That the speed of its expansion is increasing
1 - The flow of the river may change as water is fed out into tributaries. 2- As a river flows it may etch out the river bed and create a gulley as it moves sediment and debris. 3- Depending on the speed of a stream it can form into a meandering river with twists and turns. What is interesting about these rivers is they actually move as debris is deposited on one side of the meander and picked up on the other. 4 - Depending on topography the river may increase in speed and give you rapids.
