Multi-scale analysis of the effects of forestry operations on the stream morphology and sedimentology of the Cascapédia River, eastern Québec

• Main Author: Rousseau, Mélanie
• Format: Others
• Language: en
• Published: McGill University 2004
• Subjects: Logging > Environmental aspects > Québec (Province) > Cascapédia River Watershed.; Sediment transport > Québec (Province) > Cascapédia River Watershed.; River channels > Québec (Province) > Cascapédia River Watershed.
• Online Access: http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81429

Forest harvesting is blamed for a perceived increase in the flashiness and turbidity of the Cascapedia River's water. This has raised questions over the source of the sediment (harvest parcels, roads, or stream banks) and its potential impact on the sedimentology of the river. The objectives of this research are twofold. The first is to ascertain if harvesting operations are associated to a widening of low-order tributaries, creating a source of sediment. The second is to determine if variations in the sedimentology along four segments of the Cascapedia can be associated to harvesting operation intensity. Firstly, analysis of stream width in low-order tributaries shows that, once the variations associated with basin area and D50 are removed and within the range of harvesting in our dataset, there appears to be a 25% increase in width associated with the harvesting activities of the last five years, as well as with road density, both in a 60 m stream buffer for a number of the sampled streams. Secondly, the models relating harvesting intensity and changes in sedimentology are sensitive to a few sites or contrary to theory. Future studies should determine the underlying hydrological processes responsible for stream enlargement and the process of sediment deposition.