River landscapes

Question 1

Physical weathering

Answer 1

Water gets into cracks in the rock.When the temperature falls below freezing, the water will expanded it turns into ice This expansion puts pressure on the rock around it fragments of rock break off

Question 2

Biological weathering

Answer 2

Seeds that fall into cracks in the rocks will start to grow when moisture is present. The roots of the young plant force their way in and in time can break up rocks.

Question 3

Chemical weathering

Answer 3

Rain water contains weak acids that can react with certain rock types. Carbonate in limestone are dissolved by weak acids and this causes the rock to break off or disintegrate.

Question 4

Mass movement

Answer 4

When material moves down a slope due to the pull of gravity

Question 5

Slumping

Answer 5

Happens on river banks, where part of it slips into the river. Common where the river passes clay as the dry weather makes clay contract and crack. Therefore rainwater gets into the cracks and the soil becomes saturated. Due to the pull of gravity, the large piece of weakened rock slips into the river. It is said to have slipped on the slip plane of saturated rock.

Question 6

Abrasion

Answer 6

Material carried in the river is thrown against the river bed and banks by the force of the water,breaking of rocks.

Question 7

Hydraulic action

Answer 7

The pressure of the water against the river bed.

Question 8

Solution

Answer 8

Chemical reaction between certain types of rocks and minerals,wearing it away.

Question 9

Attrition

Answer 9

Rocks in the water hit each other and break into smaller pieces.

Question 10

Traction

Answer 10

Large rocks and boulders are rolled along the river bed.

Question 11

Saltation

Answer 11

Small pebbles and stones are bounced along the river bed.

Question 12

Suspension

Answer 12

Fine light material is carried along the river.

Question 13

Solution [deposition]

Answer 13

Minerals are dissolved in the water and carried along in solution.

Question 14

Deposition

Answer 14

The laying down of materials, such as sand and pebbles that are being transported by the river. Rivers deposit materials when they slow down and lose energy, such as on the shallow bank of a river

Question 15

Change in the Characteristics of the River

Width/Depth:

Answer 15

The river will become wider/deeper as the amount of water in it
grows due to it being joined by tributaries as it moves towards the sea.

Question 16

Change in the Characteristics of the River

Velocity:

Answer 16

As the river moves towards the sea and becomes deeper and wider, less water is in contact with the bed and banks, therefore, less friction occurs and the velocity increases

Question 17

Change in the Characteristics of the River

Discharge

Answer 17

The amount of water in the river increases as the river moves towards
the sea because of the increase in volume due to it being joined by tributaries.

Question 18

Change in the Characteristics of the River

Gradient:

Answer 18

The slope will become less steep as the river moves out of the hills and into flatter areas on its way to the sea

Question 19

How does the UK’s seasonality affect river procceses?

Answer 19

In winter, the differences in temperatures between night and day can cause freeze thaw weathering on river banks, possibly causing the banks to collapse

Question 20

How do storms affect river processes?

Answer 20

• In times of storms or heavy rainfall rivers will contain a lot of water, giving them greater erosive power and landforms such as river cliffs will be attacked by water
• During times of heavy rainfall trees on river banks can have their roots undermined by erosion and mass movement, eventually causing the river banks to collapse

Question 21

How do droughts affect river processes?

Answer 21

-When droughts occur rivers have less water and therefore less power to erode

Question 22

Drainage Basin:

Answer 22

It is a land drained by the river system. It acts like a funnel, collecting all the water within one area and then channelling it into a waterway.

Question 23

Mouth

Answer 23

where a river meets the sea

Question 24

Source

Answer 24

the start of a river

Question 25

Confluence

Answer 25

the point where two rivers meet

Question 26

Waterfall

Answer 26

• A band of more resistant rock (granite) lies on top of the less resistant rock (clay), the softer rock is eroded more quickly, undercutting the hard rock
• The hard rock overhangs until it eventually collapses due to the pull of gravity and the pressure of its own weight.
• The collapse adds large blocks of rock to the base of the waterfall. These can increase erosion by abrasion
• The base of the waterfall is eroded to form a plunge pool by abrasion and hydraulic action
• The softer rock continues to be eroded and the overhang collapses again causing the waterfall to retreat
• The process is repeated again and again and the gradual retreat of the waterfall forms a steep-sided gorge of recession.

Question 27

Interlocking spurs

Answer 27

As the river meets the hard rock in the v-shaped valley it doesn’t have enough energy to cut through it (erode) so it just winds around the spurs leaving them to be interlocked

Question 28

Formation of a river cliff

Answer 28

On the outside of a meander, the water is deeper so there is less friction and the current flows faster. The force of the water erodes and undercuts the outside bend by abrasion, forming a steep bank called a river cliff.

Question 29

Oxbow Lakes

Answer 29

Erosion by abrasion narrows the neck between the two meanders
The river will usually cut through the neck during a flood
The river then flows along the straight path which is the shortest route which takes less energy
Alluvium deposition will seal off the ends and the cut-off becomes an oxbow lake

Question 30

Floodplain

Answer 30

A floodplain is a flat area of land either side of the river
When a river holds too much water to stay in its channel, it will flood
The water is shallower on the land than the river so it deposits the material it is carrying causing the formation of a flood plain
Every time it floods deposition builds up the floodplain

Question 31

Levees

Answer 31

These are high banks of a river that build up over time.
When a river floods it deposits the heaviest of particles it is carrying first
The larger particles, often pebble sized, form the levees
Sand, silt and clay are lighter so they can be carried further due to not much energy being needed by the river. Sand and silt are deposited first and clay is last

Question 32

Physical Causes of River Flooding

Answer 32

• If a valley has steep slopes, water will move into the river more quickly causing frequent floods
• Area formed from impermeable rock is more likely to flood more often
• Rain for a number of days causes ground saturation. Meaning excess water will then flow straight into rivers causing them to flood
• A sudden rise in temperature after heavy snowfall causes rapid thaw.
• Rivers will be unable to cope with the amount of water and will flood

Question 33

Human Causes of River Flooding

Answer 33

• Vegetation removed from slopes causes less interception. Meaning water will move to the river more quickly
• A dam could burst to lead to more water in the river channel and large areas close to the river would be flooded
• Large areas of tarmac are found in urban areas. This stops rainwater from soaking into the ground so it runs into the drains which allow it to move into the river at a greater speed. Therefore it is more likely to flood
• If farmers plough up and down slopes instead of around the hillside, the channels created by the plough allow rainwater to travel faster to the river

Question 34

Point bar

Answer 34

• Forms on the inside of the meander bend because of deposition.
• Deposition occurs on the inside because the water is moving more slowly and is shallower.
• As a result there is more friction here and the river is less powerful, meaning its unable to carry its load and deposition occurs
• An underwater current takes the river and deposits it on the slip off slope

Question 35

Hard Engineering

Answer 35

• Dams
• Reservoirs
• Channelisation

Question 36

Advantages and disadvantages of dams:

Answer 36

Dams: a large usually concrete structure built across a river valley to hold back water
-Effective for many years
-Very visible making residents feel safe
-Stores water behind the dam; hydroelectric power can be produced as water is released through the dam
HOWEVER
-Ugly, putting tourists off
-Expensive

Question 37

Advantages and disadvantages of dams:

Answer 37

Dams: a large usually concrete structure built across a river valley to hold back water
-Effective for many years
-Very visible making residents feel safe
-Stores water behind the dam; hydroelectric power can be produced as water is released through the dam
HOWEVER
-Ugly, putting tourists off
-Expensive

Question 38

Advantages and disadvantages of reservoirs:

Answer 38

Reservoirs; large areas of water that are created after a river has been controlled (often by building a dam)
-Can provide drinking water for urban areas
-Creates a large area of water which can be used for recreational activities
HOWEVER
-Settlements and farming land can be lost wehn valley is flooded
-Very expensive to control flow of river
-Disrupts the natural process at work in the river valley as sediment is trapped in the reservoir

Question 39

Advantages and disadvantages of channelisation:

Answer 39

Channelisation: the river is made deeper, wider and straighter
-Visual, making residents feel safe
-Long lasting
-The river can hold more water so less likely to flood
HOWEVER
-Expensive
-The water can travel faster to places downstream and possibly cause flooding there

Question 40

Soft engineering

Answer 40

• Flood plain zoning

- Washlands

Question 41

Advantages and disadvantages of flood plain zoning

Answer 41

Floodplain zoning: Land close to the river is seen as low value because of flood risk
-Provides recreational facilities such as sport fields for locals
-Very cheap as no defence need to be built
HOWEVER
-Large areas of land cannot be built on; residents may not understand why

Question 42

Advantages and disadvantages of washlands

Answer 42

Washlands: the river is allowed to these areas: these could be close to farmlands
-Very cheap
HOWEVER
-flooding takes land out of use regularly
-ecology of land is changed each time the river floods

Question 43

How has industry affected the river landscape of the river wye?

Answer 43

• Quarrying: the sides of the gorge have been extensively quarried for limestone for building materials
• Iron ore smelting: the valley had a plentiful supply of iron, charcoal wood and water - perfect setting for iron ore smelting

Question 44

How has tourism affected the river landscape of the river wye?

Answer 44

• Wye valley was one of the earliest tourist honeypots with visitors flocking to the area in the 1700s
• The cliff ascent and walks at Piercefield park were landscaped at the time
• There are many lookout points, walks, a number of castles and Tintern Abbey

Question 45

How has human development affected the river landscape of the river wye?

Answer 45

• A road was built along the valley along the valley in the early 19th century and the railway followed in 1876
• Before this the river was the economic backbone of the area allowing access for industry and tourists
• Settlement in the valley goes back 12,000 years

Question 46

How has forestry affected the river landscape of the river wye?

Answer 46

• Many trees were felled in the 18th and 19th century for ship building and other industrial uses such as making charcoal
• Up to WW2 the woodlands were mainly deciduous but after this time extensive planting led to the area having 40% of its woods dominated by coniferous trees
• Since the 1980s this type of planting has stopped and broadleaved trees are the only trees being planted now

Question 47

How has weathering affected the river landscape of the river wye?

Answer 47

The process of biological, physical and chemical weathering are all present in the area , providing material for the river to use in deposition and erosion processes

Question 48

How has erosion affected the river landscape of the river wye?

Answer 48

The river erodes and deposits material forming meanders and floodplains