river proccesses Flashcards

1
Q

Transportation of rocks(suspension)

A

tiny particles of sediment

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2
Q

Transportation of rocks(solution)

A

dissolved chemicals being carried

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3
Q

Transportation of rocks(salutation)

A

smaller stones picked up and dropped again

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4
Q

Transportation of rocks(traction)

A

large stones dragged across

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5
Q

Erosion of the river bed(abrasion)

A

sand and pebbles dragged along the river wearing away the bed

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6
Q

Erosion of the river bed(attrition)

A

rocks and stones wear each other as they knock together

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7
Q

Erosion of the river bed(hydraulic action)

A

fast flowing water is forced into cracks

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8
Q

Erosion of the river bed(solution)

A

alkaline are dissolved

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9
Q

How water falls work

A

1) a bed of more resistant rock
2) erosion of less resistant rock by abrasion and hydraulic action
3) the rivers energy causes a plunge pool underneth
4) This creates a ledge that collapses
5) takes up new position leaving a gorge

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10
Q

Features of the upper course

A

steep and narrow forming a v shaped valley, produces interlocking spurs which jut into the river valley

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11
Q

weathering(biological)

A

small crack allow plant to grow and the roots push it apart

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12
Q

weathering(physical)

A

physical force breaks rock like freeze thaw

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13
Q

weathering(chemical)

A

chemical change

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14
Q

mass movement

A

all process that cause rock material to move down slope

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15
Q

mass movement(rapid)

A

landslides and mud flow fast flowing

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16
Q

mass movement(slow)

A

soil creep caused by rain dislodging tiny soil particles

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17
Q

shape of the valley is effected by

A

rate of weathering, mass movement and how quickly the river removes material

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18
Q

Features of the middle course

A

gradient is gentler, discharge has increases(volume of water), Velocity increases due to smaller rocks, meanders, point bars, u shaped valley

19
Q

meanders how they are created

A

1) water flows in a helicodial flow
2) fastest current called the thalweg is forced to the outer bend
3) this creates a river cliff
4) helicodial flow shifts sediment to the other side here it is deposited to create a point bar
5) as river channel shifts it forms a flood plain

20
Q

lower course features

A

wide and deep, flat gradient, discharge is larger, low lying flood plain

21
Q

the channel of the lower course(how its made)

A

twice a day the incoming tide meets the outgoing tide and forces the river to stop depositing sediment
this forms a wide area called mudflats, some rivers drop so much it forms a delta

22
Q

natural levees

A

as a river reaches bankful it deposits sand and clay forming a natural barrier.

23
Q

artificial levees

A

built by engineers

24
Q

long profile

A

showing graidient

25
cross profile
showing valley shape
26
what is the interception zone
leaves and branches collect some rain water
27
surface run off(how fast it happens)features
how much rain has recently fallen(antecedent rainfall) heavy rain(low infiltration high run off) shape of river basin
28
throughflow
seeps into the river through soil air spaces
29
groundwater flow
when water hits the the limit of saturation(water table)the water seeps as groundwater flow
30
factors that influence hydrographs(land use change)
crops and buildings increase runoff
31
factors that influence hydrographs(deforestation)
less plants for the interception zone
32
hard engineering(flood walls)effectiveness/costs
fairly cheap disperse water quickly and can increase downstream risks depends on wall
33
hard engineering(levees)effectiveness/costs
expensive increase flood risk down stream can fail by over topping 1million
34
hard engineering(dredging)effectiveness/costs
needs to be done every year concrete lining is expensive £50000
35
hard engineering(flood relief)effectiveness/costs
protects built up areas | £14 million
36
soft engineering(flood plain reducing)effectiveness/costs
store flood water reduces flooding | 1.2 million
37
soft engineering(river channel restoration)effectiveness/costs
improved ecology natural look | 1.2 million
38
Sheffield(human causes)
surfaces are concrete drains were overwhelmed fallen trees blocked the loxey and don city council said they only prepared for 30 years not 35
39
Sheffield(rivers and the landscape causes)
steep hills | foot of the pennines where the rivelin, loxey and don meet
40
what are the summer set levels like
lowest lying areas during the last ice age it was covered with water its wetland with fertile soils also seven rivers drain into the levels
41
physical causes of floods in summer set
``` high jet streams 6-10km 12 major storms more severe gales most rainfall more rainy days ```
42
Sheffield(deaths and floods, power,company's)
``` two people 1200 homes flooded football club flooded 13000 without power shopping center was flooded ```
43
what of the future flood risks
greater storminess longer lasting floods higher spring tides more storm surges
44
dredging
digging the river deeper