Dissertations / Theses: 'Physical geography'

1

Brown, David Patrick. "Spatial patterns of multi-decadal climate variability in the Western United States." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280677.

Full text

Abstract:

Advances in the understanding of the nature and causes of multi-decadal precipitation and temperature variability in the western United States could assist stakeholder groups in their management and distribution of resources and personnel. The three studies undertaken in this dissertation address this issue of multi-decadal climate variability and its potential implications for user groups. In the first study, the relationship between ENSO conditions and winter precipitation in the Western U.S. is examined within the context of decadal-scale variability, as represented by phasing of the Pacific Decadal Oscillation (PDO). Spatial inconsistencies in the ENSO-precipitation relationship, commensurate with PDO phase shifts, are identified, taking the form of a 'dipole' signature across the Western U.S. This finding has implications for the knowledge of uncertainty of ENSO teleconnections, and may prove meaningful for users of climate information throughout the region. In the second study, the reliability of fall season ENSO conditions as a predictor of Western U.S. winter circulation anomalies is shown to vary depending on the phase of the PDO pattern. During the PDO cold phase of 1948-1976, fall season El Nino events tended not to precede the expected winter troughing pattern over the West, while during the PDO warm phase of 1977-1998, fall season El Nino conditions were a more reliable predictor of winter circulation anomalies over the Western U.S. Fall season La Nina conditions during both the cold and warm phases of the PDO generally correlated well with the occurrence of wintertime high-pressure ridging centered off the Pacific coast. These results highlight uncertainty on multi-decadal time scales surrounding the use of ENSO conditions as a seasonal climate forecast tool. In the third study, the spatio-temporal variability of spring season minimum temperatures in the western United States is examined as a function of multi-decadal Pacific climate variability for the period 1925--1994. Variations in minimum temperature patterns, as determined by a principal components-based regionalization analysis, indicate a significant statistical relationship between March and April minimum temperatures and an index of the PDO. These results have implications for an improved understanding of multi-decadal climate dynamics across the West, including growing season length and intensity.

APA, Harvard, Vancouver, ISO, and other styles

2

Cin, Mustafa. "The influence of direct experience of the physical environment on concept learning in physical geography." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4480/.

Full text

Abstract:

This investigation examines the relationship between children's direct experience of the physical environment and their conceptual understanding of it. In order to determine the extent of the influence of the physical environment on understanding, two groups of children living in different geographical environments were selected and their perceptions and understanding of the selected physical features related to their immediate surroundings were compared. The children's ideas about the features selected were examined using a number of research techniques. The results tended to support the central assertion of the study that the physical environment has an influence on children's conceptual understanding. The data also showed that the children held a number of alternative conceptions about their near and far environment prior to the experience of formal instruction. The relevance of these conclusions for geographical education is presented. Suggestions are made to improve the quality of teaching and learning in physical geography. Fieldwork, hardware models, simulation activities and Information and Communication Technology (ICT) are suggested for use as teaching approaches. The significance of the conclusions in the context of Turkish geographical education are also considered.

APA, Harvard, Vancouver, ISO, and other styles

3

Trend, Roger David. "Earth science and physical geography in the secondary school curriculum." Thesis, University of Exeter, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280451.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Wilke, Eric. "The Influence of Geography and Physical Ecology on Economic Development." OpenSIUC, 2010. https://opensiuc.lib.siu.edu/theses/226.

Full text

Abstract:

The World Bank estimated that 1.4 billion people in the world were living in poverty in 2008. In the last several decades, many countries have succeeded in not only reducing the number and percent of people living in poverty, but also increasing overall economic strength. Yet, while some countries have succeeded, many others have not. This unequal growth has led to newer development theories that include the importance of geography and the physical environment. A leading researchers in this field, Jeffrey Sachs, argues that geography and physical ecology, along with some economic indicators are responsible for this difference in success. This research tests the theory that was suggested by Sachs. Spatial statistics techniques were used to analyze these theories with new methods and shed new light on the variables. Results showed that certain variables (coastal population, proximity to a major market) were not as significant in development, when regional differences were accounted for. However, other variables, particularly malaria and consumption, were very significant. In addition, testing variables regionally provided much better results than previously-used global models. Lastly, the results were used to analyze outliers. The outliers helped to discuss other important variables and pave the way for future research.

APA, Harvard, Vancouver, ISO, and other styles

5

Amante, Christopher Joseph. "Consideration of Elevation Uncertainty in Coastal Flood Models." Thesis, University of Colorado at Boulder, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10844867.

Full text

Abstract:

Digital elevation models (DEMs) are critical components of coastal flood models. Both present-day storm surge models and future flood risk models require these representations of the Earth’s elevation surface to delineate potentially flooded areas. The National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI) develops DEMs for United States’ coastal communities by seamlessly integrating bathymetric and topographic data sets of disparate age, quality, and measurement density. A current limitation of the NOAA NCEI DEMs is the accompanying non-spatial metadata, which only provide estimates of the measurement uncertainty of each data set utilized in the development of the DEM.

Vertical errors in coastal DEMs are deviations in elevation values from the actual seabed or land surface, and originate from numerous sources, including the elevation measurements, as well as the datum transformation that converts measurements to a common vertical reference system, spatial resolution of the DEM, and interpolative gridding technique that estimates elevations in areas unconstrained by measurements. The magnitude and spatial distribution of vertical errors are typically unknown, and estimations of DEM uncertainty are a statistical assessment of the likely magnitude of these errors. Estimating DEM uncertainty is important because the uncertainty decreases the reliability of coastal flood models utilized in risk assessments.

I develop methods to estimate the DEM cell-level uncertainty that originates from these numerous sources, most notably, the DEM spatial resolution, to advance the current practice of non-spatial metadata with NOAA NCEI DEMs. I then incorporate the estimated DEM cell-level uncertainty, as well as the uncertainty of storm surge models and future sea-level rise projections, in a future flood risk assessment for the Tottenville neighborhood of New York City to demonstrate the importance of considering DEM uncertainty in coastal flood models. I generate statistical products from a 500-member Monte Carlo ensemble that incorporates these main sources of uncertainty to more reliably assess the future flood risk. The future flood risk assessment can, in turn, aid mitigation efforts to reduce the vulnerability of coastal populations, property, and infrastructure to future coastal flooding.

APA, Harvard, Vancouver, ISO, and other styles

6

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

7

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

8

Arfeuille, Gilles. "Modelling the interannual variability of the Arctic sea ice cover." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21505.

Full text

Abstract:

A thermodynamic-dynamic sea ice model based on the granular material rheology of Tremblay and Mysak is used to study the interannual variability of the Arctic sea ice cover during the 41-year period 1958--1998. The sea ice model is coupled to both a mixed layer ocean model and a one-layer thermodynamic atmospheric model. The model is first run with monthly climatology for most of the thermodynamic and dynamic forcing components to obtain a stable periodic seasonal cycle. For the 41-year run, the monthly wind stress forcing is derived from analyzed sea level pressures from the National Centers for Environmental Prediction (NCEP Reanalysis) data. The atmospheric thermodynamic forcings are based on monthly climatology.
In this thesis we explore the high-latitude sea ice circulation and thickness changes due to year-to-year variations in the wind field. We focus our study on the interannual variability of the sea ice. volume in the Arctic Basin, and the subsequent changes in the export of sea ice from the Arctic Basin into the northern North Atlantic via Fram Strait. (Abstract shortened by UMI.)

APA, Harvard, Vancouver, ISO, and other styles

9

Yi, Dingrong 1969. "Singular value decomposition of Arctic Sea ice cover and overlying atmospheric circulation fluctuations." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=20610.

Full text

Abstract:

The relationship between the Arctic and sub-Arctic sea-ice concentration (SIC) anomalies, particularly those associated with the Greenland and Labrador Seas' "Ice and Salinity Anomalies (ISAs)" occurring during the 1960s/1970s, 1970s/1980s, and 1980s/1990s, and the overlying atmospheric circulation (SLP) fluctuations is investigated using the Empirical Orthogonal Function (EOF) and Singular Value Decomposition (SVD) analysis methods. The data used are monthly SIC and SLP anomalies, which cover the Northern Hemisphere north of 450 and extend over the 38-year period 1954--1991.
One goal of the thesis is to describe the spatial and temporal variability of SIC and atmospheric circulation on interannual and decadal timescales. Another goal is to investigate the nature and strength of the air-ice interactions. The air-ice interactions are investigated in detail in the first SVD mode of the coupled variability, which is characterized by decadal-to-interdecadal timescales. Subsequently, the nature and strength of the air-ice interactions are studied in the second SVD mode, which shows a long-term trend. The interactions in the third SVD mode which has an interannual timescale are briefly mentioned. (Abstract shortened by UMI.)

APA, Harvard, Vancouver, ISO, and other styles

10

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

11

Diem, Jeremy Everett 1972. "A climatological examination and modeling of carbon monoxide concentrations in central Phoenix, Arizona." Thesis, The University of Arizona, 1997. http://hdl.handle.net/10150/291965.

Full text

Abstract:

This thesis examines the temporal characteristics and climatology of wintertime carbon monoxide (CO) concentrations in central Phoenix (AZ). Variations in CO concentrations on several temporal scales are explored to determine the relationship between atmospheric conditions, CO concentrations, and motor vehicle traffic levels as well as to spotlight the timing of high CO concentrations. Typical surface atmospheric conditions that are related to high and low CO mornings are revealed through compositing. Finally, a set of CO forecasting models are developed that predict 3 AM 8 hour average CO concentrations. Important results are as follows. The first three weeks of December have the most CO exceedance days. High CO concentrations are associated with anticyclonic conditions while low CO concentrations are linked to the passage of a cold front or trough. Final models had little systematic mean squared error and predictions that were within 1 ppm of the observed CO concentration.

APA, Harvard, Vancouver, ISO, and other styles

12

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

14

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

15

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

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

16

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

17

Foteu, Madio Eliane S. "Physical and geotechnical influences on peat instability." Thesis, Kingston University, 2013. http://eprints.kingston.ac.uk/27600/.

Full text

Abstract:

There is an urgent need to develop robust tools and policies for stability and hazard risk assessments in order to manage upland peat landslides in locations such as the British Isles where they have frequently occurred and caused harm to the environment. One of the particular difficulties is that reliable values of peat strength are difficult to obtain. The objectives of this research were to establish the nature of any relationships between the strength characteristics and the botanical, physical and chemical properties of the peat, and to determine whether palaeobotanical analyses of samples of the basal peat can provide a reliable indication of potential instability in upland blanket bogs. The research was carried out at the Straduff Townland (Co. Sligo), Slieve Anierin (Co. Leitrim) and Slieve Rushen (Co. Cavan) landslides, all located in northwest Ireland, from the margins of which monolith and core peat samples were collected. Standard and validated paleobotanical, chemical and geotechnical protocols, modified or refined where necessary to suit the nature of the peat, were used in the study. The triaxial, direct shear and tensile strength tests were conducted using experimental very low stress conditions in order to fully replicate in-situ conditions. The reliability of the measured strength parameters was examined by performing deterministic and probabilistic stability analyses of the failed slopes using industry-standard „limit equilibrium‟ software (SLOPE/W). The nature, extent and spatial distribution of the hydrocarbons unexpectedly found in the basal peats during the fieldwork were also investigated. This research found that blanket peat dominated by monocotyledons (with mainly E. vaginatum) is likely to be susceptible to failure because its „effective structural properties‟, specifically the high degree of humification and low fibre content of its basal peat, cause it to have very low strength and also therefore a very low bearing capacity. Furthermore, monocotyledons or its remains in peat have morphological, chemical, biological features that can promote bogflow-type failure. These may include for example (i) their parallel and elongated leaf veinations that promote flow, (ii) the genesis of hydrocarbons such as bitumen from their lignified tissues and (ii) being host to a hydrocarbon-producing aphid Colopha compressa. Laboratory measurements of undrained strength of the weak basal peats were consistently < 3 kPa, and deterministic stability analyses revealed that the value of the tensile strength can be used as an indicator of the undrained shear strength. A new classification (i.e. "the modified fibre content scheme") and a modified procedure for assessing upland peat failure for construction projects has been proposed based on peat fibre and humification characteristics and their apparent influences on peat strength. Deposits of hydrocarbons such as bitumens within the basal peat constitute a previously unrecognised factor that probably contributed to the occurrence of the studied landslides due to their hydrophobic properties.

APA, Harvard, Vancouver, ISO, and other styles

18

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.

Full text

Abstract:

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.)

APA, Harvard, Vancouver, ISO, and other styles

19

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

20

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.

Full text

Abstract:

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.)

APA, Harvard, Vancouver, ISO, and other styles

21

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

22

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

23

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

24

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.

Full text

Abstract:

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.)

APA, Harvard, Vancouver, ISO, and other styles

25

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

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

26

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.

Full text

Abstract:

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.)

APA, Harvard, Vancouver, ISO, and other styles

27

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.

Full text

Abstract:

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.)

APA, Harvard, Vancouver, ISO, and other styles

28

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.

Full text

Abstract:

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.)

APA, Harvard, Vancouver, ISO, and other styles

29

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

30

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.

Full text

Abstract:

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.)

APA, Harvard, Vancouver, ISO, and other styles

31

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

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

32

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

33

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

34

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.

Full text

Abstract:

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.)

APA, Harvard, Vancouver, ISO, and other styles

35

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

36

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.

Full text

Abstract:

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.)

APA, Harvard, Vancouver, ISO, and other styles

37

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.

Full text

Abstract:

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.)

APA, Harvard, Vancouver, ISO, and other styles

38

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

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

39

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

40

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.

Full text

Abstract:

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.)

APA, Harvard, Vancouver, ISO, and other styles

41

Van, Wychen Wesley. "Spatial and Temporal Variations in Ice Motion, Belcher Glacier, Devon Island, Nunavut, Canada." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28611.

Full text

Abstract:

This study presents surface ice motion patterns across Devon Ice Cap, with a particular focus on the Belcher Glacier drainage basin. Between summer 2007 and summer 2009, continuous differential GPS (dGPS) measurements were made to determine the motion at points along the centerline of the Belcher Glacier with ∼cm accuracy. In summer 2008, marker stakes were set out on all accessible tributaries in the Belcher basin, with each stake being surveyed with dGPS several times throughout the season. Using synthetic aperture radar (SAR) speckle tracking techniques new velocity maps were produced of seasonal changes in ice motion for the Belcher Glacier. These were validated against the field dGPS results. Ground penetrating radar (GPR) was used to determine the ice depths of each tributary basin in the Belcher Glacier study region. These ice depths are combined with velocities derived from the speckle tracking results to create flux gates which allow for estimates of total ice discharge for the Belcher basin. These volume estimates can be used to improve mass loss estimates for future modeling of Devon Ice Cap. The velocity results are compared to the work of Burgess et al (2005), who provided flow dynamics and mass loss from the Devon Ice Cap and Belcher Glacier systems using interferometry and speckle tracking of ERS 1/2 data from the mid-1990s and Radarsat-1 data from 2000. These comparisons reveal higher ice velocities on a large glacier in the southeast part of the ice cap (Southeast2 Glacier), which agrees with recent thickening of the stagnant ice into which the glacier drains.

APA, Harvard, Vancouver, ISO, and other styles

42

Throop, Jennifer. "Spatial and temporal variability in permafrost conditions, northern Canada." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28663.

Full text

Abstract:

The data from nine permafrost thermal monitoring sites at widely separated locations across northern Canada were examined individually, spatially, and temporally. Three sites are in Nunavut (Alert, Iqaluit, and Baker Lake), two in the Northwest Territories (Table Mountain and Wrigley), and four in the Yukon Territory (Wolf Creek, Sixty Mile, Alpine Burwash, and Red Creek). The sites have between one and five boreholes that are instrumented to between 3 and 60 m with records of varying durations. Most of the boreholes are co-located with weather stations recording air temperatures and snow depths. A comprehensive analysis of each site is presented assessing the relations between climate and permafrost temperatures, both in the near surface and at depth. The local characteristics at each site, and among sites, were assessed using various methods including mean annual temperatures, surface and thermal offsets, n-factors, and the apparent thermal diffusivity. Time series analyses were conducted at sites with longer air and ground temperature data records. Regional mean annual air temperatures were defined as the primary determinant of permafrost temperatures at the study sites, but this relationship is modulated by snow (depth, duration, and timing) and vegetation characteristics, the substrate material, and the moisture content, both frozen and unfrozen, within the active layer and the permafrost. Of the study sites, permafrost temperatures at Iqaluit are the most sensitive to changes in climate due to little buffering between the air and the permafrost, and permafrost temperatures at Wrigley, Table Mountain, and Wolf Creek are the least sensitive to changes in climate due to the significant latent heat effects in this isothermal permafrost associated with high amounts of ice and unfrozen moisture. Climatic cooling was observed in the earlier part of the record at Iqaluit from the late 1940's until the early 1990's, and at Alert between the early 1950's and the mid 1970's. Climatic warming was observed in mean annual and winter average temperatures at Alert, Baker Lake, Iqaluit, Table Mountain, and Wrigley in recent decades. This was reflected in warming permafrost temperatures at all of the long-term thermal monitoring sites. The greatest magnitude of ground temperature warming occurred at Iqaluit (+1.6 to +1.9°C/decade), then Alert (+0.2 to +0.6°C/decade), and Baker Lake (+0.3°C/decade). Ground temperatures at Table Mountain warmed the least (+0.1 to +0.2°C/decade), but the warming at this site is important because it represents a progressive change in unfrozen moisture in the fine-grained, ice rich permafrost.

APA, Harvard, Vancouver, ISO, and other styles

43

Telmer, Kevin H. "Biogeochemistry and water balance of the Ottawa River basin." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21018.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Rocheleau, Martine. "Sédimentologie des paléoplages de la plaine d'Old Crow, Territoire du Yukon, Canada." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq20949.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Daviau, Jean-Luc. "Spatially explicit regional flood frequency analysis using L-moment, GIS and geostatistical methods." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq36680.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Cabana, Yannick. "Étude comparative par analyse chronologique et sédimentologique d'accumulations éoliennes du Pléistocène supérieur et de l'Holocène dans le nord-ouest du Yukon." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq36670.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Vigneux, Sonia-Gabrielle. "Relations entre les diverses concrétions cavernicoles dans la région de l'Outaouais québécois et de la Haute Gatineau." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0001/MQ36753.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Viau, André E. "Lake level variations and global hydrological change, a spatio-temporal analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0004/MQ45255.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Mihalasky, Mark John. "Mineral potential modelling of gold and silver mineralization in the Nevada Great Basin, a GIS-based analysis using weights of evidence." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0015/NQ45186.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Chauret, Yanie. "Étude sur le développement des calcrètes de fissures du Yukon septentrional, du pléistocène à aujourd'hui." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0019/MQ48142.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Physical geography'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles