Floodplain Morphology or River Hydrology: Why are Chute Cutoffs Becoming More Common on Meandering Rivers?

Keywords: river, hydrology, floodplain, cutoff
Session Type: Virtual Paper
Day: Thursday
Session Start / End Time: 4/8/2021 09:35 AM (Pacific Time (US & Canada)) - 4/8/2021 10:50 AM (Pacific Time (US & Canada))
Room: Virtual 3

Abstract

The archetypal unregulated, sinuous meandering river has inspired research into channel planform dynamics and floodplain morphology for centuries. Meandering river cutoffs result in the formation of oxbow lakes and meander scars and prevent an unbounded increase in channel sinuosity, and are thus critical controls on the evolution of meandering rivers and the architecture of their floodplains. Cutoffs are classified as chute style when the cut channel that bypasses the bend is longer than one channel-width in length, and neck style when the cut channel is less than one channel-width long. While research on cutoffs has yielded insights into their formation, only recently have remote sensing tools allowed researchers to better understand the spatial and temporal distribution of each style of cutoff on a global scale. This study builds upon previous work that demonstrates a trend in increasing chute to neck cutoff ratio with time, and the results suggest that changes in floodplain morphology and river hydrology can both be responsible for the increase in chute cutoffs relative to neck cutoffs. We enrich conclusions made from global trends of chute to neck ratio with a combination of aerial and satellite imagery and river discharge observations at specific rivers in the USA and Papua New Guinea. The results of this research begin to explain why certain styles of river cutoff occur at specific times and in specific places.