Form Approved
REPORT DOCUMENTATION PAGE
OMB No. 0704-0188
Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and
maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information,
including suggestion for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington,
VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503.
1. AGENCY USE ONLY (Leave blank)
2. REPORT DATE
3. REPORT TYPE AND DATES COVERED
December 1997
4. TITLE AND SUBTITLE
5. FUNDING NUMBERS
Unsteady Ice Jam Processes
6. AUTHORS
Jon E. Zufelt and Robert Ettema
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)
8. PERFORMING ORGANIZATION
REPORT NUMBER
CRREL Report 97-7
U.S. Army Cold Regions Research and Engineering Laboratory
72 Lyme Road
Hanover, New Hampshire 03755-1290
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)
10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
Office of the Chief of Engineers
Washington, DC 20591
11. SUPPLEMENTARY NOTES
For conversion of SI units to non-SI units of measurement, consult ASTM Standard E380-93, Standard Practice for Use of the International
System of Units, published by the American Society for Testing and Materials, 1916 Race St., Philadelphia, Pa. 19103.
12a. DISTRIBUTION/AVAILABILITY STATEMENT
12b. DISTRIBUTION CODE
Approved for public release; distribution is unlimited.
Available from NTIS, Springfield, Virginia 22161
13. ABSTRACT (Maximum 200 words)
Ice jams cause flooding in northern temperate-climate areas, usually forming rapidly, often with little warning,
constricting water flow and elevating water levels. Consequently, jam formation comprises highly unsteady pro-
cesses: drifting ice pieces are brought to rest, accumulated ice shoves and thickens, and initial water depths and
velocities change. Those processes are even more unsteady when a jam collapses. Prior simulations of ice jams,
however, treat them as simply stationary, uniformly thick accumulations of ice pieces. No account is taken of the
impact forces exerted by moving ice, an estimation that is further complicated by the need to couple equations
describing water flow and ice movement. Under the dynamic conditions attendant to jam formation, water flow
and ice movement interactively influence each other. This report evaluates the importance of ice momentum on ice
jam thickness and thickness distribution using experiments conducted with laboratory flumes and a numerical
model in which the equations of motion for one-dimensional flow of water and ice are solved as fully coupled. In
this regard, the model is unique, enabling simulation of the important unsteady interactions of water and ice, and
determination of their effects on jam thickness. Ice momentum should be taken into account for most jams because
it leads to significantly thicker jams and affects the thickness profile. A useful dimensionless parameter is identified
for generalizing this finding.
14. SUBJECT TERMS
15. NUMBER OF PAGES
Ice jams
Simulations
95
Laboratory experiments
Unsteady processes
16. PRICE CODE
17. SECURITY CLASSIFICATION
18. SECURITY CLASSIFICATION
19. SECURITY CLASSIFICATION
20. LIMITATION OF ABSTRACT
OF REPORT
OF THIS PAGE
OF ABSTRACT
UNCLASSIFIED
UNCLASSIFIED
UNCLASSIFIED
UL
Standard Form 298 (Rev. 2-89)
NSN 7540-01-280-5500
Prescribed by ANSI Std. Z39-18
298-102
Previous Page
