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geography
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mississippi
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caitlin fay
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Mississippi River
Largest
drainage basin in USA and parts of
Canada
Located in
SE
of USA
Uses of the Mississippi River
Shipping channel
Recreation
Hydroelectric power
Drinking water
The
Mississippi River
is hard to engineer
Levee engineering
1. Raised
15m
2. Strengthened to enclose
channel
for
3,000km
Levees failing
Riverbed
silting up
Hard
engineering is more effective in the
short
term but less
sustainable
New
floodplain
ends below risen river bed in New Orleans, which is
4.3m
Less alluvium deposited
Soil less fertile,
artificial
fertilisers needed
Dams on main tributaries
1.
100
dams controlling tributaries
2.
Expensive
to construct and
maintain
3.
Unsustainable
River straightening
1.
Meanders
cut through stretch of
1,750km
2. Creates
fast flowing channel
3. May cause
floods
downstream
Soft engineering: Afforestation
Trees planted in upper course to
intercept
(
Tennessee
)
Not applied over
wide
enough area
Trees haven't grown large enough to be
effective
Soft engineering:
Safe flood zones
Housing
bought by country and
demolished
to allow flooding
Some states still developing housing on floodplains e.g.
St Louis
Soft engineering: Washlands
1.
Morganza
spillway opened in
2011
to flood 12,000 km² of farmland
2.
2011
flood showed lack of washland
US conservation spent
£25
million buying
farmland
hard engineering methods
•
levees
•
dams
•
river
straightening
soft engineering methods
•
afforestation
•
safe flood zones
•
washlands
river outside british isles : mississippi