river processes

Question 1

what are the characteristics of a river in the upper course?

Answer 1

• river channel is narrow and shallow
• v-shaped valley

Question 2

what are the characteristics of a river in the lower course?

Answer 2

• the river in the lower course is at its widest and deepest

Question 3

describe hydraulic action:

Answer 3

the sheer force of the water causing the bed and the banks to erode.

Question 4

describe abrasion:

Answer 4

when material carried by the river scrapes along the bed and the banks.

Question 5

describe attrition:

Answer 5

eroded material carried by the river hit into each other, creating much smaller, rounded, smoother pebbles.

Question 6

describe corrosion:

Answer 6

the acids in the water causing erosion.

Question 7

describe the difference between lateral and vertical erosion:

Answer 7

lateral erosion:
- sideways, widening the bank of the river
- mainly through hydraulic action

vertical erosion:
- downwards, deepening the bed of the river
- mainly through abrasion/attrition

at times, one of these may be dominating - at the top of a mountain, vertical erosion would be dominant because of gravity.