Question

Describe and explain variation in upper course, middle course and lower course in river velocity

Answer 1

Answer:

Before looking at river landforms it is important to understand the more general role of rivers and to develop an awareness of the processes at work within rivers. It is through this knowledge that we will better undertand the processes at work in the geomorphology of the drainage basin. The role of rivers can be understood in very simple terms. The river's role is to balance its load and transport it to the ocean. But this idea of rivers, as merely transporting weathered material to the ocean is too simplistic. In reality the river changes in energy, discharge, velocity, channel charactersitics and load as it extends down its course. These changes show a recognisable pattern, that you may be familiar with from the Geography textbook. In reality however, there is a great deal more variation. The river is in constant interaction with its physical environment as well as climate and human factors. This interaction leads to considerable variation in both the landforms and processes of rivers. These variations can be seen at both a spatial and temporal scale.

Picture

It's well known that rivers increase in size as they transport water from their source in their headwaters to the mouth. The river channel becomes wider and deeper and as a result its cross-sectional area increases. We can also observe along the river's course an increase in both quantity of water and bedload. The nature of bedload also changes downstream. In the upper course of the river bedload is larger and more angular