Dissertations / Theses: 'Geomorphology'

7

Bisht, Deepti. "Structure and geomorphology, southeast Dinarides, Croatia." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708060.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Moore, Edwin Neville. "Glacial geology and geomorphology of Weardale." Thesis, Durham University, 1994. http://etheses.dur.ac.uk/1625/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Alsheeb, Ali I. M. "Coastal geomorphology of the Qatar Peninsula." Thesis, Swansea University, 1988. https://cronfa.swan.ac.uk/Record/cronfa43167.

Full text

Abstract:

This study concerns the geomorphology of the coastline of the Qatar Peninsula. In all, the coastline is approximately 750kg long and is dominated by Tertiary and Quaternary limestone rocks. Since little previous work has been carried out into the coastal geomorphology of the Arabian Gulf in general and Qatar in particular, a fundamental task was to undertake a classification of the coastal types. There are: 1) sand dunes and sheets; 2) sabkhas; 3) cliffs; 4) coral reefs; 5) beaches and 6) mangroves. A second task in this study was to investigate the processes responsible for the different coastal types. This was achieved using different field and laboratory techniques. Aerial photo interpretation enabled the nature of forms to be better understood and photos of different dates enabled temporal change to be investigated. Both Abeny level and Dumpy level were used to show the forms of the different coastal types. Particle size analysis was used to differentiate the origin of sediments. Laboratory experiments of salt weathering on rocks of the Qatar shoreline indicated the effectiveness of this process. SEM analysis showed the mix of aeolian and beach transport histories in the coastal sediments. The study shows that the following factors are particularly important in producing the distinctiveness of the Qatar coastline: these are warm sea temperatures leading to rapid chemical weathering; the prevailing NW ('shamal') wind, which influences strongly sand supply at the coast and longshore drift direction; and a low tidal range.

APA, Harvard, Vancouver, ISO, and other styles

10

Gales, Jenny Anne. "The geomorphology of Antarctic submarine slopes." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/the-geomorphology-of-antarctic-submarine-slopes(d117ad12-927b-44f1-bf67-d195e2fef51b).html.

Full text

Abstract:

The Antarctic continental margin contains a diverse range of continental slope morphologies, including iceberg keel marks, gullies, channels, mass-wasting features (slides, slumps), ridges, furrows, mounds and trough mouth fans. These features vary significantly in morphology, with bedforms varying in size (width, amplitude and length), shelf incision, sinuosity, branching order, spatial density and cross-sectional shape. The processes which form these features and the environmental controls influencing their morphology are not well documented or well constrained. Understanding the processes operating on the Antarctic continental margin is essential for interpreting seafloor erosion patterns, continental margin evolution, slope instability and sediment core records from the continental slope and rise. Through quantitative analysis of multibeam bathymetric data along >2670 km of the outer shelf and upper-slope of high latitude continental margins, five distinct Antarctic gully types are identified. Gully morphology was found to vary with local slope character (slope geometry, gradient), regional factors (location of cross-shelf troughs, trough mouth fans and drainage basin size), sediment yield and ice-sheet history. Most gullies are likely formed by: (1) flows generated as a result of the release of subglacial meltwater from beneath an ice-sheet grounded to the shelf edge during glacial maxima; (2) turbidity currents initiated by intense iceberg scouring; or (3) small-scale mass-wasting. Erosion by cascading dense water overflow does not form the deeply incised and V-shaped gullies that occur over much of the Antarctic continental margin. A comparison of some Arctic and Antarctic gully morphologies shows that the Antarctic gullies have much deeper mean incision depths and greater shelf-incisions, suggesting that they either formed over significantly longer periods, or by a greater release of meltwater in the areas with greater gully incision depths. The first morphological analysis of the southern Weddell Sea outer shelf and upper slope is presented. Two large and relatively recent submarine slides occur on the Crary Fan, the first Quaternary slides to be documented on an Antarctic trough mouth fan. These slides provide evidence for recent large-scale mass-wasting events on the Antarctic continental margin. The interpretation of bedforms on the outer shelf of the southeastern Weddell Sea provide insight into the timing and extent of past ice and points to grounded ice near to the shelf edge during the Late Quaternary.

APA, Harvard, Vancouver, ISO, and other styles

11

Alqahtani, Faisal A. "3D seismic geomorphology of fluvial systems." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6180.

Full text

Abstract:

Fluvial sandstones constitute one of the major clastic petroleum reservoir types in many sedimentary basins around the world. This is especially true in the Tertiary basins of Southeast Asia, which display a wide range of fluvial channel reservoir types. This study is based on the analysis of high-resolution, shallow (seabed to ca. 500 m depth) 3D seismic data which provide exceptional imaging of the geometry, dimension and temporal and spatial distribution of fluvial channels. The Malay Basin comprises a thick (>8 km), rift to post-rift Oligo-Miocene to Pliocene basin-fill. The youngest (Miocene to Pliocene), post-rift succession is dominated by a thick (1-5 km), cyclic succession of coastal plain and coastal deposits, which accumulated in a humidtropical climatic setting. This study focuses on the Pleistocene to Recent (ca. 500 m thick) succession, which comprises a range of seismic facies, mainly reflecting changes in fluvial channel style and gross stratigraphic architecture. The succession has been divided into four seismic units (Unit 1-4), bounded by basin-wide stratal surfaces. Units 3 and 4 have been further divided into two sub-units. Two types of boundaries have been identified: 1) a boundary that is defined by a regionally-extensive erosion surface at the base of a prominent incised valley (e.g. Horizons C.1 and D.1); 2) a sequence boundary that is defined by more weakly-incised, straight and low-sinuosity channels which is interpreted as lowstand alluvial bypass channel systems (e.g. Horizons A, B, C, and D). Each unit displays a predictable vertical change of the channel pattern and scale, with wide low-sinuosity channels at the base passing gradationally upwards into narrow high-sinuosity channels at the top. The wide variation in channel style and size is interpreted to be controlled mainly by the sea-level fluctuations on the widely flat and tectonically-quiescent Sundaland Platform.

APA, Harvard, Vancouver, ISO, and other styles

12

McCarthy, Forrest G. "Landcover change in Arctic Alaska observations through repeat photography /." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1594501471&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Thompson, Chris J. Physical Environmental &amp Mathematical Sciences Australian Defence Force Academy UNSW. "The geomorphology of Southeast Australian mountain streams." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Physical, Environmental and Mathematical Sciences, 2006. http://handle.unsw.edu.au/1959.4/38681.

Full text

Abstract:

This thesis is a study of the morphology and sediment transport dynamics of mountain streams in southeast Australia. Mountain streams represent important geomorphological and ecological systems in Australia which have hitherto been poorly studied. The variability of mountain stream reach morphology was investigated at the regional scale using topographical surveys and sediment sampling techniques. Study sites were stratified by slope and local lithology. Eight channel-morphologies including Bedrock, Cascade, Step-pool, Planebed, Pool-Riffle, Cascade-pool, Riffle-step and Infilled, were identified using an objective statistical approach. Overall, channel types were found to correspond to existing reach-scale mountain stream templates. Five morphologies were associated with a specific lithology type which controlled the size and shape of grains supplied to the channels. Differences in coarse sediment transport processes between morphologies were investigated using stream monitoring techniques and Optically Stimulated Luminescence (OSL) dating. Monitoring results from a 3 year period indicated that channel beds are resistant to entrainment with shear stress thresholds for bedload transport ranging between 64 to 74 N/m2. Transport of reach median grain sizes requires floods that exceed bankfull discharge. Existing competence equations were found to over-predict the hydraulic driving force and consequently, a modified entrainment model was used to account for the regional channel characteristics. OSL dating was investigated as a tool to provide data on long-term sediment transport processes. Minimum age model results from the OSL dates show overall agreement with a selected entrainment model, and indicate differences in sediment transport dynamics between some reach morphology types. A regime model was used to quantify the physical domains of different channel morphologies. Limitations of the model were overcome by modifying the sediment supply surrogate to better reflect the dominant transported bedload size. Morphology types were delineated according to different sediment transport capacity-sediment supply domains. The distribution of channel morphology types within a series of catchments in southeast Australia was modelled within a GIS platform using the diagnostics of reach morphology derived from this study. The model provides a conceptual framework to evaluate the potential link between channel form, potential habitat diversity and aquatic biodiversity within the channel network in mountain streams.

APA, Harvard, Vancouver, ISO, and other styles

14

Elvidge, Elizabeth Mary. "Aspects of glacial geomorphology of northern Scotland." Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261199.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Redda, Araya. "Quaternary geomorphology of the Vale of Edale." Thesis, University of Sheffield, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392762.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Saville, Christopher. "Fluvial and tectonic geomorphology of orogenic plateaux." Thesis, Durham University, 2013. http://etheses.dur.ac.uk/7718/.

Full text

Abstract:

Geomorphology is an expression of processes acting upon an area. The links between driving processes and the resulting geomorphology are far from being fully understood. This thesis investigates controls on the dynamics and behaviour of fluvial systems from the interior of orogenic plateaux to the tectonically active plateaux margins. Orogenic plateaux provide a good study area by juxtaposing different tectonic and climatic settings that are served by the same sediment transport systems, allowing for observation of different variables on the same or similar fluvial systems. This is the first time that rivers draining orogenic plateaux have been extensively investigated. The Turkish-Iranian and Tibetan plateaux are the study areas. Forms of rivers draining from plateaux interiors, through the plateaux margins are analysed, along with alluvial fans within both the plateaux interior and plateaux margins. Plateau draining rivers act as the major route for material leaving the plateau region and a first-order control on erosive processes retarding plateau growth. Alluvial fans redistribute material within the plateau interior, enhancing the low relief topography diagnostic of a plateau. It is found that rivers draining plateaux show a sigmoidal form associated with the edge of the plateaux. High gradients and curvatures occur within the mountain ranges at the plateaux margins, while low values are present within the plateau interiors. Modelling work demonstrates that such forms to be likely responses for all plateau-draining rivers, but are most sensitive to the effects of precipitation upon a river’s ability to incise in-to the underlying sedimentary cover and bedrock lithologies. Alluvial fans in orogenic plateau regions are larger and with a lower surface gradient within the plateau interior than those nearer the active tectonic margins. It is theorised that this is due to the lack of lateral control on the accommodation space of alluvial fans within the plateau interior.

APA, Harvard, Vancouver, ISO, and other styles

17

Mathew, Manoj joseph. "Geomorphology and Morphotectonic Analysis of north Borneo." Thesis, Lorient, 2016. http://www.theses.fr/2016LORIS408/document.

Full text

Abstract:

L’analyse géomorphologique d'une zone d’étude permet d’identifier et de comprendre le rôle des facteurs de contrôle tectonique et climatique sur l’évolution passée, récente et future de la surface topographique. Ce travail de recherche porte sur l’analyse géomorphologique des paysages du secteur de l’état de Sarawak, localisé au nord de l’île de Bornéo en contexte tropical. À travers l'analyse morphotectonique des deux plus grands bassins versants : le bassin versant du Rajang et du Baram, il a été possible de dresser une première évaluation du cadre morpho-tectonique de la région et des conséquences topographiques. Les bassins versants étudiés et situés au centre et au Nord de Sarawak drainent une superficie totale d'environ 75 000 km². L'île de Bornéo présente une couverture végétale dense spécifique aux régions tropicales, et demeurant souvent difficile d’accès. Cette île témoigne de terrains montagneux et accidentés, découpés par de vallées profondes aux flancs abruptes, entraînant des taux de dénudation notables depuis le Miocène. La première contribution est d’identifier les principales failles mineures et majeures ayant par réactivation participées au rajeunissement de la surface topographie à l’échelle régionale. À l’échelle des deux bassins versants, les facteurs géomorphologiques suivants comme l’intégrale hypsométrique, les facteurs d’asymétrie, les anomalies de pente identifiées le long des rivières ont été cartographiées à l’aide des techniques d'autocorrélation spatiale. Les principaux mouvements verticaux identifiés sont accommodés le long des accidents structuraux majeurs et des chevauchements spécifiques de la zone Nord de Bornéo. Parmi les autres résultats, il est également observé des surfaces planes reliques, à haute altitude, n’ayant pas encore réajustées leur surface d’équilibre depuis les 5 derniers Ma malgré de phases rapides de soulèvement connues. Enfin, à l’échelle de la zone d’étude, où les contrastes lithologiques sont absents, la présence de nombreuses ruptures de pente ou knickpoints sont observés le long des principaux profils longitudinaux des rivières. Les ruptures de pente fortes sont dans la majorité corrélables aux principaux accidents structuraux. Des observations de terrain viennent renforcer nos hypothèses par la présence de terrasses fluviatiles soulevées. Ce travail d’analyse d’indices géomorphologiques complétés par des observations de terrain permet alors de proposer un modèle synthétique des principaux facteurs de contrôle responsables du rajeunissement de la surface topographique de l’état de Sarawak jusqu’alors sous-estimé et méconnu Geomorphic assessment of a region is considered to be crucial in understanding the present day landscapeand forces that have acted and is currently acting on the ever evolving topography. This thesis explores the geomorphology of the tropical landscape of Sarawak, north Borneo through morphotectonic analysis of two of the largest drainage basins of the entire Borneo Island: the Rajang and Baram basin; making this work the first systematic tectono-geomorphic evaluation of the region. The island of Borneo is enveloped by thick rainforests, hostile rugged mountainous terrain with deep and steep valleys, and is characterized by high denudation rates since Miocene. The studied drainage basins flow across entire central and north Sarawak and drain a total combined area of ca. 75, 000 km². The first contribution to the field is by conducting a study on the presence of active tectonic forces that modify the topography through rejuvenation of major and minor faults. The analysis using basin-scale hypsometry, asymmetry factor, normalized channel steepness index and spatial autocorrelation techniques showed that the landscape has been rejuvenated and experiences tectonic deformation to present-day in the form of active folding of the fold-thrust orogenic belts of the Interior Highlands which form the backbone of Borneo. From the results, we highlighted the presence of relict surfaces of landscapes which were isolated at high elevations unable to balance a rapid uplift phase experienced after 5 Ma. We extended the study in order to identify the current stage of landscape development by conducting stream profile analysis which displayed an array of knick-zones and knick points devoid of lithological and climatic controls. Deep V-shaped valleys formed in the zones that demonstrated active folding of the highlands also revealed relief anomalies highlighted through topographic analysis. We showed that enhanced orographic precipitation following the rapid creation of relief has supported adjustment of the topography to a state of transience. In the next part of this work, we conducted swath profile analysis, minimum bulk erosion and channel steepness anomaly maps in order to identify the role of rapid incision in exacerbating erosion rates as a response to tectonic and climatic forcing. We show that there exists a coupling between incision rates, precipitation and channel steepness which shows a relation of direct proportionality. Extensive geomorphic and sedimentological field campaigns were carried out in order to substantiate our results and conclusions. The field work revealed the presence of uplifted fluvial terraces, waterfalls and cataracts corresponding to knick-points identified by us. Finally, we combine our results from the geomorphic analysis and stratigraphic field work in order to construct a conceptual model showing the geomorphic evolution of Sarawak, north Borneo

APA, Harvard, Vancouver, ISO, and other styles

18

Borsa, Adrian Antal. "Geomorphology of the salar de Uyuni, Bolivia /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3171116.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

20

Belliard, Jean-Philippe. "Bio-physical controls on tidal network geomorphology." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/7904.

Full text

Abstract:

Looking over a tidal wetland, the tidal network characterised by its intricate system of bifurcating, blind-ended tidal courses clearly stands out from the overall landscape. This tidal landform exerts a fundamental control on the morphology and ecology within the tidal environment. With today’s recognition of the ecological, economical and societal values provided by tidal wetlands, which has been notably reflected in the development of restoration management strategies across Europe and USA, there is a need to fully understand the nature and development of tidal networks as well as their relationships with associated landforms and biotic components (e.g. vegetation), to eventually guarantee the success of current and future restoration practices. Accordingly, this research aims to bring further insights into the bio-physical controls on the geomorphology of tidal networks. To this end, a combination of remote sensing, modelling and field activities was employed. A geo-spatial analysis was performed at Queen Mary, University of London (UK), to address the variability of tidal network patterns. A series of network scale morphometric variables was extracted using airborne LiDAR data among selected tidal networks across the UK depicting different planview morphologies, and supplemented with the collection of corresponding marsh scale environmental variables from published sources. Multivariate statistics were then performed to characterise the variability of tidal network patterns and identify the inherent environmental controls. The analysis has revealed that every network type can be characterised based upon measures of network size and complexity, with each network pattern depicting proper morphometric aspects. Particularly, the stream Strahler order and the median depth of the network main channel have the highest discriminating weight on the patterns investigated. High correlation between the latter variable and network main channel width has revealed that linear, linear-dendritic and dendritic networks followed a transitional gradient in their aspect ratio approximated by a power law and thus are seen to depict similar erosional processes. To the contrary, meandering networks clearly depart from this relationship, and show particular segregation in their aspect ratios with respect to dendritic networks. Globally, differentiation on network morphometric properties has been linked to environmental conditions specific to the marsh physiographic setting within which a tidal network develops. Conceptually, tidal networks seem to adapt to marsh environmental conditions by adopting suitable morphologies to drain their tidal basin effectively. An eco-geomorphic modelling framework was developed at University of Trento (Italy), to address tidal network morphological development. In line with current theories as well as modelling advances and challenges in the field of tidal network ontogeny, emphasis was thus placed on the investigation of tidal channel formation and evolution in progressive marsh accretional context. Under these environmental conditions, tidal network development can be ascribed to the combination of two channel-forming processes: channel initiation results from bottom incisions in regions where topographic depressions occur; channel elaboration results from differential deposition, contributing to the deepening of the tidal channels relative to the adjacent marsh platform. Further evolutionary stages including channel reduction proceed from the horizontal progradation of the marsh platform which may lead eventually to channel infilling. Moreover, both qualitative and quantitative results allude to an acceleration of the morphological development of the synthetic tidal networks with increasing sediment supply. These different observations thus emphasise the prevalence of depositional processes in shaping tidal channels. In a second stage, the investigation was extended to the role of the initial tidal flat morphology as an inherent control on tidal network development, by considering different scenarios of topographic perturbations, which has revealed its legacy on tidal network morphological features. Modelling experiments have also acknowledged salt marsh macrophytes as a potential control on network evolution depending on their biomass distribution within the tidal frame. However, tidal channel morphodynamcis appears to be sensitive to the way biomass growth is mathematically parameterised in the model. In view of the current challenges in transcribing mathematically such a dynamic process and the relevance of bio-physical interactions in driving salt marsh and tidal network evolution, a field survey was conducted in a temperate salt marsh in the Netherlands, as part of the mobility to UNESCO-IHE (Netherlands) in partnership with University of Antwerp (Belgium), to assess vegetation distribution and productivity in the tidal frame. Particularly, emphasis was placed on extending investigations on the possible presence of relationships involving vegetation properties in different climatic and ecological conditions from those characterising these previously documented relationships. Regression analysis has revealed that biomass growth can be expressed as a linear function of marsh relative elevation, providing therefore direct empirical validation for corresponding assumptions reported in the literature and used in the present modelling framework; surprisingly, that increase did not correlate with an increase in species richness and diversity. Analysis of likely associations between vegetation morphometrics and total standing biomass yielded only a single linear relationship linking the latter variable to stem height. In truth, these observations may bear reconsiderations on the global validity of the assumptions used in the formulation of some eco-geomorphic processes which are applied in the study and prediction of wetland resiliency facing climate change.

APA, Harvard, Vancouver, ISO, and other styles

21

Belliard, Jean-Philippe. "Bio-physical controls on tidal network geomorphology." Doctoral thesis, Università degli studi di Trento, 2014. https://hdl.handle.net/11572/368998.

Full text

Abstract:

Looking over a tidal wetland, the tidal network characterised by its intricate system of bifurcating, blind-ended tidal courses clearly stands out from the overall landscape. This tidal landform exerts a fundamental control on the morphology and ecology within the tidal environment. With todayâ€™s recognition of the ecological, economical and societal values provided by tidal wetlands, which has been notably reflected in the development of restoration management strategies across Europe and USA, there is a need to fully understand the nature and development of tidal networks as well as their relationships with associated landforms and biotic components (e.g. vegetation), to eventually guarantee the success of current and future restoration practices. Accordingly, this research aims to bring further insights into the bio-physical controls on the geomorphology of tidal networks. To this end, a combination of remote sensing, modelling and field activities was employed. A geo-spatial analysis was performed at Queen Mary, University of London (UK), to address the variability of tidal network patterns. A series of network scale morphometric variables was extracted using airborne LiDAR data among selected tidal networks across the UK depicting different planview morphologies, and supplemented with the collection of corresponding marsh scale environmental variables from published sources. Multivariate statistics were then performed to characterise the variability of tidal network patterns and identify the inherent environmental controls. The analysis has revealed that every network type can be characterised based upon measures of network size and complexity, with each network pattern depicting proper morphometric aspects. Particularly, the stream Strahler order and the median depth of the network main channel have the highest discriminating weight on the patterns investigated. High correlation between the latter variable and network main channel width has revealed that linear, linear-dendritic and dendritic networks followed a transitional gradient in their aspect ratio approximated by a power law and thus are seen to depict similar erosional processes. To the contrary, meandering networks clearly depart from this relationship, and show particular segregation in their aspect ratios with respect to dendritic networks. Globally, differentiation on network morphometric properties has been linked to environmental conditions specific to the marsh physiographic setting within which a tidal network develops. Conceptually, tidal networks seem to adapt to marsh environmental conditions by adopting suitable morphologies to drain their tidal basin effectively.An eco-geomorphic modelling framework was developed at University of Trento (Italy), to address tidal network morphological development. In line with current theories as well as modelling advances and challenges in the field of tidal network ontogeny, emphasis was thus placed on the investigation of tidal channel formation and evolution in progressive marsh accretional context. Under these environmental conditions, tidal network development can be ascribed to the combination of two channel-forming processes: channel initiation results from bottom incisions in regions where topographic depressions occur; channel elaboration results from differential deposition, contributing to the deepening of the tidal channels relative to the adjacent marsh platform. Further evolutionary stages including channel reduction proceed from the horizontal progradation of the marsh platform which may lead eventually to channel infilling. Moreover, both qualitative and quantitative results allude to an acceleration of the morphological development of the synthetic tidal networks with increasing sediment supply. These different observations thus emphasise the prevalence of depositional processes in shaping tidal channels. In a second stage, the investigation was extended to the role of the initial tidal flat morphology as an inherent control on tidal network development, by considering different scenarios of topographic perturbations, which has revealed its legacy on tidal network morphological features. Modelling experiments have also acknowledged salt marsh macrophytes as a potential control on network evolution depending on their biomass distribution within the tidal frame. However, tidal channel morphodynamcis appears to be sensitive to the way biomass growth is mathematically parameterised in the model. In view of the current challenges in transcribing mathematically such a dynamic process and the relevance of bio-physical interactions in driving salt marsh and tidal network evolution, a field survey was conducted in a temperate salt marsh in the Netherlands, as part of the mobility to UNESCO-IHE (Netherlands) in partnership with University of Antwerp (Belgium), to assess vegetation distribution and productivity in the tidal frame. Particularly, emphasis was placed on extending investigations on the possible presence of relationships involving vegetation properties in different climatic and ecological conditions from those characterising these previously documented relationships. Regression analysis has revealed that biomass growth can be expressed as a linear function of marsh relative elevation, providing therefore direct empirical validation for corresponding assumptions reported in the literature and used in the present modelling framework; surprisingly, that increase did not correlate with an increase in species richness and diversity. Analysis of likely associations between vegetation morphometrics and total standing biomass yielded only a single linear relationship linking the latter variable to stem height. In truth, these observations may bear reconsiderations on the global validity of the assumptions used in the formulation of some eco-geomorphic processes which are applied in the study and prediction of wetland resiliency facing climate change.

APA, Harvard, Vancouver, ISO, and other styles

22

Belliard, Jean-Philippe. "Bio-physical controls on tidal network geomorphology." Doctoral thesis, University of Trento, 2014. http://eprints-phd.biblio.unitn.it/1383/1/belliard_phd_thesis.pdf.

Full text

Abstract:

Looking over a tidal wetland, the tidal network characterised by its intricate system of bifurcating, blind-ended tidal courses clearly stands out from the overall landscape. This tidal landform exerts a fundamental control on the morphology and ecology within the tidal environment. With today’s recognition of the ecological, economical and societal values provided by tidal wetlands, which has been notably reflected in the development of restoration management strategies across Europe and USA, there is a need to fully understand the nature and development of tidal networks as well as their relationships with associated landforms and biotic components (e.g. vegetation), to eventually guarantee the success of current and future restoration practices. Accordingly, this research aims to bring further insights into the bio-physical controls on the geomorphology of tidal networks. To this end, a combination of remote sensing, modelling and field activities was employed. A geo-spatial analysis was performed at Queen Mary, University of London (UK), to address the variability of tidal network patterns. A series of network scale morphometric variables was extracted using airborne LiDAR data among selected tidal networks across the UK depicting different planview morphologies, and supplemented with the collection of corresponding marsh scale environmental variables from published sources. Multivariate statistics were then performed to characterise the variability of tidal network patterns and identify the inherent environmental controls. The analysis has revealed that every network type can be characterised based upon measures of network size and complexity, with each network pattern depicting proper morphometric aspects. Particularly, the stream Strahler order and the median depth of the network main channel have the highest discriminating weight on the patterns investigated. High correlation between the latter variable and network main channel width has revealed that linear, linear-dendritic and dendritic networks followed a transitional gradient in their aspect ratio approximated by a power law and thus are seen to depict similar erosional processes. To the contrary, meandering networks clearly depart from this relationship, and show particular segregation in their aspect ratios with respect to dendritic networks. Globally, differentiation on network morphometric properties has been linked to environmental conditions specific to the marsh physiographic setting within which a tidal network develops. Conceptually, tidal networks seem to adapt to marsh environmental conditions by adopting suitable morphologies to drain their tidal basin effectively.An eco-geomorphic modelling framework was developed at University of Trento (Italy), to address tidal network morphological development. In line with current theories as well as modelling advances and challenges in the field of tidal network ontogeny, emphasis was thus placed on the investigation of tidal channel formation and evolution in progressive marsh accretional context. Under these environmental conditions, tidal network development can be ascribed to the combination of two channel-forming processes: channel initiation results from bottom incisions in regions where topographic depressions occur; channel elaboration results from differential deposition, contributing to the deepening of the tidal channels relative to the adjacent marsh platform. Further evolutionary stages including channel reduction proceed from the horizontal progradation of the marsh platform which may lead eventually to channel infilling. Moreover, both qualitative and quantitative results allude to an acceleration of the morphological development of the synthetic tidal networks with increasing sediment supply. These different observations thus emphasise the prevalence of depositional processes in shaping tidal channels. In a second stage, the investigation was extended to the role of the initial tidal flat morphology as an inherent control on tidal network development, by considering different scenarios of topographic perturbations, which has revealed its legacy on tidal network morphological features. Modelling experiments have also acknowledged salt marsh macrophytes as a potential control on network evolution depending on their biomass distribution within the tidal frame. However, tidal channel morphodynamcis appears to be sensitive to the way biomass growth is mathematically parameterised in the model. In view of the current challenges in transcribing mathematically such a dynamic process and the relevance of bio-physical interactions in driving salt marsh and tidal network evolution, a field survey was conducted in a temperate salt marsh in the Netherlands, as part of the mobility to UNESCO-IHE (Netherlands) in partnership with University of Antwerp (Belgium), to assess vegetation distribution and productivity in the tidal frame. Particularly, emphasis was placed on extending investigations on the possible presence of relationships involving vegetation properties in different climatic and ecological conditions from those characterising these previously documented relationships. Regression analysis has revealed that biomass growth can be expressed as a linear function of marsh relative elevation, providing therefore direct empirical validation for corresponding assumptions reported in the literature and used in the present modelling framework; surprisingly, that increase did not correlate with an increase in species richness and diversity. Analysis of likely associations between vegetation morphometrics and total standing biomass yielded only a single linear relationship linking the latter variable to stem height. In truth, these observations may bear reconsiderations on the global validity of the assumptions used in the formulation of some eco-geomorphic processes which are applied in the study and prediction of wetland resiliency facing climate change.

APA, Harvard, Vancouver, ISO, and other styles

23

Warwick, Gail L. "The geomorphology and sedimentology of terminal fluvial systems." Thesis, University of Aberdeen, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487421.

Full text

Abstract:

The geomorphology and sedimentology of terminal fluvial systems. Fluvial systems operating within drylands commonly experience downstream discharge reduction due to infiltration, evaporation and limited tributary inputs. Sediment bodies developed within the distal zones of rivers that do not drain into the sea or a lake (terminal fluvial systems) are currently represented by the terminal fan facies model. This model summarises the development of a distally thinning and fining sedimentary wedge from a coeval network of low sinuosity distributary channels as induced by the sub aerial termination ofchannelised flow under a dryland climate regime.. Extensive review of sediment fan bodies located within modern drylands highlights pronounced disequilibrium between planform character and present ephemeral flow conditions. Out of eighty documented fluvial systems no convincing examples fit the terminal fan model, including two commonly cited analogues used to support this model. In order to fully evaluate the terminal fan concept and redress the current imbalance in modern analogue studies, field work was undertaken to characterise sub aerial fluvial system termination within a single physiographic province - the Basin and Range rift complex of the southwestern U.S.A. Documentation of the potential range in fluvial style and character within this modern dryland environment is provided by the detailed study of seven terminal fluvial systems. Basin and Range terminal fluvial systems demonstrate strong geomorphic form inheritance. Fan landforms observed within medial and distal reaches of these systems predominantly represent relic Late Pleistocene highstand delta bodies into which the modern system is inset. Active terminal reaches operate within basin centre playa environments where shallo~ gradients induce frequent avulsion and the generation of composite lowstand fan bodies located downstream of lateral system confinement. These terminal features record non-coeval channel activity and the dominance of sinuous channel forms. Morphometric trends distinguish a general downstream reduction in channel scale characterised by the development of progressively narrower and shallower channel forms. Channelised flow is maintained within proximal and medial reaches but does not dominate distal reaches where sheetflow discharge is readily attained. Concomitant reductions in channel capacity and competence control the volume and calibre of fluvial material supplied to basinal environments. Progressive downstream thinning is associated with selective deposition and general basinwards sediment fining and sorting. Terminal reaches transport negligible bedload material and display a comparable depositional record to that generated by background playa sedimentation. Identified similarities with the terminal fan model include downstream loss of channel definition, sediment thinning, fining and improved sorting. Conversely, coeval distributive flow is not observed, constituent channels record moderate to high sinuosity and negligible fluvial material reaches basin centre locations. Basin and Range systems are principally responding to streampower reduction controlled primarily by gradient and enhanced by discharge attenuation. Sub aerial termination dominates due to the absence of basin centre lacustrine bodies; a condition forced by limited discharge supply from catchment reaches, compounded by transmission losses and maintained by excessive evaporation from extensive, low elevation flat playa surfaces. In conclusion, fluvial fan landforms generated exclusively from discharge attenuation do not characterise modern dryland environments. Selection of modern analogue systems for use in the interpretation and prediction of ancient fluvial successions must acknowledge the influence of high frequency and high magnitude climate fluctuations upon modern fluvial geomorphology. Key to this is an appreciation of modern processform disequilibrium and the identification of inherited planform characteristics.

APA, Harvard, Vancouver, ISO, and other styles

24

Smith, Brent. "An examination of desert geomorphology throughout geologic time /." Connect to resource, 1998. http://hdl.handle.net/1811/28576.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Spence, James B. "Habitat analysis by hierarchical scheme and stream geomorphology." Huntington, WV : [Marshall University Libraries], 2005. http://www.marshall.edu/etd/descript.asp?ref=555.

Full text

Abstract:

Theses (M.S.)--Marshall University, 2005. Title from document title page. Includes abstract. Document formatted into pages: contains ix, 139 p. including illustrations and map. Bibliography: p. 83-89.

APA, Harvard, Vancouver, ISO, and other styles

26

Abuodha, Joseph Zedekia Odhiambo. "Geomorphology of the Malindi Bay coastal sand dunes." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/55857.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Wilson, David William. "On the problem of indeterminacy in fluvial geomorphology." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246883.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Huppert, Kimberly Lynn. "Climatic and geodynamic influences on ocean island geomorphology." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/108915.

Full text

Abstract:

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2017. Cataloged from PDF version of thesis. Includes bibliographical references. With homogeneous bedrock, dramatic rainfall gradients, and remnant surfaces that constrain their age, initial topography, and vertical motions relative to sea level, volcanic ocean islands provide an exceptional natural experiment in landscape evolution. Analyses traversing gradients in island climate and bedrock age have the potential to advance our understanding of landscape evolution in a diverse range of continental settings. Yet, islands are initially conic, net subsiding, boundary-dominated, and initially permeable landmasses, in many ways dissimilar to most continental landscapes. This thesis examines unique aspects of island landscape evolution, and it exploits steep climate gradients and variations in bedrock age on volcanic ocean islands to understand controls on rates and patterns of erosion and the contribution of lithosphere and mantle processes to surface deformation at hotspots. Through physically-based modeling, analysis of remote sensing and geochronologic data, and field measurements, this thesis examines (1) the dominant mechanisms of vertical motion in the Hawaiian Islands, (2) the influence of wave power on cliff retreat rates in the Hawaiian Island over geologic timescales, (3) the control of rainfall rates on the efficiency of bedrock river incision on the Hawaiian Island of Kaua'i, (4) the evolution of erosion rates over the course of landscape development on Kaua'i and other volcanic ocean islands, and (5) the mechanisms that cause volcanic ocean islands to ultimately subside below sea level to form atolls and guyots. These analyses provide empirical evidence for climatic control on erosion processes and they constrain the dynamics of plume-plate interactions at oceanic hotspots. by Kimberly Lynn Huppert. Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

29

Costigan, Katie Helen. "Hydrology and geomorphology of select Great Plains rivers." Diss., Kansas State University, 2013. http://hdl.handle.net/2097/15761.

Full text

Abstract:

Doctor of Philosophy Department of Geography Melinda Daniels Great Plains rivers are unique systems that vary from large, continental scale, to small intermittent streams with grain sizes that range from bedrock to cobbles to silt. These rivers have been subject to widespread hydrologic alteration both within the channel and the watershed, which has resulted in an alteration in their hydrologic and geomorphic regimes. Although there is an acknowledgement of this alteration, to date there has not been a synthesis of the hydrology of Great Plains rivers or of their longitudinal morphologies. Chapters in this dissertation provide, to my knowledge, the first comprehensive analyses of the hydrology and morphology of Great Plains rivers over a range of spatial and temporal scales. In the first study, I found that there was no uniform pattern of hydrologic alteration throughout the Great Plains, which is likely attributable to variable system-specific reservoir management objectives, land use changes, and climatic regimes over the large area the Great Plains encompass. Results of this study are the first to quantify the widespread hydrologic alteration of Great Plains rivers following impoundment. In the second study, I found an apparent decoupling between local moisture conditions and streamflow in intermittent prairie streams. Results of this study used statistical models to identify relationships between flow intermittence, mean annual flow, and flood flow characteristics with moisture to characterize flow in an intermittent prairie stream. In the final study, I found that the downstream trends in hydraulic geometry and substrate characteristics of the Ninnescah River were consistent with the expected trends proposed by hydraulic geometry and substrate theories. However, there were points that deviated from the expected trends, most notably where a substantially large tributary enters the Ninnescah River and as the Ninnescah River approaches the Arkansas River, and causal explanations for these deviations were explored. Results of this study are, to my knowledge, the first of its kind to assess the longitudinal hydraulic geometry and substrate characteristics of a large sand-bed river over a large spatial scale. To our knowledge, there have been no comparable studies exist that attempted to describe hydrologic and geomorphic characteristics of prairie streams.

APA, Harvard, Vancouver, ISO, and other styles

30

Beeslaar, Salome. "Geomorphology of a portion of Mariepskop, South Africa." Diss., University of Pretoria, 2013. http://hdl.handle.net/2263/40238.

Full text

Abstract:

Hillslopes usually have high heterogeneity in terms of landscape processes. Interactions occur between geology, geomorphological processes, and vegetation distribution on a hillslope. This study was undertaken to assess the processes and interactions of geology, regolith production, geomorphological processes, channel formation and how these are influenced by the vegetation on a portion of Mariepskop. Mariepskop forms part of the Drakensberg Escarpment, but is a separate hillslope within the Mpumalanga Province. A north-eastern portion of the Mariepskop forms the study site, with a drainage line located within the site. Deciduous bush covers most of the study site, and grassland patches occur on the southern parts of the study site. Quartz-feldspar-biotite gneiss dominates most of the area with the cliff and higher parts consisting of feldspar-rich schist. Three site visits were undertaken where bedrock geology, weathering, soil formation, erosion, mass movement processes and the drainage channel were assessed. Maps of these processes as well as slope profiling and plan forms were compiled. According to the results, Mariepskop shows heterogeneous processes both laterally and vertically, with various degrees of interactions taking place. Underlying geology, mass movements on higher altitudes, and soil creep on lower altitudes occur on both the northern and southern parts. Processes mainly occurring on the northern part are rockfall from drainage channel incision, weathering, rill erosion and fluvial erosion within the drainage channel. Main processes on the southern part are mass movement in term form of slumping/debris flow, and erosion, in particular rainsplash and overland flow. Soil is deeper on northern part than on southern part of the study site. Geomorphological processes interact with the vegetation distribution over the study area. Grassland patches on the southern part of the study site are mainly due to slumping/debris flow, rainsplash erosion, convexity of the plan form (therefore no valleys) and oxidic soils occurrence. Similar geomorphological processes will probably influence grassland patches over the rest of Mariepskop. Dissertation (MSc)--University of Pretoria, 2013. gm2014 Geography, Geoinformatics and Meteorology unrestricted

APA, Harvard, Vancouver, ISO, and other styles

31

Phillips, William Morton. "Applications of noble gas cosmogenic nuclides to geomorphology." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282369.

Full text

Abstract:

The buildup of the cosmogenic nuclides ³He and ²¹Ne in surficial rocks permit exposure ages and erosion rates to be estimated. This dissertation extends the cosmogenic exposure technique to garnets, plagioclase with significant nonspallation ²¹Ne components, and alluvial fill terraces. Garnets from Nanga Parbat, Pakistan have low nucleogenic ³He and moderate radiogenic ⁴He concentrations. ³He exposure ages from garnets in glacial erratics indicate glacial advances at Nanga Parbat at about 16 ka and 55 ka. 3He in alluvial garnets suggests that denudation in small unglaciated basins proceeds 5 to 7 times slower than glacial erosion, and 10 to nearly 100 times slower than regional rock exhumation and surface uplift. Rocks older than several million years possess nucleogenic and mugenic ²¹Ne and ³He components that must be resolved for accurate exposure ages. These nonspallation components in plagioclase and clinopyroxene from the Miocene Columbia River Basalt Group are best isolated with shielded samples. Analyses of ⁴He, U, Th, and Li systematically underpredict the amount of nonspallation ²¹Ne and ³He present in shielded samples, probably because of mugenic production. Step heating experiments suggest that ²¹Ne diffusive loss from plagioclase is possible, but most samples do not exhibit such ²¹Ne loss. The ratio of ²¹Ne in plagioclase and ³He in clinopyroxene is generally constant after correction for the nonspallation component, indicating that little or no ²¹Ne loss has occurred. The last highly erosive floods at Grand Coulee occurred at about 21 ka, early in the cycle of Missoula flooding. Nuclide inheritance must be resolved for accurate exposure ages of stream fill terraces. Depth profiles of cosmogenic ²¹Ne in quartz from terraces on the Pajarito Plateau, northern New Mexico resolve nuclide inheritance. Three patterns of depth profiles are recognized: (1) downward decreasing; (2) downward increasing; and (3) uniform; types 2 and 3 are associated with cumulate deposits and bioturbation, respectively. Inheritance corrected exposure ages for the terraces agree with independent radiocarbon and soil development ages. Denudation rates estimated from the profiles are higher for fill terraces than for straths.

APA, Harvard, Vancouver, ISO, and other styles

32

Clement, David T. "Fluvial geomorphology of the Yukon River, Yukon Flats, Alaska." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0015/MQ47994.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

McGuinness, Michaella. "The geomorphology of the Campbell Uplift, Northwest Territories, Canada." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0019/MQ48400.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Merrill, MaximilIan Atlas. "The Effects of Culverts and Bridges on Stream Geomorphology." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-11302005-175258/.

Full text

Abstract:

Culverts and bridges are necessary in order to cross waterways during road construction. However, these structures have detrimental affects on the hydrology and ecology of the streams they cross. The objective of this study was to investigate how these bridges and culverts alter stream hydrology and geomorphology by determining the effects on the upstream and downstream reaches of a road crossing on the cross sectional area, the hyporheic depth, on riffle habitat, and substrate types. Three types of culverts (arch, box, and pipe) and small bridges were evaluated. All four types of stream crossings were determined to increase the cross sectional area downstream of the structure. Crossing structures also affected hyporheic zone depths by decreasing average depths downstream of the structure. Finally, most mussels seemed to occur in substrates that were dominated by relatively large particles (gravel and cobble) that were less movable by sheer stress during higher flows. Each of the problems discovered with these structures is a result of the channel restriction and the increased flow velocity and turbulence scour that it creates. These detrimental conditions can be mitigated by providing for floodplain access for higher flows. It is recommended that culverts be designed for low flows and high flows. Oversizing culverts, compared to current design criteria will allow floodplain access and build bankfull benches in the extra openings to restrict low flows to a few openings. The use of bridges that span across the valley limiting fill and allowing floodplain access may even be more beneficial. When valley fill is necessary, then side culverts in the floodplain may alleviate degradation and allow more natural floodplain hydrology.

APA, Harvard, Vancouver, ISO, and other styles

35

Walker, Andrew Curtis. "A morphometric analysis of the geomorphology of Florida's springs." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001679.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Gore, Shannon. "Beach geomorphology and management in the British Virgin Islands." Thesis, University of Ulster, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589521.

Full text

Abstract:

The geomorphology of tropical island beaches has received little attention in literature compared to their temperate equivalents. This is particularly true of studies of the spatial and temporal variability of carbonate beaches. The British Virgin Islands (BVI), a small archipelago located in the north-eastern Caribbean contains numerous beaches in a wide variety of settings within a small geographical area. Over 100 beaches across 60+ high volcanic and reef islands were selected for study. Through the analysis of benthic habitat maps, aerial photographs, sedimentary characteristics, and ground-truthing, beach distribution and form are interpreted in terms of their geologic, oceanographic and ecologic setting. The Atlantic-facing beaches exhibit modally high energy waves which drive carbonate-rich sediment onshore from extensive reef systems and a carbonate bank. In contrast, Caribbean-facing beaches, primarily those of coral rubble, are dominated by modally low energy waves punctuated by very high energy events (i.e. hurricanes) and contain a lower proportion of fine-grained carbonate sands. While some of these high energy events have significant short-term impact, many beaches exhibit long-term stability. There has, however, been a general narrowing of beaches over the past 50 years which is tentatively attributed to sand mining in the past. In contrast to the high volcanic islands, Anegada is an emergent reef island comprising a lithified Pleistocene reef core and a sequence of Holocene deposits (beach ridges, lagoons, and mangroves). The form and distribution of the island's contemporary sedimentary environment reveal four distinctive coastlines. Three of these coastlines have shown relative stability over the past 149 years while one coastline has morphologically adjusted to surrounding environmental conditions by rotating in a counter clockwise motion. All the beaches are subject to a variety of human impacts and require a formal coastal management response, however, this has not yet been realised. Despite an existing statutory framework for beach management, environmental degradation from uncontrolled coastal development and space-use conflicts caused by unmanaged mass tourism continues. A current case study reveals the management plan requires implementation via a co-management regime between the local beach community and stakeholders with support from the local government. A simple framework is presented that provides thirteen environmental, socio-cultural, economic and governance goals which define the context in which the management plan operates. This framework ensures not only a clear understanding of what constitutes sustainable beach management, but also sustainable development specifically within the BVI.

APA, Harvard, Vancouver, ISO, and other styles

37

Saleem, Shihadah M. "Geomorphology of Submarine Spring West of Fort Myers, Florida." Scholar Commons, 2007. http://scholarcommons.usf.edu/etd/3836.

Full text

Abstract:

In March of 2000, March of 2001, and April of 2002, multibeam bathymetry and backscatter data were collected, which revealed several low-temperature hydrothermal submarine springs in the Mudhole Submarine Springs (MHSS) area that were investigated by SCUBA divers. High-resolution multibeam sonar provides a precise way of defining the geomorphology of the seafloor. The bathymetry data were used to understand (1) vent geomorphology and how it varied from vent to vent; (2) spatial patterns of active vents compared to extinct vents and known land springs identified by Kohout (1977) and Breland (1980); and (3) potential correlations between geochemical and geomorphological characteristics of the vents in the study area. SCUBA observations show that MHSS, Spring #3, New Spring, Northern Rusty, Rusty, and Near Rusty are active springs, while Dormant Spring and Sinister Spring were extinct or inactive at the time of the March 2001 cruise.During the April 2002 cruise the locations of Rusty Spring, New Spring and MHSS were confirmed. Two submarine springs, Creature Hole and Sparky Lee were also confirmed. Spring #3 is the deepest spring and Dormant Spring is the shallowest. There appears to be a rough spatial correlation between vents located on land and the vents on the seafloor, in which all known vents are either to the west or north of Lake Okeechobee. Vent distribution in the MHSS study area appears to correlate with the structural pattern of the local seafloor. Backscatter data and SCUBA observations show that fine to medium grain siliciclastic sediment bands overlie limestone hardbottom in a NE-SW orientation. Although vent geomorphologies are generally distinctive, vent activities generally correlate with the steepness of vent depressions.Most active vents had slopes of 6 degrees or greater, with the exception of Rusty Spring and Near Rusty Spring whose slopes ranged from 2.5 degrees and 6 degrees; whereas all the inactive vents had slopes of 5 degrees or less. Most active vents have "V"-shaped profiles versus the "U"-shaped profiles of most of the inactive vents. The inactive springs have shallower maximum depths and shallower ambient seafloor depths than the active vents.

APA, Harvard, Vancouver, ISO, and other styles

38

Rosser, Nicholas John. "The geomorphology of coarse clastic surfaces in arid environments." Thesis, Durham University, 2002. http://etheses.dur.ac.uk/3745/.

Full text

Abstract:

This study explores the linkages between slope form and slope process in arid environments. In doing so, questions of the development of slopes in arid environments are examined. The age of many arid environment surfaces, combined with the sporadic nature of formative events, means that long-term surface and slope development remains an elusive question in geomorphology. Deserts have inspired many of the most enduring theories of landscape evolution and continue to provide a test-bed for new and emerging ideas in geomorphology. The clast-mantled surface of the northeast Jordan Badia presents an ideal opportunity to study the links between surface character and slope processes in arid environments. The northeast Badia also provides an opportunity to explore theories of slope development and the behaviour of earth surface systems. The nature of the clast covered ground surface has been assessed using a new digital aerial photography and image analysis technique. A field study of surface processes has been used to explore links between surface form and slope process. Additionally, a computer based simulation of long-term modification of the spatial distribution of surface clast has been undertaken. Given the subtle variation in earth surface form between disparate locations, a new semi-quantitative method of locating sample sites has been developed. The characterization of surface form has identified statistically significant relationships between ground surface character and two-dimensional slope form. Systematic variations in ground surface configuration, both within and between basalt flows, are found to be indicative of the action of slope processes. The first study of ground surface hydrology in the north eastern Badia has been undertaken. The results from a series of rain-storm simulation experiments show subtle but significant links between the action of surface processes and variations in ground surface form. The controls on surface process are diverse and vary in significance with position in the landscape. A combination of ground surface characterization and process studies has identified several interesting geomorphological phenomena The surfaces exhibit systematic variations in structure and organization. Homeostatic links between form and process are clearly apparent, which suggests that surface form influences and is influenced by process action via a process of positive feedbacks. Given the sporadic and infrequent recurrence of formative events in arid environments, a modelling approach has been developed to understand the long-term, spatial dynamics of the ground surface. The model has been used to simulate structure in the surface clast arrangement and the sensitivity of surface organization to physically constrained variations in model parameters. The model also allows the surfaces to be considered as self-organizing earth surface systems. The model results provide new insights into the process-form linkages in operation on clast-mantled arid surfaces. The model results provide new ways of examining and understanding the dynamics of clast mantled arid surfaces and have implications for the application of self-organization in geomorphology.

APA, Harvard, Vancouver, ISO, and other styles

39

Hodskinson, Andrew. "Flow structure and geomorphology of non-classical river bends." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360484.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

McGuinness, Michaella (Michaella Kathleen) Carleton University Dissertation Geography. "The Geomorphology of the Campbell Uplift, Northwest Territories, Canada." Ottawa, 1999.

Find full text

APA, Harvard, Vancouver, ISO, and other styles

41

Pal, Saroj Kumar. "Geomorphology of river terraces along Alaknanda valley, Garhwal Himalaya /." Delhi : B.R. publ. corporation, 1986. http://catalogue.bnf.fr/ark:/12148/cb374724540.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Hall, Douglas Benjamin. "Geomorphology of welded tuffs, Chiricahua National Monument, southeastern Arizona." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186400.

Full text

Abstract:

The Chiricahua National Monument in southeastern Arizona presents several interesting questions to the process geomorphologist. First, why are columnar landscapes characteristic of the tuffs? Air photo analysis reveals that column geometries in both cross section and plan view are controlled by two locally radiating, vertical joint sets and a third horizontal joint set. Differential compaction of the tuff may also have led to jointing. The resultant joint planes provide avenues for water migration and consequent focusing of chemical weathering. Second, how can we arrive at the rate of formation of such landforms? The total amount of material erosionally removed from the entire Turkey Creek Caldera ash flow facies present in the monument watersheds was calculated using a digital elevation map. An average denudation rate of 0.017 mm/yr was calculated for the watershed based on the eroded volume. Third, the column ages determined by the denudation rate and the prevalence of different erosional processes, each with its own efficiency, during different climatic periods, suggest a two stage erosional history with rapid erosion during glacial periods and slow erosion during interglacial periods. Fourth, how mechanically stable are the "balanced rocks" and "hoodoos"? Strength parameters for the tuffs were measured. Six columns with very different profiles were measured and then modelled by finite element meshes. Despite their fragile appearances, all columns were well within their static mechanical failure limits. Failure by slip along joint surfaces is the most likely block failure mode, but is greatly minimized by erosional necking of columns into hourglass shapes. Necking causes the principal stresses in the column to rotate out of vertical and focus on the neck. The redirected stresses act as a normal confining stress across dipping joints that would, in the absence of the neck, imperil the column. Fifth, what can the preservation of columns tell us about the seismicity of southeastern Arizona? The dynamic loads of an earthquake should induce resonances that would greatly imperil the larger, thinner columns. The upper height limit of the column population indicates the past occurrence of an earthquake that triggered this resonant vibration and consequent failure. It appears, therefore, that the last column-destroying quakes occurred 2.4 My ago. (Abstract shortened by UMI.)

APA, Harvard, Vancouver, ISO, and other styles

43

Dietrich, James. "Applications of Structure-from-Motion Photogrammetry to Fluvial Geomorphology." Thesis, University of Oregon, 2015. http://hdl.handle.net/1794/18701.

Full text

Abstract:

Since 2011, Structure-from-Motion Multi-View Stereo Photogrammetry (SfM or SfM-MVS) has gone from an overlooked computer vision technique to an emerging methodology for collecting low-cost, high spatial resolution three-dimensional data for topographic or surface modeling in many academic fields. This dissertation examines the applications of SfM to the field of fluvial geomorphology. My research objectives for this dissertation were to determine the error and uncertainty that are inherent in SfM datasets, the use of SfM to map and monitor geomorphic change in a small river restoration project, and the use of SfM to map and extract data to examine multi-scale geomorphic patterns for 32 kilometers of the Middle Fork John Day River. SfM provides extremely consistent results, although there are systematic errors that result from certain survey patterns that need to be accounted for in future applications. Monitoring change on small restoration stream channels with SfM gave a more complete spatial perspective than traditional cross sections on small-scale geomorphic change. Helicopter-based SfM was an excellent platform for low-cost, large scale fluvial remote sensing, and the data extracted from the imagery provided multi-scalar perspectives of downstream patterns of channel morphology. This dissertation makes many recommendations for better and more efficient SfM surveys at all of the spatial scales surveyed. By implementing the improvements laid out here and by other authors, SfM will be a powerful tool that will make 3D data collection more accessible to the wider geomorphic community.

APA, Harvard, Vancouver, ISO, and other styles

44

Grams, Paul E. "Geomorphology of the Green River in Dinosaur National Monument." DigitalCommons@USU, 1997. https://digitalcommons.usu.edu/etd/6561.

Full text

Abstract:

Longitudinal profile, channel cross-section geometry, and depositional patterns of the Green River in its course through the eastern Uinta Mountains are each strongly influenced by river -level geology and tributary sediment delivery processes. We surveyed channel cross sections at 1-km intervals, mapped surficial geology, and measured size and characteristics of bed material in order to evaluate the geomorphic organization of the 70- km study reach. Canyon reaches that are of high gradient and narrow channel geometry are associated with the most resistant lithologies exposed at river level and the most frequent occurrences of tributary debris fans. Meandering reaches that are characterized by low gradient and wide channel geometry are associated. with river-level lithology that is of moderate to low resistance and very low debris fan frequency. The channel is in contact with bedrock or talus along only 42 percent of the bank length in canyon reaches and there is an alluvial fill of at least 12 m that separates the channel bed from bedrock at three borehole sites. The influence of lithology primarily operates through the presence of resistant boulders in debris fans that are delivered by debris flows from steep tributaries. The depositional settings created by debris fans consist of (1) channel-margin deposits in the backwater above the debris fan, (2) eddy bars in the zone of recirculating flow below the constriction, and (3) expansion gravel bars in the expansion below the zone of recirculating flow. These fan-eddy complexes are the storage location of about 70 percent. by area, of all fine- and coarse-grained alluvium contained within the canyons above the low-water stage. Immediately adjacent meandering reaches contain an order of magnitude more alluvium by area but have no debris fan-created depositional settings. This study also describes the flood-plain and terrace stratigraphy of the Green River in the eastern Uinta Mountains and changes due to the operations of Flaming Gorge Dam, upstream from the study area. These landforms are vertically aggrading deposits that are longitudinally correlative throughout the 65-km study reach. The suite of surfaces identified includes a terrace that is inundated by rare pre- or post-dam floods, an intermediate bench that is inundated by rare post-dam floods, and a post-dam flood plain that is inundated by the post-dam mean annual flood. Analysis of historical photographs in the study reach shows that both the intermediate bench and post-dam flood plain are landforms that were not present in any of the 6 years for which photographs were examined between 1871 and 1954. Photographic replications also show that gravel bars consisting of bare gravel in 1922 and earlier photographs are now covered by fine-grained alluvium and vegetation . Decreased gravel-bar mobility is indicated by estimates of critical and average boundary shear stress. Comprehensive surficial geologic mapping of the study area indicates that the bankfull channel has decreased in width by an average of about 20 percent.

APA, Harvard, Vancouver, ISO, and other styles

45

Cao, Wenfang. "The quantification of the socio-economic impact on geomorphology." Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3423190.

Full text

Abstract:

It is acknowledged that the Earth’s surface was shaped by natural processes such as tectonic uplift, erosion and sediment movement. Nevertheless, recently, the human society as a new force to reshape the landscape has been perceived by the scientific community. The Anthropocene working group (AWG), which is a part of subcommission on Quaternary Stratigraphy – International commission on Stratigraphy of International Union of Geological Science (IUGS) proposed to mark the current geologic time unit as Anthropocene. The AWG declared human beings stepped into an epoch that our societies have become a global geophysical force and the extent of human intervention on geomorphic processes has become comparable to nature, and the trend is accelerating. Humans act as a geomorphic agent shaping Earth’s surface through activities ranging from agricultural tillage, mining, road networks and building constructions. These activities leave significant signatures on the topography, literally and figuratively across millennia and reflecting the socio-economic conditions of the societies that produce them. People tend to live in the surroundings where resources such as food and fuel are cheaper and more accessible, and the economic and social demands of resources drive the land-use changes to meet the demands. As the human population has grown and the power of technology has expanded, the socio-economic demands have scaled up, the landscapes were imprinted by the rapid increase of anthropogenic modification caused by deforestation, agricultural expansion and urban construction to supply the food and energy demands. The Great Acceleration witnessed remarkable explosion of socio-economic development, with significant consequences on the surface topography. It is estimated that humans have shaped around one-third of the landscape through agricultural fields, pastures, or urban landscapes. However, an empirical computation to link between socio-economic development, land-use changes and the geomorphology alterations is still a gap. Societal-based understanding of anthropogenic geomorphology provides the way of how human activities involved in natural environmental changes such as soil erosion, floods and tectonic uplifts with the timeline. We synthesized scientific evidence on the emergence, history of present anthropogenic features and illustrated how these features impact the Earth's surface processes. Then we integrated social-geophysical approaches to interpreting a full range of anthropogenic features with identification of remote sensing techniques and reconstruction of the long-term changes by archaeologists, as diagnostic fingerprints of the social processes that formed them. Further, we testified that the natural landscape and anthropogenic landscape present a significant difference in geomorphic signatures, and implied that anthropogenic force shapes the geomorphology in a way different from natural force. Lastly, we used the nighttime light data to represent the socioeconomic status and SLLAC (Slope Local Length of Autocorrelation) metrics to measure the anthropogenic modification on the landscape, and then to assess the correlation between socio-economic impact on the geomorphology based on each stratification of a global pattern. This thesis helps to understand how the features that human left on the topography affect the Earth surface processes, interpret those features as sociocultural fingerprints, demonstrate that the anthropogenic forcing leaves a different topographic signature on the surface from the natural forcing, and quantify the correlation between socio-economic development and anthropogenic geomorphology. This research not only fill the gap in why people shape the landscape through a diversity of activities; it also presents a possible correlation between socio-economic development and anthropogenic geomorphology. This work also provides the possibility towards an empirical estimation of landscape under the human’s impact at a global scale, and underlines that an integrated approach combining social economy, ecology and geomorphology is needed for the future landscape management.

APA, Harvard, Vancouver, ISO, and other styles

46

Bishop, Mark A. "The spatial and temporal geomorphology and surficial sedimentology of the Gurra Gurra crescentic dunes, Strzelecki Desert, South Australia /." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phb6223.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Emerson, Samuel D. "The role of bed shear stress in sediment sorting patterns in a reconstructed, gravel bed river." Thesis, San Jose State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10128515.

Full text

Abstract:

The role of bed shear stress in bed surface grain size sorting was investigated on a reconstructed reach of the Merced River in the Central Valley of California. Pebble count data were collected at the inside, middle, and outside of ten bends in April 2015 and compared to data from pebble counts conducted in previous years. Output from a previously developed 2D flow model (FaSTMECH) was compared to critical shear stresses calculated from median grain-size data. Comparison of pebble count results from 2002 through 2015 showed that there was no temporally consistent pattern of coarsening or fining along the study reach; however, the bed surface coarsened between 2002 and 2015. Pebble count data from April 2015 revealed a distinct spatial distribution of grain sizes with a larger median grain size (D50) at the outside of bends and a smaller D50 at the inside of bends. Regression analyses performed on pebble count data from point bars revealed statistically significant downstream changes in surface grain size on two of the seven bars. Analysis of shear stress data showed a weak relationship between the modeled bed shear stress (τb) and the calculated critical shear stress (τcr ). The weak relationship between τb and τcr indicated that bed shear stress was not solely responsible for the grain size sorting in the study reach. It is likely that the observed grain size sorting patterns resulted from helical secondary flows at the bends.

APA, Harvard, Vancouver, ISO, and other styles

48

Coleman, Daniel J. "The Role Of Suspended Sediment In Assessing Coastal Wetland Vulnerability." W&M ScholarWorks, 2020. https://scholarworks.wm.edu/etd/1593091737.

Full text

Abstract:

Coastal wetlands sequester carbon, attenuate waves and storm surge, filter out nutrients and pollutants, and act as nursery habitat for important fisheries. The value of these ecosystems is underscored by their vulnerability to climate change, especially sea level rise. To persist under the threat of rising sea level, coastal wetlands must build elevation vertically. Delivery of sediment to the marsh during tidal flooding is a key component in the ecogeomorphic feedbacks that lead to elevation gain. Despite the importance of suspended sediment to assessing coastal wetland vulnerability, many questions remain unanswered. This dissertation addresses the impact of suspended sediment concentration on wetland geomorphology from fine-scale processes to global patterns and from thriving systems to those experiencing significant environmental change. In Chapter I, I explore alterations to sediment transport and geomorphology caused by an acute vegetation disturbance in a Georgia saltmarsh. My results showed that the loss of vegetation was reversed the trajectory of the site from a prograding marsh to an eroding marsh. In Chapter II, I investigate how suspended sediment travels across the marsh platform using high frequency, long-term measurements in the Plum Island Estuary, Massachusetts. In contrast to the current paradigm, I found that sediment supply in the marsh interior is largely decoupled from channel sediment supply. Chapter III focuses on the role of sediment transport in mangrove encroachment into salt marshes in Australia. My work suggests that mangroves do not inhibit the ability of salt marsh to accrete vertically and that the removal of mangroves to preserve salt marsh would be ineffective. In Chapter IV, I analyze the relationship between suspended sediment concentration, tidal range, and accretion in salt marshes from around the world. My work emphasizes the importance of mineral accretion and marsh elevation when making predictions about marsh response to sea level rise. These results help bridge the gap between numerical models which predict marshes are capable of surviving high rates of relative sea level rise and field studies which suggest drowning at much lower rates. As a whole, my dissertation demonstrates that physical processes and the ways in which biology mediate these processes are critical to the ability of coastal wetlands to persist. As the rate of sea level rise continues to accelerate, it is increasingly important to understand the controls on vertical elevation growth in coastal wetlands at the scale of several meters to thousands of kilometers and in pristine systems to degraded environments.

APA, Harvard, Vancouver, ISO, and other styles

49

Meyers, Matthew Armand. "Fluvial Processes Affecting the Texture of a Gravel Bed with an Emphasis on Salmon Spawning Habitat." Thesis, University of California, Santa Barbara, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10600721.

Full text

Abstract:

Spawning salmon depend on fluvial processes to maintain the bed texture of gravel bedded rivers as suitable spawning and incubation habitat. The coarse texture of a gravel bed is maintained by flow strengths capable of moving the gravel and removing fine sediments, thereby providing loose substrate that enhances its ability to conduct flow (i.e., its hydraulic conductivity). The flow strength that corresponds to the beginning of movement (i.e., entrainment) of a grain on a gravel bed is variable and, therefore, it needs to be measured to predict flow levels capable of bed texture maintenance. Lower flows can deliver fine sediment, which may accumulate in the gravels overlying salmon nests (i.e., redds) reducing the hydraulic conductivity and impairing salmon embryo development. I examine these processes to explain the variability in (i) the rate of change in the proportion of a gravel size fraction entrained as a function of flow strength and (ii) the rate of decrease in hydraulic conductivity as a function of the cumulative transport of fine sediment that depends on flow level. I used tracer gravel and cobble grains and a two dimensional flow model to determine the flow strengths capable of gravel bed entrainment using binary plots of the occurrence or absence of tracer movement to approximate the fraction of the bed sediment entrained as a logistic function of increasing flow strength. The method provides an approximation of the flow strength capable of entraining the least resistant through the most resistant grains, thereby providing a new method to approximate the flow strength that is capable of fully entraining the bed. The results are confirmed by comparing the measurements of two study sites. To measure the resistance of individual gravel and cobble grains to downstream movement, I used force gages and a theoretical force balance model that incorporates the frictional resistance of a grain and the lift and drag forces applied by stream flow. I measured the frictional resistance of grains at six sites with different morphologies to evaluate influences on grain resistance. Grain resistance varied depending on the grain size and sorting, amount of infiltrated sand, streamwise position along a gravel bar, and degree of fluctuation in the flow strength. The force balance model predicts that the dimensionless instantaneous flow strength capable of entraining a given proportion of a relative grain size varies along a bar. I tested the force balance model predictions by comparison with the tracer measurements from the tracer study. The differences between the force balance predictions and the tracer entrainment measurements are due to the definition of the flow strength as the time-averaged value from the 2D flow model and the instantaneous value from the force balance model. Adjusting the force balance model predictions by a simple factor that quantifies their difference and that corresponds with an index describing the fluctuations of the instantaneous flow strength about its time-averaged value produces agreement with the tracer measurements. This adjustment to force gage measurements from two sites on opposite limbs of a bar indicates that the time-averaged dimensionless flow strength capable of entraining a given proportion of a relative grain size is constant along a bar. I constructed artificial redds at five sites to monitor changes in hydraulic conductivity and sand accumulation with cumulative bed load transport. I applied two backfill treatments to examine the effects of the presence and absence of grains smaller than 6.4 mm. Hydraulic conductivity varies temporally due to sand deposition and spatially due to the initial sand content of the backfill and the local sediment supply rate. The rate of change in hydraulic conductivity as a function of increasing cumulative transport is statistically significant but does not differ between backfill treatments or with location. I predicted the effect of flow on egg survival using an empirical relationship between hydraulic conductivity and egg survival with results that indicate hydraulic conductivity is dependent on sediment transport rate as a function of flow rate. This work provides additional understandings of the relationship between flow and bed texture maintenance processes and useful tools for managing gravel bed rivers.

APA, Harvard, Vancouver, ISO, and other styles

50

Gammisch, Robert A. "Geological History of a Holocene Drainage System: Hack Creek, Virginia." W&M ScholarWorks, 1986. https://scholarworks.wm.edu/etd/1539617562.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Geomorphology'

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