Mississippi Flood 1993 Flashcards

1
Q

Background of Mississippi (5)

A
  • 3800km in length
  • Flows through 10 states
  • Receives over 100 major tributaries
  • widest floodplain 200 km
  • 300 dams
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2
Q

What year was Mississippi?

A

1993

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3
Q

Human causes of the Mississippi Flood (2)

A
  • Got rid of flood plains by building on them

* The levées couldn’t stand the pressure of so much water

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4
Q

Physical causes of the Mississippi Flood (3)

A
  • Cold(antarctica) and warm air(gulf of mexico) met 2000km further south so lots of rain in USA rather than snow in Canada
  • Heavy rain in April saturated upper basin
  • Thunderstorms in June and July -> rapid surface run-off and flash floods
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5
Q

How many killed in the Mississippi Flood?

A

43

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6
Q

How many evacuees from the Mississippi Flood?

A

50,000

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7
Q

How much land flooded from the Mississippi Flood?

A

26,000 km of land

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8
Q

How much did the damage cost from the Mississippi Flood?

A

£12 billion

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9
Q

What was the cost of the lost crop from the Mississippi Flood?

A

$2.46 billion as ground was too wet to farm

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10
Q

Other social effects of the Mississippi Flood (3)

A
  • Waterways + sewage = diseases (eg. cholera)
  • Lots of high insurance claims
  • Area of the British Isles flooded
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11
Q

Why control the Mississippi? (4)

A
  • Every time it flooded, it would change its course - unpredictable
  • To make shipping easier (average paddle boat lasted 18 months)
  • Shipping easier -> build economy
  • Better economy = develop industry, agriculture and cities
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12
Q

Wing Dykes (hard)

A

To trap sediment to narrow the river to create a faster and deeper flow

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13
Q

Levées (hard)

A

To protect riverside development

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14
Q

Control Dams (hard)

A

To hold back floodwater

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15
Q

Concrete Mattresses (hard)

A

To stabilise banks and fix the channel in place

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16
Q

Blow up Meanders (hard)

A

To speed water downstream quicker - 250km shorter by the end

17
Q

Wing Dykes evaluate (1,1)

A

☑Makes channel deeper and narrower by trapping sediment

☒Doesn’t stop the flooding

18
Q

Levées evaluate (1,2)

A

☑Prevents smaller floods

☒Can make floods worse by holding back the water
☒Ugly and expensive

19
Q

Control Dams evaluate (2,2)

A

☑Controls flood water - reservoirs
☑Can create electricity - HEP

☒Dams are very expensive to build
☒Creating a reservoir can flood settlements and farmland, destroying environment

20
Q

Concrete Mattresses evaluate (2,1)

A

☑Fixes river in place
☑Allows development on banks

☒Expensive

21
Q

Straightening Meanders evaluate (3,3)

A

☑Water flows to mouth more quickly
☑Reduces flood risk
☑Speeds up river - better for transportation

☒Flooding may happen downstream of where straightening has happened
☒More erosion downstream due to faster flow
☒Destroys environment - 250km shorter

22
Q

Afforestation (4,3)

A

☑Absorbs some of the flood’s energy (interception)
☑Evapotranspiration
☑Stabilises soil
☑Jobs to look after trees

☒Takes up space
☒Doesn’t stop the flooding
☒Takes a long time to plant trees

23
Q

Afforestation (soft) evaluation (4,3)

A

☑Absorbs some of the flood’s energy (interception)
☑Evapotranspiration
☑Stabilises soil
☑Jobs to look after trees

☒Takes up space
☒Doesn’t stop the flooding
☒Takes a long time to plant trees

24
Q

Diversionary Spillways (soft) evaluation (2,2)

A

☑No damage to property
☑Reduced pressure in river

☒Takes up space - less space for expansion, bad for a growing population
☒Risky, it may overspill

25
Q

Flood warnings (soft) evaluate (1,2)

A

☑Impact reduced - move things upstairs, sandbags, evacuate, etc

☒Warnings don’t stop a flood from happening
☒Some people may not have access to a warning system

26
Q

For engineering on the Mississippi (5)

A
  • No more shifting channels - no longer dangerous and unnavigable (Paddle boat lasts 18months)
  • Otherwise no development
  • Better transport of good/crops
  • Helps economy
  • Protect property near river
27
Q

Against engineering on the Mississippi (3)

A
  • Can’t tame mother nature
  • $180 million maintenance and repair a year
  • Make floods worse?
28
Q

How long in length is the Mississippi?

A

3,800km

29
Q

How much to maintain and repair the Mississippi each year?

A

£180 million

30
Q

How much further South did the airs meet?

A

2,000km