Fluvial Processes

Question 1

How do rivers erode?

Answer 1

• downwards (vertical erosion) and sideways (lateral erosion).
• requires large amounts of energy

Question 2

Name 4 types of erosion

Answer 2

• abrasion / corrasion
• attrition
• hydraulic action
• solution / corrosion

Question 3

Abrasion

Answer 3

The scraping, scouring and wearing away of the bed and banks by rock fragments carried by the river flow.

Question 4

Attrition

Answer 4

Wearing down of the river load itself as particles strike each other and the bed and banks.

Question 5

Hydraulic action

Answer 5

Process of river bed and bank erosion; it involves the energy of the flowing water itself.

Question 6

Solution

Answer 6

Material chemically dissolved in water.

Question 7

Name 4 types of transportation

Answer 7

• traction
• saltation
• suspension
• solution

Question 8

Traction

Answer 8

Involves bed load material rolling downstream

Question 9

Saltation

Answer 9

Process by which material is transported in a bouncing motion

Question 10

Suspension

Answer 10

Light particles are held and carried in the flowing water

Question 11

Solution

Answer 11

Material chemically dissolved in water

Question 12

When will a river deposit its load?

Answer 12

If there is not enough energy to transport the particles. Larger
particles are dropped off first, then smaller.

Question 13

What logic does the Hjulström curve follow?

Answer 13

a) the larger the particle, the more energy needed to erode or transport it
b) erosion will need more energy than transport

Question 14

Anomalies in the Hjulström curve

Answer 14

• clay or silt have a natural cohesion and stick together, requiring more energy to lift them. Once separated the individual particles are easily carried and clay will remain suspended even at low velocities
• clay and silt particles can be very tightly packed, making the water flow smooth with little friction. The clay is less likely to be disturbed by water flow