Report
Ice jams in river confluences
CRREL report, Vol.99-6
U.S. Army Corps of Engineers, Cold Regions Research & Engineering Laboratory
05/1999
Abstract
Two laboratory models of confluences are corroborated with observations interpreted from field observations of ice jams in the vicinity of confluences. One model was used to identify the processes whereby ice can jam in confluences and to determine how selected parameters (e.g., confluence angle) influence them. The confluences of primary interest were those formed by channels whose beds are at about the same level. The second model was used to examine ice jam formation in the confluence of the Mississippi and Missouri Rivers. Three relatively complex processes were found to lead to ice jams: the merging of ice runs, hydrodynamic pressure from a confluent flow impacting on ice run from the second confluent channel, and ice congestion at a confluence bar. The latter process is a significant factor triggering ice jams at the confluence of the Mississippi and Missouri Rivers. Also, three simple processes account for many ice jams at river confluences: ice blocked by an ice cover in the confluence, large ice pieces arching at the confluence, and ice entering a region of sluggish flow. The main practical contributions of the study are formulations for estimating the maximum rate of ice conveyance through channel confluences, and the confirmation of the efficacy of a series of bendway weirs to mitigate ice jam formation at the confluence of the Mississippi and Missouri Rivers. The bendway weirs have additional benefits, such as greatly reducing the amount of ice accumulating in the approach to the Chain-of-Rocks Canal, which is located at the confluence exit.
Details
- Title: Subtitle
- Ice jams in river confluences
- Creators
- Robert EttemaMarian MusteAnton Kruger
- Resource Type
- Report
- Publication Details
- CRREL report, Vol.99-6
- Publisher
- U.S. Army Corps of Engineers, Cold Regions Research & Engineering Laboratory
- ISSN
- 0501-5782
- Number of pages
- v, 61 pages
- Grant note
- Contract No.: DACA 4303900
- Language
- English
- Date published
- 05/1999
- Academic Unit
- Geographical and Sustainability Sciences; Electrical and Computer Engineering; IIHR--Hydroscience and Engineering; Mechanical Engineering; Civil and Environmental Engineering
- Record Identifier
- 9984197906102771
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