Stream Bank Erosion
Rivers and streams are not fixed landscape features. Over time their banks shift and move through out a wider area called a floodplain which results in a natural level of erosion. The results can be dramatic like during a flood event or very subtle such as the down cutting of a stream bed.
Erosion along a streambank can also be the result of human land use and associated infrastructure. Land use and infrastructure often impacts the larger forces within a watershed. For example, land use can that reduced the retention of precipitation within the soils or within the stream itself, increase the overall velocity of water moving from the upper portions of a watershed to the lower areas. Increased velocity can cause stream bed downcutting which can ultimately leave banks vulnerable to erosion. Human activity along a stream can impact the natural buffer zone of a river, called the riparian area, which can in turn increase the susceptibility of erosion. If the riparian area of a stream has been compromised, erosion can occur unchecked at unatural levels reslting in loss of property and decreased water quality that negatively affect aquatic organisms like fish as well as municipal drinking water sources.
Assessing what is causing erosion is important before addressing the concern. If watershed level downcutting is causing your streambank to become too steep for vegetation to exist, there is often little a landowner can do to protect a streamside home other than extremely expensive and often only temporary fixes. If however the erosion is primarily due to human activity along the riparian area, like cutting down vegetation for a better view, or allowing livestock access along long portions of a stream, conservation practices and restoration efforts can often restore the function that riparian areas provide. These functions include bank stabilization, water quality protection (filtration and shade), and fish and wildlife habitat.This function is provided primarily through the establishment of appropriately adapted native, perennial vegetation.
Soil bioengineering is a solution that can address moderate to localized streambank erosion depending upon the scale of erosion present. The general concept relies upon restoring strongly rooted, woody vegetation. Woody vegetation protects streambanks in several ways:
Erosion along a streambank can also be the result of human land use and associated infrastructure. Land use and infrastructure often impacts the larger forces within a watershed. For example, land use can that reduced the retention of precipitation within the soils or within the stream itself, increase the overall velocity of water moving from the upper portions of a watershed to the lower areas. Increased velocity can cause stream bed downcutting which can ultimately leave banks vulnerable to erosion. Human activity along a stream can impact the natural buffer zone of a river, called the riparian area, which can in turn increase the susceptibility of erosion. If the riparian area of a stream has been compromised, erosion can occur unchecked at unatural levels reslting in loss of property and decreased water quality that negatively affect aquatic organisms like fish as well as municipal drinking water sources.
Assessing what is causing erosion is important before addressing the concern. If watershed level downcutting is causing your streambank to become too steep for vegetation to exist, there is often little a landowner can do to protect a streamside home other than extremely expensive and often only temporary fixes. If however the erosion is primarily due to human activity along the riparian area, like cutting down vegetation for a better view, or allowing livestock access along long portions of a stream, conservation practices and restoration efforts can often restore the function that riparian areas provide. These functions include bank stabilization, water quality protection (filtration and shade), and fish and wildlife habitat.This function is provided primarily through the establishment of appropriately adapted native, perennial vegetation.
Soil bioengineering is a solution that can address moderate to localized streambank erosion depending upon the scale of erosion present. The general concept relies upon restoring strongly rooted, woody vegetation. Woody vegetation protects streambanks in several ways:
- Root systems help hold the soil particles together increasing bank stability.
- Vegetation creates a rougher surface that can dissipate energy and increase erosion resistance from adjacent stream flow along the bank.
- Vegetation acts as a buffer against the hydraulic forces and abrasive effect of transported materials.
- Dense vegetation on streambanks can induce sediment deposition and build banks.
- Vegetation can redirect flow away from the bank naturally.
- Unlike rock, which transfers stream energy downstream, dense vegetation can dampen this force reducing erosion downstream.
Download the following document to get familar with techniques that can be used for bioengineering. Please consult Lincoln SWCD, the Oregon Department of State Lands, or a professional before excavating (removing) or adding (filling) rock, soil or any other material in a stream or along the streambank. This activity is regulated by the State of Oregon and can result in fines if done without a proper permit
Lincoln SWCD is available to help with erosion concerns by providing technical assistance to landowners in Lincoln County.
Lincoln SWCD is available to help with erosion concerns by providing technical assistance to landowners in Lincoln County.
| Soil Bioengineering Techniques |
