Describe the characteristics of different stages in course of a river.

Springs in high altitudes create rivers. They grow is size and volume when different rainfed streams join the main river course as it travels from the source to the mouth. Almost all river courses have three different stages determined by the difference in slope from its source to mouth. The three stages are the upper course, the middle course and the lower course. Their characteristics have been described below –

1. Upper course –

• The river originates here, and its originating point is called the source.

• Owing to high altitude, the river flows over steep slopes.

• Owing to steep slopes, the river speed is highly accelerated which in turns intensifies the rate of erosion.

• This also reduces the chances of deposition and almost nullifies it.

• Most landforms created at this stage are erosional landforms like valleys, waterfalls etc.

2. Middle course –

• This course covers the river flow over gently sloping foothills.

• Owing to the gentle slopes, the river speed decreases, reducing the intensity of erosion and deposition starts.

• Landforms like meanders and ox-bow lakes which are created through both erosion and deposition are observed at this stage.

3. Lower Course –

• This course covers the river flow over the plains.

• Owing to the minimum slope of land, the river flows at a slow pace, and this causes active deposition and almost no erosion.

• The sediments carried over the last courses are deposited in this course creating depositional landforms like flood plains, deltas etc.