River Channel Dynamics: Retrospect and Prospect

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.