Uncovering the Secrets of River Migration: A Study Reveals the Complex Interplay Between Bar Push and Bank Pull

In a study to investigate river migration rates, Greenberg and Ganti collected data from existing measurements and added information from approximately 60 additional rivers. They used satellite imagery to model each river channel as a series of line segments and track how these segments shifted over time. This allowed them to measure the river’s migration rate.

The researchers found that while vegetation can slow down river migration by stabilizing the outer bank against erosion, sediment load is also a significant factor. Sediment-rich rivers tend to migrate faster than those with no vegetation. The analysis revealed that rivers with high sediment loads relative to their size migrated four times faster than similar-sized counterparts, rather than the reported 10-fold increase. This indicates that bar push, rather than bank pull, has a stronger influence on meandering rivers.

Ganti noted that in meandering rivers, one process cannot dominate the other. If there is not enough sediment supply, bank pull will outpace bar push, leading to a braided river. Therefore, it is the balance between bar push and bank pull that creates stable meandering rivers.