Ellen E Wohl and Keith J Tinkler (1998)
Rivers over rock: Fluvial processes in bedrock channels
AGU, Washington, D.C..
Bedrock river channels are sites of primary erosion in the landscape, fixing the baselevel for all points upstream. This volume provides for the first time an integrated view of the characteristics and operation of this important, though hitherto neglected, class of channels. Examples are provided from several continents and cover a wide range of spatial scales from the large river basins (such as the Colorado River in the United States and the Indus River in Pakistan) down to reach scales and individual sites. Likewise the geologic timescales considered range from erosion and transportation during individual flows to accumulated effects over periods of tens of millions of years. Bedrock channels are characteristically steep and generate transcritical flow conditions. These are channels where the Froude number indicates that the fluid flow ranges from subcritical, through critical, to supercritical flow both along streamlines and in cross-sections. These flow conditions have important consequences for the distribution of shear stress and stream power on the stream bed, and for the ways in which such conditions control erosion on the boundary and the transport of coarse caliber sediment up to the size of large boulders. For these reasons, bedrock channels behave very differently than the alluvial river systems more commonly described in textbooks and journal papers. Previous work on bedrock channels has been sporadic and frequently focused on small-scale spectacular features of worn rock surfaces such as potholes or upon the results of a single catastrophic flood, ancient or modern. In this volume we have tried to ensure a comprehensive treatment of the topic by leading experts so that bedrock channels are not treated as exotic items, but as central and important elements in the development of regional landscapes. As the first state-of-the-art survey of bedrock river channels, this book will interest hydrologists, geomorphologists, and civil and environmental engineers, as well as anyone else concerned with high-gradient fluvial channels with part of the boundary in rock. The volume was developed from a conference on the same topic held in 1996 at Pingree Park, a mountain campus of Colorado State University. In our introductory chapter, we have tried to summarize the state of knowledge as well as point out obvious lacunae and fruitful lines of attack for future work. We are extremely grateful to all who have helped in various ways with the manuscripts, especially all the reviewers who read and commented upon the papers. Reviewers for the volume include authors of other chapters in the volume and the following individuals: A.D. Abrahams, D. J. Anthony, P. Bishop, J. E. Costa, L. L. Ely, A. Gupta, D. J. Harbor, H. Ikeda, L. A. James, R. D. Jarrett, A. Kirkbride, S. J. Kite, H. H. Mills, J. Nott, J. E. O'Connor, S. Ouchi, G. Pickup, J. E. Pizzuto, S. A. Schumm, R. L. Slingerland, and M. G. Wolman. The chapter authors have been models of helpfulness and patience during the revision stages, and of course we thank them for their manuscripts, which have very amply justified the hopeful vision that we had several years ago in preparing first the conference and later the volume. We would also like to thank Richard Pyrce for proofreading the final manuscripts.
by Colin Stark — last modified 2006-06-15 13:34