Paper 1 - River Landscapes In The UK

Question 1

What is vertical erosion?

Answer 1

This deepens the river valley (and channel) making it V-shaped.
Its dominant in the upper course of the river.

High turbulence causes the rough, angular particles to be scraped along the river bed, causing more intense downwards erosion.

Question 2

What is lateral erosion?

Answer 2

This widens the river valley (and channel) during the formation of meanders.
Its dominant in the middle and lower courses.

Question 3

What are the types of erosion?

Answer 3

Hydraulic action
Abrasion
Attrition
Solution

Question 4

What is hydraulic action?

Answer 4

The force of the water breaks rock particles away from the river channel.

Question 5

What is abrasion?

Answer 5

Eroded rock picked up by the river scrape and rub against the channel, wearing it away. Most erosion happens by abrasion.

Question 6

What is attrition?

Answer 6

Eroded rocks picked up by the river smash into each other and break into smaller fragments. Their edges get rounded off as they rub together. The further material travels, the more eroded it gets

Question 7

What is solution?

Answer 7

River water dissolves some types of rock (e.g - chalk and limestone)

Question 8

What is traction?

Answer 8

Large particles like boulders are pushed along the river bed by the force of the water.

Question 9

What is suspension?

Answer 9

Small particles like silt and clay are carried along by the water.

Question 10

What is saltation?

Answer 10

Pebble sized particles are bounced along the rive bed by the force of the water.

Question 11

What is deposition?

Answer 11

Its when a river drops the eroded material its transporting.

It happens when rivers slow down.

Question 12

Why do rivers slow down and deposit material?

Answer 12

The volume of water in the river falls.
The amount of eroded material in the water increases.
The water is shallower (e.g - on the inside of a bed).
The river reaches its mouth.

Question 13

Where are waterfalls and gorges found?

Answer 13

In the upper course

Question 14

How do waterfalls form?

Answer 14

1. They form where a river flows over an area of hard rock followed by an area of softer rock.
2. The softer rock if eroded more than the hard rock, creating a ‘step’ in the river.
3. As the water goes over the step it erodes more and more of the softer rock.
4. A steep drop is eventually created, which is called a waterfall.

Question 15

How does a plunge pool form?

Answer 15

The hard rock on a waterfall is eventually undercut by erosion. It becomes unsupported and collapses.

The collapsed rocks are swirled around at the foot of the waterfall where they erode softer rock. This creates a deep plunge pool.

(Also the pressure/force from the falling water)

Question 16

How does a gorge form?

Answer 16

The waterfall will retreat, leaving behind a steep-sided gorge.

Question 17

How are meanders formed?

Answer 17

1. The current is faster on the outside of the bend because the river channel is deeper (less friction to slow down).
2. So more erosion takes place on the outside of the bend, forming river cliffs.
3. The current is slower on the inside of the bend, because the river channel is shallower (more friction to slow down).
4. So eroded material is deposited on the inside of the bend, forming slip-off slopes.

Question 18

How are ox-bow lakes formed?

Answer 18

1. Erosion causes the outside bends to get closer until there’s only a small bit of land left between the bends (called the neck).
2. The river breaks through this land, usually during a flood and the river flows along the shortest course.
3. Deposition eventually cuts off the meander forming an ox-bow lake.

Question 19

What is a flood plain?

Answer 19

Its the wide valley floor on either side of a river which occasionally gets flooded.

Question 20

What are estuaries?

Answer 20

They’re tidal areas where the river meets the sea.

Question 21

Where are estuaries found?

Answer 21

They’re found at the mouth of a river, where it meets the sea.

The land is close to sea level and the river valley is at its widest.

Question 22

What is river discharge?

Answer 22

The volume of water flows in a river per second.

Question 23

What is peak discharge?

Answer 23

The highest discharge in the period of time you’re looking at.

Question 24

What is lag time?

Answer 24

The delay between peak rain fall and peak discharge.

Question 25

What is rising limb?

Answer 25

The increase in river discharge as rainwater flows into the river.

Question 26

What is falling limb?

Answer 26

The decrease in river discharge as the river returns to its normal level.

Question 27

What is meant by prolonged rainfall?

Answer 27

After a long period of rain, the soil becomes saturated. Any further rainfall cant infiltrate, which increases runoff into rivers. This increases discharge quickly, so flooding is more likely.

Question 28

What is meant heavy rainfall?

Answer 28

The water arrives to rapidly for infiltration, so there’s a lot of runoff. This increases discharge quickly, increasing the rick of flooding?

Question 29

What is meant by geology (rock type)?

Answer 29

Clay soils and some rocks (granite) are impermeable so runoff in increased. When it rains, discharge increases quickly, which can cause a flood.

Question 30

What is meant by relief (change in the height of the land)?

Answer 30

If a river is in a steep-sided valley, water will reach the river channel much faster because the water flows more quickly on steeper slopes. Discharge increases rapidly, increasing flood risk.

Question 31

What is meant by land use?

Answer 31

1. Buildings are often made from impermeable materials ans they’re surrounded by roads made from tarmac.
   Impermeable surfaces increase runoff and drains quickly take runoff to rivers - discharge increases.
2. Trees intercept rainwater on their leaves, which then evaporates. Trees also take up water from the ground and store it. This means cutting down trees increases the volume of water that reaches the river channel, which increases discharge.

Question 32

What is hard engineering?

Answer 32

Man-made structures built to control the flow of rivers and reduce flooding.

Question 33

What is soft engineering?

Answer 33

Schemes set up using knowledge of a river and its processes to reduce the effects of flooding.