Prevalence of juxtaposed anabranching-meandering channel planform in Midwestern US: morphological characteristics and power regimes

Keywords: river dynamics, anabranching, planform
Session Type: Virtual Paper Abstract
Day: Friday
Session Start / End Time: 2/25/2022 09:40 AM (Eastern Time (US & Canada)) - 2/25/2022 11:00 AM (Eastern Time (US & Canada))
Room: Virtual 20

Abstract

Channel planform is the result of present and past hydrologic, sedimentary, and geologic conditions, and represents an adjustment of the river to these conditions. Rivers with varying planform generally have different boundary conditions, evolution trajectories, and underlying processes. An important, yet overlooked aspect of geomorphic heterogeneity in intensively managed agricultural landscapes of the midwestern United States is spatial variability in channel planform. Otherwise meandering rivers in the midwest often contain anabranching reaches characterized by multiple channels separated by stable, vegetated islands. Morphologically, these anabranching reaches appear to differ from anabranching forms previously reported in the literature in terms of island shape and bifurcation angle. This research quantitatively characterizes the morphological characteristics of anabranching reaches within meandering river systems based on number of channels, island shape and size, bifurcation angles, and cross-sectional geometry across the channel belt. A combination of high resolution imagery and LiDAR elevation data is used to construct a three-dimensional classification scheme (planform + bed profile) to better characterize anabranching river types. Although differences in planform types have been explained as a function of stream power, which represents the energy of a river to perform geomorphic work, the environmental domain of anabranching rivers has yet to be defined precisely, especially in relation to other planform types. The study is a first attempt at characterizing juxtaposed anabranching-meandering systems and provides the basis for further process-oriented fieldwork exploring the role of natural versus human-induced processes on the formation and evolution of mixed planform river characteristics in intensively managed agricultural landscapes.