Does variable channel morphology lead to dynamic salmon habitat?. Issue 2 (9th January 2020)

• Record Type: Journal Article
• Authors: Reid, David A.; Hassan, Marwan A.; Bird, Stephen; Pike, Robin; Tschaplinski, Peter
• Is Part Of: Earth surface processes and landforms. Volume 45:Issue 2(2020)
• Page Start: 295
• Page End: 311
• Publication Date: 2020-01-09
• Subjects: Geomorphology -- Periodicals; 551.4
• DOI: 10.1002/esp.4726
• Languages: English
• ISSNs: 0197-9337

Abstract

Abstract: Stream channel morphology forms the template upon which hydraulic aspects of aquatic habitat are created, yet spatial and temporal variability in habitat imposed by changing morphology is not well understood. This paper presents a conceptual model linking sediment supply patterns to spatial and temporal variability in channel form and aquatic habitat. To evaluate this model, change over time in three habitat variables is quantified using a 2D hydrodynamic modeling approach. A 45‐year record of topographic data from Carnation Creek, a catchment in coastal British Columbia, is used for the flow modeling. Using the Nays2DH modeling platform, water depths and velocities are simulated in eight channel segments located at different positions relative to locations of historical colluvial input using seven flow levels ranging from 3% to 400% of mean annual discharge (0.02 to 3.31 m 3 s − 1 ). Results indicate that habitat availability changes through time as a result of sediment supply‐driven changes to channel morphology and wood loads, but patterns in habitat vary as a function of dominant channel segment morphology. Spatial and temporal variability in morphology also influences the relationship between habitat availability and river discharge, leading to non‐stationary habitat‐discharge rating curves. When habitat areas are predicted by applying these curves to daily flow series spanning annual dry seasons, over 50% of the variance in cumulative seasonal habitat area can be explained by year‐to‐year changes in channel morphology and wood loading, indicating that changing morphology is an important factor for driving temporal habitat variability. This variance is related to the morphological variability of a channel segment, which in turn is associated with the segment position relative to zones of colluvial input. Collectively, these results suggest that variability in habitat is impacted by channel morphology, and can be evaluated partly on the basis of a channel's sediment supply regime. © 2019 John Wiley & Sons, Ltd. Abstract : Using a 2D modeling approach coupled to a 45‐year record of streambed topography, this paper presents and then evaluates a conceptual model linking catchment organization and sediment delivery to variability in channel form and aquatic habitat. Changing morphology explains up to 50% of variability in modeled habitat, variability which is greater in regions closer to episodic supply. Overall, these results support the conceptual model, providing a means to distinguish variability in habitat on the basis of the sediment supply regime.