Changing Channel Characteristics Flashcards
What is the gradient
The slope of the river channel.
What does a high and low gradient mean
A high gradient means the channel has lost height quickly.
A low gradient means a much gentler slope
What is the method of measuring gradient (equipment needed)
Gradient is measured along stretch of river by placing TWO CLINOMETERS against a height mark on one ranging pole and lined up with the same height mark on the other ranging pole.
Measurement for the gradient of channel
Degrees
What will happen to the gradient as it goes downstream
Decreases
What happens to the gradient in middle course
Slope becomes gentler
What happens to the gradient in lower course
Becomes gentler, it has completed much of its vertical erosion and is now cutting sideways. The gradient is less steep and by lower course, almost flat.
What is the width of a river
The distance across the channel from one bank to another
Width is measured how
by placing one end of a tape where water meets the bank at one side of the river then pulling the tape and measure tight across the surface where water meets the bank at the point directly opposite
What will happen to the width as we go downstream
It will increase
Why will the width increase as we go downstream
As the river flows along abrasion and hydraulic action wear away at the river banks making the channel wider particularly in the middle and lower courses. where there is lateral erosion
