1.3-River landscapes Flashcards

1
Q

What are 2 physical processes that shape a river?

A

weathering and mass movement

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2
Q

What are the 3 types of weathering?

A

mechanical
chemical
biological

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3
Q

What is biological weathering?

A

Roots growing and animals burrowing into cracks in rocks causing them to split apart.

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4
Q

What is chemical weathering?

A

slightly acidic rainwater dissolves rocks

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5
Q

What is mechanical weathering?

A

freeze thaw action

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6
Q

What is the process of freeze thaw action?

A

water fills a crack
water freezes and the crack widens
repeated action increases the size of the crack
loose blocks if rocks are called scree

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7
Q

What are 2 processes of mass movement?

A

sliding and slumping

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8
Q

What is sliding?

A

where rock or material moves down a slope under the influence of gravity

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9
Q

what is slumping?

A

Where the river erodes the bottom of the valley slope causing the rock to become saturated and slump/collapse, making the slope steeper.

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10
Q

What does slumping cause?

A

material to slide downwards particularly if it’s saturated with rainwater

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11
Q

What is hydraulic action?

A

where the force of the water of the bed and banks removes material

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12
Q

What is attrittion?

A

the load that is carried by the river bumps together and wears down into smoother pieces

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13
Q

what is solution?

A

some minerals dissolving in river water

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14
Q

What is abrasion?

A

material carried by the river rubs against the bed and banks

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15
Q

What are the 4 main types or river transportation?

A

traction
salatation
suspension
soloution

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16
Q

What is it when large boulders are rolled along the river bed?

A

traction

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17
Q

What is it when smaller pebbles are bounced along the river bed?

A

salatation

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18
Q

What is it when finer sand and silt particles are carried along in the flow?

A

suspension

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19
Q

What is it called when some minerals are dissolved in the water and carried along in the flow?

A

solution

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20
Q

What shows how a river changes from source to mouth?

A

The Bradshaw model

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21
Q

what are charectaristics of the upper course of rhe river?

A
steep gradient 
small discharge 
shallow depth
narrow steep sides
fast velocity
22
Q

What are some charectaristics characteristics of the middle course?

A
shallower gradient 
large discharge 
deeper depth
flatter channel shape
fast velocity
23
Q

What are some charectaristics of the lower course of a river?

A

shallow gradient
very large discharge
deep depth
fast velocity

24
Q

What features are formed in the upper course?

A

waterfalls

interlocking spurs

25
Q

What features are formed in the lower course?

A

meanders
floodplain
leeves
ox bow lakes

26
Q

What features are formed in the middle course?

A

meanders

floodplains

27
Q

What increases the frequency of storms?

A

more periods of heavy rain and overflowing rivers

28
Q

What increases the risk of flooding?

A

frequency of storms
periods of hot dry weather
soil becoming inpermeable during cold conditions

29
Q

how are waterfalls formed?

A

The soft rock erodes more quickly,undercuttingthe hard rock.

The hard rock is leftoverhangingand because it isn’t supported, it eventually collapses.

The fallen rocks crash into theplunge pool. They swirl around, causing more erosion.

Over time, this process isrepeatedand the waterfall moves upstream.

A steep-sidedgorgeis formed as the waterfall retreats.

30
Q

how are gorges formed?

A

over time this undercutting process is repeated and the waterfall retreats

31
Q

What is a floodplain?

A

the wide flat area of land either side of a river that experiences frequent floods.

32
Q

how do levees develop?

A

the deposition process which takes place during flooding continues until embankments are created along the side of the river.

33
Q

What is formed in the inside bend of a meander?

A

a point bar

34
Q

how is an ox bow lake formed?

A
narrow neck gradually eroded
water takes the quickest route
deposition seals of old meander
neck has been cut off completely
free flowing lake left behind when meander is cut off
35
Q

is the current stronger on the inside or outside of river bends?

A

outside

36
Q

What 3 main human activitys change river land use?

A

urbanisation
agriculture
industry

37
Q

how does urbanisation change river landscapes?

A

houses being build on flood plains changes the natural landscape

channelisation for urban developments means deposition and erosion can’t take place

growing towns means there are fewer permeable surfaces so flooding is increased

38
Q

how does agriculture change river landscapes?

A

abstracting water for irrigation causes a reduced velocity so deposition occurs instead

ploughing fields increases the around amount of sediment in rivers

trees intercepting rainfall reduces surface run off so water reaches rivers more quickly

field drains destroy natural wetland landscapes

39
Q

how does industry change river landscapes?

A

reducing water in rivers leads to less erosion

industry processes can pollute rivers and destroy plants and animals

40
Q

What are 4 physical causes of flooding?

A

rainfall intensity
geology
snowmelt
drainage basin

41
Q

how does rainfall intensity affect flooding?

A

a lot of rarainfall prevents soil infiltration which means it flows towards the river quicker and cause the bank level to rise

42
Q

how does geology affect flooding?

A

rocks like granite are impermeable so water is unable to percolate from the thin soil above which means it flows
towards the river quicker and cause the bank level to rise

43
Q

how does snowmelt affect flooding?

A

at spring time warmer temprature will will melt snow creating more water which means it flows towards the river quicker and cause the bank level to rise

44
Q

how does the drainage basin affect flooding?

A

steep sides valleys mean the water enters the river system quicker which means it flows towards the river quicker and cause the bank level to rise

45
Q

what are 2 methods of hard river engineering?

A

channelisation

dams and resevoirs

46
Q

what are 2 types of soft river engineering?

A

floodplain zoning

washlands

47
Q

what are the advantages and disadvantages of dams and resevoirs?

A

+store water until needed
+can be used to generate hydrielecteuc power
-expensive to build
-sediment can build up in reservoirs

48
Q

what are the advantages and disadvantages of channelisation?

A

+allows water to flow more quickly away from areas of flood risk

  • -visually unattractive
  • -more water is taken downstream which increases flood risk elsewhere
49
Q

what are the advantages and disadvantages of flood plains zoning?

A

+ reduces number of homes at risk
+allows infiltration so surface runoff is reduced
–restricts growth of settlements

50
Q

what are the advantages and disadvantages of washlands?

A

+creates area for floodwater to go
+allows natural river processes
–might limit the use of land