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Gradational Thresholds and Landform Singularity: Significance for Quaternary Studies

Published online by Cambridge University Press:  20 January 2017

Ze'ev B. Begin
Affiliation:
The Geological Survey of Israel, Jerusalem, Israel
Stanley A. Schumm
Affiliation:
Colorado State University, Fort Collins, Colorado

Abstract

Geomorphic threshold conditions have been identifed at which stream patterns change and gully initiation occurs. For both, the threshold conditions are defined by the parameter of “relative shear stress” which is a measure of the energy state of the system and is based on known values of stream slope and mean annual discharge (for patterns) or drainage area (for gullies). The probability of passing from a stream pattern to another, or from stable to gullied valley floors, is a smooth function of relative shear stress and so the thresholds separating the different states of the geomorphic systems are gradational. The singularity of landforms prevents the identification of a sharp threshold, and as a result landform sensitivity will differ within the same area and under the same conditions. Therefore, geomorphic predictions and postdictions will be uncertain, and Quaternary correlations will lack precision.

Type
Research Article
Copyright
University of Washington

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References

Begin, Z.B. (1981). The relationship between flow shear stress and stream pattern Journal of Hydrology 52, 307319 CrossRefGoogle Scholar
Begin, Z.B., Schumm, S.A. (1979). Instability of alluvial valley floors—A method for its assessment American Society of Agricultural Engineers, Transactions 22, 347350 Google Scholar
Brunsden, D., Thornes, J.B. (1979). Landscape sensitivity and change Institute of British Geographers, Transactions 4, 463484 Google Scholar
Bull, W.B. (1979). Threshold of critical power in streams Geological Society of America, Bulletin, Part I 90, 453464 Google Scholar
Euler, R.C., Gumerman, G.J., Karlstrom, T.N.V., Dean, J.S., Hevly, R.H. (1979). The Colorado Plateaus: Cultural dynamics and paleoenvironment Science 250, 10891101 Google Scholar
Gessler, J. (1970). Self-stabilizing tendencies of alluvial channels American Society of Civil Engineers, Journal of Waterways and Harbors Division 96, 235249 Google Scholar
Gessler, J. (1971). Beginning and ceasing of sediment motion Shen, H.S. River Mechanics Vol. 1, 7.17.22 Google Scholar
Graf, W.H. (1971). Hydraulics of Sediment Transport McGraw-Hill New York Google Scholar
Hack, J.T. (1957). Studies of Longitudinal Stream Profiles in Virginia and Maryland Geological Survey Professional Paper 294BGoogle Scholar
Kirkby, M. (1972). Alluvial and non-alluvial meanders: AREA Institute of British Geographers, Transactions 4, 284288 Google Scholar
Lane, E.W. (1957). A Study of the Shape of Channels Formed by Natural Streams Flowing in Erodible Material U.S. Army Engineer Division, Missouri River, M.R.D. Sediment Series, No. 9Google Scholar
Leopold, L.B. (1976). Reversal of erosion cycle and climatic change Quaternary Research 6, 557562 Google Scholar
Leopold, L.B., Wolman, M.G. (1957). River Channel Patterns: Braided, Meandering and Straight. U.S. Geological Survey Professional Paper 282-B Google Scholar
Leopold, L.B., Wolman, M.G., Miller, I.P. (1964). Fluvial Processes in Geomorphology Freeman San Francisco/London Google Scholar
Love, D.W. (1979). Quaternary fluvial geomorphic adjustments in Chaco Canyon, New Mexico Rhodes, D.D., Williams, G.P. Adjustments of the Fluvial System Kendall-Hunt Dubuque, Iowa 277308 Google Scholar
Nairn, A.E.M. (1965). Uniformitarianism and environment Palaeogeography, Palaeoclimatology, Palaeoecology 1, 511 Google Scholar
Osterkamp, W.R. (1978). Gradient, discharge and particle-size relations of alluvial channels in Kansas, with observations on braiding American Journal of Science 278, 12531268 CrossRefGoogle Scholar
Patton, P.C. (1973). Gully Erosion in the Semi-arid West Unpublished M.S. thesis Colorado State University Fort Collins Google Scholar
Patton, P.C., Schumm, S.A. (1975). Gully erosion, northern Colorado, a threshold phenomenon Geology 3, 8890 Google Scholar
Schumm, S.A. (1968). River adjustment to altered hydrologic regimen—Murrumbidgee River and palaeochannels, Australia U.S. Geological Survey Professional Paper 598 Google Scholar
Schumm, S.A. (1983). Extrapolation in the earth sciences In preparationGoogle Scholar
Schumm, S.A., Khan, H.R. (1972). Experimental study of channel patterns Geological Society of America, Bulletin 83, 17551770 Google Scholar
Schumm, S.A., Lichty, R.W. (1963). Channel widening and flood plain construction along Cimmarron River in Southwestern Kansas U.S. Geological Survey Professional Paper 352-D 7188 Google Scholar