Principles and Objectives of Soft Shoreline Stabilization

Protection or mitigation of shorelines using soft approaches has some simple objectives and three basic principles. The first principle is really simple: try to imitate nature. Within each geomorphic environment, sediment characteristics, shoreline slope, and terrestrial and submerged habitat will be specific, hence using native plants, and sediments that have already been exposed and shaped by forces within the specific coastal zone are critical to the success of soft mitigation methods. Plants and their roots help retain the soil matrix with their roots, and often offer good protection to erosion. On the other hand, if an area is subjected to higher energy conditions where vegetation is not naturally found, such as a beach, trying to steady the shoreline using vegetation along the high energy environment of the beach might not be a good idea. The fast moving water and energy resulting for tidal currents and breaking waves will uproot the plants and quickly render the plants ineffective. The second principle is maintaining gentle slopes. Unless we are in rocky coasts or regions with bedrock exposure, natural slopes where sediment is stable under gravity (less than the angle of repose) are relatively gentle. Maintaining gentle slope allows for gradual dissipation of wave energy across a longer distance, hence the energy acting on each unit area is much lower compared to a vertical wall. The third principle suggests employing combined or mixed material approaches. Along many shorelines we see a variety of terrestrial plants, various sediment sizes ranging from mud to sand or gravel, and shorelines are often lined up with trees and other organic debris, and slopes can vary widely. Therefore, using a combination of approaches that imitates nearby natural shorelines is the best recipe for successful implementation of soft approaches. Although not a principle of soft shoreline stabilization, methods of protection often involve integrated approaches that include a combination of soft and non-traditional hard structure approaches.