Although several studies have indicated that vegetation on coastal marshes protects the coast from erosion by providing soil reinforcement, wave buffering, sediment trapping, and overall hydro logic regime control, the complex nature of coastal erosion processes makes it too difficult to quantify the net erosion resistance provided by the vegetation. This research uses a novel method of combining different available tools: laboratory tests, in situ tests, and analytical models, to study the soil binding ability provided by smooth cordgrass, Spartina alterniflora. Field vane shear tests and direct shear tests were conducted to investigate the overall effect of roots on the shear strength of dredged soils in Sabine Refuge Marsh Creation Project in Louisiana. Laboratory tensile strength tests of the plant roots were conducted, and two different root reinforcement models were used to estimate the root reinforcement. Root reinforcement calculated from the direct shear tests was compared with that from the analytical models. Analysis using the root reinforcement models showed an overestimation of root-induced cohesion and a new correlation was proposed.
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