Survey of River Ice Influences on Channel Bathymetry Along the Fort Peck Reach of the Missouri River, Winter 1998-1999

• Main Authors: Zabilansky, Leonard J., Ettema, Robert, Wuebben, James, Yankielun, Norbert
• Other Authors: ENGINEER RESEARCH AND DEVELOPMENT CENTER HANOVER NH COLD REGIONS RESEARCH AND ENGINEERING LAB
• Format: Text
• Language: English
• Published: 2002
• Subjects: Snow; Ice and Permafrost; Civil Engineering; *ICE FORMATION; *CHANNELS(WATERWAYS); *MISSOURI RIVER; COLD REGIONS; BATHYMETRY; ARMY CORPS OF ENGINEERS; CHANNEL FLOW; HYDROGRAPHIC SURVEYING; HYDRAULIC MODELS; FLOOD CONTROL; WATER EROSION; RIVER ICE; RIVERBANK EROSION; Ice; permafrost
• Online Access: http://www.dtic.mil/docs/citations/ADA406302; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA406302

This report documents the findings of a comprehensive survey that investigated the extent to which river ice influences channel bathymetry along the Fort Peck reach of the Missouri River. The Fort Peck reach stretches about 170 miles from Fort Peck Dam Montana to Lake Sakakawea North Dakota. The reach comprises a channel of alluvial sinuous-braided morphology historically known for its shifting thalweg and erosion-prone banks. The survey which entailed extensive monitoring and detailed measurements of channel bathymetry ice conditions and flow velocity distribution was conducted at five sites during the winter of 1998-99. The observations and data though still preliminary and incomplete indicate fundamental processes whereby river ice formation may influence channel bathymetry along the Fort Peck reach as well as other flow-regulated alluvial-channel rivers. Prior to the survey the river ice processes had only been conceptualized but not documented. The results provide evidence the ice cover formation can trigger shifts in the channel thalweg location and can exacerbate riverbank erosion. The observations and data provide insights for operating Fort Peck Reservoir as well as for engineering activities in the Fort Peck reach of the Missouri River. More generally, they indicate which riverbank stabilization structures likely work better in winter conditions where riverside water intakes might best be located and the effects of ice formation on local channel morphology at bridge crossings. The information also has significance for dredging work. The conclusions are based on measurements made-during the 1998-99 winter season on the Fort Peck reach when the hydraulic and ice conditions were unique during the time of the measurements. Further work is needed to confirm the processes and to understand the short- and long-term interactions between the variables influencing the bank-ice-sediment system. The original document contains color images.