• A flooded road hampers transportation.flood image by brelsbil from Fotolia.com
  
  Floods are one of the most common types of natural disasters that can be caused by several different naturally occurring events such as thunderstorms, hurricanes, tidal waves and melting ice or snow. Floods can cause huge amounts of damage to man-made structures, but floods can also have several positive and negative effects on the environment.
  
  

Pollution

• One problem that flooding presents to the environment is the potential to spread pollution. When cities and other areas used by humans are flooded, it is likely that various contaminants will be washed away by flood waters and spread into the environment. Solid waste in farmland with livestock can be washed away with the flood.
  
  

Animals

• Land-based animals face many of the same threats from flooding as humans. Large floods can trap animals and potentially cause them to drown. Flood waters can displace animals like snakes and rodents, which can pose dangerous conditions for animals and humans.
  
  

Crop Damage

• Flooding can potentially damage crops and other plants that become oversaturated with water. According to North Dakota State University's Extension Service, prolonged soil saturation affects crop growth and yield, which can severely hamper production of important crops like corn and soybeans. The university states that research indicates the oxygen concentration in flooded soil approaches zero within a day. Without oxygen, certain plants, such as corn, cannot perform critical life-sustaining functions. Many nonagricultural plants are also harmed being submerged in water.
  
  

Wetlands

• Floods serve an important role in balance of wetland ecosystems. According to the Fitzroy Basin Association, regular flooding in wetlands allows the soil to release nutrients that can promote biodiversity. Floods can also potentially help control invasive weeds. Flooding also provides a way for fish species to move to different areas. The research paper "Environmental Impacts of Extreme Floods," written by John Hickey, of the U.S. Army Corps of Engineers, and Jose Salas of Colorado State University, says some fish species depend upon periodic extreme flooding.
  
  

Considerations

• Floods are a natural phenomenon and are part of the natural balance of the environment. Hickey's and Salas' paper concludes that floods can be thought of as a "reset" button for nature. The problem is that humans introduce pollution as a result of flooding, as even efforts to prevent flooding, such as building dikes and other structures, cause pollution because such operations require a large amount of energy.