Fluvial (river) processes

Question 1

erosion

Answer 1

the process by which a river wears away the land

Question 2

transportation

Answer 2

the process by which a river carries its load

Question 3

deposition

Answer 3

the process by which a river drops its load

Question 4

what are the types of erosion?

Answer 4

-abrasion
-hydraulic action
-corrosion
-attrition

Question 5

abrasion

Answer 5

erosion of banks and beds by load transported by a fast flowing current

Question 6

hydraulic action

Answer 6

the sheer force and power of moving water on the sides of the river bed and in the cracks of the rock

Question 7

corrosion

Answer 7

chemical action that dissolves the bed and banks

Question 8

attrition

Answer 8

erosion of the bedload by contact with other loads, the bed and the banks, attrition rounds and smooths the bedload

Question 9

what are the different types of transportation?

Answer 9

-traction
-saltation
-suspension
-solution

Question 10

traction

Answer 10

heavy rocks and boulders are rolled along the river bed when the current is strongest

Question 11

when does traction happen the most?

Answer 11

happens most in times of flood

Question 12

saltation

Answer 12

small pebbles are bounced along the river bed when river flow is less than that needed for traction to take place

Question 13

suspension

Answer 13

very small particles of sand or clay that are suspended in the water, these particles will settle if kept in a jar of water overnight and the water will look clear

Question 14

solution

Answer 14

takes place when material is dissolved in water, it is invisible and does not colour the water

Question 15

when does solution occur?

Answer 15

often in limestone landscapes where the water is very acidic

Question 16

when does deposition occur?

Answer 16

when there is a reduction in river velocity which results in its load being deposited, starting with the largest sediment as this requires a lot of energy to remain in suspension

Question 17

how does deposition occur?

Answer 17

1. there is a sudden reduction in gradient
2. the river enters a lake or a sea
3. river flow has reduced following a period of low rainfall
4. where there is shallow water
   5.there is a sudden increase in the volume of sediment available
5. river overflows its bank so velocity outside the channel is reduced

Question 18

how do fluvial processes cause vertical erosion?

Answer 18

hydraulic action deepens the river as there’s little energy left after overcoming friction which deepens the channel by eroding downwards

Question 19

how do fluvial processes cause lateral erosion?

Answer 19

when the river goes into lower course it becomes less steep and it starts to meander, when the water goes round a bend the water is forced onto the outside of the bend which causes erosion sideways

Question 20

what does the Hjulstrom curve show?

Answer 20

it’s very difficult for rivers to get smaller rocks moving but once they’ve been picked up they are very easy to transport