Volume Estimation From Planform Characteristics of Washover Morphology

Abstract

Overwash is the cross-shore transport of water and sediment from a waterbody over the crest of a sand or gravel barrier beach, and washover is the resulting sedimentary deposit. Washover volume, and alongshore patterns of washover distribution, are fundamental components of sediment budgets for low-lying coastal barrier systems. Accurate sediment budgets are essential to forecasting barrier system sustainability under future climate-driven forcing. However, comprehensive surveys of three-dimensional washover morphology are challenging to deliver. Here, we use the results of a physical experiment, analysis of lidar data, and examples of washover characteristics reported in the literature to develop scaling relationships for washover morphometry that demonstrate volume can be reasonably inferred from planform measurements, for washover in natural (non-built) and built barrier settings. Gaining three-dimensional insight into washover deposits from two-dimensional information unlocks the ability to analyze past aerial imagery and estimate contributions from washover flux to sediment budgets for past storms.