Water flows one way – downhill. The speed and velocity of soil particles (sediment) is influenced by the topography of the property. The size, shape and slope of a watershed influence the amount and rate of runoff. Obviously, as slope and gradient increase, the velocity and volume of runoff increase and the erosion potential magnifies. Climate is another fundamental factor in the amount of runoff generated. The frequency, intensity and duration of rainfall varies dramatically. When storms are frequent, intense, or of long duration, erosion risks are high.
For these two reasons, the erosion risk is rated higher for certain Florida areas than rain forests in Oregon and Washington States. The rainfall is much higher in those western States but far more intense in the eastern States. Country wide, it is estimated that 4 billion tons of sediment reaches ponds, rivers and lakes each year and about 1 billion tons reach the ocean. Now that is a lot of truck loads!
The impact is two-fold:
- Physical Impacts
- Biological Impacts
Physically, large deposits of sediment create obstruction of stream channels and navigable rivers. It severely reduces hydraulic capacity which in turn causes an increase in flood crests and thus, an increase in flood damage. Sediment also fills stormwater conveyances and plugs culverts. The impact on stormwater systems is disastrous. Additionally, reservoir water supplies are affected due to loss of water storage capacities. Not to mention the added expense of dredging or water purification.
Biologically, sediment deposition in lakes and rivers increase water turbidity, making it difficult for light to penetrate the water. Aquatic plants need sunlight for photosynthesis. Without light, they die. Sediment is also rich in nutrients – such as phosphorus and nitrogen – and promote excessive algae growth. Algae depletes oxygen in the water and fish populations suffer or die. Light reduction and oxygen deprivation also lead to the decline of benthic plant growth. Benthic organisms are a major food source for fish and a disruption of the food chain would be evident. This is a double onslaught for aquatic species and can largely be prevented through proper erosion control.
Michael Cordier, Director: Business Development & Strategy, Landshore Enterprises LLC, 188 Triple Diamond Blvd., Suite A4, North Venice, FL 34275 firstname.lastname@example.org ©2018