Fluvial (river) Processes

Question 1

Two types of erosion

Answer 1

• vertical erosion (downwards)
• lateral erosion (sideways)

Question 2

Upper course

Answer 2

Mostly erosion landforms, ex. Rainfalls

Question 3

Middle course

Answer 3

Mostly erosion and deposition landforms, ex. meanders and transportation

Question 4

Lower course

Answer 4

mostly deposition landforms, ex. levées

Question 5

Deposition

Answer 5

Sediment is deposited on the bed and banks of the river and at the mouth, where velocity falls

Question 6

Processes if erosion that can take place in a river

Answer 6

1. Hydraulic action
2. Abrasion
3. Attrition
4. Solution

Question 7

Hydraulic action

Answer 7

The force of the water hitting the river bed and banks. This is most effective when the water is moving fast and when there is lots of it.

Question 8

Abrasion

Answer 8

When the load carried by the river repeatedly hits the bed or banks dislodging particles into the flow of the river

Question 9

Attrition

Answer 9

When stones carried by the river knock against each other, gradually making the stones smaller and more rounded

Question 10

Solution

Answer 10

When the river flows over limestone or chalk, the rock is slowly dissolved. This is because it is soluble in mildly acidic water.

Question 11

Main types of transportation that occur in a river

Answer 11

• traction
• saltation
• suspension
• solution

Question 12

When does deposition occur

Answer 12

It occurs when the velocity of a river decreases. It no longer has energy to transport its sediment so it is deposited

Question 13

Where are larger rocks deposited

Answer 13

In the upper course of a river
- only transported for very short distances mostly by traction, during periods of very high flow

Question 15

Finer sediment is

Answer 15

Carried further down stream, mostly held in suspension. This material will be deposited on the river bed or banks, where velocity is slowed by friction

Question 16

Where does a large amount of deposition take place

Answer 16

At the river mouth, where the interaction with tides, along with very gentle gradient, greatly reduced the rivers velocity