Meander cutoff and the controls on the production of oxbow lakes

Abstract

Using satellite images archived by Google Earth™, we measured channel and oxbow-lake characteristics of 30 large meandering rivers to identify the controls on the production of oxbow lakes by meander cutoff. Cutoff produced lognormal distributions of lake lengths within the studied reaches, and the geometric mean lake length of each population correlated positively and exponentially with sinuosity, due to more highly sinuous reaches being comprised of longer meanders and to cutoff removing longer segments of more sinuous channels. We successfully predicted the size-frequency distributions of lakes stored within the flood-plains of five freely meandering reaches using only channel sinuosity and an assumption of the variance about the geometric mean lake length, a variable that did not significantly vary between the studied reaches. While the river's sinuosity remains steady, the temporal rate of cutoff can be estimated using channel sinuosity, the fraction by which cutoff reduces channel length, and the rate at which the reach lengthens by meander growth.