Catastrophic Events
Impact on Ecosystems
Hurricanes
Hurricanes
• An intense, rotating
oceanic weather system
with sustained winds of at
least 74 mph and a welldefined eye
• Conditions for formation:
• Warm water
• Light upper-level winds
• Pre-existing disturbance
of thunderstorms
• Hurricanes produce
damaging surface winds
and storm surges
Hurricane videos
• http://www.youtube.com/watch?v=s76Qn7bp
CsQ
• http://www.youtube.com/watch?v=sXM5q1t
GB6o&feature=pyv&ad=5241746182&kw=kat
rina
How Hurricanes Affect the
Ecosystem
Wind
– Trees damaged,
snapped, or uprooted
http://www.nhc.noaa.gov
/aboutsshws.php
Storm Surge
– The storm surge causes
sediment to erode and shift.
– Coastal wetlands and barrier
islands take the brunt of the storm
surge.
– Sediment erosion and deposition
often affect
– Oyster beds
– Coral reefs
– Sea grass beds
http://www.comet.ucar.edu/ns
flab/web/hurricane/313.htm
Salt Water
Invasion!
• Saltwater intrusion in
lakes, streams, and
wetlands change
ecosystems (e.g. causes
massive fish kills)
• The storm surge kills
tree species that are not
tolerant of salt water.
Flooding Moves Contaminants
– Contaminants (e.g.
chemicals used to treat
crops or solid and liquid
wastes) are transported
into groundwater
• Phytoplankton blooms
lead to a decrease in
dissolved oxygen
Floods
Floods
• Is an overflowing of water onto land that is normally dry
• Caused by intense or long term precipitation from thunderstorms,
hurricane surges, or melting snow
• Most impact results from paving the ground and the precipitation
becomes runoff
• Cause loss of life, disease, property damage or loss, contamination
of water, and destruction of crops and livestock
Environmental Impact of
Floods
• Floods are important in
maintaining ecosystem
habitats and soil
fertility
• Nutrients carried by
floodwaters can benefit
ecosystems and crops
• Expand habitats for fish,
birds
• Recharge groundwater
Environmental Impact of
Floods
• Flood-management practices
have affected floodplains and
the nature of flooding
• Wetlands drained
• Land cleared for farming
• Upstream development that
replaces natural vegetation
with paved asphalt
• Construction of channels,
levees, reservoirs
Effects of
Floods
Animals
• Flooding forces
many wild animals
from their natural
habitats.
• Domestic animals
are also left
without homes
after floods.
• The large amounts
of pooled water
lead to an increase
in mosquito
populations.
Runoff Flushes Away
Contaminants
• The sudden
appearance of an
overflow of water
can wash away
– Unneeded salt
– Contaminants like
chemical waste
– Debris
Tornadoes
Tornadoes
• A rotating column of air
reaching from a
thunderstorm to the
ground.
• The most violent
tornadoes can have winds
up to 300 mph.
Tornado videos
• http://www.youtube.com/watch?v=vhKjv9Gu
ARQ
• http://www.youtube.com/watch?v=TxsxKi0W
gxU
Volcanoes
• A volcano is a mountain that
opens downward to a pool of
molten rock below the surface
of the earth. When pressure
builds up, eruptions occur.
• Volcanoes are formed when
magma from within the
Earth’s upper mantle works its
way to the surface.
• Eruptions occurring close to
human settlements may spill
and destroy lives and
property.
Volcano video
Tornadoes Effect on
Ecosystems
• Trees damaged, stripped,
or uprooted
• Open forest canopies to
sunlight
• Fallen trees offer shelter
for small animals
• Potential destruction of
waste storage or
treatment facilities or
chemical plants
Earthquakes
Earthquake
Earthquakes
• Is the vibration of the Earth’s surface that
occurs after a release of energy in the crust
• This release of energy can be caused by a
volcanic eruption, or movements of the crust
Earthquake videos
Tsunami
Tsunami
• Are large ocean waves produced by earthquakes,
volcanic eruptions, or underwater landslides
• The waves can travel upstream in coastal
estuaries and rivers
• Areas of risk are less than 25ft about sea level
and within one mile of shore
• Impact includes drowning, flooding,
contamination of water, fires from broken gas
lines, etc.
Tsunami video
Wild fires
A wildfire is an uncontrolled fire often occurring in wildland areas, but
which can also consume houses or agricultural resources.
Common causes of wildfires include lightning, human carelessness,
arson, and volcano eruption.
Wildfires can occur anywhere, but are common in the forested areas
of the United States and Canada.
• The Federal Government annually
spends billions of dollars to suppress
wildfires.
• Wildfires increase the potential for
flooding, debris flows, and landslides.
• Smoke and other emissions contain
pollutants that can cause significant
health problems.
• Short-term effects: destruction of
timber,
forage, wildlife habitats, scenic vistas,
and watersheds
• Long-term effects: reduced access to
recreational areas; destruction of
community infrastructure and cultural
and economic resources
Impact of
Wild fires
Causes of
Droughts
• Is an unusually long period of dry weather.
• Droughts are the result of many causes including,
global weather patterns, high pressure, the
tropical outlook and other global-scale variables.
• Severity depends upon moisture deficiency,
duration, and size of area.
Impacts of droughts
causes:
•
•
•
•
water supply shortage
crop failure
livestock death
increased forest fires.