Using This Website
Slope Stabilization and Erosion Control Using Vegetation provides coastal landowners and government officials with basic information concerning the nature and use of slope planting techniques to manage soil erosion and shallow seated land movements. Information is introduced on site evaluation, planning, vegetation systems, materials, planting techniques, and general compatibility of the installation with traditional property owner use. This website is a companion document to two other Washington State Department of Ecology websites entitled Vegetation Management: A Guide for Puget Sound Bluff Property Owners, and Surface Water and Groundwater on Coastal Bluffs: A Guide for Puget Sound Property Owners. The online documents should be used together to foster a better understanding and appreciation for the role and maintenance of vegetation along the coastal zone of Puget Sound. The following sections present an idealized scheme of how these websites might be used by landowners and local government.
Readers who own coastal property and who are concerned about soil erosion control and shallow land movement prevention can use this and other Washington Department of Ecology documents to select and employ general slope protection practices which may be applicable to their property. Additionally, readers can access a wealth of information available through public agencies and library systems. For many situations, professional design assistance should be sought. The information provided in this website provides the basic information necessary to make general planning decisions and simple installations on slopes. The website is not intended as a substitute for professional geotechnical/biotechnical engineering design or site-specific consultation.
Readers working for government agencies, whose responsibilities may involve policy creation, geologically hazardous areas, and development/permit application reviews, can use this website to help them determine whether projects address vegetative systems as a viable component of slope stability maintenance. Permitting agencies will find this online document useful in suggesting alternative slope maintenance practices to coastal land owners who are unfamiliar with the advantages of slope planting techniques. This site may also allow agency personnel to better understand the cause and effect relationship of shoreline development and the continuing maintenance of slope stability and erosion control.
The coasts of Puget Sound contain a variety of landforms which can vary greatly in their composition and historical use. This makes it difficult to cover all of the problems landowners may encounter on their properties in one website. Nevertheless, this site will introduce some general planting techniques that may be used alone or in combination with other revegetation programs and existing natural areas to protect coastal slopes.
It is important for you, the property owner, to understand
your site characteristics, and the erosion and land movement
processes which may effect it. Only then can you begin to select
appropriate protection measures to reduce potential slope
erosion and land movements.
Once you have generally characterized the existing conditions and uses of your slope, the next practical step is to determine which slope planting techniques may provide solutions to your identified problems. Use Table 1 as general guide to the appropriate slope protection measures for your site. The sections on the role of vegetation in slope stabilization and erosion control and vegetative planting techniques should be reviewed to determine the specific goals and limitations of each technique.
Figure 1. Typical Puget Sound Coastal Slope Profiles.
This website addresses only the unconsolidated soil portions of coastal zone slopes. Bedrock exposures forming the cliffs of the Puget Sound coastal zone are not discussed in any detail in this website because most vegetation installation techniques are not applicable to these areas. The general shapes of Puget Sound coastal slopes are illustrated in Figure 1 above. Use Figure 1 to recognize some of the slope shapes that are familiar to you. When you identify your general slope shape(s), you can begin to understand the behavior of your property and start to account for erosion and landslide processes which may act upon your slope. You then can implement a number of vegetative slope protection measures discussed later in this online document.
The placement and maintenance of vegetation on a slope is
important to a slope protection program. However, there are
limits to the stabilization role that vegetation can perform
which must be recognized at the onset of the planning process.
First, vegetation alone can not control deep seated earth
movements that may result from a combination of geologic and
environmental influences. Additionally, the placement of
vegetative components into actively failing slope areas such as
landslides or earth flows can not be expected to have any
short-term stabilization benefits until these movements are
arrested and the sources of the problem are eliminated.
For your convenience, we have created several documents to aid in your interpretation of this website. They can be reached via the links below, or accessed at any time using the navigation menu at left.
Copyright © Washington State Department of Ecology. See http://www.ecy.wa.gov/copyright.htm