1. Catastrophic Events Impact on Ecosystems

2. Hurricanes

3. Hurricanes
An intense, rotating oceanic weather system with sustained winds of at least 74 mph and a well-defined eye
Conditions for formation:
Warm water
Light upper-level winds
Pre-existing disturbance of thunderstorms
Hurricanes produce damaging surface winds and storm surges

4. How Hurricanes Affect the Ecosystem

5. Wind Trees damaged, snapped, or uprooted
Hurricane waves striking sea wall  Image ID: wea00415, NOAA's National Weather Service (NWS) Collection  Category: Monsters/Hurricanes/Waves/  • High Resolution Photo Available 

6. 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
Many barrier islands end up shifted or eroded below sea level.

7. 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.
The aftermath of Katrina. Image ID: wea02851, NOAA's National Weather Service (NWS) Collection  Location: Louisiana, Southeast coastal parishes Photo Date: 2006 January Credit: Collection of Wayne and Nancy Weikel, FEMA Fisheries Coordinators  Category: Monsters/Hurricane Katrina/  • High Resolution Photo Available 

8. 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
Lieut. Commander Mark Moran, NOAA Corps, NMAO/AOC

9. Floods

10. Floods Most common of all natural hazards.
Occur during heavy rains, when rivers overflow, when ocean waves come onshore, when snow melts too fast, or when dams or levees break.
It can happen in every U.S. state and territory.

11. 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 Impacts Floods are naturally occurring phenomena that are part of the physical and biological processes which have shaped our nation's landscapes. Smith claims "More than any other environmental hazard, floods bring benefits as well as losses." He points especially to the importance of floods in maintaining ecosystem habitats and soil fertility. (Smith, pg 257). Consideration of the negative impacts of floods on the environment more often appraise the detrimental aspects of human attempts to manage flood prone areas which, in turn, disrupt the natural flood cycle. For example, the Federal Interagency Floodplain Management Task Force reports that human activities have deeply affected floodplains and the nature of flooding. Activities such as drainage of wetlands and land clearance for farming; upstream development that replaces natural vegetation with paved asphalt; and construction of channels, levees, reservoirs change the flood cycle and often result in increased runoff, destruction of riparian habitat, and increased water pollution--all of which can be considered destructive to the natural environment (FIFMTF, pp ). However, systematic assessment of the environmental benefits and costs of flooding and the environmental benefits and costs of floodplain management programs has not been done.

12. 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
Natural Hazards Research and Applications Information Center

13. Effects of Floods Destruction of riparian habitat
Significant erosion can lead to more frequent flooding if not repaired
Water pollution
Damaged drainage systems release raw sewage
Damaged buildings can be a source of toxic materials (e.g. paint, pesticide, gasoline)
Effects of Floods

14. 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.

15. Runoff Carries Sediment and Contaminants
Sediment may obscure the sunlight which inhibits photosynthesis of marine organisms
Contaminants (e.g. pesticides and fertilizers) are carried into the ocean ecosystem
Coral reefs are particularly at risk from the runoff from floods

16. Runoff Flushes Away Contaminants
The sudden appearance of an overflow of water can wash away
Unneeded salt
Contaminants like chemical waste
Debris

17. Tornadoes http://www.photolib.noaa.gov/bigs/nssl0210.jpg

18. Tornadoes
A rotating column of air reaching from a thunderstorm to the ground.
The most violent tornadoes can have winds up to 300 mph.

19. 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