkade studier: (i) tillämpning av ett lågkostnads-laseravsökningssystem för att fånga kornstorleksfördelningar i ett litet vattendrag, (ii) syntetiskt förtunnad flygburen laserskanningsdata (ALS) applicerad i en fysiskt baserad hydraulisk modell för att utveckla avbördningskurvor, (iii) lågupplösta ALS från Svensk nationell höjdmodell kopplade med ADCP-batymetri för att ta fram en avbördningskurva med en hydraulisk modell, och (iv) undersökning av effekterna av osäkerheter på mätdata för att generera avbördningskurvor med en hydraulisk modell. Denna avhandling belyser potentialen för fjärranalystekniker för avståndsmätning på nära håll, för att fånga strömfårans exakta topografi och ifrån dessa data härleda de parametrar som krävs för hydrauliska modelleringstillämpningar.

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 5: Manuscript.

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Hsu, Li-Chih. "VISUALIZING BARRIER DUNE TOPOGRAPHIC STATE SPACE AND INFERENCE OF RESILIENCE PROPERTIES." UKnowledge, 2019. https://uknowledge.uky.edu/geography_etds/63.

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The linkage between barrier island morphologies and dune topographies, vegetation, and biogeomorphic feedbacks, has been examined. The two-fold stability domain (i.e., overwash-resisting and overwash-reinforcing stability domains) model from case studies in a couple of islands along the Georgia Bight and Virginia coast has been proposed to examine the resilience properties in the barrier dune systems. Thus, there is a need to examine geographic variations in the dune topography among and within islands. Meanwhile, previous studies just analyzed and compared dune topographies based on transect-based point elevations or dune crest elevations; therefore, it is necessary to further examine dune topography in terms of multiple patterns and processes across scales. In this dissertation, I develop and deploy a cross-scale data model developed from resilience theory to represent and compare dune topographies across twelve islands over approximately 2,050 kilometers of the US southeastern Atlantic coast. Three sets of topographic variables were employed to summarize the cross-scale structure of topography (elevational statistics, patch indices, and the continuous surface properties). These metrics differed in their degree of spatial explicitness, their level of measurement, and association with patch or gradient paradigms. Topographic metrics were derived from digital elevation models (DEMs) of dune topographies constructed from airborne Light Detection and Ranging (LiDAR). These topographic metrics were used to construct dune topographic state space to investigate and visualize the cross-scale structure of dune topography. This study investigated (1) dune topography and landscape similarity among barrier islands in different barrier island morphologic contexts, (2) the differences in barrier island dune topographies and their resilience properties across large geographic extents, and (3) how geomorphic and biogeomorphic processes are related to resilience prosperities. The findings are summarized below. First, dune topography varies according to island morphologies of the Virginia coast; however, local controls (such as human modification of the shore or shoreline accretion and erosion) also play an important role in shaping dune topographies. Compared with tide-dominated islands, wave-dominated islands exhibited more convergence in dune topographies. Second, the dune landscapes of the Virginia Barrier Islands have a poorly consistent spatial structure, along with strong collinearity among elevational variables and landscape indices, which reflects the rapid retreat and erosion along the coast. The dune landscapes of the Georgia Bight have a more consistent spatial structure and a greater dimensionality in state space. Thus, the weaker multicollinearity and higher dimensionality in the dataset reflect their potential for resilience. Last, islands of different elevations may have similar dune topography characteristics due to the difference in resistance and resilience. Notwithstanding the geographic variability in geomorphic and biogeomorphic processes, convergence in dune topography exists, which is evidenced by the response curves of the topographic metrics that are correlated with both axes. This work demonstrates the usefulness of different representations of dune topography by cross-scale data modeling. Also, the two existing models of barrier island dune states were integrated to form a conceptual model that illuminates different, but complementary, resilience properties in the barrier dune system. The differences in dune topographies and resilience properties were detected in state space, and this information offers guidance for future study’s field site selections.

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Sandström, Sonja. "Central Asian ice-marginal moraines of the global last glacial maximum : An analysis of topographic features affecting the glaciation pattern in the Tian Shan and Altai mountains." Thesis, Stockholms universitet, Institutionen för naturgeografi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-155171.

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Glacial runoff from the Tian Shan and Altai Mountains is an important water resource, especially for people living in the arid areas of Central Asia. Measured water volumes from glaciers have decreased, and glacier area have shrunk with 50-90% since the Little Ice Age. Lack of knowledge regarding glaciers in high mountain areas, and the impact from climate change makes this an important field to investigate. This thesis focuses on topographic features and their impact on spatial glaciation patterns; today and during the global last glacial maximum, 19-30 thousand years ago (ka). From selected marginal moraines in the Tian Shan and Altai mountains, with a deglaciation age between 19-30 ka, an analysis was created in ArcMap (GIS, Geographic Information System) with 1 arc second resolution ASTER GDEM2 (Digital Elevation Model) and in Google Earth. An elevation profile, hypsometry and mapping were created for the analysis. The interpretations made from the limited dataset resulted in topographic features affecting the glaciation extension today and percentage of decreasing glacier area since 19-30 ka, to be connected to north/south-facing direction of the drainage area and the elevation. Drainage areas experiencing the highest percentage of glacial shrinkage were southfacing and/or at elevation below 3961 m a.s.l.
Central Asia Paleoglaciology Project

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Rull, Patricia. "Hydrological modeling enhancement using GIS : An improved topographic wetness index for wetland detection." Thesis, Stockholms universitet, Institutionen för naturgeografi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-126004.

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Hydrological modeling, like runoff modelling for flood prevention, is based on digital elevation models (DEMs). The fact that the DEMs do not represent existing road culverts can lead to considerable hydrological misinterpretations. In order to overcome this limitation, a GIS method was developed to automatically adjust the elevation model, hydrologically enforcing the DEM, so that the results of hydrological modeling accounts for flow through culverts. The hydro-enforced DEM showed to better represent the drainage network than the former DEM when compared with the river map. The topographic wetness index is the most commonly applied topographic index and a good indicator of soil moisture distribution. It has been integrated into many hydrological models and pollution risk indices as well as into the prediction of wetland distribution. Using the hydro-DEM from the previous step and the soil map in conjunction with the TWI, an improved TWI was achieved, namely a soil-topographic wetness index (STI). The linkages between specific soil types and TWI or STI values were analyzed. They revealed a clear linkage between STI values and soil type based on the soil transmissivity (R2=0.77). However, the TWI values showed low correlations to the soil types (R2=0.02). As a specific application, both TWI and STI were tested for the detection of wetlands. Wetlands are important ecosystems which act as buffer zones by filtering pollutants and slowing floodwater. Being able to identify their distribution is important in landscape planning and ecology. A wetland threshold value was determined for each index and their results where compared with the wetland map from the property map (assumed as ground truth) and with the potential wetland area. Finally, a visual validation was performed with the use of an aerial photography. The results showed that the STI performed slightly better than the TWI for the detection of wetlands, detecting 3% more wetlands. The impact of the soil map on the topographic wetness index was therefore determined as positive.

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Gaffney, Charles. "Topographic microclimate influence on radial growth responses of sugar maple (acer saccharum marsh.) and white oak (quercus alba L.) to regional climate stresses." Virtual Press, 1995. http://liblink.bsu.edu/uhtbin/catkey/941379.

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Tree-rings were analyzed to assess the relative importance of slope position and aspect as determinants of the climate-sensitivity of sugar maple and white oak radial growth. Tree size, crown condition, forest and soil composition, and site indices were assessed to document environmental differences between site-types and to verify similarity of stands within the same site-type. Climate-sensitivity was assessed using mean between-tree correlation, principal components analysis, mean sensitivity, regression analysis, and analysis of radial growth decline after severe drought. Ecological differences were found between high and low sites on north and south facing aspects. Sugar maple did not exhibit greater climate-sensitivity than white oak. Both species showed greater climate-sensitivity on upper and south-facing slopes.
Department of Biology

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Eklöv, Pettersson Anna. "Glaciala och fluviala dalgångar i södra Norge : Ett resultat av mesozoisk sprickbildning och kenozoisk erosion." Thesis, Uppsala universitet, Kulturgeografiska institutionen, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-427256.

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The dramatic landscape of Norway has a long history of different events during the Phanerozoic. During the Caledonian orogeny, the basement became fractured, and during the warm climate in the Mesozoic, the fractures became deeply weathered. These fracture systems later became eroded, forming the main structures for valleys. The landscape today is characterized by an elevated plateau with deeply incised valleys. Several theories discuss when and how the landscape became elevated. The main theory for this suggests uplift events of the plateau during the Tertiary. The uplifts resulted in a later elevated landscape with erosional plateaux in different distinct levels. This often referred to as the Palaeic relief. The uplift events also followed formation of incised fluvial valleys. During the Quaternary, glaciers partly reshaped these valleys. This study aims to investigate the shape of these valleys, and how much they have been reshaped during the glaciations. The study further aims to investigates if the identified shapes within the valleys can be connected to pre-glacial landforms. To investigate this, satellite images and topographic maps have been studied. A digital terrain model (10 m resolution) were used to create topographic cross sections across eight valleys in southern Norway. This study identifies possible pre-glacial forms and fluvial generations within five of the investigated valleys. Three of the valleys show a gradual transition from a broad, glacial, U-shape near the coast to become a narrower, V-shaped, fluvial valley further inland. The analysis also shows that the joints and fractures affect the width of the valleys which has affected the amount of glacial erosion. The results of this study clearly show that old fluvial valley remains is common, even within these major glacial valleys of southern Norway.

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Soalt, Jennifer. "A New Topography: Elizabeth Bishop's Late Poems." Oberlin College Honors Theses / OhioLINK, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=oberlin1396537622.

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Sambuco, Emily Nicole. "Exploring Great Basin National Park using a high-resolution Embedded Sensor Network." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555579768450066.

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Boland, Emma Joan Douglas. "Jets, mixing, and topography in the Southern Ocean." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/245073.

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The Southern Ocean holds a unique place in our planet. It is home to the world’s longest and strongest ocean current, the Antarctic Circumpolar Current (or ACC), which is formed of jets (alternating velocity structures), thought to be significant surface transport barriers. The dynamical processes (particularly mixing processes) in the Southern Ocean are crucial to driving the global overturning circulation, which is in turn responsible for the global transport of heat, CO2, and nutrients. Despite the evident importance of the Southern Ocean to current and future climate, the important dynamical processes that occur there are poorly understood. This thesis attempts to contribute towards the understanding of some of the open questions in Southern Ocean dynamics. In particular, we investigate the effect that topography might have on the jets that form the ACC, with regards to their formation and in particular, their transport properties. Through a quasi-geostrophic model we investigate the properties of jets that form over a zonal slope in bottom topography, and find that the jets become tilted, aligning perpendicular to the large-scale barotropic potential vorticity gradient. As the jets tilt more, they become significantly more energetic, corresponding with an increase in across-jet transport. We compare various theories regarding the formation of such jets, involving linear analysis of the system. It is found that the analytical form of the Rossby wave frequencies correctly predicts the anisotropy of the energy spectra of simulations, and so the jet direction. Additionally, there is a need to characterise accurately the isopycnal mixing occurring throughout the Southern Ocean. We utilise satellite measurements to estimate isopycnal diffusivities in the Southern Ocean in two different studies. Using an effective diffusivity diagnostic to extend a previous study, we find reduced surface horizontal mixing at the latitudes of the ACC core. By comparing a tracer advection simulation with measurements from an experiment in the Southern Ocean, we find that simulations with a vertically averaged horizontal diffusivity of 20m2s−1 best match observations in the Pacific sector of the ACC.

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Cherian, Deepak Abraham. "When an eddy encounters shelf-slope topography." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107086.

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Thesis: Ph. D., Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 129-135).
Eddies in the ocean move westwards. Those shed by western boundary currents must then interact with continental shelf-slope topography at the western boundary. The presence of other eddies and mean flows complicates this simple picture, yet satellite images show that mesoscale eddies translating near the shelfbreak routinely affect the continental shelves of the Mid-Atlantic Bight, the Gulf of Mexico etc. The consequent cross-shelfbreak transports are currently of unknown importance to shelf budgets of heat, salt and volume. Thus motivated, this thesis uses idealized continuously stratified numerical experiments to explore eddy-slope interactions under four questions: 1. Can the continental slope prevent an eddy from reaching the shelfbreak? 2. What is the structure of the eddy-driven offshore flow? 3. How is the continental shelf affected by an eddy at the shelfbreak? 4. Given surface observations, can one estimate the volume of water transported across the shelfbreak? The experiments show that the efficiency of Rossby wave radiation from the eddy controls whether it can cross isobaths: by radiating energy the eddy becomes shallow enough to move into shallower water. For wide continental slopes, relative to an eddy diameter, a slope can prevent an anticyclone from reaching the shelfbreak by shutting down such radiation. For narrow continental slopes, the interaction repeatedly produces dipoles, whose cyclonic halves contain shelf-slope water stacked over eddy water. The formation of such cyclones is explained. Then, the structure of shelf flows forced by the eddy are studied: their vertical structures are rationalized and scalings derived for their cross-isobath scales; for example, the extent to which the eddy influences the shelf. A recipe for estimating cross-isobath transports based on eddy surface properties is put forward. Finally, the findings are tested against observations in the Middle Atlantic Bight off the northeastern United States.
by Deepak Abraham Cherian.
Ph. D.

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Bruhn, Erik. "Anpassning av data för gemensam karta över kommuner i Dalarnas län." Thesis, Karlstad University, Division for Environmental Sciences, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-496.

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Detta arbete har utförts under 10 veckor och har resulterat i en gemensam digital karta över Falun, Borlänge och Säters kommun. För att lyckas komma fram till resultatet har jag utfört en rad analyser av ingående data, och likriktat data så att framställandet av en gemensam karta blivit möjligt. Arbetet har varit indelat i två delar, insamling och likriktning av data samt kartografisk anpassning av data. Den första delen av examensarbetet har tagit upp den största delen av tiden, medan betydligt mindre tid lagts på den kartografiska anpassningen. Data som använts har samlats in från kommunernas primärkartor, Lantmäteriets fastighetskarta samt Vägverkets Nationella vägdatabas (NVDB). Programvaran FME från Safe Software har varit ett mycket bra verktyg för att likrikta data, och har använts i stor omfattning. De rutiner för uppdatering av data som föreslagits, har också tagits fram med denna programvara som grund. För att studera och kontrollera datas utseende har ArcGIS från ESRI använts. ArcGIS har dessutom utnyttjats för den kartografiska anpassningen. Den framtagna kartan gör inga som helst anspråk på att vara topologiskt korrekt, även om topologin i vissa avseenden beaktats. Fokuseringen har legat på att få fram en tydlig och enkel karta, som efter mindre justering skall kunna användas av olika intressenter förutom Räddningstjänsten DalaMitt. Exempel på dessa intressenter kan vara andra verksamheter inom kommunen såsom gatukontoret, eller externa intressenter som önskar en gemensam karta för sin verksamhet.

This project has been carried out during 10 weeks, and has resulted in a common digital map containing the municipalities of Falun, Borlänge and Säter. To reach the desired result I have had to carry out a number of analyses on the ingoing data, and standardize the data to make the completion of a common map possible. The project has been divided into two large parts, collection and standardization of data, and cartographic adaptation of data. The first part has demanded most time, while considerably less time has been spent on the cartographic adaptation. Data that has been used was collected from the municipalities’ primary maps, the Swedish Land surveying’s parcel map and the Swedish National Road Administration’s National road database (NVDB). The software FME from the manufacturer Safe Software has been a very helpful tool to standardize data, and has been used in a large scale. The routines for updating the data that is suggested, has also been developed with the software. To study and control the look of data, the software ArcGIS from ESRI has been used. ArcGIS has also been used for the cartographic adaptation. The developed map doesn’t claim to be topological correct, even though the topology has been considered in some ways. The focus has been to develop a map that is clear and simple, and that after minor adjustments can be used by other actors other than the Rescue Service of Dala-central. Example of these actors can be other activities within the municipalities, such as the street offices, or external actors who wish to use a common map in their activities.

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Heyman, Jakob. "Glacial geology of Bayan Har Shan, northeastern Tibetan Plateau." Licentiate thesis, Stockholm University, Department of Physical Geography and Quaternary Geology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7507.

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The paleoglaciology of the Tibetan Plateau is still largely unexplored, despite its importance for regional and global climate reconstructions. In this thesis a comprehensive glacial geological record is presented from an extensive part of the northeastern Tibetan Plateau centred on the Bayan Har Shan. Glacial reconstructions for this region range from restricted mountain glaciers through the intermediate-size regional-scale Huang He ice sheet to a plateau-scale Tibetan ice sheet. To provide a robust basis for glacial reconstructions, this thesis provides conclusions based on two principle methods, remote sensing and field studies. The remote sensing of a 90 m resolution digital elevation model and 15- and 30 m resolution satellite imagery renders a detailed data set with complete spatial coverage of large- and medium-scale glacial landforms, and large-scale plateau geomorphology. Observations from fieldwork campaigns add detailed point information for the distribution of glacial deposits. Geomorphological glacial traces such as glacial valleys, glacial lineations, marginal moraines, meltwater channels, and hummocky terrain occur frequently in elevated mountain areas, indicating former alpine-style glaciations. Glacial deposits in the form of till, erratic boulders, and glaciofluvial sediments are common in areas with mapped glacial landforms, but also beyond, in areas lacking large-scale glacial landforms. For extensive plateau areas in-between formerly glaciated mountain blocks, there is a striking absence of glacial landforms and sediments, indicating that these areas, perhaps, never were ice covered. Interestingly, glacial deposits occur further away from the mountain blocks than the large- and medium-scale glacial landforms, indicating insignificant erosion beneath the maximum ice covers close to their margins.

The large-scale geomorphology of the northeastern Tibetan Plateau is characterised by a low-relief plateau surface with glacial valleys in elevated mountain blocks and marginal steep V-shaped valleys. This geographical distribution indicates a dominance of glacial erosion in the elevated mountain areas and a dominance of fluvial erosion along the steep plateau margins, dissecting a relict plateau surface. The outline of the relict plateau surface mimics the proposed outline of the Huang He ice sheet, suggesting that the inferred ice sheet may represent a misinterpreted relict surface with scattered glacial traces.

In conclusion, the glacial geology examined in the Bayan Har Shan region is consistent with paleo-glaciers of varying extent restricted to elevated mountain areas. Even though extensive icefields/ice caps were centred on discrete mountain areas, there is no indication that these ice masses merged but rather that they were separated from each other by unglaciated plateau areas. The presented glacial geological record will be used in further studies towards a robust paleoglaciological reconstruction for the northeastern Tibetan Plateau.

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20

Thomson, James M. (James McArthur). "Infragravity waves over topography: generation, dissipation, and reflection." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/39222.

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Thesis (Ph. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2006.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references.
Ocean surface infragravity waves (periods from 20 to 200 s) observed along the southern California coast are shown to be sensitive to the bottom topography of the shelf region, where propagation is linear, and of the nearshore region, where nonlinearity is important. Infragravity waves exchange energy with swell and wind waves (periods from 5 to 200 s) via conservative nonlinear interactions that approach resonance with decreasing water depth. Consistent with previous results, it is shown here that as waves shoal into water less than a few meters deep, energy is transfered from swell to infragravity waves. In addition, it is shown here that the apparent dissipation of infragravity energy observed in the surfzone is the result of nonlinear energy transfers from infragravity waves back to swell and wind waves. The energy transfers are sensitive to the shallow water bottom topography. On nonplanar beach profiles the transfers, and thus the amount of infragravity energy available for reflection from the shoreline, change with the tide, resulting in the tidal modulation of infragravity energy observed in bottom-pressure records on the continental shelf. The observed wave propagation over the shelf topography is dominated by refraction, and the observed partial reflection from, and transmission across, a steep-walled submarine canyon is consistent with long-wave theory. A generalized regional model incorporating these results predicts the observed infragravity wave amplitudes over variable bottom topography.
by James M. Thomson.
Ph.D.

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21

O'Connor, Erin E. "Post-fire Vegetative Regrowth Associated with Mature Tree Stands and Topography on Sofa Mountain." Youngstown State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1432908700.

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22

McCarthy, Laura 1960. "Riparian habitat changes in Cibola National Wildlife Refuge: 1959-1991." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278174.

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In 1959, the Bureau of Reclamation proposed a channelization project through the Cibola Valley along the Lower Colorado River. The project entailed rerouting the river through a dry cut in order to lower groundwater levels in the Palo Verde Irrigation District upstream, thereby improving irrigation drainage. In conjunction with this, Cibola National Wildlife Refuge was created in 1964 to mitigate the effects of habitat loss from the channelization project. Aerial photographs of the Cibola Valley were analyzed for 1959, and vegetation community types were determined. A vegetation type map was developed for 1959 and compared with vegetation type maps for 1976 and 1986. Between 1959 and 1986, a lowering of the water-surface level in some parts of the refuge resulted in the draining of some lakes and the creation of slow-moving backwaters. Cottonwood-willow and marsh communities saw a significant reduction in area while the salt-cedar community saw rapid growth.

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23

Aist, Rodney. "Willibald of Eichstätt (700-787 CE) and Christian topography of early Islamic Jerusalem." Thesis, University of Wales Trinity Saint David, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683272.

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24

Sun, Xumin 1972. "Small scale flow features near a straight coastline and wharf area in the Lower St. Lawrence estuary." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=20876.

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Small-scale flow features were examined near a straight coastline off Ste. Flavie and an adjacent wharf in the Lower St. Lawrence estuary, using moored current meter and acoustic doppler current profiler (ADCP) data. The leading order velocity was found to be dominated by the mean and lunar semi-diurnal (M2) tidal currents. In the straight shoreline area, no eddy was found. The presence of stratification led to baroclinic low frequency (LP, including the mean) velocities with depth. Freshwater forcing and wind stress dominated the "non-tidal" surface layer dynamics. Near the bottom, friction and other factors induced an Ekman-like spiral in the LP velocity profile. The tidal currents were barotropic, with the M2 constituent dominating the tidal energy. In the wharf area, flow in the lee was found to be an order of magnitude weaker than the free strewn flow offshore. Time-mean spatial eddies were also evident in the lee. Evolution maps within a single M2 tidal cycle show the existence of transient eddies, characterized by a pair of counter-rotating eddies generated both during maximum flood and ebb tide.

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25

Sund, Camilla. "Paleogeografi i östra Svealand de senaste 7000 åren." Thesis, Stockholm University, Department of Physical Geography and Quaternary Geology, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-38389.

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Strandlinjen i Sverige har sedan den senaste inlandsisen präglats av isostatisklandhöjning. Höjningen var som kraftigast straxt efter deglaciationen men verkar påtagligt än idag i landets norra delar, framförallt Ångermanland och Västerbotten, medan rörelsen minskat i landets södra delar där den är liten eller avtagit helt. Strandförskjutning är resultatet av isostatisk landhöjning och eustatisk havsytenivåförändring. För att rekonstruera strandförskjutningens utveckling upprättas strandförskjutningskurvor. Kurvan är således resultatet av landhöjning och havsnivåförändringar i meter som en funktion av tiden. Då den isostatiska landhöjning påverkar strandförskjutningsförloppet både i nord-sydlig samt öst-västlig riktning med varierande storlek i olika delar av landet, bör områden modelleras utifrån lokala förutsättningar för att uppnå en så korrekt detaljnivå som möjligt.

Examensarbetes syfte är att belysa paleogeografiska förändringar i östra Svealand under de senaste 7000 åren. Information har hämtats från såväl arkeologiska som geologiska källor, såsom strandnära bosättningar och isolerade sjöar. Genom att använda geografiskt läge, nuvarande höjd över havet och ålder, kunde en trendyta anpassas för att beräkna en synkron forntida strandlinje för valfri tidpunkt inom hela undersökningsområdet.

Trendytan skapades med hjälp av multivariat regressionsanalys vilket resulterade i en andragradsekvation baserad på åldern i kvadrat, vilket indikerar att hastigheten av strandförskjutningen har varierat med tiden, i detta fall avtagit med tiden. Ytan visade på ojämn isostasi i både nord-sydlig och öst-västlig riktning med högst höjning i nordväst och lägst i sydost.

Tidigare studier har påvisat indikationer på transgressiva förlopp söder om Mälardalen under senaste 7000 åren. Inga sådana trender kunde dock identifieras genom denna matematiska funktion då detta kräver fördjupade sedimentstratigrafiska studier.

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26

Edström, Carl. "Skred i Flian och Lidan, jämförande studier mellan områdena Kristinedal och Sköttorp." Thesis, Uppsala University, Department of Naturegeography, 1997. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-87399.

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Denna uppsats syfte har varit att

studera jordarter och morfologi
försöka bestämma om skreden i dagsläget kan betecknas som recenta eller stabiliserade. Detta bla. genom att studera vegetation; ålder och utbredning av denna.
beskriva vad människorna i området gjort efteråt.

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27

Pere, Verne Harlan. "Antiscarp initiation and evolution." Thesis, University of Canterbury. Geological Sciences, 2009. http://hdl.handle.net/10092/3690.

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Antiscarps are defined here as any uphill facing scarp that may be observed on slopes, regardless of size or scale. They are not present on all slopes, but where they have been observed, they typically occur sub-parallel to the valley axis near the ridge crests in mountainous regions. Antiscarps are generally, but not exclusively, found in glaciated regions, where loading and unloading of the rock mass has effected changes to the in situ stress fields through cycles of compression and elastoplastic rebound and has also removed large volumes of material by the formation of cirques. Non-glacial antiscarps are commonly associated with tectonic activity. An extensive review of current literature has been used to assist in the identification of key parameters associated with antiscarps and to provide a basis for clearly defining the terminology used to address antiscarp related processes and features. All of the reviewed material has been collated into a chart where the factors that have been extracted from the articles are grouped and compared. The chart has been instrumental in selecting the nomenclature to be used when addressing different types of antiscarp and also in constraining the extent to which the term can be reasonably used. A flowchart has been developed to assist in the identification of the primary antiscarp forming process. The flowchart was successfully used to identify the primary processes associated with antiscarps observed in field studies in both the South Island of New Zealand and in the Scottish Highlands. Physical base friction models and numerical finite element modelling, using Plaxis v6.1 and FLAC 2D v3.40, both indicate that antiscarps can form solely under a gravitational load. Base friction models used individual elements of various geometries. Antiscarps formed in most of the models and were best identified in models that had a clearly defined discontinuity surface. The numerical models also indicate that shear along existing discontinuities is the dominant mode for the formation of antiscarps under a gravitational load in homogeneous massifs.

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28

Kokelj, Steven V. "The effect of detachment sliding on surface wash erosion in the continuous permafrost zone, Hot Weather Creek, Fosheim Peninsula, Ellesmere Island, Northwest Territories." Thesis, University of Ottawa (Canada), 1998. http://hdl.handle.net/10393/4070.

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An experimental design was developed to evaluate the effect of active-layer detachment sliding on surface wash erosion. Specifically, the aim was to examine to what extent the disturbance of vegetation cover, changes in hydrological conditions due to topographic modification by detachment sliding and the formation of a fresh active layer affect rates of surface wash erosion. Detachment slides generally accumulated more snow than adjacent slopes and yielded greater amounts of surface runoff than vegetated slopes with similar snow covers. Surface drainage was inhibited on well-vegetated hummocky slopes where lags between radiation inputs and discharge responses were greater than at the rilled detachment slide plots. During rainfall events following snowmelt, plot response was affected by antecedent moisture conditions and the vegetation cover: surface flow was generated only in detachment slide scars and at the mixed plots but not on vegetated undisturbed slopes or on the bare undisturbed slope. Suspended sediment concentrations at the fresh detachment slide scars are two orders of magnitude greater than on vegetated slopes. Greater amounts of surface runoff production at fresh scars and the removal of vegetation result in high rates of surface erosion and high sediment yields (1560 g/m$\sp2)$ at fresh detachment slide scars. (Abstract shortened by UMI.)

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29

Riel, Alain. "Histoire alluviale de la riviere Porcupine dans la plaine de Bluefish au Yukon septentrional, de 14 ka B.P. a aujourd'hui." Thesis, University of Ottawa (Canada), 1997. http://hdl.handle.net/10393/4174.

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La riviese Porcupine qui prend naissance dans les monts Ogilvie, au Yukon septentrional, est caracterisee par de nombreux meandres quand elle traverse la plaine de Bluefish. Cette plaine, etablie dans un bassin tectonique datant du Tertiaire, a accumule au cours du Cenozoique des sediments qui, a l'Holocene, ont ete entailles par la riviere. La photo-interpretation des depots superficiels de la riviere Porcupine a l'interieur de la plaine de Bluefish a permis d'identifier trois categories de depots meubles soit du gravier, du sable et du limon. Une etude sedimentologique a ete effectuee le long de la riviere Porcupine sur une distance d'environ 84 kilometres. A l'interieur de cette section, 6 coupes stratigraphiques ont ete etudiees et 87 echantillons ont ete retenus pour des fins d'analyses sedimentologiques. Les resultats de l'analyse granulometrique ont ete soumis a une analyse bivariees: le diagramme Md/Qd (phi) de Krumbein. La combinaison de cette analyse avec celles des datations radiocarbones et a la position geographique des coupes etudiees, a permis de reconstruire l'histoire alluviale de la riviere Porcupine dans la plaine de 14 ka B.P. a aujourd'hui. Les principaux resultats sont: (1) Un encaissement rapide (50 m), entre 14 ka et 12 ka B.P. suite a une decharge fluvio-glaciaire qui mit en place des terrasses d'erosion. (2) L'edification d'une terrasse liee a une phase de sedimentation intense associee a la fin de la decharge glacio-lacustre. (3) L'edification d'une terrasse moderne a quelques metres de la surface de la riviere Porcupine. Cette terrasse est en equilibre avec l'hydrologie actuelle.

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30

Clarke, Shawne Arianne. "An experimental study on the influence of climatic fluctuations on solifluction, Fosheim Peninsula, Ellesmere Island, Northwest Territories." Thesis, University of Ottawa (Canada), 1998. http://hdl.handle.net/10393/4538.

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A field experiment, involving direct manipulation of surface microclimate, was undertaken in the continuous permafrost zone to examine the influence of climatic fluctuations on solifluction rates and movements throughout the active layer. Movements and soil temperature were measured continuously from 1993-1997 using five electro-mechanical meters and thermocouple cables on an 8$\sp\circ$ colluvial slope in Hot Weather Creek valley, Ellesmere Island. Natural variation of movement among the years and the meters was measured until summer of 1996 when surface climatic treatments (surface warming, wetting, a combination of these two, and cooling) were performed. The longer-term effects of the treatments were monitored until August 1997. Near-surface measurements alone do not provide an accurate picture of solifluction in areas with two-sided freezing ("cold" permafrost) because there can be substantial variation in movement rates at depth. In addition, multi-year average rates potentially hide a considerable range of annual variability and do not allow for the examination of a relationship between climatic fluctuations and annual movement. (Abstract shortened by UMI.)

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31

Akdim, Brahim. "Genèse des carbonates terrestres dans la dépression de Quarzazate (Maroc méridional)." Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/5783.

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The carbonate encrusting process and its consequent products (crusts, tufa and travertine) in the southern Morocco (Ouarzazate) are studied in this thesis. A detailed inventory of the carbonate deposits is given. The dynamic aspects of carbonate precipitation and dissolution are considered from an environmental point of view. The main factors influencing their genesis are discussed on the basis of a multidisciplinary investigation. Among the accumulated carbonates, caliches are the most abundant. Their genesis invokes a changing environment where sedimentation has the same importance as the biogenic and pedogenic processes. Dated by the Uranium/Thorium method, these caliches are older than 300 ka. They indicate that the encrusting process is ancient. These deposits have become progressively rare during the Quaternary period except for the important hydrothermal travertine of Skoura. Only a few accumulations are still forming nowadays (Ait Arbi and Ifesfas). Their absence in present day water, especially in rivers is interpreted as indicating an environmental change. It is hypothesised that a desequilibrium affects the incrusting process. A comparative study between rivers and sources in different settings is carried out. The saturation degree of water, its chemical composition, especially in elements that may have particular origins (potassium, nitrate, sulfate, etc.) and its bacteriological characteristics are investigated in the thesis. Results seem to indicate that differences exist between the calcite - precipitating waters of some sources (not affected by human activities) and the sterile waters of rivers (Dades and M'goun). The latter are polluted by chemical fertilizers or turbulent, such that no carbonate deposits are permitted. The conclusion is that the reduced incrusting phenomena indicate an environmental change. A progressively drier climate and progressively reduced discharge make the deposits more limited in space and rare. The human impact on the quality of water must be considered to explain the limited extend of present day encrusting processes.

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32

Hugenholtz, Christopher H. "Morphometry and biophysical characteristics of turf-banked lobes and terraces, Kluane Lake, Yukon Territory." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6356.

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The distribution, morphometry and biophysical characteristics of turf-banked lobes and terraces are described from a small subarctic alpine plateau (1300--1900 m a.s.l.) overlooking Kluane Lake in the southwest Yukon Territory, Canada. Observations on the distribution of lobes and terraces at this site indicate that the main controlling factors are the complexity of the topography and the properties of snow cover. Morphometric analysis of 85 lobes subdivided into five different slope orientations indicates a morphogenetic underpinning in which lobe form remains consistent (length-to-width ratio below unity) at different scales and between aspects, however, morpho-biophysical correlations could not provide an explanation for this. Nonparametric and multivariate parametric statistical tests indicate significant inter-aspect differences in the dimensions and biophysical characteristics of the lobes. These appear to be related to differences in site-specific factors. Measurements made along certain transects reveal a definitive downslope trend in the size of lobes. This organization is developed as a result of downslope gradients of various biophysical factors, primarily soil moisture and frost-susceptible soil (silt and clay), which are created by slopewash processes.

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33

LeBlanc, Michelle. "A diatom-based Holocene paleoenvironmental record from a lake on Boothia Peninsula, central mid-Arctic, Nunavut, Canada." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6414.

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An important source of information about climate change comes from sedimentary deposits from the arctic region. However, there are few lacustrine fossil records from the central mid Arctic region of Canada. A 485 cm sediment core, from a lake unofficially called JR01, Boothia Peninsula, Nunavut, yielded a high-resolution diatom record. Five radiocarbon dates provided the chronology. Three distinct zones are revealed in the relative percent abundance and diatom concentration diagrams. A more diverse and productive flora in the first zone implies warmer temperatures in the middle Holocene. A complete shift in diatom composition to a predominantly Fragilaria flora and a reduction in diversity and production suggests a cooler climate in this region after approximately 4360 years B.P. Smaller-scale climatic trends, such as the Little Ice Age (LIA) (ca. 550--150 yr. B.P.) and the Medieval Warm Period (ca. 1000--700 yr. B.P.), caused shifts in the diatom flora and production. Subtle shifts in floristic diversity within the LIA may reflect climate variability at a decadal scale. This variability is also recorded in other high-resolution paleoclimate records from the Arctic. A gradual shift to a more diverse and productive flora in the last 180 years B.P. (1790 years A.D.) suggests a response to the recent warming trend. This study permits us to address ambiguities with respect to the timing, the geographic extent and the severity of the recent warming. Changes in total diatom concentrations, magnetic susceptibility, organic and carbonate content may also reflect changes in the diatom assemblages and indicate shifts in vegetation, soil erosion, or in hydrology from the surrounding catchment. The morphological variance of Fragilaria and other taxonomy issues are also discussed.

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34

Coultish, Tara L. "Long-term development of palsas and other permafrost-cored mounds in mountainous terrain, Wolf Creek, southern Yukon." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6454.

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Fifty-one frost mounds were examined in Wolf Creek, Yukon Territory (60°30'N, 135°13'W) at an elevation of 1235 m a.s.l. Cryostratigraphic analyses and aerial photographic interpretation were undertaken to investigate the origin and longevity of the mounds, and to assess their utility as climatic indicators. It was determined that 37 mounds were palsas, as evidenced by their dimensions, cryostructure of segregated ice and location within a fen; one mound was a frost blister, as evidenced by its core of intrusive ice; one mound may have been a compound form, with segregation and possibly intrusive ice; and 12 mounds were termed aggradational permafrost mounds as their cores were of segregated ice but they did not fit the locational requirements to be palsas. Aerial photographs, spanning the period from 1946 to 2001, showed that palsas at the study site have been aggrading and degrading continually over the past 55 years, and are continuing to do so. (Abstract shortened by UMI.)

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35

Lacelle, Denis. "Ground ice investigation in the Far Northwest of Canada." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6455.

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Ground ice formation in the Far Northwest of Canada was investigated using stable isotopes (delta18O and deltaD) and 14C dating. These have proven to be valuable tools when inferring the origin of ground ice bodies. The major findings are: (1) During the Late Pleistocene, massive tabular ground ice bodies formed extensively in the Willow River area, Richardson Mountains. These ice bodies are currently exposed in the headwalls of retrogressive thaw slumps as a result of climate warming. Two units were recognized on the basis of ice structure: a debris-rich ice overlain by a diamicton. The debris-rich ice, characterized by low delta 18O values (-30‰ to -27‰), is believed to have formed by in situ freezing of subglacial meltwater derived from the Laurentide ice sheet. The meltwater flowed through water-saturated till between relict and aggrading permafrost. A decrease in subglacial meltwater flow from the ice sheet and a decrease in enthalpy transfer from the meltwater caused the freezing of the meltwater within the proglacial water-saturated till. The ice in the diamicton is characterized by relatively high delta 18O values (-26‰ to -20‰) and formed from the freezing of isotopically enriched Holocene waters. (2) In the northern Yukon, a delta18O analysis of surface and subsurface ice was undertaken. The results indicate that the delta18O composition of the various ice types is dependent upon a number of factors, such as surface air temperature, relative humidity and freezing rates. Holocene age waters are characterized by delta18O values >-27‰, while Pleistocene age waters have delta18O values <-27‰, indicating colder air temperature at the time of precipitation. The effect of evaporation on the isotopic composition of water was best observed on open surfaces where enrichment in the order of 5--11‰ in 18 O was measured.

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36

Crevier, Yves. "La réflectance et l'albédo de la neige dans la chaîne des monts Kluane : une méthode d'estimation utilisant des données satellitaires et un modèle numérique d'élévation." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6579.

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This paper proposes an estimating method of snow reflectance based on Landsat-5 Thematic Mapper (TM) data (June 21 1988) and a 30-meter resolution digital terrain model that correct and adjust the problems mentioned above. A radiative transfert model (LOWTRAN-7) in conjunction with radiosonde data was used to eliminate the radiometric distortion on the signal created by the presence of the atmosphere. A software package called PRODEM was use to model the terrain shape from the digital elevation data. PRODEM was also very helpful for integrating the digital elevation model to the digital analysis of the remote sensing data. The results were compare to a series of data extracted from the literature. The estimated values of reflectance and albedo are in good correspondence with the values in the literature. However, we observed various problems to estimate the reflectance and albedo of surfaces that present extreme topographic characteristics. First, we think that those problems can be related to an under evaluation of the diffuse component of the incident radiation. Second, it can also be attributed to an imperfect match between the satellite data and the incident solar radiation image. Also, the differences between the estimated and the observed snow reflectance values (literature) can be imputed coarsely to the approximation of the different model constituents and the spatial and temporal correspondence of satellite and in situ data. (Abstract shortened by UMI.)

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37

Kruszynski, Glen A. "Variations in the relation between suspended sediment and solute delivery in glacial meltwaters, Maxwell Glacier, Yukon Territory." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6638.

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The purpose of this thesis is to investigate the interactions between meltwaters and sedimentary material at the base of an alpine glacier which are indicated by intra- and interseasonal variations of discharge, solute and sediment outflow from the terminus. During the 1989 and 1990 ablation seasons, discharge, suspended sediment concentration and dissolved solids draining from Maxwell Glacier, St. Elias Mountains, Yukon Territory, were obtained at hourly intervals. The discharge time series of Maxwell Creek reveals that flow varies at a period of one to two weeks, at a diurnal level and over one to three hours. Over all three time scales, electrical conductivity is inversely proportional to discharge suggesting that during high during high diurnal flows, outwash water is derived primarily from surface melt while at low nocturnal discharge, water originates from subglacial and englacial stores. In spring, when supraglacial meltwater begins to access the subglacial drainage system the basal water pressure is raised. Large areas previously hydraulically isolated are integrated releasing stored basal sediment. During periods of increasing discharge in the early summer hydroglacial events resulting from gradual expansion and/or isolation of subglacial cavities, temporary blockage of subglacial conduits or from input from adjacent gravity deposits occur. As flow increases, conduit diameters increase and water gradually spreads out over the glacier bed as a diffuse network of linked cavities. Throughout the ablation season, different areas of the sole are integrated with flow. Towards the end of the ablation season, meltwater supply declines resulting in the reduction of flow in subglacial passageway and reduced sediment and solute supply. (Abstract shortened by UMI.)

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38

Kodybka, Richard Joseph. "Aspects of the Quaternary evolution of the plateau regions of the northern Ruby Range, southwest Yukon Territory." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6921.

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The main objective of this thesis was to offer explanations on the evolution of the plateau surfaces in the northern Ruby Range, Yukon Territory. Specifically, to determine whether the geological and geomorphological evidence from the plateau surfaces could support the belief that these regions were subjected to glaciation, or does the evidence indicate other evolutionary processes. The more traditional geological techniques of geochemical and heavy mineral compositional analyses have been used previously in both geological and glacial related studies in the Canadian Shield and other regions of Canada, and have aided in the description of environments. However these types of analyses have had limited application in alpine environments with expensive plateau regions, such as those experienced in the northern Ruby Range. The data also made it possible to delineate, in a regional context, mineralized zones that have not yet been identified. This pursuit constituted an ancillary objective in this thesis. It was determined that the average proportion of heavy minerals identified was similar for both plateau and valley sediment samples. The range of the proportions was found to vary considerably in most minerals. The significance of these comparisons was not clear, but probably indicated that the sediments from both plateau and valley sites did not vary greatly in heavy mineral species and proportions, but demonstrated a variable range. As well, there was no appreciable difference in the heavy mineral assemblages between plateau and valley sediment samples, except for the relative lack of allanite from plateaus, and goethite from valleys. The data did not support a clear association between heavy mineral assemblages from plateau and valley sediments, and those derived from bedrock within or outside the study area. However, the sediment assemblages may not be exclusively related to local bedrock sources. The provenance of orthopyroxene, goethite, and allanite may be attributed, in part, to bedrock from outside the study area, volcanic ash, and meteoritic impacts, or a combination of these. The occurrence of these minerals may also be associated with mineral alterations. Both the heavy mineral and geochemical data indicated there were no discernable dispersal patterns in either an up-valley or down-valley direction. The random dispersals of minerals and elements in the valleys can be characterized as secondary, epigenetic dispersals, and can be further classified as resembling clastic, hydromorphic, or biogenic patterns. Heavy mineral and element analyses performed on surficial sediments from the plateau surfaces indicated that some of the material may not be of local origin, and discernable dispersal trends were evident in certain heavy minerals and elements which were traced to known sources of mineralizations. The most striking characteristics of these trends were their continuous form, spanning many kilometres, and their patterns which extended over extensive plateau surfaces that were dissected by numerous valleys. (Abstract shortened by UMI.)

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39

Chamberland, Jean. "La télédétection d'un environnement forestier abitibien : comparaison des images MSS, TM et SPOT." Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7822.

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Three satellite images originating from MSS (06-19, 1983), TM (09-19, 1984) and SPOT (04-22, 1987) were analysed in a forestry context for a region part of north-western Quebec. The result of this work was mainly based on visual analysis; the TM image best performed according to the parameters on which this research was conducted.

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Prévost, Clément L. "Processus et intensité actuelle et holocène de l'érosion du marbre de Grenville, région de Gatineau-Lièvre, Québec." Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7853.

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Limestone tablets placed in various aquatic environments yielded a mean rate of erosion of 22,8 mm/1000 years. Within different soil media, the same method gave a 12,4 mm/1000 years intensity of erosion. The hydrochemical approach gave a mean rate of 21,4 mm/1000 years, but the median rate of 17,2 mm/1000 years is believed to be closer to reality. The karsts developed on the crystalline (metamorphic) limestone of the study area are found at the surface as well as underground. Fossil caves hang on the valley slopes far from the actual streams. Many active caves show in their path fossil phreatic tubes superimposed on active vadose corridors. Rates of erosion topographic position, and the sediment filling of the fossil caves, suggest that these could be pre-Holocene in age. One model implies a sub-glacial dissolution by meltwater (phreatic tube) and a subsequent Holocene erosion (vadose corridor). The second model implies a washing-away of sediments by glacial meltwater within a pre-holocene cave, followed by Holocene erosion. (Abstract shortened by UMI.)

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41

Gingras, Denis. "Regional flood frequency analysis by nonparametric methods." Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/7879.

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Parametric methods, currently used in regional flood frequency analysis, have numerous drawbacks and limitations, especially with regard to flood distribution selection and regional relationship form. Alternative approaches involving nonparametric methods are investigated in this thesis on a set of New Brunswick annual maximum floods. Nonparametric methods were employed at the three steps of regional analysis: at-site flood frequency analysis, homogeneous region delineation and regional relationship development. Nonparametric flood frequency analysis indicated that an annual maximum flood data set from New Brunswick contained some unimodal distributions along with many mixed distributions of bimodal and heavy-tailed shapes. A simulation study showed that sampling variability from a unimodal distribution could not account for the bimodality in nonparametric frequency analysis, confirming the existence of mixed distributions. L-moment analysis, a parametric method, confirmed that the entire set of floods from New Brunswick could not be appropriately described by a unimodal distribution. In this study, a new method is proposed for the purpose of homogeneous region delineation which effectively combines geographical considerations and flood data characteristics. The technique is based on the grouping of stations with similar density function shape, which reflect similar flood generating mechanisms. In New Brunswick, flood densities of three different shapes were grouped on a geographical basis to delineate homogeneous regions. Statistical tests based on L-moment analysis confirmed that the stations within a homogeneous bimodal region came from the same distribution. But L-moment analysis would propose either the Generalized Logistic or the Generalized Extreme Value as the regional distribution. Nonparametric frequency analysis revealed, however, that the floods within that region actually came from a mixed distribution. Nonparametric regression was employed for regional relationship development in New Brunswick; however, no significant improvement over the parametric approach of linear regression resulted. Using bootstrapping of pairs, a new method to compute the confidence interval at the center of a nonparametric regression was investigated. A comparison of linear and nonparametric regression confidence intervals can assist in evaluating the appropriateness of a linear model, and thus the need to employ nonparametric regression. Nonparametric regression was shown to be useful in screening irrational relationships that could be developed with the parametric approach. A new regional analysis methodology, involving nonparametric methods at the three steps of regional analysis, is proposed in this study, resulting in improved homogeneous region delineation, in more accurate at-site quantile estimates, and more realistic regional relationships.

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Lamirande, Iannick. "La météorisation des grès des terrasses de Bug Creek, Territoires du Nord-Ouest, Canada." Thesis, University of Ottawa (Canada), 2001. http://hdl.handle.net/10393/9136.

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The purpose of this study is to determine the origin of the sediments that lie on the treads of the cryoplanation terraces of the Richardson Mountains in the Northwest Territories, Canada. A series of 15 bore holes were done on the treads of the terraces, at the bottom of which organic material was found and dated by radiocarbon method. Petrographic, granulometric, exoscopic and geochemical analyses were done on the sandstone of the Aklavik Formation of the Bug Creek Group, on the surface sediments and on the core sediments. The objectives of these analyses were to compare the petrology of the local sandstone to the sediments found on the treads of the terraces, to determine the granulometric distribution of the sediments, to determine the scarp's rate of weathering and the chronology of the events that took place. The results show that the sediments are produced by disintegration of the local sandstone of the Aklavik Formation. The weathering of the rock causes an increase in the intergranular porosity and fractures in the grains of quartz. The weathering of the sandstone releases sands, silts and clay. This material constitutes a potential source of loess in glacial times. The accumulation of sediments that lie currently on the treads of the terraces which are derived from the weathering of the sandstone, could have begun to accumulate about 5397 +/- 84 BP or even earlier at about 9420 +/- 90 BP. A weathering rate of the rock scarp was calculated at about 20 mm/1000 years and would seem to indicate that the terraces could have started to develop in the Tertiary period.

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Eddy, Brian G. "A GIS-based fuzzy logic method for mineral potential mapping: An experiment with a geological map of the Parry Islands, Northwest Territories, Canada." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/9837.

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The application of fuzzy logic in a GIS framework is a valuable method to assist in mineral resource assessments (MRA) in areas where data are sparse. This study uses a digital geological map, backed by a digital geological data model, derived from published legends and reports. Together they function as a 'spatial-attribute relational data model' that provides evidence, in the form of derivative maps, to support mineral potential according to deposit model criteria. A knowledge-base is created with fuzzy membership functions linked to the classes of each derivative map that indicate favourability between geological features present in the database with those required by model criteria. A fuzzy-logic-based 'inference net', as implemented in the GIS modelling language, is used to combine spatial evidence to determine mineral resource potential for three mineral deposit sub-types: (1) MVT Pb-Zn, (2) Sedimentary Cu and (3) Sediment-Hosted Sulphides. This method is shown to be valuable for providing an 'audit trial' for the complex decision-making process associated with resource assessment; it provides a means for experimenting and testing various hypotheses and viewpoints associated with mineral deposit models, and mimics some aspect of how geologists determine mineral potential for a region using information provided in geological maps and mineral deposit model literature.

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Frappier, Monique G. "Late-glacial, fine-resolution pollen and sediment analyses of Little Dyke Lake sediments, Central Nova Scotia." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/10247.

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A detailed analyses of Little Dyke Lake basal sediments revealed two environmental disturbances occurred during the late-glacial. These disturbances were correlated to the previously reported Killarney and Younger Dryas climatic oscillations of the Maritimes. Organic accumulation commenced at about 11 500 yrs BP. Macrofossil and pollen evidence indicate that a forest-tundra including abundant juniper and spruce krummholz had developed 300-600 years after deglaciation. Changes in the vegetation composition were followed by an increased inwash of coarser, siltier sediment. With climate amelioration, a spruce woodland grew during the time when paleo-Indians occupied the nearby Debert site. The deposition of clayey and organic rich sediments are associated with the spruce woodland. Plants found in the understory, especially herbs and grasses, and those most apt to grow under cooler, drier and disturbed conditions then became more important in the landscape. This shift in the vegetation cover is accompanied with the sudden replacement of dark clayey sediment by a reddish coarse silt. The termination of the Killarney cooling is reflected by an increase abundance of coarse mineral sediment. However, high Juniperus pollen percentages accompany a shrub Betula maxima when maximum erosion of sands arrives to the lake basin. Changes in the character of the sediment appear to coincide with pollen changes resulting from climatic cooling. (Abstract shortened by UMI.)

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45

Hurtubise, Paula. "The distribution of lightning-caused forest fires in Quebec: 1978-1992." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/10333.

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This study is more in the nature of "exploratory" than "confirmatory" in its exploration of the temporal and spatial patterns of lightning-caused forest fires in Quebec, for the fifteen year period 1978 to 1992. Economic returns garnered from forest products, as well as species and habitat loss, make lightning-caused forest fires an important area for investigation. Natural forest fires are affected by many factors. For the purposes of this study two classes of variables are used in the investigation of the location and timing of lightning forest fires; these are species and weather data. The species data is gathered at the zone forest level and forest age is used at a mature or young level. Weather variables are limited to temperature, precipitation and thunderstorms. These are selected as a result of agreement in related literature that they are valid variables to work with. Lightning-caused fires are mapped at various temporal scales and these are compared with the species and weather data. The study reveals a dichotomous relationship, where fuel characteristics, or forest species, determine the location of fires (or spatial component), and weather dominates the temporal component. Finally, an attempt was made to make generalisations based on the findings so as to identify issues for further research. Understanding the mechanisms which drive the occurrence and distribution of lightning-caused forest fires, is one of the first steps in creating lightning-caused forest fire models.

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46

Amyotte, Henri. "Étude des variations climatiques (1921-1990) des Prairies canadiennes à partir de la classification de Köppen : une application des SIG dans l'étude des changements environnementaux." Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/10336.

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The primary objective of this thesis was to study climatic variations that occurred in the Grassland Ecoclimatic Province (Canadian Prairies), between 1921 and 1990, using a geographic information system (GIS). DBASE IV was used to establish the Koppen classification. The annual classification showed important climatic variations within the study period. No station could be associated to only one climatic classification, but to many categories. For example, the climate for Medicine Hat cannot be considered as purely semiarid (31 years classified as BSk) because it also has many years classified as Dvb (12) and Dsb (11). The climatic maps, representing each decade, showed much more information, concerning the spatial variations of the Prairies climate. The 1981-90 period had the most important surface classified as semiarid (BSk), this classification representing 7.73% of the total area covered by this study (579 800 km$\sp2$). This semiarid area, generally situated around Medicine Hat, completely disappeared if not almost between 1931 and 60. The 1931-40 map did not show the presence of very dry conditions reported for the Prairies during the Dust Bowl period (1936-38). Yearly maps created for this important dry spell, agreed with some of the information published by Phillips (1990) and Jones (1991), concerning the areas affected by the Dust Bowl droughts. However, the map for 1936 showed no station classified as BSk, despite the fact that it was very dry that year. The use of the Koppen's classification permitted a climatic analysis based on critical thresholds of temperatures and precipitation, which favor or limit vegetation growth. The use of a GIS, helped to easily process large amounts of data, in order to create climatic maps according to this climatic classification. (Abstract shortened by UMI.)

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47

Ednie, Mark. "Evaluation of the basal temperature of snow (BTS) method to map permafrost in complex mountainous terrain, Wolf Creek, Yukon Territory." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26478.

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This study is the first known attempt in North America to use the basal temperature of snow (BTS) method to predict the distribution of mountain permafrost. The study site, Wolf Creek Research Basin, Yukon Territory (60°30'N, 135°13'W), is a 195 km2 basin ranging in elevation from 650--2100 m with a mean annual air temperature of about -4°C at 1235 m a.s.l. A modeled BTS surface, based on 394 measured BTS values and with elevation and potential incoming solar radiation as independent variables, was created within a GIS environment with an r2 value similar to European results. The distribution of permafrost within the basin was identified from pits and boreholes. A subsequent logistic regression was used to compare modeled BTS values to the actual permafrost distribution in order to produce a map of permafrost probability in the basin. A significantly higher likelihood of permafrost, observed in a confined valley bottom, was attributed to cold air drainage. This occurrence was not predicted by the BTS model and data from the affected area were removed from later analyses. (Abstract shortened by UMI.)

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48

Kinnard, Christophe. "Development of solifluction lobes, Kluane Range, Yukon Territory." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26502.

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Solifluction lobe process and morphology were studied on an alpine slope (1800 m a.s.l) above Kluane Lake, south-western Yukon Territory. Contemporary rates of surface movements, measured by theodolite survey, were found to be greatest in the first two weeks of spring thaw, and movements were consistently faster on lobe treads than on lobe risers. Precise monitoring of thaw-consolidation parameters on a lobe indicated that most thaw-settlement occurred when the soil was saturated to the surface. At the slope scale, surface rates increased downslope in response to gradients in soil moisture, while long-term rates of lobe advance, inferred from 14C dating of buried organic horizons, were found to be similar among 12 dated lobes. The internal stratigraphy and age distribution of these lobes together suggest periodic advance of the fronts. Observations of lobe stratigraphy with the age distribution of buried humus points towards a conceptual model of lobe development involving the slow accumulation of soliflucted material behind a rigid riser, the progressive steepening of the riser and build-up of stress, and finally the rupture of the front and its extensive collapse on to the slope. The period for this developmental cycle was estimated to be about 600 years. This internal cycle of lobe development constitutes a serious buffer to climatic influence and must be taken into account when using solifluction lobes as paleoclimate sources.

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49

Mercier, Geneviève. "Fluctuations des fronts glaciaires dans le sud de la Passe d'Akshayuk, parc National d'Auyuittuq, Nunavut." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26717.

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This thesis discusses the actual and modern ice margin fluctuations of valley and cirque glaciers in South Akshayuk Pass, Auyuittuq National Park (Baffin Island, NU). The fluctuation of the ice margins of the Tete de Cirque, Glacier 12, Windy Lake, Niflheim and Glacier 20A glaciers were analysed using geometrically rectified aerial photographs taken between 1948 and 1977. IKONOS and LANDSAT 7 ETM+ satellite imagery covering the 1977 to 2003 period were also used. The results indicate a mean annual ice margin retreat of 8.9 m per year during the 1948 to 2003 period. Compared to south and west-facing glaciers, the ones facing north are characterize by a smaller annual retreat rate. Ice margin fluctuations since the Little Ice Age were evaluated using lichenometric measurements of Rhizocarpon geographicum found on the moraines of the Turnweather, Tete de Cirques, Glacier 12, Windy Lake, Niflheim, Glacier 20A and Sivingavuk glaciers. Moraine ages were determined by measuring the 10 largest-diameter R. geographicum thalli in the sampling area (100 m2) and converting these measurements to ages using the regional growth curve of R. geographicum . The maximum extent of the ice margins of the valley and cirques glaciers was reached between AD 800 to 1860, mainly between 1840 and 1860 at the end of the Little Ice Age period. Size-frequency distribution, an analysis of variance, and multiple comparisons showed that some moraines were subjected to local environmental variations, which affected the growth of R. geographicum, with subsequent implications in the interpretation of the lichenometric ages of the moraines and the ice margin fluctuations.

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Parenteau, Marie-Pierre. "Cartographie de la dégradation des sols par une approche géomatique dans la région d'Azilal, Haut Atlas marocain." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26739.

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Changes in land cover at a regional scale and the assessment of the risk of soil degradation at the scale of the basin require not only information on the physical structure of soil but also appropriate tools to evaluate these changes. In order to identify the areas subject to a high risk of degradation in a region of Northern Africa, a geomatics approach integrating the following variables was considered: state of soil degradation, slope length, aspect, presence of vegetation and the erosive potential of overland flow. In order to map the state of soil degradation, the Hue and the Coloration indices were calculated from remotely sensed imagery. The complimentary nature of these two spectral indices allows the identification of the different levels of soil degradation. A vegetation index, MSAVI(2), was used to obtain a map of vegetation. Geomorphometric data (aspect, slope length, stream power index), were derived from a DEM generated in a GIS from a topographic map at a 1:50 000 scale. These data were integrated in a GIS by means of a multicriterion model. Multicriterion evaluations were then performed to identify and map areas of potential degradation. Model results were then compared with a cartographic document (reference map) using the Kappa coefficient. Comparisons between modeled potential degradation and the reference map showed overall low levels of agreement. Subsequently, a visual comparison using photographs of the study area was also performed as a way to further evaluate the results of the proposed method. (Abstract shortened by UMI.)

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Dissertations / Theses on the topic 'Physical geography and topography'

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