Question

Compared to an upper stage river, a middle stage river has
(Points : 3)
a steeper gradient
more tributaries
faster moving water
all of the above

Answer 1

In the upper stage, river valley is V-shape and steep. water runs fast because the rivers banks has not been eroded. when water runs fast, transportation of sand particles is easy.

In the middle stage, the river is a U-shape due to the erosion of the banks by running water. water runs not too fast and not too slow. the course of the river valley is not so steep. transportation of sand particles is not too fast and not too slow.

In the lower stage, the river valley is flat because the river banks have been eroded. because the water runs slow, meanders are formed. the meanders are then short-cutted and lagoons are formed on both sides along the course of the river. because the river valley is flat, there will be flooding and when river floods, sand particles deposit on the flood plain and the soil is fertile.

Answer 2

Source: http://answers.yahoo.com/question/index?qid=20120307115421AARv6wV