Application Of Natural Channel Design Principles In Conversion Of A Multiple-Thread To Single-Thread Channel On An Alluvial Fan: Mccallum Creek, Alaska

Abstract

McCallum Creek crosses the Trans Alaska Pipeline in the Central Alaska Range near Paxson, Alaska. It was converted from a braided channel on an alluvial fan to a stable single thread channel at the pipeline crossing. Objectives included controlling the position of the channel at the pipeline and minimizing aufeis accumulations through the converted reach. A natural channel design methodology was used, which involves determining the dimension, pattern, and profile of a stable reference reach for the associated valley type and stream type and emulating those characteristics in the design reach. A failure mode analysis was conducted. Mitigative measures were identified for each potential failure mode. The channel was lowered to reduce surface energy loss and associated aufeis accumulations. Performance was good during the 2000 and 2001 seasons. Aufeis accumulations have not recurred. Lessons learned are presented from this and several similar projects constructed along TAPS in 2000 and 2001. <p>