What is the main driver behind channel erosion?

Channel erosion is primarily driven by changes in sediment load from upstream sources. When there is an increase in sediment supplied to a river or stream, it can alter the existing balance within the channel. This can lead to increased erosion as the water dynamics change in response to the altered sediment load. For instance, if a river receives a sudden influx of sediment from upstream due to human activity, such as construction or deforestation, this can result in higher flow velocities and increased turbulence. The interaction between the water and the channel bed can erode the banks and the bottom of the channel, thus exacerbating erosion.

Other factors like physical weathering and increased rainfall can influence erosion but are not as directly impactful as sediment load changes. Rainfall can increase water volume but does not account for the varying sediment dynamics contributing to erosion processes. Similarly, while physical weathering processes play a role in breaking down materials, they do not primarily drive channel interactions in the context of sediment load changes. The concept of natural soil regeneration does not contribute to channel erosion, as it is more aligned with soil recovery rather than increasing erosion rates. Therefore, the relationship between sediment load variations and channel erosion is pivotal to understanding this environmental process.