THE MODERN KICKING HORSE RIVER, BC; AN INTEGRATION OF GROUND-PENETRATING RADAR, REMOTE SENSING, AND GAUGING RECORD ANALYSIS

The Kicking Horse River is a gravel-bed stream originating from glacial meltwater supplied by the Wapta Icefields in south-eastern British Columbia. An alluvial tract extends for 7 km through Field, BC, where the trunk channel undergoes diurnal and seasonal fluctuations in flow as a result of varying glacial-meltwater supply and runoff recharge. Prior studies erected the Kicking Horse River as a reference for proximal braided systems, and documented bar formation and sediment distribution patterns from ground observations. However, a consistent model of planform evolution and related stratigraphic signature is lacking. Specific objectives of this study are to examine the morphodynamic evolution and stratigraphic signature of channel-bar complexes using high-resolution satellite imagery, sedimentologic and discharge observations, and ground-penetrating radar (GPR). Remote sensing highlights rates of lateral channel migration of as much as 270 meters over eight years (~ 34 meters/year), and demonstrates how flood stages are associated with stepwise episodes of channel braiding and anabranching. Channel migration influences the size and relative abundance of mid-channel bars and bank-attached bars, through repeated processes or erosion and reworking. Furthermore, calculations in flow variance, defined as the angle between local direction of flow and bank accretion, indicate enhanced channel-flow configuration featuring recirculation cells along locally sinuous bends. GPR analysis aided in the identification of five distinct radar facies, including: discontinuous, inclined, planar, trough-shaped, and mounded reflectors. Integration of sedimentological data with remote sensing, gauging records, and GPR analysis allows for high-resolution modelling of stepwise changes in alluvial morphology. Conceptual models stemming from such analyses can be employed to understand the depositional history and stratigraphic signature of proximal and coarse-grained fluvial systems.