Explain how the characteristics of a river change as you travel downstream?

A number of river characteristics change as you travel downstream. Firstly, sediment size decreases due to erosion, which causes sediment to get finer and smoother. This happens due to hydraulic action, abrasion, attrition and solution which act on the sediment throughout the course of the river. Another characteristic of the river that changes is the channel width and depth. Due to increased erosion and more added tributaries, the river channel increases in width and depth further downstream. This also increases the volume of water the river can hold. Finally, the gradient of the river decreases as you travel further downstream, as the river begins to meander and this decreases vertical erosion and increases lateral erosion.