Question

Why do You think the speed of river decreases as it enters the plain?​

Answer 1

Answer:

The base level of river is almost same as the sea level as river enters plains and approach sea. As there is not much difference in height, water speed reduces. At plains, rivers move in meanders instead of straight and this can reduce the speed as well.

Answer 2

Answer:

the speed of the river depends upon the slope of the plane directly. in case of the plane the slope becomes zero. so the river speed decreases