Mountain channels modulate water, sediment, and wood fluxes from hillslopes, dominated by colluvial processes, to high-order streams, in which fluvial transport prevails. Owing to the variety of colluvial-alluvial interactions, and the transient forcing of tectonic activity and Pleistocene glaciations, mountain channels exhibit complex morphodynamics. Knickpoints can form in response to changes in external forcing (e.g., changes in uplift, sea-level, and more), and in many cases retreat upstream through steep mountain channels at rapid rates which set the pace of landscape evolution. An improved understanding of these systems is most needed for addressing fundamental scientific issues (e.g., hillslope-channel feedback mechanisms, long-term landscape evolution), as much as for solving more practical problems, including the prevention/mitigation of flood- and debris flow-induced disasters threatening infrastructure and residential areas.
This session seeks quantitative contributions on the hydro-geomorphic functioning of steep, mountain channels that involve fluvial and/or debris-flow transport. Topics of interest include but are not limited to: sediment entrainment conditions; site-specific to regional compilations of suspended, bedload, and debris-flow transport; hydraulic geometry; channel morphology and sediment transport in relation to hillslope-channel coupling/decoupling; in-channel transport-storage relations; lithologic and glacially-conditioned controls on fluvial and/or debris-flow sediment flux; post-debris flow channel recovery; wood recruitment and transport; and fluvial bedrock erosion, including mechanisms of knickpoint retreat.
Studies that integrate multiple techniques of data collection and analysis (e.g., field-based measurements, remotely-sensed proxies, GIS-based analysis, and modelling efforts) across different temporal scales (e.g., through real-time monitoring, tracers, sedimentologic reconstructions, or cosmogenic nuclides) are particularly welcome.