An analytical model to predict dune erosion due to wave impact Magnus Larson * , Li Erikson, Hans Hanson Department of Water Resources Engineering, Lund Institute of Technology, Lund University, Box 118, S-221 00, Lund, Sweden Available online 23 August 2004 Abstract An analytical model is developed to calculate recession distance and eroded volume for coastal dunes during severe storms. The transport relationship used in the model is based on wave impact theory, where individual swash waves hitting the dune face induce the erosion. Combining this relationship with the sediment volume conservation equation describes the response of the dune to high waves and water levels. Four different data sets on dune erosion, originating from the laboratory and the field, were employed to validate the model and to determine the value of an empirical transport coefficient appearing in the analytical solutions. The time evolution of dune recession observed in the different data sets was well described by the model, but the empirical coefficient showed some variation between cases, especially for the field data. In practical applications of the model, it is recommended to use a range of coefficient values to include an uncertainty estimate of calculated quantities, such as recession distance and eroded volume. D 2004 Elsevier B.V. All rights reserved. Keywords: Dune erosion; Analytical model; Wave impact; Large wave tank data; Storm erosion; Runup height; Swash bore 1. Introduction Coastal dunes often constitute the final defense line against high waves and water levels during severe storms. If they are overtopped or breached, serious damage due to flooding and direct wave attack could occur, resulting in loss of life and property. Thus, it is of significant value to be able to predict the impact of a storm on a dune in terms of recession distance, eroded volume, and probability of breaching. Several analytical and numerical models have been developed for this purpose (see discussion in the following section), but many of them lack a clear physical basis and have only been tested against limited data. Analytical models typically require marked simplifi- cations in the description of the governing processes, forcing, and initial and boundary conditions, whereas numerical models can deal with these aspects with less restrictions. However, analytical models still have their use since the simplicity makes them easy to apply, which is valuable in the initial stage of a project when approximate estimates are required. In addition, the limited work needed to apply them, as well as the required amount of input data, makes the analytical models attractive to employ. Another benefit is that 0378-3839/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.coastaleng.2004.07.003 * Corresponding author. Fax: +46 46 222 4435. E-mail address: magnus.larson@tvrl.lth.se (M. Larson). Coastal Engineering 51 (2004) 675 – 696 www.elsevier.com/locate/coastaleng