According to Bird (2008), natural shorelines can be defined as the unexploited fringe areas at the edge of a body of water such as an ocean, sea or a lake, which connect the aquatic strip of land with neighboring upland. Shorelines provide important contributions to the adjacent environment, such as ensuring regulated water quality and supporting the habitat for both terrestrial and aquatic organisms like fish, reptiles, invertebrates, amphibians, waterfowl and shorebirds, and mammals. Disruptions or changes to shorelines can negatively affect the survival of those organisms that depend on this type of habitat in the course of their life stages.
Therefore it is important to protect these critical habitats from natural degradation processes to ensure continued aquatic life. Shoreline degradation is a natural process brought about by frost action, gravity, wind, or wave action. Shoreline erosion can result into positive effects such as creation and refilling of natural beaches, and as well can result into negative effects for example water pollution, structural damage, destruction of habitat and property. Human activities such as clearing of natural vegetation, development or construction, agricultural practices, and impervious structures and surfaces can result into shoreline degradation. Shoreline degradation or erosion can be avoided by shoreline stabilization.
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A number of shoreline stabilization methods such as gabions, rip rap, and vertical metal, wood or concrete break-walls have been used to protect the shoreline (Bush et al. 2004). The rip rap method constitutes appropriate rock size and bank slope to protect the shoreline from current and wave action. Of these stabilization methods, the rip rap stabilization is the most preferred. With rip rap stabilization a layer of filter cloth, small stones, or gravel is placed behind or under the rock to help in preventing the release of debris and sediment into the body of water (Bird, 2008). Vegetation, particularly deep rooting type is planted behind and above the rock to increase the slope stability. Engineers and biologists have realized that these hardened vertical structures which create a physical barrier, do not absorb wave energy but reflect it instead, thereby making the turbulence even worse. They have therefore come up with methods like maintaining the natural shoreline, establishing vegetation cover along the shoreline, and bioengineering (Bush et al. 2004). These techniques are permanent.
In order to maintain the natural shoreline, the already existing grass, shrubs, and trees should not be cut. Preserving the natural vegetation encourages them to establish and the binding of their roots will stabilize the portion of earth constituting the shoreline. In case natural vegetation has been tampered with, the deep-rooting native plants should be established to accelerate the stabilization of the shoreline. The deep roots will help binding the soil particles together hence can prevent soil erosion altogether. Native plants are preferred because they re-establish easily when damage does take place. In case planting of vegetation is not enough to control soil erosion, a bioengineering technique may be more suitable. This technique incorporates vegetation together with natural materials, for instance live stakes, logs, and brush bundles, making the shoreline to have a natural appearance and therefore critical habitat for wildlife and fish. Bioengineering leads to long-lived shoreline stabilization and hence cost effective (Bush et al. 2004).
Shoreline projects and establishment of impervious structures and surfaces at the shorelines are some of the man-made developments that accelerates erosion and total destruction of the shoreline. The shoreline projects include erecting walls to prevent soil erosion. But these walls can increase water turbulence and accelerate shoreline erosion. Impervious structures and surfaces are comprised of buildings, pavements, drainage ditches, and roofs which result into increased amount of water runoff. The increased water runoff in accompanied by high velocity and storm-water energy resulting into accelerated shoreline erosion (Mason, Neal & Pilkey, 1997).