Question

when do the lower course begin​

Answer 1

Answer:

Explanation:Lower course of a river

The volume of water in a river is at its greatest in the lower course. This is due to the contribution of water from tributaries. The river channel is deep and wide and the land around the river is flat. Energy in the river is at its lowest and deposition occurs. .

Answer 2

Upper course - this is where the river starts and is usually an upland area. Slopes are steep - this can increase the velocity of the river after heavy rainfall, when discharge is high. The river channel is narrow and shallow here. The river's load is large in the upper course, as it hasn't been broken down by erosion yet. When discharge is high vertical erosion erodes the river bed and larger sediments are transported by traction!.