Unit 4 - River Processes and Pressures Flashcards

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1
Q

Name three landforms formed in the upper course

A

Waterfalls, V shaped Valleys, gorges

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2
Q

Name three landforms formed in the middle course

A

Meanders, oxbow lake, river beach

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3
Q

Need two landforms formed in the lower course

A

Floodplains, deltas

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4
Q

What is the river profile

A

A graph that shows how the weather changes during its journey

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5
Q

What happens during the upper course

A

There is the river’s source in highland areas as there is more rainfall. The river runs downstream cutting its valley by vertical erosion. The Valleyside it’s a steep and is usually large rocks on the river bed.

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6
Q

What happens during the middle course

A

Less vertical erosion and more lateral or erosion. Wider and deeper. More lateral erosion where the river cuts meanders

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7
Q

What happens in the lower course

A

Gentle gradient and the channel is wider. Tributaries s, surface run-off and groundwater have increased the volume of the river

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8
Q

Describe what the river profile looks like

A

Height on the Y axis. The length of the river from the source along the X axes with a plotted line from top left to bottom right showing the river

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9
Q

What is the Bradshaw model

A

A diagram showing how characteristics of a river change from upstream to downstream. Triangles are used to show this as they either start wider or narrow and end with the opposite

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10
Q

What is transportation

A

Rivers move material, Load, downstream from its source to its mouth. There are four types of transportation methods

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11
Q

What is erosion

A

Rivers wear away their load and the bed and banks of the river channel. There are four processes

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12
Q

What are the four types of transportation

A

Traction, saltation, suspension, solution

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13
Q

What happens during traction

A

Large stones are dragged or rolled

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14
Q

What happens during saltation

A

Smaller stones are picked up and then dropped or bounced

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15
Q

What happens during suspension

A

Tiny particles of sediment are carried in the rivers current

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16
Q

What happens during solution

A

Dissolved chemicals are carried along in the solution, invisible to the eye

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17
Q

What are the four types of erosion

A

Attrition, abrasion, solution and hydraulic action

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18
Q

What is attrition

A

Rocks and stones where each other away as they knock together

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19
Q

What is abrasion

A

Sand and pebbles are dragged along the river bed, or knock into it by saltation wearing away the bed

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20
Q

What is solution in erosion

A

Alkaline rocks such as limestone are dissolved by acidic rainwater

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21
Q

What is hydraulic action

A

Fast flowing water is forced into cracks breaking up the bank overtime

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22
Q

How are a waterfalls and gorges formed

A
  1. There must be a layer of hard rock on top of soft rock and the river must cross it
  2. The soft rock gets eroded faster by the river. This forms a ledge undercut and overhang and a plunge pool at the bottom
  3. The ledge collapses as it wasn’t supported into the plunge pool
  4. This repeats making the waterfall retreat leaving a gorge
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23
Q

How is a V shaped valley formed

A

The river erodes vertically making the valley like a V.
The steep valley sides are attacked by weathering processes like freeze thaw
The valley sides weaken making them collapse
River valleys may have interlocking spurs, slivers of land that interlock. These are more resistant so it is left behind and the river moves between them

24
Q

What is velocity

A

The speed of the river, measured in metres per second

25
Q

What is discharge

A

The volume of water flowing in a river, measured in cubic metres per second

26
Q

How does a meander form

A

The weather is naturally curved slightly which means the water flows at different speeds in different parts. On the outer edge of a curve it is fastest so it erodes the edge. On the inner edge, it is slow so sediment builds up.

27
Q

What happens at the outer edge of a river

A

It is fast flowing so it is eroded. This forms an undercut or a river cliff

28
Q

What happens at the inner edge of a river

A

It is slow flowing so sediment carried from the outer edge is the positive here which forms a slip off slope

29
Q

What are the three types of flow in a river

A

Inside flow, outside flow or thalweg, helicoidal flow

30
Q

What is an oxbow lake

A

When a loop of a meander is left and split from the river

31
Q

How an oxbow lake formed

A

The outside of the meander bend which is the neck is eroded more
It is continued to be eroded until only a thin piece of land separates the two channels
The river floods over the neck where it is eroded and the Ariver takes the easier course.

32
Q

What is a floodplain

A

A flat area of land that the river spills onto when it bursts its banks

33
Q

What is a levee

A

A small raised area of land on the banks of the river made up of sediment. It can be natural or man-made

34
Q

What is a river delta

A

When the river deposits its material faster than the sea can remove it

35
Q

What is estuary

A

It appears where the river meets the sea

36
Q

How is a levee formed

A

During a flood sediment builds up along the banks small ridge. This then continues to grow as more floods happen

37
Q

What are the three types of deltas

A

Fan shaped
Cuspate
Birds foot

38
Q

What is a fan shaped delta

A

The river splits into many smaller ones to create a fan effect as the river mouth arches out into the Sea

39
Q

What is a cuspate Delta

A

The land around the mouth juts out like an Arrow into the sea

40
Q

What is a birds foot delta

A

The river splits on the way to the sea and each part juts out into the Sea

41
Q

Give an example of a fan shaped delta

A

The Niger delta

42
Q

Give an example of a cuspate Delta

A

The Ebro Delta

43
Q

Give an example of a birds foot delta

A

The Mississippi Delta

44
Q

How is a river delta formed

A

When the river meets slower water, like the sea or a lake, it loses power as it slows down so the sediment being carried is deposited forming the deltas.

45
Q

What are water stores

A

Different places where bodies of water are stored

46
Q

What is most of the earths water

A

Salt water

47
Q

What is interception

A

Water being prevented from reaching the surface by trees or grass

48
Q

What is infiltration

A

Water sinking into the soil from the ground surface

49
Q

What is groundwater flow and through flow.

A

Groundwater flow is flowing through the rock layer and through flow is flowing through the soil layer

50
Q

What is percolation

A

Water seeping deeper below the surface

51
Q

What is transpiration

A

Water lost through pores in vegetation

52
Q

What is the lag time

A

The peak flow of water time - the peak amount of rainfall

53
Q

Give three points of a short lag time

A

Intense rainfall, urban area, high drainage density

54
Q

Give three points of a long lag time

A

Gentle Valleyside, forest, low drainage density

55
Q

What is antecedent rainfall

A

The amount of moisture already in the ground before a rainstorm

56
Q

Three causes that make hydrographs look different

A

Antecedent rainfall, geology, vegetation