Browsing by Author "Osborn, Gerald"

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    Insights into Recharge Processes in Mountain-Block Hydrology Using Isotopic and Geochemical Characterization
    (2021-09) Campbell, Éowyn; Ryan, M. Cathryn; Osborn, Gerald; Stadnyk, Tricia
    Mountain block hydrology, including mountain streamflow generation and aquifer recharge in both mountains and prairies, depends on the infiltration and transport of mountain precipitation. Yet these recharge processes are not yet fully understood, and the two dominant paradigms regarding mountain recharge appear to be in conflict – Mountain Block Recharge (MBR) suggests adjacent prairie aquifers are recharged by deep flowpaths from mountain blocks, while alpine recharge suggests local flowpaths generate most mountain streams, which then recharge prairie aquifers at the mountain front. This thesis investigates this apparent dichotomy by analysing mountain recharge, aquifer storage, and streamflow generation using water geochemistry and isotopes in the upper (unreqgulated) reach of the Elbow River, an eastern slopes watershed. Water isotopes in precipitation and streamflow demonstrate that the young water fraction (Fyw) methodology is not well suited to areas with overwinter snowpack, but that average water isotope composition of winter baseflow shows ~20% of streamflow is derived from the previous year’s precipitation, suggesting rapid infiltration and throughflow. Silica and sulfate in streamflow and groundwater samples, along with sulfate isotopes, show that siliciclastic and carbonate aquifers contribute water equally to the Elbow River despite greater carbonate volume in the watershed, and that aquifer residence times are less than 10 years. Finally, analyzing the same geochemical components in late October baseflow along the length of the Little Elbow shows that high, cold precipitation infiltrates and is transported along intermediate and deep flowpaths before becoming streamflow at low elevations. Together, these findings suggest that the dominant paradigms are really two aspects of the highly dynamic and interconnected nature of mountain block hydrology.
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    Investigating the effects of topography on glaciers in the Purcell and Rocky Mountain Ranges during the LIA and in 2005
    (2013-04-25) Vallis, Vanessa Gail Sakiko; Sjogren, Darren; Osborn, Gerald
    The purpose of this study is to investigate the spatial variability of glaciers and how topography affects disparate glacier response to climate change in the Canadian Cordillera. This research identifies topographic variables which may have affected glacier response to climate during and after the Little Ice Age (LIA). Changes in glacier area, shape, length, elevation, height, aspect, hypsometry, slope and upslope area were measured for sixteen glaciers from orthophotos and digital surface models (DSM). DSMs were created to represent glacier surface elevation in 2005. LIA glacier surfaces were reconstructed by interpolating the elevation along the former margin. Multivariate statistics were used to determine which topographic variables explained variance in glacier geometry. Glacier sensitivity scores based on the topographic characters of each glacier were developed and calculated. Glacier cover in the study area has decreased by 49.4 % with an estimated volume loss of 1.97 ± 0.2 km³.
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    Legal Perspectives on Channel Migration of Wandering Gravel-Bed Rivers in Southern Alberta
    (2013-05-01) Campbell, Eowyn; Osborn, Gerald
    Property boundaries in Alberta that are defined by rivers are subject to the doctrine of accretion. A review of the history and development of this doctrine reveals that it accommodates all types of river channel change, including episodic movement, and that it is the overall progress of the change rather than the moment to moment process that should be considered when addressing whether an event is accretionary or avulsive. A behavioural model developed here for wandering gravel-bed rivers in southern Alberta indicates that change to these rivers is largely episodic and is mainly due to non-overbank peak seasonal flows rather than floods, but that rapid change can occur in response to certain events. Application of the behavioural model and the interpretation of the doctrine of accretion developed here to the 2000 Robertson v Wallace court case supports the judge’s rulings in all three disputed reaches.
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    Measurement of deflation of a debris-covered glacier in Opabin Basin, Yoho National Park
    (2009) Adams. Kristyn; Tennent, Christina; Vallis, Vanessa; Menounos, Brian; Osborn, Gerald