Evaluation of engineering alternatives to reduce volume loss from a beach nourishment project influenced by a severe erosional hot spot

摘要

Beach erosion, a problem along many sandy shores, can be caused by human interventions to the coast or natural processes. Remediation of beach erosion (i.e. beach restoration) along eroding developed beachfronts is commonly practiced in the U.S. by periodic beach renourishment with or without coastal structures. Rates of erosion within beach'fills generally vary greatly and areas that erode faster than the nourishment average are commonly termed "erosional hot spots" (EHS). To be able to understand and forecast beach nourishment performance and hot spot erosion is essential for proper beach nourishment design. Beach nourishment predictions have been conducted in the last decade utilizing empirical formulations, one-line models, and lately process-based coastal morphology models. Process-based coastal morphology models are complex and computationally intensive. In order to maintain a balance between model complexities, computational effort, and processing capacity, schema-tization of model input (input reduction) is necessary. In this paper, a morphological model combined with advanced wave climate schematization techniques are used to evaluate coastal engineering interventions aimed at reducing volume losses from an EHS at the south end of a beach nourishment project in southeast Florida (Delray Beach). Engineering solutions evaluated in the morphological model included construction of a breakwater field, backfilling all dredge pits located offshore of the project site, construction of a groin field at the downdrift end of the project, and backfilling the single deepest dredge pit. These engineering interventions reduced beach volume losses within the project limits with varying levels of effect on the downdrift beaches. Reduction of the volume loss from the project site is technically feasible but further analysis is needed to evaluate economic and environmental feasibility.