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 Appendix B: Bioengineering for Streambank Erosion Control -- Guidelines
engineers, hydrologists, and life scientists with expertise in bioengineering approaches. Other
disciplines, such as economists, sociologists, and attorneys can be consulted as needed during
the planning stage of development.
Questions to be Developed and Answered.
Any streambank erosion control project has several components. Each component may
have constraints that have to be overcome. These components with associated constraints
are interdependent and must be considered, thus generating an abundance of questions that
should be answered, if possible. They include the political, economic, climatatological,
physical, edaphic (soils), and biological components of the project. Both the asking and
answering of these questions relative to these components lead to the Plan of Development.
Once the plan is developed and permits acquired, procurement of plants will be required (See
Part III). After or concurrent with this procurement, implementation of the plan can proceed.
The political component includes governmental regulations, such as those presented in
Section 404 of the The Clean Water Act (formerly known at the Federal Water Pollution
Control Act, 33 U.S.C. 1344). It also includes public pressures, such as restricting
bioengineering to the use of only native plant species or plants that are grown in a nursery as
opposed to those harvested from the wild. Governmental regulations and/or public pressures
may also mandate that certain vegetation species or types of species be used. If a certain
species blocks the view of a river in an urban setting, for instance, public pressures may cause
plans to change to use a different species or a different erosion control treatment altogether.
Lack of grazing controls, limitations on use of chemicals for rodent, insect, or weed control
or fertilizers are other examples of these constraints and must be considered in any
bioengineering design criteria protocol. The political component also includes the negative
human factors of vandalism and trespass by foot and off road vehicles as well as the positive
factor of public pressure for improvement of the environment.
The economic component could be one of the more important factors to enable
bioengineering erosion control efforts. Usually, bioengineering projects are less expensive
than traditional engineering approaches. However, economics invariably affects the final
decisions on the selection of plant species and planting densities, as well as pre-project
experimentation and after care activities. A bioengineering design protocol must include
funding for monitoring and allow for remedial planting and management of the site to meet
the objectives of the project. Bioengineering projects will often require more funds early in
the project's history for possible repair and assurance of effectiveness than traditional
engineering, but will be more self sustaining and resilient over the long term. If traditional
engineering projects need remediation over the life of the project (and they frequently do),
the remediation occurs later in the life of the project but with higher overall costs.
The climatatological component includes several aspects of a project site: rainfall (amount
and distribution), temperature (heat and cold, time, duration, and intensity), humidity, day
length, etc. Climatatological components affect plant species selection, how those plants will
be planted, and treatment after planting. With some exceptions, bioengineering projects in
humid regions with ample rainfall and projects along permanent flowing streams will probably
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