Effects of a rise in base level on graded streams
- Univ. of Wisconsin, Kenosha, WI (United States). Geology Dept.
What changes take place in a longitudinal river profile due to a rise in base level would seem to be a fundamental question in geomorphology, however, little has been accomplished toward answering this question, and the prevailing views are contradictory. Most authors say that a river will adjust its entire profile in response to a rise in base level. This misconception appears to have started in Elmo G. Harris' 1901 article, Effects of Dams and Like Obstructions in Silt-bearing Streams. The hypothesis became popular after publication of J. Hoover Mackin's classic 1948 paper, Concept of the Graded River. In the section Rise of Base Level'' Mackin explained that ''...the only generalization that can be made is that the new profile will be everywhere adjusted to the new prevailing conditions.'' Although Mackin's idea was a conceptual one, the concept has subsequently been taken literally. Contrary to this perception, the small amount of work that has been completed shows rivers will adjust their profiles only a short distance upstream from reservoir level. This may be due to the adjustment becoming infinitesimally small upstream and grading into the original profile so that the adjustment upstream is negligible. Unfortunately the misconception of stream aggradation in response to a rise in base level has prevailed for over 90 years and is widespread in the literature. Many textbooks, both introductory and advanced, from 1971 to the present, and some of the leading names in geomorphology have accepted the misconception without question.
- OSTI ID:
- 7141010
- Report Number(s):
- CONF-9404217-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 26:5; Conference: 27. annual conference of the North-Central Section of the Geological Society of America (GSA), Kalamazoo, MI (United States), 28-29 Apr 1994; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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