Sediments and sediment transport in mountain channels

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In the recent geologic past, numerous glaciations sculpted and reorganized the landscapes of BC, redistributing sediment over large areas and often leading to thick deposits of erodible material. These paraglacial valley fill deposits have been identified as a major sediment source to lowland streams. Modern landuse changes and climate change are imposing increasing stresses on BC river ecosystems and leading to their progressive deterioration. Future climate projections predict a warming trend with increased precipitation seasonality, resulting in more extreme floods in the winter/spring and a decreased spring freshet. More frequent landsliding will likely increase the amount of sediment supplied to channels and the likelihood of landslide damming in mountain rivers with resultant changes to channel morphology. How will these probable hydroclimatic shifts impact freshwater ecosystems, most notably rivers and mountain streams? The long-term objective of my research program is to build a more complete knowledge base of river systems in mountainous regions. Over the next five years I plan to focus on four themes covering a wide range of channel morphologies, sediment supply regimes, and landscapes, by analyzing: (1) bedload movement in gravel bed streams under low intensity sediment transport regimes; (2) sediment transport and channel evolution under unsteady conditions; (3) channel response to landslide damming and breaching; and (4) landscape connectivity, sediment sources, storage. To achieve my goals, I propose to conduct flume experiments, theoretical modelling, numerical simulations, and fieldwork. The proposed themes will integrate information across spatial and temporal scales (from the grain scale (Theme 1) to the basin scale (Theme 4)). The proposed projects will generate immediate and ongoing training and research opportunities for graduate students. By working on research questions outlined in this proposal, students will be exposed to a wide range of research topics and will gain valuable experience in state-of-the-art measurement techniques, data analysis procedures, and mathematical and numerical modeling. In total, I envision that this DG will train 22 graduate and undergraduate students. This proposal will provide theoretical and mechanistic frameworks to advance our understanding of channel morphodynamics across scales and from source to sink, reflecting the diversity of climatic, geologic and geomorphic factors that control channel dynamics. By integrating across scales, we will develop predictive tools that help mitigate the future effects of climate change and land use on landscapes, and help solve many practical problems such as ecological restoration, predicting and managing sediment inputs to reservoirs and other water resources infrastructure, flood mitigation and management, and diagnosing and mitigating sediment-related impacts of land use and climate change.