Fluvial Processes + Transportation

Question 1

What is Hydraulic Action?

Answer 1

Where the sheer force of the water erodes the river bed and the bank. This is most effective when the river is flowing fast and there is lots of water (flood conditions)

Question 2

What is Abrasion?

Answer 2

Where stones in transport are thrown at the river bed and the river banks causing some of the material to break off (i.e. erosion)

Question 3

What is Attrition?

Answer 3

It is where the stones and boulders carried by the river knock against each other, causing pieces to break off. The stones become smaller, smoother and more rounded.

Question 4

What is a solution?

Answer 4

This process of river erosion occurs when water flows over certain type of rocks like chalk or limestone. These are soluble in slightly acidic river water and are dissolved by it.

Question 4

Vertical Erosion

Answer 4

Vertical Erosion is the downward erosion which deepens the river channel

Question 5

Lateral Erosion

Answer 5

Lateral Erosion is the sideward erosion which widens the river channel

Question 6

What Occurs in the Upper Course section of a river?

Answer 6

• Vertical Erosion
• Narrow V-shaped Valley
• Pot-Holes
• Interlocking spurs
• Waterfalls
• Rapids
• Gorges
• Large Boulders

Question 7

What Occurs in the Middle Course of a River?

Answer 7

• Lateral Erosion

- Transportation

Question 8

What occurs in the lower course of a River?

Answer 8

• Transportation
• Deposition
• Friction is reduced, so greater velocity (speed of water flow)

Question 9

How does Traction work?

Answer 9

This is the method that the river uses for moving the largest type of material. The boulders that are too heavy to lift off the river bed are rolled along in Traction

Question 9

How does Saltation work?

Answer 9

This moves the small stones and grains of sand by BOUNCING them off the river bed.

Question 10

How does Suspension work?

Answer 10

This is when the river carries along fine light material within the river downstream.

Question 11

How does Solution work?

Answer 11

This is when the local rocks are dissolved chemically into the river. This can only occur with soluble rocks (like limestone) that dissolve in rainwater.

Question 12

Capacity of a river?

Answer 12

The capacity of a river is the amount of material it can carry (i.e. the total volume of load). A river’s capacity increases according to its velocity.

Question 13

What’s the COMPETENCE of a river?

Answer 13

The competence of a river is the largest particle it can carry for a given velocity

Question 14

What is the definition of Deposition?

Answer 14

Deposition is the laying down of sediment carried by wind, flowing water, the sea or ice. Sediment can be transported as pebbles, sand and mud, or as salts dissolved in water.

Question 15

Why do rivers deposit sediment??

Answer 15

Deposition occurs whenever a river loses energy and velocity falls. This can be when:

• a river enters a shallow area (when it floods and comes into contact with a flood plain)
• at the base of a waterfall
• on the inside bend of a meander-toward its mouth where it meets another body of water

Question 16

What is the long profile of a river?

Answer 16

The long profile of a river shows the gradient of a river as it jounreys from source to mouth
The long profile of a river is a way of displaying the channel slope (gradient) of a river along its entire length. Therefore it shows how a river loses height with increasing distance towards the sea

Question 17

What is a meander and how is it formed?

Answer 17

As a river erodes laterally to the right side then the left side, it forms large bends and loops called meanders. The force of the water erodes the river bank on the outside of the bend where due to reduced friction, the water flow has most energy. On the inside bend, where river flow is slower, material is deposited as there is more friction forming a slip-off slope or river beach.

Question 18

What is the cross river profile?

Answer 18

The cross profile of a river shows how the width and depth of the river valley and channel change as you travel downstream.

Question 19

Why does the cross profile of a river change along its course?

Answer 19

In the upper course, the river erodes its bed by hydraulic action and abrasion.
As the river flows downstream tributaries increase the volume of water, velocity and its erosive power. This enables it to cut a deeper channel becomes wider as the gradient becomes more gentle leading to less vertical erosion. By the middle course of the river lateral erosion becomes the dominant type of erosion causing the river to become wider.

Question 20

Explain the formation of a waterfall

Answer 20

Waterfalls form where there are layers of horizontal rock.
Hard rock is on top of the soft
Where the soft rock is close to the surface under the hard, it is eroded faster by abrasion and hydraulic action and an overhang is created of the cap rock
Over time, this will get bigger and eventually it will collapse creating a waterfall,
Repeated erosion by material in the plunge pool deepens the waterfall

Question 21

Difference between hard and soft engineering

Answer 21

Hard engineering river management involves building artificial structures ewhich try to control natural processes
Soft engineering involves taking a more sustainable and natural approach to managing rivers

Question 22

Social, economic and environmental affects of flooding

Answer 22

Social:
-Damage to property
-Injury or loss of life
Economic:
-Cost of repairs
-Reduced toursim
-Closure of businesses
Environmental:
-Loss of habitat
-Loss of wildlife

Question 23

Explain how deforestation increases flood risk

Answer 23

Cutting down trees causes increased run-off (water flowing over surface of Earth) Rainwater reaches rivers faster. Floodin becomes more likely

Question 24

`Explain the formation of a flood plain

Answer 24

Flood plains are formed due to meander migration, where the outside bends erode laterally into the edges of the valley. Their position is also gradually moving downstream. Eventually, a wide valley cut. Deposition during flooding results in a flood plain being slightly higher.

Question 25

What is a drainage basin?

Answer 25

Area of land drained by a river and its tributaries

Question 26

Whats a tributary?

Answer 26

Smaller river flowing into a larger one

Question 27

What is a confluence?

Answer 27

Point at which two rivers/tributaries join

Question 28

What is a watershed?

Answer 28

A watershed is a boundary of drainage basins often on a ridge

Question 29

What is transpiration?

Answer 29

Water is released through the stomata of the leaves

Question 30

What is interception?

Answer 30

interception refers to precipitation that does not reach the soil, but is instead intercepted by the leaves, branches of plants and the forest floor.

Question 31

What is through-flow?

Answer 31

Water flows horizontally through the rock into a river

Question 32

What is percolation?

Answer 32

Water flowing vertically through the soil and rocks

Question 33

What is infiltration?

Answer 33

When water seeps into the ground

Question 34

What is groundwater flow?

Answer 34

Groundqater flow is when water flows horizontally through the soil into the river

Question 35

What is evaporation?

Answer 35

Water turns water droplets into water vapour

Question 36

What is surface run-off?

Answer 36

Surface run off is when water flows horizontally over the land into the river