An Analytical Model to Predict the Response of Mounds Placed in the Offshore

PURPOSE: An analytical model to predict the response of mounds placed in the offshore is presented, with the overall aim of providing a technique for the preliminary design of mounds subjected mainly to cross-shore sediment-transport processes induced by non-breaking waves. For example, offshore mounds created from dredged material can be used to protect sandy beaches by dissipating wave energy during severe storms or used as a source of beach nourishment. The model discussed here employs a diffusion equation to describe the mound response with respect to an equilibrium beach profile, where the diffusion coefficient is related to the local wave conditions at the mound. Analytical solutions to the diffision equation are readily available provided the initial and boundary conditions are sufficiently simplified. Solutions yield characteristic quantities that are useful in preliminary design of offshore mounds when a number of project alternatives are considered and evaluated. The model provides quantitative information on how quickly a mound disperses under the influence of non-breaking waves at a particular site. With this information, one can estimate how quickly a beach may be nourished with material from the mound or how long the mound may protect the beach from severe storms (via attenuation of incident wave energy).