What process results in the lengthening and branching of a river channel?

The lengthening and branching of a river channel primarily result from a process called river incision and erosion. As water flows, it erodes the riverbed and banks, causing the channel to deepen and widen. Additionally, factors such as changes in water flow, sediment deposition, and tectonic activity can lead to the formation of new channels through meandering or avulsion, contributing to the river's branching pattern over time. This dynamic process is influenced by both natural factors and human activities.