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Rivers are inherently dynamic environments with fluctuations in water quality, hydrology, connectivity and geomorphology. Though geomorphology has long been recognized as an important driver defining biological, ecological, and physical habitat characteristics of rivers, a readily applied classification tool that links such characteristics has been lacking. The Geomorphic Response Unit (GRU) method provides a novel approach to identifying large scale patterns in geomorphic character that provide a link between the hydrological regime and different habitat types to which species respond. Specifically, I investigated whether Geomorphic Types and GRUs are related to the distribution and abundance of different fish species, reflecting unique physical habitat characteristics of individual GRUs. The thesis chapters are manuscript based. The second chapter identifies relationships between specific Geomorphic Types, identified using the Geomorphic Response Unit (GRU) methodology, and Lake Sturgeon overwintering locations in the South Saskatchewan and Saskatchewan Rivers. Habitat selection ratios suggest that Lake Sturgeon in the Upper South Saskatchewan River significantly selected for one of seven possible Types for overwintering. Logistic regression results found both Type 0 and Type 4 predicted significantly higher Sturgeon presence than all other Types (P = < 2e-16 for both). The third chapter examines relationships between GRUs and abundance of both mature and immature Carmine Shiner in the Birch River, Manitoba. Differences in the median mature Carmine Shiner CPUEs among the GRUs are not statistically different (Kruskal-Wallis test H =1.723; df = 3, p value = 0.632), though interesting qualitative relationships were identified which may inform further studies. The fourth chapter investigates whether GRUs derived using a large scale network approach are linked to the abundance of specific fish species in the Assiniboine River, Manitoba. A Kruskal-Wallis test identified significant differences in CPUE among GRUs for 10 of 14 tested species. Post-hoc pairwise multiple comparisons using Dunn’s Method with Bonferroni p-value correction for multiple paired tests isolated the GRUs that were different from one another. Overall, my findings suggest that Geomorphic Response Units (GRU) are an effective means of identifying patterns in geomorphic structure within Prairie Rivers at both reach and segment scales. Further, I identified links between both Geomorphic Types and GRUs and patterns in abundance of various fish species covering a wide range of life history traits. These findings suggest that GRUs have potential as a valuable fisheries habitat management tool, increasing efficiency of monitoring efforts through quantification of habitat availability, connectivity, and complexity in Prairie River systems.

This dissertation presents results from a multi-year interdisciplinary study of the Late Quaternary geomorphic history of northwest Calvert Island, British Columbia, Canada. There is a considerable knowledge gap in the region pertaining to Cordilleran ice cover and extent as well as landscape response to a uniquely stable relative sea-level history. The objective of this study was to reconstruct this regional landscape response to deglaciation including post-LGM ice cover and extent, relative sea-level changes, coastal landform development, and climate and ecological variance. Methods used to inform this reconstruction included airborne lidar, aerial photography interpretation, sedimentary stratigraphy and detailed sedimentology of samples from shovel pits and lake cores, surficial geology and geomorphic mapping, palaeoecological examinations, and the development of a geochronology using radiocarbon and optical dating. To assist with landscape reconstruction, a new method was developed and used to differentiate littoral and aeolian sands in sediment samples that range in age from Mid to Late Holocene by using modern reference samples. The method utilized a standard optical microscope paired with freely available software (ImageJ) to characterize grain shape parameters. The method was tested on nearly 6,000 sand grains from samples of known and hypothesized depositional settings and was able to correctly identify the depositional setting for 76% of the samples. After testing, the method was used to differentiate littoral and aeolian sands in a number of shovel pit, exposure, and core sediment samples to give context to stratigraphic and geomorphic interpretations. A short-lived Late Pleistocene re-advance of Cordilleran ice occurred in the study area, with radiocarbon ages indicating ice advanced to, and then retreated from, the western edge of Calvert Island between 14.2 and 13.8 ka cal BP, respectively. Sedimentological and palaeoecological information that suggests a cold climate and advancing/retreating glacier as well as lidar remote sensing and field-based geomorphic mapping of moraines in the region provide evidence of the re-advance. After ice retreated from the area, a broad suite of geomorphic landforms developed, including flood plains, iv aeolian dunes, beaches, spits, marshes, and tombolos. Coastal reworking was extensive, with progradation rates greater than 1 m a-1 occurring in some locations during the Late Holocene. These data provide the first evidence of a re-advance of the retreating ice sheet margin on the central coast of British Columbia, contribute an important methodology to advance Quaternary reconstructions, and give a unique account of the geomorphic development of a Pacific Northwest coastline that experienced little relative sea-level change over the Late Pleistocene and Holocene. Results help fill a spatial and temporal gap in the landscape history of British Columbia and have implications for climate and sea-level reconstructions, early human migration patterns, and the palaeoenvironment of an understudied area of the Pacific Northwest coast of North America. / Graduate / 0368 / 0372 / 0426 / jeamer7@gmail.com

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.

Made available in DSpace on 2014-06-11T19:31:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2000-02-29Bitstream added on 2014-06-13T19:40:47Z : No. of bitstreams: 1 cunha_p_dr_jabo.pdf: 1311654 bytes, checksum: 87ec93400498e89ff36f299da52649f1 (MD5) / O presente trabalho teve por objetivo relacionar as superfícies geomórficas em uma vertente na região de Jaboticabal (SP) com a mineralogia, química e física de latossolos nelas distribuídos, bem como a variabilidade espacial destes atributos, com a finalidade do estabelecimento de áreas mais homogêneas, específicas para manejo, planejamento e transferência de informações, além de subsidiar informações para gênese de solos. Foram identificadas e caracterizadas três superfícies geomórficas, os solos sob estas foram amostrados em detalhe e seus atributos físicos, químicos e mineralógicos foram analisados, bem como sua variabilidade através da estatística descritiva e geoestatística. Os resultados deste estudo evidenciaram que: (1) a razão dos latossolos sob a superfície III, mais jovem de todas, serem mais oxídicos, enquanto que os latossolos da superfície I, mais velha, são mais cauliníticos, é conseqüência da litoestratigrafia regional arenito-basalto; (2) o ambiente sob a superfície I, mais estável, favoreceu a formação de caulinita e hematita com maior grau de cristalinidade, menor largura à meia altura (LMA) e maior diâmetro médio do cristal (DMC) quando comparados aos mesmos minerais dos solos sob a superfície III, a mais jovem e menos estável; (3) os atributos do solo mais coincidentes com aqueles limites pré-determinados das superfícies geomórficas no campo, foram em ordem decrescente: inclinação do terreno, ferro do ataque sulfúrico (Fes), razões minerais leves/pesados e silte/argila, densidade de partículas e caulinita/(caulinita+gibbsita); (4) os solos sob a superfície III apresentam uma maior variabilidade espacial de seus atributos quando comparados aos solos sob a superfície I, evidenciando que solos muito intemperizados (Latossolos) quando sob superfícies geomórficas mais recentes e erosionais são mineralogicamente menos... / The present work had as objective to relate the geomorphic surfaces of a transect at Jaboticabal (SP) region with the mineralogy, chemistry and physics of Latosols (Oxisols) distributed on it and the spatial variability of these attributes. The found results, in this context, supply important data for planning and experimental evaluations, besides subsidising information about the genesis and the evolution of the soils in the landscape. In this work, three geomorphic surfaces were identified and characterised, the soils under them were sampled in detail and analysed, and the spatial variability of them were studied through descriptive statistics and geo-statistics. The results of this study evidenced that: (1) the reason for the Latosols under the youngest geomorphic surface (III) have an oxidic mineralogy, and the soils under the oldest surface (I) have a kaolinitic mineralogy, is consequence of the regional sandstone–basalt lithostratigraphy; (2) the pedogenic environment under the geomorphic surface I, favoured minerals of better degree of crystallisation, confirmed by the larger value of crystallite average diameter and smaller width at half height of XRD peaks, when compared with the same minerals under the geomorphic surface III; (3) the best soil attributes to confirm the limits among geomorphic surfaces were: terrain inclination, iron from sulphuric acid digestion, light/heavy minerals ratio, silt/clay ratio, particle density, and kaolinite/(kaolinite+gibbsite) ratio; (4) the soil (Dusky-Red Latosol) under the more recent, erosional geomorphic surface (III), is less homogeneous (higher spatial variability), with relation to the selected attributes than the soil (Dark-Red Latosol) under the older and flatter geomorphic surface (I); and (5) the differential spatial dependence, represented by the values of the reaches(r) in soils under the three geomorphic surfaces, for the majority... (Complete abstract click electronic access below)

Made available in DSpace on 2017-07-10T17:30:45Z (GMT). No. of bitstreams: 1 Wanessa S P Dal Berti.pdf: 7008811 bytes, checksum: 38f5735759abf5feff9301bbc4b7810d (MD5) Previous issue date: 2015-12-08 / The research presents the characterization of surface formations in the sector covering the geomorphic surfaces IV and III in the Araucária Plateau, including transitions to surfaces II and V, in order identify the stage of materials evolution in representative profiles of each geomorphic surface. For this we used the lifting of macro morphology characteristics of surface, and laboratory analyzes of particle size, macronutrients, sulfuric attack and clays diffractogram of X-rays. The representative profile of the surface IV, developed on basaltic substrate, in surface with elevation between 1000 and 1100m, has over 4 meters thichness and solum more than 230cm, corresponding to Nitossolo Bruno Distroférrico Aluminico. It s mineral matter consists of quartz, anatase, ilmenite, hematite, goethite, gibbsite, kaolinite and possible presence of vermiculite. Between the geomorphic surfaces IV and III, the change of profile is developed on rhyolite, with soil 220cm thick whose morphological characteristics individualize Oxisol Distrofic, aluminum character. The Horizon B mineral matter consists of quartz, anatase, gibbsite, kaolinite and possible presence of VHE (vermiculite hydroxy between layers). The morphological characteristics of this profile indicate evolved weathering stage, although the horizon B has only 55cm. On the surface III, the profile described amendment corresponds to Oxisol Distroferric aluminum, whose mineralogy in the sand and silt fractions are made up of quartz, tridymite, cristobalite, spinel, magnetite, ilmenite, hematite, goethite and it s polimorfo, the lepidocrocite. In the clay fraction occur goethite, hematite, brookita, diaspore, boehmite, kaolinite and diquita, although vermiculite Al-OH between layers (VHE), besides the boehmita and mineral zeolites group. In the transition area between the geomorpfic surfaces V and IV, the changing profile showed 550cm thick, of which 370cm correspond to soil. Presents very weathered material, the type Oxisol Distroferric aluminium, the characteristics of sulfuric attack indicate that volumes appear to have no evolutionary relation with each other, indicating that is not changing material developed in situ. The minerals in the sand and silt fraction are cristobalite, tridymite, magnetite, ilmenite, hematite, goethite and apinel. In the clay fraction occurring minerals similar to those recorded in the B horizon of the representative profile of the surface III. In short, the weathering profile identified in geomorphic surfaces studies (IV, III and transitions) have very similar morphological characteristics indicating overall, high change stage. The four representative profiles analyzed there fall into the class of Oxisol, varying only distrophic,for distroferric, and is presented in Nitossolo Bruno Distroferric aluminium class. Of these profiles, three have development features from indigenous parent material (P1, P4 and P11), while the P13 profile shows parental relation with allochthonous material. / A pesquisa apresenta a caracterização das formações superficiais em setor que abrange as superfícies geomórficas IV e III no Planalto das Araucárias, incluindo as transições para superfícies II e V, buscando identificar o estágio de evolução dos materiais em perfis representativos de cada superfície geomórfica. Para tal utilizou-se do levantamento das características macromorfológicas da cobertura superficial em campo, bem como de análises laboratoriais de granulometria, macronutrientes, ataque sulfurico e difratogrametria de raios-X de argilas. O perfil representativo da superfície IV, desenvolvido sobre substrato basáltico, em superfície com elevação entre 1000 e 1100m, apresenta mais de 4 metros de espessura e solum com mais de 230 cm, correspondendo a Nitossolo Bruno Distroférrico Alumínico. Sua matéria mineral é constituída por quartzo, anatásio, ilmenita, hematita, goethita, gibbsita, caulinita e possível presença de vermiculita. Entre as superfícies geomórficas IV e III, o perfil de alteração desenvolve-se sobre riolito, apresentando solum com 220 cm de espessura cujas características morfológicas individualizam Latossolo Bruno Distrófico, caráter alumínico. A matéria mineral do horizonte B é constituída por quartzo, anatásio, gibbsita, caulinita e possível presença de VHE (vermiculita hidroxi entre camadas). As características morfológicas desse perfil indicam estágio de intemperismo evoluído, apesar do horizonte B apresentar apenas 55 cm. Na superfície III, o perfil de alteração descrito corresponde a Latossolo Bruno Distroférrico Alumínico, cuja mineralogia nas frações areia e silte constituem-se de quartzo, tridimita, cristobalita, espinélio, magnetita-magenita, ilmenita, hematita, goetita e seu polimorfo, a lepidocrocita. Na fração argila ocorrem goetita, hematita, brookita, diásporo, boehmita, caulinita e diquita, bem como vermiculita Al-OH entre camadas (VHE), além da boehmita e mineral do grupo da zeólitas. Na área de transição entre as superfícies geomórficas V e IV, o perfil de alteração mostrou 550 cm de espessura, dos quais 370 cm correspondem a solum. Apresenta material muito intemperizado, do tipo Latossolo Bruno Distroférrico Alumínico, cujas características do ataque sulfúrico indicam que os volumes não aparentam ter relação evolutiva entre si, indicando que não se trata de material de alteração desenvolvido in situ. Os minerais presentes na fração areia e silte são cristobalita, tridimita, magnetita, ilmenita, hematita, goetita e espinélio. Na fração argila ocorrem minerais similares aos registrados no horizonte B do perfil representativo da superfície III. Em suma, os perfis de intemperismo identificados nas superfícies geomorfológicas estudadas (IV, III e transições) apresentam características morfológicas bastante similares indicando, no geral, estágio de alteração elevado. Dos quatro perfis representativos analisados, três se enquadram na classe dos Latossolos, com variação apenas de distrófico para distroférrico, e um apresenta-se na classe Nitossolo Bruno Distroférrico Alumínico. Desse total de perfis, três apresentam características de desenvolvimento a partir de material parental autóctone (P1, P4 e P11), enquanto o perfil P13 mostra relação com material parental alóctone.

Made available in DSpace on 2017-05-12T14:42:17Z (GMT). No. of bitstreams: 1 Wanessa S P Dal Berti.pdf: 7008811 bytes, checksum: 38f5735759abf5feff9301bbc4b7810d (MD5) Previous issue date: 2015-12-08 / The research presents the characterization of surface formations in the sector covering the geomorphic surfaces IV and III in the Araucária Plateau, including transitions to surfaces II and V, in order identify the stage of materials evolution in representative profiles of each geomorphic surface. For this we used the lifting of macro morphology characteristics of surface, and laboratory analyzes of particle size, macronutrients, sulfuric attack and clays diffractogram of X-rays. The representative profile of the surface IV, developed on basaltic substrate, in surface with elevation between 1000 and 1100m, has over 4 meters thichness and solum more than 230cm, corresponding to Nitossolo Bruno Distroférrico Aluminico. It s mineral matter consists of quartz, anatase, ilmenite, hematite, goethite, gibbsite, kaolinite and possible presence of vermiculite. Between the geomorphic surfaces IV and III, the change of profile is developed on rhyolite, with soil 220cm thick whose morphological characteristics individualize Oxisol Distrofic, aluminum character. The Horizon B mineral matter consists of quartz, anatase, gibbsite, kaolinite and possible presence of VHE (vermiculite hydroxy between layers). The morphological characteristics of this profile indicate evolved weathering stage, although the horizon B has only 55cm. On the surface III, the profile described amendment corresponds to Oxisol Distroferric aluminum, whose mineralogy in the sand and silt fractions are made up of quartz, tridymite, cristobalite, spinel, magnetite, ilmenite, hematite, goethite and it s polimorfo, the lepidocrocite. In the clay fraction occur goethite, hematite, brookita, diaspore, boehmite, kaolinite and diquita, although vermiculite Al-OH between layers (VHE), besides the boehmita and mineral zeolites group. In the transition area between the geomorpfic surfaces V and IV, the changing profile showed 550cm thick, of which 370cm correspond to soil. Presents very weathered material, the type Oxisol Distroferric aluminium, the characteristics of sulfuric attack indicate that volumes appear to have no evolutionary relation with each other, indicating that is not changing material developed in situ. The minerals in the sand and silt fraction are cristobalite, tridymite, magnetite, ilmenite, hematite, goethite and apinel. In the clay fraction occurring minerals similar to those recorded in the B horizon of the representative profile of the surface III. In short, the weathering profile identified in geomorphic surfaces studies (IV, III and transitions) have very similar morphological characteristics indicating overall, high change stage. The four representative profiles analyzed there fall into the class of Oxisol, varying only distrophic,for distroferric, and is presented in Nitossolo Bruno Distroferric aluminium class. Of these profiles, three have development features from indigenous parent material (P1, P4 and P11), while the P13 profile shows parental relation with allochthonous material. / A pesquisa apresenta a caracterização das formações superficiais em setor que abrange as superfícies geomórficas IV e III no Planalto das Araucárias, incluindo as transições para superfícies II e V, buscando identificar o estágio de evolução dos materiais em perfis representativos de cada superfície geomórfica. Para tal utilizou-se do levantamento das características macromorfológicas da cobertura superficial em campo, bem como de análises laboratoriais de granulometria, macronutrientes, ataque sulfurico e difratogrametria de raios-X de argilas. O perfil representativo da superfície IV, desenvolvido sobre substrato basáltico, em superfície com elevação entre 1000 e 1100m, apresenta mais de 4 metros de espessura e solum com mais de 230 cm, correspondendo a Nitossolo Bruno Distroférrico Alumínico. Sua matéria mineral é constituída por quartzo, anatásio, ilmenita, hematita, goethita, gibbsita, caulinita e possível presença de vermiculita. Entre as superfícies geomórficas IV e III, o perfil de alteração desenvolve-se sobre riolito, apresentando solum com 220 cm de espessura cujas características morfológicas individualizam Latossolo Bruno Distrófico, caráter alumínico. A matéria mineral do horizonte B é constituída por quartzo, anatásio, gibbsita, caulinita e possível presença de VHE (vermiculita hidroxi entre camadas). As características morfológicas desse perfil indicam estágio de intemperismo evoluído, apesar do horizonte B apresentar apenas 55 cm. Na superfície III, o perfil de alteração descrito corresponde a Latossolo Bruno Distroférrico Alumínico, cuja mineralogia nas frações areia e silte constituem-se de quartzo, tridimita, cristobalita, espinélio, magnetita-magenita, ilmenita, hematita, goetita e seu polimorfo, a lepidocrocita. Na fração argila ocorrem goetita, hematita, brookita, diásporo, boehmita, caulinita e diquita, bem como vermiculita Al-OH entre camadas (VHE), além da boehmita e mineral do grupo da zeólitas. Na área de transição entre as superfícies geomórficas V e IV, o perfil de alteração mostrou 550 cm de espessura, dos quais 370 cm correspondem a solum. Apresenta material muito intemperizado, do tipo Latossolo Bruno Distroférrico Alumínico, cujas características do ataque sulfúrico indicam que os volumes não aparentam ter relação evolutiva entre si, indicando que não se trata de material de alteração desenvolvido in situ. Os minerais presentes na fração areia e silte são cristobalita, tridimita, magnetita, ilmenita, hematita, goetita e espinélio. Na fração argila ocorrem minerais similares aos registrados no horizonte B do perfil representativo da superfície III. Em suma, os perfis de intemperismo identificados nas superfícies geomorfológicas estudadas (IV, III e transições) apresentam características morfológicas bastante similares indicando, no geral, estágio de alteração elevado. Dos quatro perfis representativos analisados, três se enquadram na classe dos Latossolos, com variação apenas de distrófico para distroférrico, e um apresenta-se na classe Nitossolo Bruno Distroférrico Alumínico. Desse total de perfis, três apresentam características de desenvolvimento a partir de material parental autóctone (P1, P4 e P11), enquanto o perfil P13 mostra relação com material parental alóctone.

Nursery habitat availability is considered a bottleneck to successful recruitment of Colorado squawfish (Ptychocheilus Lucius). Detailed geomorphic studies were conducted in a 1.5-km reach to examine channel response to flows and the geomorphic setting of nursery habitats during a 2-year period. Videography was used to extend relationships in the 1.5-km reach to a longer 10-km reach. Nursery habitat availability varied yearly with little persistence in location or geomorphic setting of individual habitats for the 2 years of this study. A small number of habitats provided most of the area of high-quality (i.e., deep) habitat, and most of the total area of habitat was formed by three geomorphic classes. Although the 1993 flood reduced the area of available habitat, area of deep habitat increased. The 1994 low-peak flood increased the area of habitat, but most habitats were shallow. The 1993 and 1994 multi-peaked habitat availability curves for the 1.5-km-reach bank-attached bar were the result of the superposition of curves from habitats in each geomorphic classification, and showed that the discharge that maximized habitat availability changed yearly. A complexity index was evaluated for the 10-km reach as surrogate for habitat availability. Total base-flow habitat availability was significantly correlated to the complexity index, but deep habitat availability was not. Measured channel topography was used as input to a flow and sediment transport model. Simulated hydrograph runs produced greater bank-attached bar aggradation and thalweg scour than steady flows, although some unrealistic patterns of scour occurred. New flow recommendations must include occasional high flows sufficient to rebuild channel topography. Flaming Gorge Dam releases should be used to augment the Yampa River flood peak, but not increase low flood-peak duration. The conceptual model for habitat availability developed here may be used to target the formation and availability of habitats. Base flow recommendations designed to maximize habitat availability should be evaluated annually. Winter flows should be reevaluated for their negative effects on habitat.

In case of exceptional floods induced by the failure of a dam, huge amounts of sediments may be eroded. This results in large-scale modifications of the valley morphology and may drastically increase the resulting damages. The objective of the research is to advance the understanding of sediment transport under dam-break flows. For such highly erosive and transient floods, it is crucial to account explicitly for sediment inertia, and therefore traditional “clear-water” modelling approaches are largely inappropriate. The present approach relies on a two-layer idealisation of the flow behaviour. Separating a clear-water flow region from the underlying sediment bed, the transported sediments are confined in a flow layer of finite thickness, endowed with its proper inertia, density and velocity. The thesis also pinpoints granular dilatancy as an essential mechanism of interaction between the layers. When passing from a solid-like to a fluid-like behaviour as they are entrained by the flow, the eroded sediment grains dilate along the vertical, and this generates vertical exchanges of mass and momentum that should be accounted for. The thesis proceeds first with experimental investigations. Laboratory dam-break waves are reproduced in a dedicated flume, exploring different bed configurations and sediment densities. Imaging observations are used to support the proposed phenomenological description of the flow. Within a shallow-water framework, theoretical and numerical endeavours are then developed to investigate the implications on the flow dynamics of the two essential contributions of the proposed description, i.e. the two-layer flow behaviour, and the effects of granular dilatancy.

This thesis presents an assessment of the variation in solifluction occurrence, morphometry and movement rates in the Abisko region, northern Sweden. Variations in movement rates are analyzed both on a regional and local scale. The main methodological contributions of this thesis have been to provide new techniques of analyzing spatial and temporal variations of solifluction in order to detect long term temporal trends and to regionalize the variations in movement rates. The spatial analysis is achieved by using a combination of field measurements, GIS and remote sensing techniques and statistical analysis. The results are presented in six papers, focusing on the morphometry of solifluction landforms (paper I), the occurrence of permafrost (paper II), the spatial and temporal variations of lobe front movement rates using aerial photographs (paper III), the temporal, regional and local spatial variations in movement rates (paper IV – VI) and statistical modelling of the occurrence of solifluction landforms and calculation of geomorphic work (paper V and VI). The results show that, on a regional scale, vegetation patterns are a major control on the occurrence of turf-banked solifluction landforms, with high NDVI-values (vegetation) associated with the presence of forms. Elevation is also a major control on a regional scale with a decrease in lobe dimensions and movement rates with increased elevation. High soil moisture values are associated with larger landforms and increased movement rates. Movement rates are generally higher in the western part of the region and appear to increase with higher MAAT. Equally, geomorphic work is greatest in the western part of the region. The important controls on a local scale vary from site to site, but include vegetation, slope angle and soil moisture. The photo analysis indicates that annual movement rates of lobe fronts in Kärkevagge and Låktatjåkka valley over the period 1959-2000 ranges from not-detectable to 63mm/yr. The permafrost model shows probabilities &gt;0.8 for permafrost at elevations above 1300 m a.s.l. in the western part of the region, decreasing to altitudes over 850 m a.s.l. in the eastern part of the region. Calculated geomorphic work suggests that solifluction is a significant denudational agent in the sub-Arctic mountains of northern Sweden, but less so than previously estimated.