River dynamics and process-based restoration of fluvial systems

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River systems are under considerable pressure due to human impacts and global environmental changes. As we enter the United Nations Decade on Ecosystem Restoration, it is increasingly recognized that river management approaches must move away from form-based restoration and hard-engineering structures that maintain rivers in a fixed position. The long-term objective of the research program is to advance our understanding of the links between river dynamics and river ecosystems to support the development of sustainable, process-based river restoration. Such restoration involves leaving sufficient space for flooding and erosion processes to operate, which is particularly critical in a context of climate change where increased variability in discharge is expected in the coming decades. This long-term objective will be reached through the combination of, and interactions between, numerical modelling and laboratory and field experimentation. The increased availability of LiDAR high-resolution digital elevation models (DEM), with for example data for the entire southern Quebec now freely accessible, will also greatly help in reaching this objective. The short-term objectives are to 1) develop tools to help predict effects of implementing a freedom space on future river channel evolution; 2) assess the impact of reconnecting former meanders in straightened agricultural streams in various geomorphological contexts and 3) investigate the role of confluence zones as key control points in fluvial system restoration. The scientific approach of this research program is based on the collection of field data at several river reaches in different geomorphological contexts and in a range of anthropogenic disturbances, including agricultural watersheds affected by channelization, dredging and bank stabilization. Field measurements include detailed bed topography, velocity, piezometer monitoring, stage and discharge, and will make use of drone imagery analysis tools. The field component is combined with experiments conducted at the new Outdoor Experimental River Facility (OERF) at Université de Sherbrooke. Geographical Information System (GIS) analysis of LiDAR data is a central part of my research program, with hydrogeomorphological tools designed to examine both mobility and flood processes that will be further developed. The confluence zones will receive particular attention to further our understanding on how these zones affect the physical heterogeneity of the main channel and to pursue detailed analysis on the (so far) underestimated role of density difference between the tributary and main channel. This program will allow significant progress in establishing an expertise in river management based on hydrogeomorphological concepts to tackle major environmental problems in a range of rivers, and on developing GIS and modelling tools to better inform river managers about sustainable process-based restoration approaches.