What are stabilization techniques for erosion control?
Riprap / Hard Armoring
Riprap (a type of hard armoring) has been the go-to method for shoreline and riverbank stabilization for years. This method involves using large natural rock along the shoreline to help protect against erosion. Like with seawalls, riprap can cause issues in the long-term. For example, wave flanking or scouring can occur. Riprap can also be costly.
Bioengineering for riverbank stabilization is the use of vegetation to reinforce a riverbank and prevent erosion. Natural trees and plants have deep root systems which help hold soil in place and protect the shoreline from erosion.
According to the US Army Corps of Engineers, the benefits of bioengineering are: “first, the root system helps hold the soil together and increases the overall bank stability by its binding network structure, i.e., the ability of roots to hold soil particles together. Second, the exposed vegetation (stalks, stems, branches, and foliage) can increase the resistance to flow and reduce the local flow velocities, causing the flow to dissipate energy against the deforming plant rather than the soil. Third, the vegetation acts as a buffer against the abrasive effect of transported materials. Fourth, close-growing vegetation can induce sediment deposition by causing zones of slow velocity and low shear stress near the bank, allowing coarse sediments to deposit. Vegetation is also often less expensive than most structural methods; it improves the conditions for fisheries and wildlife, improves water quality, and can protect cultural/archeological resources.”
There are also limitations to bioengineering. For example, the plants may fail to grow due to weather conditions or wildlife.
The TrapBag® barrier system can be applied to stabilize the riverbank for temporary, semi-permanent or even permanent purposes when filled with concrete.