Variable hillslope-channel coupling and channel characteristics of forested mountain streams in glaciated landscapes |
| |
| Authors: | Marwan A Hassan Stephen Bird David Reid Carles Ferrer-Boix Dan Hogan Francesco Brardinoni Shawn Chartrand |
| |
| Institution: | 1. Department of Geography, The University of British Columbia, Vancouver, BC, Canada, V6T 1Z2;2. Fluvial Systems Research Inc., 501-15216 North Bluff Road, White Rock, BC, Canada, V4B 0A7;3. Department of Civil and Environmental Engineering, Technical University of Catalonia, Barcelona, Spain;4. Department of Biological, Geological and Environmental Sciences (BiGeA), University of Bologna, 40126 Bologna, Italy |
| |
| Abstract: | Channel morphology of forested, mountain streams in glaciated landscapes is regulated by a complex suite of processes, and remains difficult to predict. Here, we analyze models of channel geometry against a comprehensive field dataset collected in two previously glaciated basins in Haida Gwaii, B.C., to explore the influence of variable hillslope–channel coupling imposed by the glacial legacy on channel form. Our objective is to better understand the relation between hillslope–channel coupling and stream character within glaciated basins. We find that the glacial legacy on landscape structure is characterized by relatively large spatial variation in hillslope–channel coupling. Spatial differences in coupling influence the frequency and magnitude of coarse sediment and woody material delivery to the channel network. Analyses using a model for channel gradient and multiple models for width and depth show that hillslope–channel coupling and high wood loading induce deviations from standard downstream predictions for all three variables in the study basins. Examination of model residuals using Boosted Regression Trees and nine additional channel variables indicates that ~10 to ~40% of residual variance can be explained by logjam variables, ~15–40% by the degree of hillslope–channel coupling, and 10–20% by proximity to slope failures. These results indicate that channel classification systems incorporating hillslope–channel coupling, and, indirectly, the catchment glacial legacy, may present a more complete understanding of mountain channels. From these results, we propose a conceptual framework which describes the linkages between landscape history, hillslope–channel coupling, and channel form. © 2018 John Wiley & Sons, Ltd. |
| |
| Keywords: | mountain streams hillslope–channel coupling hydraulic geometry wood landslides process domains channel classification divide breaching glacial history |
|
|
