When it comes to halting the detrimental effects of erosion on streams, ravines, and creeks, traditionally we have employed engineered solutions such as retaining walls, rip rap, gabions, and other physical barriers to stabilize slopes around streams and rivers and control erosion. The engineers and scientists at Associated Environmental have advanced the use of natural methods for erosion control. With climate change and the need to reduce greenhouse gas emissions, sustainable methods of restoring sites are more important than ever.
Soil bioengineering involves the use of soil remediation and living plants to repair and stabilize slopes. Using vegetation for erosion protection offers many benefits. The root systems of introduced plants knit together and penetrate deep into the soil, holding soil particles together, which strengthens slopes and decreases the risk of slope failure. Plants and their deep root systems absorb water, preventing saturated ground from slumping or shifting. Vegetation is self-sustaining. Plants grow stronger with time, simultaneously stabilizing the soil and slope. Plants help mitigate climate change by absorbing and reducing carbon in the atmosphere, and improve biodiversity by providing homes for wildlife, like places for birds to perch and build nests.
Bioengineering works by planting native species of trees and plants, which would reestablish themselves with time, and accelerating their ability to colonize a site that has experienced natural or rapid erosion, for example after a flood or wildfire. Typically, live stakes of a fast growing species like balsam, poplar, or willow are planted in different configurations, tailored to the needs of the site. Other measures, like roughening the soil, provide immediate benefits to decrease runoff by slowing the flow of surface water. Once planted, the root systems of live stake plantings develop very quickly and the plants begin to grow, increasing soil stability and further reducing surface runoff.
Bioengineering methods can function independently, or be combined with engineered structures, depending on the site. Bioengineered slope protection is typically economical, and has minor maintenance requirements. The ability to use plants and trees to perform an engineering function is a valuable, environmentally sustainable alternative in the engineering toolkit. For municipalities and communities, bioengineering is an attractive option to traditional physical erosion control structures to evaluate with your consultant.
See our Soil Bioengineering page for more information