Rivers Topic Refresh πŸ’§πŸŒ³ Flashcards

1
Q

erosion - hydraulic action

processes affecting a river landscape

A

the sheer force of the water hitting the river bed and banks.
most effective when the water is moving fast and there is a lot of it.

processes affecting a river landscape

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2
Q

transportation - traction

processes affecting a river landscape

A

heaviest material is rolled along the river bed - it is too heavy to lose contact with the bed.
this requires the most energy.

processes affecting a river landscape

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3
Q

erosion - abrasion

processes affecting a river landscape

A

occurs when the load the river is carrying repeatedly hits the river bed and banks, causing some of the material to break off.

processes affecting a river landscape

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4
Q

erosion - attrition

processes affecting a river landscape

A

when the stones and boulders carried by the river knock against each other.
over time they are weakened, causing bits to fall off and reduce in size.

processes affecting a river landscape

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5
Q

erosion - solution

processes affecting a river landscape

A

occurs only when the river flows on certain types of rock that are soluble in rainwater. they dissolve in the water and become part of it as a result.
eg chalk and limestone.

processes affecting a river landscape

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6
Q

transportation - saltation

processes affecting a river landscape

A

sand sized particles are bounced along the river bed in a β€˜leap frog’ motion.

processes affecting a river landscape

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7
Q

transportation - suspension

processes affecting a river landscape

A

small particles (clay and silt sized) are carried within the water by a turbulent flow.

processes affecting a river landscape

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8
Q

transportation - solution

processes affecting a river landscape

A

the dissolved load (it is not visible).
occurs only with certain rock types that are soluble in rainwater.
eg chalk and limestone.

processes affecting a river landscape

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9
Q

what is river deposition?

processes affecting a river landscape

A

material transported by a river is dropped.
deposits the largest material first as this is the heaviest to carry.
smaller load is deposited further downstream as it can be transported further.

processes affecting a river landscape

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10
Q

why does river deposition occur?

processes affecting a river landscape

A

drops some of its load when there is a fall in the speed of the water or the amount of water.
often occurs when the gradient changes at the foot of a mountain or when a river enters a lake/sea.

processes affecting a river landscape

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11
Q

mass movement

processes affecting a river landscape

A

broken rock fragments (as a result of weathering) move down the slope through mass movements.
these can be rapid eg landslides or slow eg soil creep.

processes affecting a river landscape

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12
Q

weathering

processes affecting a river landscape

A

as the river flows, it erodes the land, creating a valley.
the river valley and channel sides are broken down by weathering.

processes affecting a river landscape

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13
Q

what is mechanical weathering?

processes affecting a river landscape

A

physical changes causing rock to break down
eg changes in temperature causing water to freeze and expand, melt and contract, leading to freeze-thaw weathering.

processes affecting a river landscape

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14
Q

what is chemical weathering?

processes affecting a river landscape

A

rainwater is slightly acidic and over time wears away the rock.

processes affecting a river landscape

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15
Q

what is biological weathering?

processes affecting a river landscape

A

occurs when plants and animals wear away rocks
eg roots growing in cracks in the rock or rabbits burrowing into rock.

processes affecting a river landscape

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16
Q

what is the river like in the upper course?

how rivers contrast

A
  • steep gradient
  • narrow and shallow channel - no flat valley floor.
  • erodes vertically
  • creating v shaped valleys, interlocking spurs, rapids, waterfalls, and gorges.

how rivers contrast

17
Q

what is the river like in the middle course?

how rivers contrast

A
  • wider and deeper river channel
  • gentler gradient
  • erodes laterally
  • creating wider and shallower valleys, meanders, and oxbow lakes.

how rivers contrast

18
Q

what is the river like in the lower course?

how rivers contrast

A
  • low gradient
  • wide floodplains
  • river channel deep and wide
  • bounded by levees
    -deposits sediments

how rivers contrast

19
Q

what is hard engineering?

flood prevention strategies

A
  • building artificial (man-made) structures to stop flooding.
  • usually more expensive than soft engineering.

flood prevention strategies

20
Q

GIVE and DEFINE some examples of hard engineering strategies

flood prevention strategies

A
  • Embankments - raising the banks of a river means it can hold more water.
  • Dams and reservoirs - dam traps the water, which builds up behind it, forming a reservoir. water can be released in a controlled way.

flood prevention strategies

21
Q

EXPLAIN advantages of embankments

flood prevention strategies

A

Embankments ADVANTAGES:
- one-off cost.
- durable
- increased carrying capacity of the river, making nearby settlements safer from flooding.

flood prevention strategies

22
Q

EXPLAIN advantages of dams and reservoirs

flood prevention strategies

A
  • can be used to produce electricity by passing the water through a turbine within the dam.
  • reservoirs can attract tourism.

flood prevention strategies

23
Q

EXPLAIN disadvantages of dams and reservoirs

flood prevention strategies

A
  • very expensive
  • dam traps sediment so reservoir can hold less water
  • habitats are flooded often leading to rotten vegetation.

flood prevention strategies

24
Q

EXPLAIN disadvantages of embankments

flood prevention strategies

A

Embankments DISADVANTAGES:
- looks unnatural
- water speeds up and can increase flood risk downstream.
- expensive to install.

flood prevention strategies

25
what is a flood? | causes and effects of flooding
when a river overflows its bed and banks because the river discharge is greater than the capacity in the river channel. | causes and effects of flooding
26
what is soft engineering? | flood prevention strategies
techniques which work with the natural environment and don't harm/change the river environment sustainable | flood prevention strategies
27
greater surface area ... the chance of flooding | causes and effects of flooding
increases | causes and effects of flooding
28
greater infiltration ... the chance of flooding | causes and effects of flooding
reduces | causes and effects of flooding
29
when is flooding more likely to happen? | causes and effects of flooding
when water reaches the river channel quickly. | causes and effects of flooding
30
NAME 3 causes of flooding and EXPLAIN them | causes and effects of flooding
- human: urbanisation - impermeable surfaces - physical: more tributaries - increases river discharge - human: deforestation - reduces interception which would slow down rainfall so it doesn't accumulate. | causes and effects of flooding
31
name 3 social effects of flooding | causes and effects of flooding
- agriculture affected, shortage of food, affects wellbeing. - damages buildings. - road links flooded so no access to flooded settlements. | causes and effects of flooding
32
name 3 economic effects of flooding | causes and effects of flooding
- agriculture affected, cannot trade, affects wealth. - businesses may not be insured and go bust. - infrastructure issues eg power | causes and effects of flooding
33
name 2 environmental effects of flooding | causes and effects of flooding
- land contaminated - mixed with sewage plants and water treatment plants. - destruction of wildlife habitats | causes and effects of flooding
34
when is a meander scar formed? | river landforms
when the oxbow lake dries up. | river landforms
35
what are floodplains? | river landforms
large, flat area of land next to the river usually in the lower course. | river landforms
36
what are levees? | river landforms
- small raised embankments along the side of the channel. - can be cm to m high - often artificially heightened and straightened to act as flood embankments. | river landforms
37
how are floodplains formed? | river landforms
when alluvium is deposited on the land. | river landforms
38
what is alluvium? | river landforms
fine sediment suspended in the river. | river landforms