Rivers

Question 1

What are the 4 types of erosion?

Answer 1

Attrition, abrasion, soluion, hydraulic action

Question 2

What is attrition?

Answer 2

Rocks bash together and get smaller and smoother

Question 3

What is abrasion

Answer 3

Rocks thrown at cliff base break apart or are dragged along the river bed

Question 4

What is solution (erosion)?

Answer 4

Chemical reaction that dissolves rocks

Question 5

What is hydraulic action?

Answer 5

Water enters cracks in river bank, air compresses and causes crack to expand- sheer force of water

Question 6

What are 4 types of transportation?

Answer 6

Solution
Suspension
Saltation
Traction

Question 7

What is solution (transportation)?

Answer 7

Minerals dissolved in water are carried along

Question 8

What is suspension?

Answer 8

Sediment carried along in flow of water

Question 9

What is saltation?

Answer 9

Pebbles bounce along the river bed

Question 10

What is traction?

Answer 10

Boulders roll along bed by force of water

Question 11

What is the definition and the two types of weathering?

Answer 11

The breakdown of rocks in situ

Mechanical and biological

Question 12

What is mechanical weathering?

Answer 12

Breakdown of rocks without changing its chemical composition

Question 13

What is biological weathering?

Answer 13

Breakdown of rock by plants and animals

Question 14

What is deposition?

Answer 14

When river loses energy it drops sediment. Heaviest material deposited first.

Question 15

What are 3 landforms resulting from erosion?

Answer 15

Interlocking spurs
Waterfalls
Gorges

Question 16

How are interlocking spurs formed?

Answer 16

Most erosion is vertical in upper course.
Creates steep v-shaped valley
Not powerful enough to laterally erode
Wind around hillsides

Question 17

How are waterfalls formed?

Answer 17

River flows over area of hard rock changes into soft rock
Soft erodes via hydraulic action and abrasion quicker
Creates step in river
Hard rock creates undercut and plunge pool
Unsupported and collapses

Question 18

How are gorges formed?

Answer 18

More water full undercutting leads to collapses
Waterfall retreats
Leaves steep sided gorge

Question 19

How are oxbow lakes formed?

Answer 19

Flow stronger on outside of river
Where flow is slower, sediment is deposited
Meander gets bigger and cuts through neck of meander
River takes shorter course
Sediment builds up and cuts off loop from river

Question 20

What are 3 landforms resulting from deposition?

Answer 20

Levees
Floodplains
Estuaries

Question 21

How are floodplains formed?

Answer 21

Erosion removes interlocking spurs
Flat area either side of river
Height of floodplain increases as material deposits either side

Question 22

How are levees formed?

Answer 22

Flooding occurs due to increase in water volume
When river floods, sediment spreads across floodplain
Most material deposited on sides of bank, and smaller bits further away
Sediment builds and increases height of river bank
Chanel can carry more water
However, levees are fragile and made from loose silt

Question 23

What are human risk factors and physical risk factors of floods?

Answer 23

Urbanisation and river capacity

Precipitation and geology

Question 24

How is urbanisation a flood risk factor?

Answer 24

More impermeable surfaces
Decreases time taken for water to flow into river
Flash flooding

Question 25

How is capacity of river a flood risk factor?

Answer 25

Filled with rubbish
Channel size decreases
River carries less water- more likely to flood

Question 26

How is precipitation a flood risk factor?

Answer 26

If there’s a storm, amount of water in river increases

Increases risk of flash flooding downstream

Question 27

How is geology a flood risk factor?

Answer 27

Impermeable rocks
Rainwater cant run into soil and underground storage
Runs straight into river
Increases risk of flash flooding