This study was motivated by an interest in understanding the effects of glacier retreat on late summer stream temperatures in an above-treeline proglacial stream and lake system in the southern Coast Mountains of British Columbia, Canada. Fieldwork was carried out during August and September of 2007 and focused on thermal processes controlling water temperature in the proglacial lake and a 1 km alpine reach directly downstream of the lake outlet. The proglacial lake was small (0.07 km²), featured a single inflow and outflow channel and had a residence time of approximately 4 days. The alpine reach featured continual cascading flow (25% channel gradient), marked diurnal fluctuations in discharge and variable terrain shading. It was found that warming between the inflow and outflow of the lake (1.8°C, on average) was controlled by the total heat content of the lake and cycles of mixing and stratification. A heat budget analysis indicated that the heat content of the lake was dominantly controlled by absorbed shortwave radiation and the advective effect of the inflow and outflow streams. Application of a dynamic reservoir model (DYRESM) to model observed lake temperatures (inflow, outflow and a temperature-depth profile), and comparison to other studies, suggested that suspended sediment concentration in the inflow had a dominant control on lake mixing and stratification. Based on equations developed from low-gradient channels, a stream energy budget model failed to replicate observed downstream warming rates. A spatially distributed net radiation model, along with statistical modification of the energy budget, provided insight into the processes that control stream temperatures in alpine areas. The final hybrid model showed a good match with observed downstream warming. This model accounted for the variation of width and albedo with discharge, and the spatial variability in net radiation due to topographic shading and the slope and aspect of the channel. The model also included parameters that increased the sensible and latent heat fluxes relative to values calculated from standard equations, which is consistent with the hypothesis that these fluxes are enhanced by cascading flow.

This study was motivated by an interest in understanding the effects of glacier retreat on late summer stream temperatures in an above-treeline proglacial stream and lake system in the southern Coast Mountains of British Columbia, Canada. Fieldwork was carried out during August and September of 2007 and focused on thermal processes controlling water temperature in the proglacial lake and a 1 km alpine reach directly downstream of the lake outlet. The proglacial lake was small (0.07 km²), featured a single inflow and outflow channel and had a residence time of approximately 4 days. The alpine reach featured continual cascading flow (25% channel gradient), marked diurnal fluctuations in discharge and variable terrain shading. It was found that warming between the inflow and outflow of the lake (1.8°C, on average) was controlled by the total heat content of the lake and cycles of mixing and stratification. A heat budget analysis indicated that the heat content of the lake was dominantly controlled by absorbed shortwave radiation and the advective effect of the inflow and outflow streams. Application of a dynamic reservoir model (DYRESM) to model observed lake temperatures (inflow, outflow and a temperature-depth profile), and comparison to other studies, suggested that suspended sediment concentration in the inflow had a dominant control on lake mixing and stratification. Based on equations developed from low-gradient channels, a stream energy budget model failed to replicate observed downstream warming rates. A spatially distributed net radiation model, along with statistical modification of the energy budget, provided insight into the processes that control stream temperatures in alpine areas. The final hybrid model showed a good match with observed downstream warming. This model accounted for the variation of width and albedo with discharge, and the spatial variability in net radiation due to topographic shading and the slope and aspect of the channel. The model also included parameters that increased the sensible and latent heat fluxes relative to values calculated from standard equations, which is consistent with the hypothesis that these fluxes are enhanced by cascading flow.

Inaug.-Diss.--Bonn.

This study was motivated by an interest in understanding the effects of glacier retreat on late summer stream temperatures in an above-treeline proglacial stream and lake system in the southern Coast Mountains of British Columbia, Canada. Fieldwork was carried out during August and September of 2007 and focused on thermal processes controlling water temperature in the proglacial lake and a 1 km alpine reach directly downstream of the lake outlet. The proglacial lake was small (0.07 km²), featured a single inflow and outflow channel and had a residence time of approximately 4 days. The alpine reach featured continual cascading flow (25% channel gradient), marked diurnal fluctuations in discharge and variable terrain shading. It was found that warming between the inflow and outflow of the lake (1.8°C, on average) was controlled by the total heat content of the lake and cycles of mixing and stratification. A heat budget analysis indicated that the heat content of the lake was dominantly controlled by absorbed shortwave radiation and the advective effect of the inflow and outflow streams. Application of a dynamic reservoir model (DYRESM) to model observed lake temperatures (inflow, outflow and a temperature-depth profile), and comparison to other studies, suggested that suspended sediment concentration in the inflow had a dominant control on lake mixing and stratification. Based on equations developed from low-gradient channels, a stream energy budget model failed to replicate observed downstream warming rates. A spatially distributed net radiation model, along with statistical modification of the energy budget, provided insight into the processes that control stream temperatures in alpine areas. The final hybrid model showed a good match with observed downstream warming. This model accounted for the variation of width and albedo with discharge, and the spatial variability in net radiation due to topographic shading and the slope and aspect of the channel. The model also included parameters that increased the sensible and latent heat fluxes relative to values calculated from standard equations, which is consistent with the hypothesis that these fluxes are enhanced by cascading flow. / Arts, Faculty of / Geography, Department of / Graduate

This research aims to improve our knowledge of debris flow occurrence and behaviour in New Zealand. Detailed field data collected in four debris flow prone areas in New Zealand are presented and compared. The travel distance of these events is then modelled with an empiricalstatistical model, UBCDflow, and an analytical, “equivalent fluid” continuum model DAN-W. While field studies are useful, they are often not linked to the underlying mechanics of debris flow motion or compared with the behavior of small scale flows due to the inherent complexity and unknown boundary conditions in field scale flows. Physical modelling simplifies the situation and allows boundary conditions to be controlled. The second part of this research uses physical modelling, including a series of novel debris flow tests in a geotechnical centrifuge, to compare and contrast flow behaviour and mechanics of laboratory and field scale flows. The debris flows events investigated in the field were categorized into hillslope, torrent, or intermediate-type events. Hillslope events were less channelized and progressively deposited on high slope angles. Consequently, high friction coefficients were needed to model their mobility. Torrent flows entrained more material than hillslope flows and deposited on lower angle slopes in response to unconfinement on the debris flow fan. Friction coefficients back-calculated for torrent events were lower than for the hillslope flows, but still larger than most of the friction coefficients given for large, channelized, debris flow events in the literature. Intermediate events were similar to hillslope events in terms of deposition angle and best-fit friction coefficients, but were very confined. Both UBCDflow and DAN-W were found to be useful decision support tools, but the capability of each model was limited. Greater modelling capability was gained by using the volume change behaviour predicted by UBCDflow in DAN-W, as DAN-W simulates flow heights and velocities, but does not predict the depth of erosion. In the second part of the research, a geotechnical centrifuge is used to model debris flow processes in a larger acceleration field than earth’s gravity. While centrifuges have been used to model a variety of processes in other geotechnical problems, debris flows are a relatively new phenomenon to be tested on a centrifuge. The centrifuge was successful in increasing the frictional properties of flow, but viscous forces were still the dominant form of shear stress with the materials used. Markedly different flow behaviour of tests using different pore-fluid rheologies suggested that the dominant mechanism of shear resistance may have changed between confined, downslope movement and unconfined runout. The results also showed that in geotechnical centrifuge testing, the viscosity of the pore fluid scales with the g-level, N. This research is an important step in developing centrifuge testing as an accepted method of modelling debris flow processes. Finally, a brief comparison of friction slopes between small-scale 1-g flume tests and field scale flows suggests that 1-g flume experiments are able to model the mobility of field scale flows if the soil used is well-graded and the pore-fluid is not too viscous. This research shows that the the ability of laboratory scale flows to model large scale processes may not be as limited as previously suggested by some investigators.

No description available.

In alpine catchments, the nature of hydrological sources and stores varies in both space and time. This thesis presents an investigation of the processes controlling the stream hydrograph in three nested sub-catchments within a small alpine catchment (the TaillonlGabietous catchment) in the French Pyrenees. The study conducts fieldwork and modelling in parallel to allow the independent corroboration of hypotheses from different sets of analytical and field techniques. Meteorological. hydrological and hydrochemical data were collected during the 1996 and 1997 summer ablation seasons. Three key observations are made following analysis of this data. First, a temporal compensation effect is observed between summer meltwater runoff and the more prolonged discharge of groundwater throughout the winter. Second. the importance of precipitation events over the ablation season in this climatically sensitive area is recognised. Third. it is suggested that it is unrealistic to assume watertight catchments in many alpine areas. A conceptual model is presented of the hydrological processes controlling the stream hydrograph in an alpine glacierized catchment with an underlying groundwater system. Links to concurrent projects on glacier hydrometeorology. climate change. and stream ecology significantly enhanced the overall conclusions of the thesis.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1974. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

No description available.

The Vera Basin is used as a case study to examine the structural evolution and sedimentary response of a basin undergoing uplift and inversion during the Plio-Pleistocene. Particular emphasis is placed on the drainage evolution during that period. Located within the Internal zone of the Betic Cordilleras, the Vera Basin is defined within a large left-lateral shear zone and has evolved as a reponse to isostatic uplift from nappe emplacement during the Oligocene, and by regional compressive tectonics. Since basin formation during the Seravallian, sedimentary fill has been dominantly marine. During the Plio-Pleistocene a switch from marine to continental conditions occurred. These sediments (Cuevas, Espiritu Santo and Salmerbn Formations) represent the final stages of basin fill and form the focus of this study. The Cuevas Formation represents an early Pliocene marine transgression within the Vera Basin. Early sedimentation mulled a pronounced submarine topography produced by a rapid late Miocene fall in sealevel. A broad, shallow shelf platform area existed which opened out to the Pliocene Mediterranean Sea towards the east. Along the northern and western basin margins, wave dominated shorelines were formed. Structural activity was confined to low amounts of basin subsidence and limited left lateral strike-slip movement along the Palomares Fault Zone. The Espiritu Santo Formation marks a major palaeogeographic reorganisation and the final marine phases of the Vera Basin during the mid to late Pliocene. Unsteady strike-slip movement along the Palomares fault zone on the eastern basin margin partially enclosed the Vera Basin by northwards movement of a structurally detached landmass. Gilbert-type fan-delta bodies prograded westwards from the landmass (Sierra Almagrera), infilling the central region of the basin. Early fan-delta sediments were reworked into shoreline areas along the western and northern basin margins. Western margin shorelines retreated northwards as a response to partial enclosure and a gradual lowering of sea-level. Late stages of the Espiritu Santo Formation, saw a fan-delta body prograde from the northern basin margins. Interaction between the basinal and marginal fan-delta bodies enclosed the northern region of the Vera Basin. A swamp/mangrove environment developed within the enclosed northern basin area suggesting a humid, sub-tropical climate. Continental conditions were established during Salmerön Formation times in the late Pliocene. Along the western and northern basin margins, the retreating Pliocene shorelines provided a topography onto which the primary consequent drainage network developed. Three separate drainage systems can be identified on the basis of clast assemblages, palaeocurrents, depositional style and morphological expression. Early deposition was characterised by the progradation of alluvial fans of two drainage systems (Cuevas & Jauro), sourced from the northern and western basin margins. Distal areas of the northern fan system intercalated with an evaporitic playa lake. A third drainage system in the northwest of the basin (Salmerbn) developed within a topographic low between the two fan systems. An increase in structural activity towards the end of the Salmerbn Formation was characterised by a basin wide phase of north-south compression. Uplift and extensional faulting lead to abandonment of the primary drainage network. Fan entrenchment and minor rerouting of sediment supplies marked the establishment of a new secondary consequent drainage network during the Pleistocene. The Pleistocene drainage network records the progressive dissection of the Vera Basin as a response to ongoing regional epeirogenic uplift. During this post-inversion phase the Rios Antas, Almanzora and Aguas developed respectively along the western, northern and southern basin margins as- a series of braided streams. Distal, coastal areas of this drainage network are recorded by a series of Pleistocene shoreline sequences which developed as a response to fluctuating sea-level during the Pleistocene glacial and interglacial periods. Early Pleistocene proximal parts of the drainage network are well preserved. Distal parts of the Pleistocene fluvial system display limited evidence for interaction between the drainage network and shoreline sequences. This lack of preservation relates to the high energy, wave dominated depositional setting of the Pleistocene shoreline areas which reworked fluvial sediment inputs into the shoreline environment. The Plio-Pleistocene evolution of the Vera Basin, and in particular the development of the fluvial during system this period has been highly complex. Despite the importance of sea-level and climatic controls, tectonic activity during this period of basin inversion has been the dominant control on the positioning of the drainage networks, depositional styles and sediment supply.