Factors Influencing Ice Conveyance at River Confluences

• Main Authors: Ettema, Robert, Muste, Marian, Kruger, Anton, Zufelt, Jon
• Other Authors: COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
• Format: Text
• Language: English
• Published: 1997
• Subjects: Snow; Ice and Permafrost; *HYDRAULIC MODELS; *ICE BREAKUP; *ICE REPORTING; ICE FORMATION; BATHYMETRY; FLOW FIELDS; DRIFT; CASE STUDIES; ARMY CORPS OF ENGINEERS; MISSISSIPPI RIVER; MISSOURI RIVER; CONFLUENCE; PIV(PARTICLE IMAGE VELOCIMETRY); Ice; permafrost
• Online Access: http://www.dtic.mil/docs/citations/ADA335571; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA335571

This report documents preliminary findings concerning ice jam conditions in river confluences, using two laboratory approaches. First is categorizing the different conditions of ice discharge into a confluence based on two general classifications: free drift of ice and movement of contiguous ice accumulations. The variables defining ice discharge for the two categories are assembled via dimensional analysis into two consistent sets of nondimensional parameters. The categorization, together with the nondimensional parameters, is used to evaluate ice jam problems at confluences the two most common causes of jams seem to be sluggish water velocities in the outflow channel and local bathymetric features. The second approach examines how confluence geometry and flow processes affect ice discharge for example, the influence on ice discharge of bathymetric features. The approach uses a large hydraulic model of a two channel confluence, which is adaptable to a variety of channels, and particle image velocimetry (PIV) for determining and mapping whole fields of water and ice velocities in a confluence. PIV, which is becoming extensively used, lends itself very well here. This study is the first demonstration of the PIV method for ice movement through a two river confluence. It shows promise. The hydraulic model and PIV method are used in a case study of ice discharge through the confluence of the Missouri and Mississippi rivers, a confluence prone to severe ice jams.