Performance Comparison of Dune Erosion Models Relative to Storm Erosion Measurements on Pacific Coast Beaches

摘要

Primary frontal dunes at sandy shores are essential features to mitigate flooding and erosion damage to coastal properties and infrastructure by coastal storms. Projecting the geomorphologic response of the beach and dune profile caused by extreme storms is required to establish risk levels to upland improvements. Procedures are available to predict dune erosion, and detailed examination of their performance would be valuable in selecting the appropriate tool for given storm and beach characteristics. Two geometric models (the Kriebel and Dean Method; the McDougal, Komar, and MacArthur method), one analytical model (the Larson, Erikson, and Hanson wave impact model), and two process-based models (SBEACH and XBeach) were applied with data for known storms to surveyed beach and dune profiles along a 10.6 km (6.6 mile) reach of shoreline south of the Grays Harbor Entrance in Washington State. To compare performance of these methods in predicting beach and dune changes in severe storms, locations were selected within this reach that demonstrate a range of morphologies and local sediment budgets. Results of applying the dune erosion models illustrate the predictive accuracy of the geometric models, for which few input adjustments are available, and the range of adjustments that are required for the process-based models to optimally represent measured beach and dune modifications. This paper presents pre- and post-storm profiles of the beach and dune at both accreting and non-accreting locations, details of the storm waves and water levels bracketed by the surveys, and an evaluation of the models' predictive capabilities.