182 research outputs found

    Some Aspects of the Hydrology of the Fraser River Basin, British Columbia

    Get PDF
    A simple computational procedure for calculating the water balance in the Fraser River basin in British Columbia is presented. The computational model uses readily available meteorological records and is based on the definitional equality that, for a given year, runoff is equal to the difference between precipitation and evapotranspiration adjusted for basin storage fluctuation. The annual hydrologic record generated by this model indicates that, for the period 1951 to 1976, precipitation basin runoff, and evapotranspiration, respectively averaged 737 mm, 433 mm and 301 mm per year, while the mean annual temperature for the same period was 2.1°C. The relationships among the hydrologic components and basin temperature are discussed. It is concluded that, given the known errors in the computational model, the measured water balance is not inconsistent with that derived from the estimating procedure of Thornthwaite and Mather. &nbsp

    Drainage Basin Morphometry and River Network Analysis: A Review and Synthesis

    Get PDF
    This discussion paper is a review of drainage basin morphometry and river network analysis. It is essentially an assemblage of techniques which have become both an important part of geomorphology ahd a useful set of morphometric inputs to hydrologic models of river basins. The paper also provides a discussion of the ideas which collectively have become known as the theory of dynamic equilibrium. It is interesting that many of the concepts and techniques which grew out of this theory have been incorporated into the conventional discipline while the original conceptual framework has become somewhat suspect

    River Channel Dynamics: Retrospect and Prospect

    Get PDF
    This paper attempts to define the state of the art in the field of channel dynamics, to identify critical problem areas, and to suggest the directions of future research. Although the manner in which rivers change the form and pattern of their channels in response to environmental change has been a recurring theme in river studies, it recently has enjoyed considerably increased attention from earth scientists. Perhaps the most significant recent evidence of this interest is the appearance of several collected works and reviews of studies of channel changes (for example, see Gregory, 1977; Gregory and Walling, 1979; Kuprianov and Kopaliani, Park, 1981), and the fact that a Session has been devoted to the topic here Second International Conference on Fluvial Sediments at Keele, England, in September 1981. The study of river channel changes, in the broadest sense of the term, is no less than the study of equilibrium channel behaviour and the nature of excursions from those equilibrium conditions. As such it includes almost all that we know about the fluid mechanics and morphology of alluvial channels. But in a more narrow sense of the term it is the collection of empirical and theoretical studies concerned with adjustment of channel cross-sectiondl size, form, and pattern, to shifts in environmental conditions, particularly those that promote changes in discharge and in sediment loads. In a still narrower sense, channel changes may be regarded as have been induced by the activities of human beings

    Early Postglacial Sedimentation of Lower Seymour Valley, Southwestern British Columbia

    Get PDF
    In lower Seymour Valley, much of the sediment derived from the erosion of valley-side drift (paraglacial sediments) remains in storage in the form of alluvial fans and aprons. Fluvial incision into these features has exposed sections for lithostratigraphic and chronological study. Radiocarbon dating of organic-rich beds within these deposits indicate that paraglacial sedimentation of lower Seymour Valley commenced before 11.4 ka, was periodic, and was essentially complete by about 9 ka; Seymour River had incised to its present vertical position by about 5 ka. Furthermore, our radiocarbon ages indicate that, although paraglacial sedimentation commenced shortly following deglaciation when the climate was cool and moist, a significant amount of sedimentation occurred during a transition from wet and moist climate to warm and dry (xerothermic) conditions (ca. 10 ka). Charcoal-rich beds indicate that some erosional events may have been a result of slope instability caused by fire.La plus grande partie des sédiments de la vallée résultant de l'érosion latérale des dépôts « paraglaciaires » demeurent accumulés sous forme de cône alluvial ou de plaine alluviale. L'encaissement fluviatile dans ces formes a mis au jour des coupes favorisant les études lithostratigraphiques et chronologiques. La datation au radiocarbone de lits riches en matière organique montre que la sédimentation « paraglaciaire » périodique a commencé avant 11,4 ka et s'est à toutes fins pratiques terminée vers 9 ka dans la vallée. L'encaissement de la Seymour River jusqu'à son niveau actuel était atteint vers 5 ka. De plus, les datations montrent que même si la sédimentation « paraglaciaire » a commencé peu après la déglaciation, alors que le climat était frais et humide, une bonne partie de la sédimentation s'est effectuée au cours d'une période de transition vers un climat chaud et sec (conditions xérothermiques) vers 10ka. Les lits riches en charbon indiquent qu'une certaine partie de l'érosion est attribuable à l'instabilité des pentes occasionnée par les feux

    Drainage Basin Hydrology: A Review and Synthesis

    Get PDF
    This paper is the second of a four-part review and discussion of the basic principles and theories of river behaviour. This discussion paper is a relatively comprehensive review of drainage basin hydrology, although it is intentionally biased towards hydrologic conditions in Canada. For example, the treatment of snowmelt runoff is more detailed than those found in standard texts. Emphasis has also been given to certain topics which are directly relevant to the discussion in other parts of this River Studies series. Throughout this work I have attempted to "translate" the often highly technical discussion into a form that a generalist in the earth sciences would find useful

    Aphasia rehabilitation: Does generalisation from anomia therapy occur and is it predictable? A case series study

    Get PDF
    Introduction: The majority of adults with acquired aphasia have anomia which can respond to rehabilitation with cues. However, the literature and clinical consensus suggest change is usually limited to treated items. We investigated the effect of an experimentally controlled intervention using progressive cues in the rehabilitation of noun retrieval/production in 16 participants with chronic aphasia. Method: Participants were sub-divided relative to the group according to performance on semantic tasks (spoken/written word to picture matching) and phonological output processing (presence/absence of word length effect and proportion of phonological errors in picture naming) in order to investigate outcome in relation to language profile. Cueing therapy took place weekly for 8 weeks. Results: Intervention resulted in significant improvement on naming treated items for 15/16 participants, with stable performance on control tasks. Change occurred at the point of intervention and not during pre-therapy assessments. We predicted particular patterns of generalisation which were upheld. Only participants classified as having relatively less of a semantic difficulty and more of a phonological output deficit demonstrated generalisation to untreated items. Outcome did not relate to traditional aphasia classification. Conclusion: A cueing hierarchy can improve word retrieval/production for adults with aphasia. In some cases generalisation to untreated items also occurs. The study demonstrates that the results of behavioural testing can be used to guide predictions of recovery with intervention. © 2013 Elsevier Ltd
    • …
    corecore