Asynchronous Terrace Development in Degrading Braided Channels
Abstract
Terrace remnants are commonly used to reconstruct longitudinal profiles of rivers and floodplains, and to establish temporal correlations of events in fluvial systems. In most cases, it is assumed that the terrace remnants represent time-equivalent surfaces. Our observations of terrace formation in flume experiments and in a degrading braided river, Ash Creek, Arizona, suggest that this assumption is not always valid. Degradation resulted from a reduction in upstream sediment delivery to braided channels. in both the flume and Ash Creek, degradation in the upstream reach produced a number of inset terraces, while the production of sediment in the degrading reach simultaneously caused further aggradation downstream. Thus, stratigraphically lower surfaces in the upstream reaches are temporally equivalent to higher surfaces in downstream reaches. The downstream progression of the wave of incision produced more terraces upstream than downstream, and terrace surfaces could not be correlated on the basis of relative position or elevation above the channel bed. River response, Terraces, Degradation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1993
- Accession Number
- ADA271044
Entities
People
- Dru Germanoski
- Michael D. Harvey
Organizations
- Colorado State University