Rivers Flashcards

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1
Q

What are the 4 processes of erosion?

A
  • abrasion
  • hydraulic action
  • attrition
  • solution
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2
Q

What are the 2 processes of transportation?

A
  • saltation

- traction

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3
Q

What is abrasion?

A

-small boulders scratch and scrape their way down the bank, wearing the bank and bed

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4
Q

What is hydraulic action?

A
  • water is forced into cracks by the fast flowing river

- repeated causes weakened rocks, banks

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5
Q

What is attrition?

A

-stones transported down the river collide with each other and the banks and causes the stones to be small and round

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6
Q

What is solution?

A

-dissolving of rocks e.g chalk and limestone

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7
Q

What is saltation?

A

-small pebbles and stones bounce along the river bed

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8
Q

What is traction?

A

-large boulders and rocks are rolled along the river bed=bedload

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9
Q

Describe the upper course of a river

A
  • wet and boggy valley
  • narrow and shallow river
  • steep v-shaped valley
  • more vertical some lateral
  • waterfalls
  • small streams
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10
Q

Describe the middle course of the River Tees

A
  • there are gorges as the waterfall moves upstream
  • river meanders-changing shape
  • the town Yarm=in a meander (18km from sea)
  • less rainfall
  • 95%of land is farmland
  • river is at it’s most powerful + broadens out
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11
Q

Describe the lower course of a river

A
  • flat and floodplain
  • no power for erosion
  • small bedload and fine silt
  • large cities and factories built on the marshy land
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12
Q

Describe the middle course of a river.

A
  • large sized bedload, smoother rocks
  • lateral erosion=wide river
  • area of warmer temps and less rain
  • towns built
  • arable and pastoral farming
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13
Q

Describe the upper course of the river Tees.

A
  • the source starts where Cumbria borders county Durham and is a big soggy mass
  • cuts a v-shaped valley and carries lots of sediment
  • at 5km, the angular rocks are mainly smooth
  • high force waterfall, made of rhinestone
  • the flow rate = 20km per second
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14
Q

Describe the lower course of the river Tees.

A
  • carries a small amount of material
  • next to a factory, used for ships to off load goods
  • 15 degrees at the end
  • man made
  • Stockton on Tees= the main town
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15
Q

How do waterfalls occur?

A

-when a band of hard rock overlies softer rock

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16
Q

What does splash back cause?

A
  • hydraulic action which weakens the rock behind the fall of water.
  • the undercutting leads to an overhang
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17
Q

What develops at the bottom of the waterfall?

A

-An indentation which turns into a plunge pool

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18
Q

What happens when the overhang breaks off?

A

-rocks swirl in the plunge pool creating abrasion

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19
Q

What is created as the undercutting continues?

A
  • the waterfall retreats upstream creating a gorge

- the gorge retreats and grows longer

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20
Q

What is an interlocking spur?

A

-projections of high land entering the valley from alternate sides

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21
Q

How are interlocking spurs made?

A
  • the winding path of the river is due to obstacles being in the way
  • the river takes the easiest route over the land resulting in projections of high land
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22
Q

Why do rivers meander and how are meanders created?

A
  • due to obstacles in the way
  • fastest flowing on outside bend which cause lateral erosion making the river wider
  • outer bends are eroded by abrasion and hydraulic action
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23
Q

What is the fastest flowing part of a river called and why is it the fastest?

A
  • the thalweg

- there is less friction because it is the deepest part

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24
Q

How are ox-bow lakes created?

A
  • the meanders become very narrow and at times of high discharge, the river takes the shortest route and does not meander
  • the deposition of alluvium seals off the meander forming a straight river channel
  • The cut off meander is called an ox-bow lake
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25
Q

What is the name for a dried up meander?

A

-meander scar

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26
Q

How are levees made?

A
  • at times of high discharge, the river will overflow it’s banks
  • the increase in friction =drop in river’s velocity, resulting in the river’s load being deposited (coarsest and sediment deposited first)
  • as this process repeats, the deposition builds up creating natural levees
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27
Q

How are floodplains created?

A
  • the deposition at the slip-off slopes provides sediment to build up on the valley floor
  • the river carries large amounts of suspended load and when it floods, it is deposited onto the flood plain as alluvium
  • this process builds up the flood plain
28
Q

List some human factors that affect flood risk. (7)

A
  • new infrastructure increases impermeable surfaces
  • more houses are being built on flood plains
  • when new houses are built, roads must also which increases impermeable surfaces
  • deforestation reduces interception and the roots no longer take water from the soil
  • felling results in the soil getting saturated, run-off occurs and river discharge increases
  • farming, loss of hedges =less interception
  • ploughing fields= more channels for the water to run down ending up in river
29
Q

List some physical factors that affect flood risk.

A
  • heavy rain and sudden bursts=surface runoff, discharge increases and flash floods occur
  • snow melt=release of stored water results in surface runoff
  • steep slopes=surface runoff occurs before rain v=can infiltrate soils
30
Q

What is the difference between deforestation and felling?

A
  • felling=cutting down a few trees

- deforestation=large scale removal of trees

31
Q

What is the rising limb on a hydrograph?

A
  • period of rising river discharge following periods of rainfall
  • the upward line of the hill
32
Q

What is (basin)lag time on a hydrograph?

A
  • time difference between the peak of the rainstorm and the peak flow of the river
  • arrow line from the bar graph to the top of the hill
33
Q

What is the recession limb on a hydrograph?

A
  • period of time when discharge is falling after reaching peak
  • the downwards part of the hill
34
Q

What is the through flow on a hydrograph?

A
  • the horizontal flow of water within the soil layer

- dot line in between hill

35
Q

What is storm flow on a hydrograph?

A

-the water that arrives in the river during surface run off

36
Q

What is the baseflow on a hydrograph?

A

-normal discharge of the river

37
Q

Where is Morpeth?

A
  • situated in a loop of the river Wansbeck
  • Northeast UK
  • 15 miles from Newcastle upon Tyne
  • 12 miles from North sea
38
Q

When was the Morpeth flood?

A

-6th and 7th of September, 2008

39
Q

What were the causes of the Morpeth flood?

A
  • prolonged rainfall, 235% that could be expected for a month
  • river Wansbeck=narrow and steep sided=lots of surface run off
  • soil already saturated because of wet summer
  • increased urbanisation since 1960
  • trash screens at the culverts of tributary were blocked
40
Q

What was the peak water level in Morpeth?

A

-3.99m

41
Q

What were the social impacts of the Morpeth flood?

A
  • 400 residents evacuated due to mud in houses
  • 913 residential properties affected
  • shelter provided in King Edward high school
  • 198 properties in middle greens area did not receive a flood warning
42
Q

What were the economic impacts of the Morpeth flood?

A
  • 89 commercial properties affected, stock destroyed
  • overall damage =£40 million
  • Morpeth flood disaster raised over £20,000
43
Q

What is the flow rate of the river Tees?

A

-20km per second

44
Q

What temp is the river Tees towards the end?

A

-15 degrees

45
Q

When does angular material turn smooth in the river Tees?

A

-5km

46
Q

What % of rainfall happened before the Morpeth flood?

A

-235% of the rainfall expected for a month

47
Q

How many properties in middle greens area did not receive a flood warning?

A

-198

48
Q

How many residential properties were affected in Morpeth?

A

-913

49
Q

How many residents evacuated due to mud in their home?

A

-400

50
Q

How many commercial properties were affected?

A

-89

51
Q

How much money was the overall damage of the flood?

A

-£40 million

52
Q

How much did the Morpeth flood disaster fund raise?

A

-£20,000

53
Q

What are the pros and cons of building dams and reservoirs?

A
  • expensive, ecosystems disrupted, can cause landslides

- highly effective, creates jobs, reduces green house gases

54
Q

What is suspension?

A

-fine, light material e.g alluvium is held up and carried within the river flow=suspended load

55
Q

What is a flood relief channel?

A

-artificially made channel that is designed as a backup channel for floods

56
Q

What is a pro and con of flood relief channels?

A
  • habitats destroyed

- reduces flooding

57
Q

How do planting tees help reduce the impacts of flooding?

A

-more interception

58
Q

Pros and cons of planting trees?

A
  • creates new habitats and cheap

- loss of potential grazing land

59
Q

Pros and cons of flood warnings and preparation?

A
  • only effective if people listen

- cheap, people can evacuate and take valuables with them

60
Q

How much did insurance costs increase to after the Morpeth flood?

A

-£900 per year to £2,500 per year

61
Q

How much water was Morpeth high street under at the peak of the flood?

A

-60cm of water

62
Q

What were the responses to the Morpeth flood?

A
  • By 2010, £2.25 million was spent on essential work and repairs
  • replaced waterproof seals on flood walls
  • repaired damaged culverts + removed debris and silt
  • environment agency created a new evacuation route
  • in August 2015, a multi million pound flood defence, including a dam and storage area on the Mitford estate
  • a new flood defence wall-1.8 m tall and 3 flood gates constructed in High Stanners
63
Q

How much money was spent on repairs by 2010?

A

-£2.25 milliom

64
Q

When and where was the multi million pound flood defence built?

A
  • August 2015

- Mitford estate

65
Q

How tall was the new flood defence wall in Morpeth?

A

-1.8m

66
Q

What area was the new flood defence wall in Morpeth?

A

-High Stanners

67
Q

How does using alternative energy production and planting trees reduce the rate of global warming?

A
  • trees take in CO2
  • renewable energy does not produce greenhouse gases
  • increasing CO2 in atmosphere increases the greenhouse effect, causing the planet to become warmer