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Floods

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Floods Most common natural disaster to strike the US A flood is typically associated with a defined body of water (river flood, ice jam, storm surge flooding etc.) – PowerPoint PPT presentation

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Title: Floods


1
Floods
2
Floods
  • Most common natural disaster to strike the US
  • A flood is typically associated with a defined
    body of water (river flood, ice jam, storm surge
    flooding etc.)
  • An overflow or accumulation of a body of water
    that submerges land
  • Floods occur when
  • The soil cannot fully absorb the rainfall
  • Bodies of water do not have the capacity to hold
    the amount of rainfall

3
Flash floods
  • According to the National Weather Service, a
    flash flood is a life-threatening flood that
    begins within 6 hours and often within 3 hours
  • Heavy rainfall
  • Rapid run-off

4
Atmospheric Conditions
  • Heavy rainfall
  • moisture in the lower to mid levels of the
    atmosphere
  • instability
  • a source of lifting

5
Soil Conditions
  • Dry soil leads to greater water absorption
    leading to greater risk of flooding
  • Although ground saturation increases the runoff
    risk, many flash floods occur when the ground is
    not saturated
  • The texture of the soil also effects the
    absorption levels

6
Where floods occur
  • The type of land that is prone to flooding are
    broad and flat usually situated on the banks of a
    river or main waterway
  • River Deltas
  • Mississippi, Nile, Amazon, Yangtze, etc.
  • Canyons (gulley washers)
  • Creeks, streams and rivers
  • Levees breaching

7
Human influences
  • Certain farming techniques, such as clear-cutting
    land, doesnt allow water to return to the
    atmosphere.
  • Construction of concrete and stone buildings-
    these man made structures do not absorb water
    well, which can lead to a sufficient amount of
    water build up. (urbanization)

8
Energy of Moving Water
  • Water possesses kinetic energy since it is moving
  • It is falling through a gravitational field
    (potential energy), and as it falls energy is
    released and is used to move (kinetic energy) the
    water
  • Energy is transferred to plants and the soil on
    the banks of the creek
  • It is pushing on the soil and forcing it
    downstream
  • Uprooting, some of the smaller trees and washing
    them downstream
  • Only takes about 18-24 of moving water to lift
    an SUV
  • Just six inches of fast-moving flood water can
    sweep a person off his or her feet.

9
Ecological benefits
  • Refill lakes and reservoirs
  • Flooding waters transport silt/soil onto areas
    (makes areas more fertile)
  • Floods was debris into waterways which can
    provide habitats of organisms

10
Surviving a Flood
  • Dont wait for bad weather. Make sure you have
    everything you need in advance
  • Create a Disaster Pack
  • Keep at home, or take along if you evacuate
  • Include enough food and bottled water for three
    days

11
Flood Terms
  • Flood Watch Flooding is possible.
  • Flash Flood Watch Flash flooding is possible. Be
    prepared to move to higher ground.
  • Flood Warning Flooding is occurring or will
    occur soon if advised to evacuate, do so
    immediately.
  • Flash Flood Warning A flash flood is occurring
    seek higher ground on foot immediately.

12
Surviving Floods Dos Donts
  • Do leave if the local authorities recommend
    evacuation
  • Do not walk through flowing water
  • Do not drive through a flooded area (Turn
    Around-Dont Drown)
  • Do not drink floodwater
  • Stay away from power lines and electrical wires
  • Look before you step

13
The Georgia Flood of 2009
  • Atlanta metropolitan area
  • Damage estimated cost to 500 million with the
    potential for it to rise
  • 17 Georgia counties received Federal Disaster
    Declarations
  • Hundreds of people were rescued by boat from
    their homes
  • At least 10 people died
  • Most in cars

14
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15
The Economy
  • Economic hardships due to
  • Temporary decline in tourism (depending on
    location)
  • Rebuilding costs
  • Food shortage leading to price increase
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