COLD CLIMATE FLUVIAL PROCESSES: AN INTEGRATED STUDY OF THE COLVILLE RIVER, ALASKA

The Colville River is the largest river on the North Slope of Alaska, draining over 50,000 km². Temperate fluvial processes may not be applicable as analogs for cold climate fluvial processes on the Colville River because of the role ice and permafrost play in the fluvial system and the timing of fluvial processes. During the winter, ice on the Colville River freezes to the channel bed, halting the flow of water and transport of sediment. This ice, and accumulated snowfall, may act as armor on channel banks, preventing erosion for a short period during spring flooding. In addition, permafrost may cause extreme instability or extreme stability of the banks of the Colville River due to thermoerosional niching during spring flooding or increasing cohesion of bank material. The goal of this research is to better understand cold climate fluvial processes through the use of remote sensing.

Remote sensing images are used to map the Colville River where the river channel changes from a braided pattern to a meandering one in order to study channel and bar morphology and lateral migration rates. Multisensor data from Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM) onboard the Landsat satellites from 1999 and 2001 and digital orthographic quadrangle photographs from 2002 have been obtained through the Alaska Satellite Facility and Geophysical Institute at the University of Alaska, Fairbanks (UAF), for use in this study. In addition, black and white aerial photographs from 1948 and false-color near-infrared (NIR) photographs from 1979 have been obtained through the Map Office at the Geophysical Institute (GI), UAF.

By mapping the Colville River, long-term changes in channel morphology, channel bar and flat evolution, and erosion and deposition rates, can be observed and measured and compared to temperate fluvial processes and rates of change in the Colville River Delta. In addition, fluvial processes and rates between the braided and meandering portions of the river can be compared. Better understanding of present day cold climate fluvial processes and the role ice and permafrost play in the cold climate fluvial system will enhance our understanding of past cold climate fluvial systems by providing a better understanding of bank stability, in-channel processes, and lateral migration rates of cold climate fluvial systems.