THE SECRET LIVES OF MEANDER BENDS
Each available Landsat image is classified, and annual bankfull-resolving composites are created by combining individual images. Binary channel masks are derived from the annual composites, and these annual masks are used to quantify planform changes. A comprehensive Matlab toolbox was developed to extract banklines and centerlines, compute widths, curvatures, and angles, and quantify planform changes via centerline migration and erosion/accretion. The toolbox was applied to binary masks of the Ucayali River to quantify changes in width, identify hotspots of migration, and map 57 cutoffs over 30 years of evolution. The analysis captures variability from the reach-scale, where climate may control average migration rates, to the bend-scale where local flow conditions and channel morphology affect meander migration. Intermediate-scale variability is also observed that corresponds to cutoff events that, in some cases, induce accelerated migration rates up- and downstream across many bends. This study demonstrates the vast potential locked within Landsat archives to identify multi-scale controls on meander migration, observe the co-evolution of width, curvature, discharge, and migration, and discover and develop new geomorphic insights such as accelerated migrations due to cutoff.