Anabranching Flume Experiments, How Channel Pattern Affect Bed Morphology

Friday, 19 December 2014
Jiaoli Ren, Christian E Frias, Catalina Escobar and Jorge D Abad, University of Pittsburgh Pittsburgh Campus, Pittsburgh, PA, United States
It is well-known that large rivers develop a special type of multi-channel planform called anabranching. Although there are several studies related to single-channel rivers for different scales and conditions, very little is known about the dynamics of anabranching rivers. An anabranching river planform presents portions where the river is split in a main channel and one or more secondary channels. For this type of planform, the morphodynamics interaction between main and secondary channels such as bed morphology, lateral migration rates, or velocity patterns is still not well understood.

The purpose of this research is to explain the interaction of the bed morphology between main and secondary channels in an anabranching river planform. To that end, a physical model that resembles a typical anabranching structure in the Amazon River was built. The model includes a main channel and two sub-channels of different lengths. By setting four gates to control the flows in sub-channels, we were able to set several types of flowing conditions which include the main channel only, the main channel with one sub-channel and the main channel with two sub-channels. The results helped to find how the factors such as flow rates and the shape of sub-channels affect the bedform which can increase our understanding of the anabranching pattern’s development.