Estimating Extreme Values of Run‐Up on Beaches

Abstract

The limit of run-up on beaches has important coastal engineering and management implications. However, existing guidance on estimating run-up on sandy beaches is sparse and is based on parameters and models developed for run-up on structures. In particular, run-up is often scaled with Hunt's equation, also called the Iribarren number or the surf parameter. It is shown that one term of that parameter, the beach-slope term, can be omitted from engineering models of extreme values of run-up on beaches. Philosophically, the beach slope is a dependent variable on sandy beaches that are free to respond to the incident wave energy and thus should not be included in a run-up model. Practically, the beach slope is hard to estimate a priori for the engineer. Holman's data on extreme run-up levels during a wide range of wave conditions at Duck, North Carolina are used to show that removing beach slope does not cause any reduction in run-up model ability.