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Geograghy > Rivers > Flashcards

Rivers Flashcards

0
Q

Formation of deltas

A

When a river reaches a sea energy is absorbed my slow movement of water of the sea.
This causes river to deposit its load.
Deposition builds up and partially blocks mouth of river.
River has to braid into several distributaries to reach sea

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1
Q

Formation of meanders

A

Alternating pools and riffles develop at equally spaced intervals.
Energy is lost from river when flowing over riffle due to friction
Spacing causes an uneven flow and to be concentrated on the one side
Turbence causes water to twist and coil- helicoidal flow
Cause more erosion and materiAl to be deposited on inside of the bend

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2
Q

Formation of levees

A

Natural raised embankments when a river overflows it’s banks.
Material is deposited during flood and river looses velocity due to friction.
Heaviest material drops first closest to river channel.
This builds up and forms a levee

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3
Q

Rejuvenation

A

When base level is lowered either by ground level rising or drop in sea level.
It increases vertical erosion and long profile is extended to a knock point

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4
Q

Formation of waterfalls

A

Soft rock meets hard rock and soft rock is eroded faster. This causes step in river bed.
Water flowing over step speeds up due to lack of friction adding to its erosive power. This causes undercutting of hard rock and will eventually collapse.
Deep plunge pool caused by abrasion and over time, further undercutting causes more collapsing so waterfall retreats

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6
Q

Suspension

A

Fine material carried by turbulence

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7
Q

Saltation

A

Larger particles bounce on river bed

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8
Q

Traction

A

Large particles rolled along river bed

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9
Q

Capacity

A

Total load that a river can transport

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10
Q

Location of Carlisle

A

North Cumbria

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11
Q

Date of Carlisle flood

A

8th January 2005

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12
Q

Causes of Carlisle flood

A

Heavy rainfall
Saturated ground
Steep sided drainage basin

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13
Q

Human causes of Carlisle flood

A

Urban area

Poor drainage and sewage systems

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14
Q

Social impacts of flood

A

3 deaths
3000 homeless
Stress related illnesses

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15
Q

Economic impacts of Carlisle

A

Repair cost £100 million and took a year
350 businesses shut down
70,000 homes lost power

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16
Q

Environmental impacts of Carlisle

A

Rivers polluted with sewage and rubbish

17
Q

Hard engineering disadvantages

A

Expensive
Dangerous if the break eg dam…
Damages environment
Ugly

18
Q

Types of hard engineering

A

Dams
Channel straightening
Levees

19
Q

Advantages of dams

A

Can be used for hep
Used for irrigation
Use reservoir for sports

20
Q

Disadvantages of dams

A

Expensive

Land has to be destroyed to build

21
Q

Advantages of soft engineering

A

Cheaper
More attractive
Creates habitats

26
Q

Solution

A

Substances dissolved that are carried in water

27
Q

Soft engineering

A

Reduces flooding by using knowledge of river basin and it’s processes and works with nature instead of building against it

28
Q

Advantages of soft engineering

A

Cheap- important to developing countries
Low maintenance
Don’t disturb natural processes

29
Q

Benefits of afforestation

A

Low cost

Causes infiltration and interception- reducing soil erosion

30
Q

Naturalisation

A

Creating floodplains so water can sit in them during storms rather than rushing downstream and flooding property
When storm is over water is gradually returned to river

31
Q

Disadvantages of naturalisation

A

Takes up a lot of land and cannot be used in urbanised areas

32
Q

Hard engineering

A

Man made structures to reduce flooding

33
Q

Examples of hard engineering

A

Dams, levees, diverting and straightening channels

34
Q

What solution to Carlisle use?

A

A retaining basin- traps water and holds it so it can be released slowly, reducing impact of flooding
Also set existing defences further away from channel to increase floodplain storage and increased height of bridges

35
Q

Advantages of hard engineering

A

Usually very successful for protection

Can have other uses- embankment are used for paths and earth embankments uses for wildlife habitats
Dams- reservoirs for sports and HEP

36
Q

Channisation

A

Putting rivers into straight, artificial channels to protect and immediate area as water is moved away quickly

37
Q

Disadvantages of hard engineering

A

Expensive
Developing countries cannot afford them
Dams destroy farmland and force people to move away
If they break flooding is worse than a natural flood

38
Q

Location of river quaggy

A

Lewisham

South East London

39
Q

What did the river quaggy do?

A

Was channelised so big amounts of water could be taken in during storms and could move away quickly BUT this caused problems down drift
So they used naturalisation instead

40
Q

Disadvantages of Carlisle’s scheme

A

Coat over £25 million

41
Q

Benefits of Carlisle’s scheme

A

Should protect the

In a 1 in 200 year event

Geograghy (4 decks)

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