Investigating spatio-temporal variability of hydrological components in the Canadian Rockies (Alberta)

This thesis addresses two questions related to the broad topic of mountain hydrology: 1) How do interannual hydrological balancee and pathway components vary in complex temperate high mountain environments at various spatio-temporal scales? 2) a) Is it possible, using dedicated hydrological models, for significant errors in simulated runoff components despite good hydrograph recreations (i.e. right results for wrong reasons)? b) If so, what kinds of errors are encountered? The first question was addressed by undertaking a hydrological tracer and hydrometric study at three basin scales (Banff —2200 km2, Lake Louise —400 km2 and the headwaters —30 km2) within the Bow Valley of the Canadian Rockies from 1996 to 1999. To address question two, hydrometeorological basin properties learned from question one were used to perform two runs of the University of British Columbia watershed model for the Bow River at Banff during hydrological years 1996-1999. Simulations were evaluated using a conceptual 5\u2780 model of the hydrological balance. Seasonal geochemical patterns in runoff were similar for all basins, indicating that interannual hydrometeorological conditions play the dominant role in controlling hydrological contributions to runoff. In both seasonal baseflow and event runoff from all basins, snow was the dominant component with rainfall contributing little, even during large rainfall events. Higher rainfall contributions were evident in the runoff from glacierised basins, suggesting that impervious surfaces lead to rapid runoff but in non-glacierised basins a large volume of rainwater is probably lost to evapotranspiration. In addition, it was considered that rainfall may have appeared to be absent from the hydrograph during the large rainfall event studied as it may have shunted out older snowmelt from karst storage in the headwaters, thus masking the actual rainfall signature. For all model runs it was found that the snowmelt component of the hydrological balance was underestimated. This was generally compensated for by an overestimation of rain inputs. From the findings that rainfall was generally a minor component of annual runoff despite hydrometric observations (and phenomenological intuition) that might indicate otherwise, it was concluded that there may be a conceptual misunderstanding of the importance of rainfall contributions to runoff in glacierised high mountain basins. Rainfall occurs during summer months and is the most susceptible flow component to evaporative loss. However, rain, snow and ice are not discriminated in many model evaporation routines, and this could lead to overestimations of rainfall in the balance. In addition, orographic enhancement of precipitation varies seasonally but this is often not accounted for in models. Using a single value to represent annual conditions likely leads to overestimations of rainfall at high elevations. Automated optimisation of a model containing such process-based conceptual flaws will ultimately force the model to overestimate certain parameters (rainfall in this case) and compensate with an underestimation of hydrologically more important components (namely snow)

The impact of glacier recession upon the discharge of the Bow River above Banff, Alberta, 1951-1993

Three methods have been used to explore the volumetric change of glaciers in the Bow Basin above Banff for the years 1951 to 1993. Using aerial photography, the extent of glacier covers for the two years were mapped at a scale of 1:50,000. The first volumetric calculation of glacier loss was based on inventory criteria; the second a hyposgraphic curve method based on Young’s investigations in Mistaya Basin (1991) and the third stereo air photogrammetry and DEM comparisons using computer software. These methods were applied to the highly glacierized Hector Lake catchment within the Bow Valley and then extrapolated up to the whole basin above Banff. Reasonable agreement was achieved between the methods and the magnitude of glacier loss is estimated to be between 930 and 1400 m3 x 106 w.e. for the entire 42 year period. The bulk glacier “wastage” estimate was divided into proportions using the Peyto Glacier mass balance record. Unfortunately, the record began in 1966 and a back-cast to 1952 was necessary. The mass balance model proposed by Letreguilly (1988) was considered inappropriate for this task due to it not adequately representing the observations of recession on Peyto for 1952 to 1965. A new model utilizing Banff maximum summer temperature and Lake Louise snow course data was constructed. The proportions of seasonal wastage contributios to the river flow were estimated using a multiple regression model of monthly average temperature and precipitation with snow course data as the antecedent condition determinant. This model was used to predict the shape of the glacier (ice and firn) melt hydrograph from June to September. An estimate of the temporal variation of glacier recession inputs to the Bow River hydrograph at Lake Louise and Banff was facilitated by comparing known basin yields with the modelled “wastage” values. For 1952 to 1993 at Banff, the average annual wastage/basin yield ration is found to be around 2.3%; for 1965 to 1992 (years of available data) at Lake Louise the same ratio is 4.5%. For the extremely low flow year of 1970 these ratios increase to 12.5% and 16.2% respectively. The proportion of flow derived from glacier recession in August of this year is estimated to be around 53% for Banff and 84% for Lake Louise. It is thought that the basin scale extrapolation may lead to under-estimations of wastage but the mass balance back-cast is more likely to preferentially weight wastage contributions toward the latter part of the time series

Building identities and relationships in commercial websites: A contrastive view of communication strategies

This paper addresses the construction of identities and relationships as a communication strategy in commercial websites. Based on a corpus of Czech and British sites, the study applies an approach grounded in Critical Discourse Analysis and identifi es ways in which text-producers attempt to create simulated identities for themselves and their readers, manipulating the reader’s mental models of the communicative situation for commercial gain. The author then addresses the texts’ construction of virtual relationships between the producer and the reader, both in terms of distance or closeness (negative and positive face) and in terms of the equality or inequality of status of the two participants. The study also discusses the extent to which the corpus reveals contrastive differences in strategies and discourse preferences between the British and Czech websites

BUILDING AN ONLINE COMMUNITY: INGROUP FACE AND RELATIONAL WORK IN ONLINE DISCUSSIONS

Based on a corpus of internet discussions on medical topics, this study examines the social dimension of the genre, focusing particularly on the strategies through which a distinct ingroup community is created and maintained. Drawing on concepts of face and relational work, the analysis shows how participants typically position themselves as holders of shared ingroup values, altercast their opponents as members of an outgroup, and enact recurring patterns of interaction indicating the existence of a distinct and coherent community of practice. The study then examines the main relational work strategies through which ingroup members establish, maintain and strengthen social bonds within the online community

APOLOGIES IN L1 AND LINGUA FRANCA ENGLISH: A CONTRASTIVE PRAGMATIC STUDY OF TRIPADVISOR RESPONSES

The article reports on a study of restaurant-owners’ public online responses to negativecustomer reviews on the TripAdvisor website, exploring the differences between thepractices used by L1 English and lingua franca English (ELF) speakers when performingpublic apologies. The focus is on the occurrence and linguistic realizations of two keycomponents of apologies: illocutionary force indicating devices (IFIDs) and accounts ofthe incident. The results indicate certain differences between the L1 and ELF responses –both in the use of IFIDs (the IFIDs in the ELF responses are more frequently ambiguousin terms of their illocution) and in the amount of facework done (the L1 responses usefacework resources more proficiently, while the ELF responses are more face-neutral)

Effect of Greyscale/Print Density on the Properties of High Speed Sintered Nylon 12

High Speed Sintering is an Additive Manufacturing process that creates parts by sintering using inkjet and infra-red lamp technology, rather than the laser systems employed in Laser Sintering. This research investigated the effects of altering the dosage of ink (greyscale/print density) on the properties of parts produced. A clear pattern emerges that shows a ‘sweet spot’ for correct dosage of ink to maximise properties. The work also shows that greyscale allows considerable control of part density that could lead to substantial reductions in part mass beyond those that may be achieved by conventional design optimisation approaches employed today.Mechanical Engineerin

Identifying Conifer Tree vs. Deciduous Shrub and Tree Regeneration Trajectories in a Space-for-Time Boreal Peatland Fire Chronosequence Using Multispectral Lidar

Wildland fires and anthropogenic disturbances can cause changes in vegetation species composition and structure in boreal peatlands. These could potentially alter regeneration trajectories following severe fire or through cumulative impacts of climate-mediated drying, fire, and/or anthropogenic disturbance. We used lidar-derived point cloud metrics, and site-specific locational attributes to assess trajectories of post-disturbance vegetation regeneration in boreal peatlands south of Fort McMurray, Alberta, Canada using a space-for-time-chronosequence. The objectives were to (a) develop methods to identify conifer trees vs. deciduous shrubs and trees using multi-spectral lidar data, (b) quantify the proportional coverage of shrubs and trees to determine environmental conditions driving shrub regeneration, and (c) determine the spatial variations in shrub and tree heights as an indicator of cumulative growth since the fire. The results show that the use of lidar-derived structural metrics predicted areas of deciduous shrub establishment (92% accuracy) and classification of deciduous and conifer trees (71% accuracy). Burned bogs and fens were more prone to shrub regeneration up to and including 38 years after the fire. The transition from deciduous to conifer trees occurred approximately 30 years post-fire. These results improve the understanding of environmental conditions that are sensitive to disturbance and impacts of disturbance on northern peatlands within a changing climate

Evolution of the melt source during protracted crustal anatexis: An example from the Bhutan Himalaya

The chemical compositions of magmatic zircon growth zones provide powerful insight into evolving magma compositions due to their ability to record both time and the local chemical environment. In situ U-Pb and Hf isotope analyses of zircon rims from Oligocene–Miocene leucogranites of the Bhutan Himalaya reveal, for the first time, an evolution in melt composition between 32 and 12 Ma. The data indicate a uniform melt source from 32 Ma to 17 Ma, and the progressive addition of an older source component to the melt from at least ca. 17 Ma. Age-corrected εHf ratios decrease from between –10 and –15 down to values as low as –23 by 12 Ma. Complementary whole-rock Nd isotope data corroborate the Hf data, with a progressive decrease in εNd(t) from ca. 18 to 12 Ma. Published zircon and whole-rock Nd data from different lithotectonic units in the Himalaya suggest a chemical distinction between the younger Greater Himalayan Series (GHS) and the older Lesser Himalayan Series (LHS). The time-dependent isotopic evolution shown in the leucogranites demonstrates a progressive increase in melt contribution from older lithologies, suggestive of increasing LHS involvement in Himalayan melting over time. The time-resolved data are consistent with LHS material being progressively accreted to the base of the GHS from ca. 17 Ma, facilitated by deformation along the Main Central thrust. From 17 Ma, decompression, which had triggered anatexis in the GHS since the Paleogene, enabled melting in older sources from the accreted LHS, now forming the lowermost hanging wall of the thrust