Erosion

Channel diagram

If you have spent years living near a stream of river you know that the channel doesn’t stay put! Erosion along stream and river banks is a natural process. Streams are rarely naturally straight; rather, they wind their way through the landscape, meandering back and forth. Erosion naturally happens at the outside of these stream bends where water is moving quickly. At the inside of stream bends, where water is moving slowly, sediment builds up. The result is a stream channel that is always slowly migrating in the directly of the outside of the bend. In some cases, especially during floods, the stream or river may make a sudden jump into a new channel.

While erosion and channel movement is natural, alterations to the landscape can cause erosion to happen more quickly. One of these alterations is removal of vegetation along streambanks. The roots of native trees and shrubs hold soil in place and slow erosion.

Removal of large pieces of wood from the stream channel can also lead to increased erosion. Wood in the channel slows water down, lessening the impact of high velocity water on some banks.

If you are concerned about erosion on your property, leaving vegetation intact is your first line of defense. Planting additional trees and shrubs can also help provide some protection, but may not provide the short-term help that is needed. Please call a Habitat Restoration Specialist to set up a site visit to discuss your erosion concerns.

 

Additional Resources

Snohomish County Surface Water Management (external partner) also provides technical advice to riverside landowners who are interested in constructing an engineered bank-stabilization project. Contact Dave Lucas at 425-388-3464 x4648 for more information about this program.