SEDIMENT, ENERGY, AND LONG PROFILE PATTERNS OF A CHANNELIZED RIVER, MISSION CREEK, B.C

This study documents the characteristics and dynamics of an actively managed channelized river. The study reach of Mission Creek is located within the city limits of Kelowna, B.C. and has been actively managed for flood control for many decades. In the late 1930's the channel displayed a braided pattern with abandoned channels located throughout the floodplain that much of the city of Kelowna was built upon. The channel was locked in its present location and significantly narrowed through diking of the channel banks. Upstream of the diked section, the channel flows through a valley just wide enough to allow large bars to form in some locations. The diking has changed the channel pattern, energy levels, sediment bed grain size patterns and depositional dynamics within the channel. Currently, Mission Creek has several important problems including limited fish habitat value and the need for gravel extraction to maintain channel capacity for flood control. For this study, 14 km of the Mission Creek channel was surveyed using a laser level and hip chain in 2007 and 2008. Bed grain size was determined at 62 sites using pebble counts. These data were used to estimate the bed shear stress and sediment mobility patterns downstream. Data from gravel extracted since the 1980's were used to estimate the sediment transport rates in the system. In light of these analyses, potential restoration approaches are discussed.