Rivers Flashcards

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1
Q

what is the river like in the upper course?

A
steep
v-shaped
steep sides
narrow
shallow channel
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2
Q

what is the river like in the middle course?

A

medium gradient
gently sloping sides
wider
depper channel

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3
Q

what is the river like in the lower course?

A
low gradient
very wide
almost flat
very wide
deep channel
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4
Q

what are the 5 processes of erosion in a river?

A
  • vertical and lateral erosion
  • hydraulic action
  • abrasion
  • attrition
  • solution
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5
Q

what does vertical erosion do the river?

A
  • deepens river channel, V-shaped

- upper course

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6
Q

what does lateral erosion do to the river?

A
  • widens Vally

- middle and lower course

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7
Q

what is hydraulic action?

A

force of water breaks down rocks away from river channel

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8
Q

what is abrasion?

A
  • eroded rock scrape channel

- most erosion is abrasion

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9
Q

what is attrition?

A
  • eroded rock smash into each other

- edges round off

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10
Q

what is solution?

A

-river water dissolves certain types of rock i.e. limestone

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11
Q

what is transportation?

A

movement of eroded material

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12
Q

what are the 4 main methods of transportation?

A
  • traction
  • saltation
  • suspension
  • solution
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13
Q

what is traction?

A

large particles push along river bed by water

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14
Q

what is saltation?

A

pebble sized bounce along river bed by water

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15
Q

what is suspension?

A

small particles like soil and clay carried in water

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16
Q

what is solution?

A

soluble material dissolved in water carried along

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17
Q

what are the 4 reasons a river deposits material?

A
  • volume of water in river falls
  • eroded material increases
  • sallow water
  • river reaches mouth
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18
Q

what are the 3 land formed formed from erosion?

A
  • waterfalls and gorges

- interlocking spurs

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19
Q

how are waterfalls and gorges formed?

A
  • river flows over hard rock which is over soft rock
  • soft rock eroded by hydraulic action and abrasion
  • step formed
  • water flows over step erodes more soft rock
  • steep drop formed, WATERFALL
  • hard rock undercut, collapse
  • rock erodes at base by abrasion
  • more undercutting, collapse
  • waterfall retreats, GORGE
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20
Q

how are interlocking spurs formed?

A
  • upper course river erode vertically
  • v-shaped valleys
  • not powerful enough to erode laterally
  • wind around high hillsides
  • leaving interlocking spurs
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21
Q

what are the landforms formed form erosion and deposition?

A

meanders and ox-bow lakes

22
Q

how are meanders formed?

A
  • current faster on outside bend
  • more erosion on outside, forming river cliffs
  • current slower as its shallower on inside
  • so eroded lateral deposited
  • this formed slip off slopes
23
Q

how are ox-bow lakes formed?

A
  • erosion in a meander, outside bend closer
  • small neck
  • breaks through, flood
  • river goes shortest course
  • deposition cuts off meander
  • ox-bow lake left
24
Q

how are the landforms formed from deposition?

A
  • levées
  • flood plains
  • estuaries
25
Q

how are flood plains formed?

A
  • wide valley floor
  • prone to flooding
  • flooded deposition occurs on floodplain
  • builds up floodplain
  • meanders get wider making it bigger
26
Q

how are levées formed?

A
  • natural embankment
  • flood, eroded material deposits on floodplain
  • heaviest closest to river
  • over time creates levées
27
Q

how are estuaries formed?

A
  • where river meets sea
  • mouth of river
  • tidal (rises and falls each day)
  • tide at high point, water moves slowly so deposition
  • creates mudflats
  • low tide, mudflats exposed
28
Q

what are some of the major erosion and deposition landforms on the River Tees?

A
  • High Force waterfall
  • meanders at Dent Bank
  • tight meander and floodplain at The Holmes
29
Q

what are the 4 main physical factors which cause a river to flood?

A
  • prolonged rainfall
  • heavy rainfall
  • geology (rock type)
  • relief (change in height)
30
Q

how does prolonged rainfall make a river flood?

A
  • soil saturated
  • rain can’t infiltrate
  • high runoff
  • flooding
31
Q

how does heavy rainfall make a river flood?

A
  • cant infiltrate, too quick
  • high runoff
  • discharge quickly
  • flood
32
Q

how does geology make a river flood?

A
  • clay soils, granite
  • impermeable, no infiltration
  • high runoff
  • discharge increases quickly
  • flood
33
Q

how does relief make a river flood?

A
  • steep sided valley
  • reach river quickly
  • flows quickly
  • discharge increases
  • flood
34
Q

what human factor makes a river flood?

A

land use

35
Q

how does land use make a river flood?

A
  • buildings are made of impermeable materials
  • drives, tarmac
  • trees intercept water, cutting down trees stops the interception
  • disappearing gardens
36
Q

what do hydrography show?

A

discharge at certain point changes over time in relation to rainfall

37
Q

what is river discharge?

A
  • volume of water flowing into river per sec.

- cumecs

38
Q

what is peak discharge?

A

highest discharge

39
Q

what is lag time?

A

delay between peak rainfall and peak discharge

40
Q

what is rising limb?

A

increase in river discharge as rainwater flows into river

41
Q

what is falling limb?

A

decrease in river discharge as river returns to normal level

42
Q

why does lag time happen?

A

most water doesn’t land directly in the river

43
Q

what are the 4 main hard engineering strategies?

A
  • dams and reservoirs
  • channel straightening
  • embankments
  • flood relief channels
44
Q

what are the advantages and disadvantages of dams and reservoirs?

A

A- store lots of water
A- drinking water
A- hydroelectric power
D- expensive

45
Q

what are the advantages and disadvantages of channel straightening?

A

A- moves out of area quickly
D- flooding downstream
D- erosion downstream, fast moving water

46
Q

what are the 5 main soft engineering strategies?

A
  • flood warnings
  • preparation
  • flood plain zoning
  • planting trees
  • river restoration
47
Q

what is an example of a flood management scheme in the UK?

A

Jubilee river flood reel channel

48
Q

why was the scheme required(Jubilee river)?

A
  • low lying
  • prone to flooding
  • royal settlement (Windsor) attracts visitors
  • Eton school
49
Q

what measures were taken(Jubilee river)?

A

Jubilee river was created to take overflow water from the Thames during high discharge

50
Q

what were the social issues(Jubilee river)?

A

-is it ethical to protect wealthier places over others

51
Q

what were the economical issues(Jubilee river)?

A
  • most expensive in the UK
  • but damaged a year later by floods
  • £330million
  • until solution found small business couldn’t operate while flooded
52
Q

what were the environmental issues(Jubilee river)?

A
  • concrete weirs are ugly

- algae collecting behind weirs disrupting other habitats