Modes of response of a gravel bed river to meander straightening: The case of the Sainte-Marguerite River, Saguenay Region, Quebec, Canada

摘要: [1] In the 1960s, extensive meander straightening (rectification) was conducted along 8 km of Sainte-Marguerite River to facilitate highway construction valley bottom. Comparison long profiles and data on bed pavement caliber from current river channel man-made oxbows sheds light multifaceted responses this anthropogenic perturbation over last 4 decades: (1) reprofiling consisting 1 m incision in upper coupled with 2 aggradation lower straightened reach; (2) a doubling zone maximum degradation; (3) regrowth three meanders within reach, increasing its length by 7% (400 m); (4) net input × 104 m3 valley-side sediment erosion into terraces. Hydraulic transport reconstructions indicate that coarsening nearly decades equally contributed reequilibration while lateral inputs terraces played minor roles.