Temporal analysis of the planform morphology of the Quevedo River, Ecuador, using remote sensing

Abstract

This study aims to characterize the channel morphology and dynamic changes of the Quevedo River during 1986–2019 using Landsat and Sentinel satellite images. We classified around one hundred bends within a 125 km long section of the river into simple and compound bends. We measured their morphometric parameters: bend length, channel width, the radius of curvature, and sinuosity index (SI). Quevedo River showed a decrease in sinuosity and its total length (−3.7 km), mainly caused by cutoffs. Then, we compared the sequential positions of 50 bends or meanders (bends with SI > 1.25) in 1986–2000 and 2000–2019 to classify their change patterns and measure their migration's distance, rate, and direction. We found that migration patterns were dominated by translation and extension of bends and the presence of two differentiated reaches. The northern reach presents average migration rates four times higher than the southern one (7.1 vs. 1.7 m/year). Along with the observed decrease in sinuosity, there is a generalized decrease in migration rates, which might be attributed to the construction of the Baba Dam upstream of the river. Finally, we found that migration rates were maximum in meanders with medium curvatures. These findings can contribute to improving river management and implementing policies to increase local communities' resilience to river hazards.