Erosion Prevention and Sediment Control

               

                                                     Before                                                                                                                                                                 After

Above Images Courtesy of Rogue Valley Sewer Services.

 

Types of Erosion

 

 

1. Raindrop erosion (splash) Raindrop erosion  occurs when rain disperses and mobilizes soil  particles on contact.

 

 

1. Sheet erosion – Sheet and rill erosion occur  when rain drops and surface flows cause  shallow stripping of soil.

 

 

 

1. Rill erosion – Rill erosion occurs when surface  flows become concentrated and begin to erode  the surface.

 

 

1. Gully erosion – Gully erosion occurs when  concentrated flows cause sharp sided entrenched  channels deeper than 0.5 meters.

 

 

1. Stream bank (channel) erosion – Stream bank  erosion occurs when streams begin cutting  deeper and wider channels as a consequence  of increased peak flows or the removal of local  protecting vegetation.

 

 

Selected definitions adapted from DPI 2005

 

Impacts of Erosion

 

Problems  resulting from erosion and sedimentation include:

• polluting lakes, wetlands, creeks, and rivers (dirt is a pollutant).
• loss of system capacity and damage to infrastructure leads to flooding and costly system repairs.
• aquatic habitat loss – sediment covers fish habitat and can smother eggs.
• loss of valuable soil (e.g., topsoil).

Human Influences on Erosion

Soil erosion is a natural process that averages 0.2 tons per acre annually.   Humans greatly accelerate the process!   The loss rate is accelerated to:

• 0.5 tons per acre for managed forests.
• 1.5 to 20 tons per acre for pasture and cultivated lands.
• 150 to 200 tons per acre for unprotected construction sites.

What Can Be Done?

1. Develop and implement erosion prevention and sediment control programs (muncipalities).
2. Develop and implement erosion control plans for construction activities (Example).
3. Incorporate best management practices (e.g., rain gardens, swales, planter boxes) to reduce the amount of water running off your property (homeowners).
4. Schedule construction and ground disturbing activities for the dry season or to avoid heavy rain.
5. Retain native trees and brush cover on the site.   Use native trees  in landscaping.
6. Cover bare  soil before it rains.   Use mulch, erosion control blankets, and other materials.
7. Protect storm drains. Example.
8. Learn more about erosion prevention and sediment  control measures.

 

Regional Stormwater Management

• Bear Creek Watershed (Ashland, Talent, Phoenix, Medford, Central Point, Rogue Valley Sewer Services, and Jackson County).
• Rogue Basin  (Grants Pass, Shady Cove, Eagle Point, Cave Junction, Rogue River, Gold Hill, Butte Falls, Gold Beach, Jackson County, Josephine County, and Curry County).