Gravel barriers on beaches help protect against storms, but predicting how they handle storm impacts is important. Researchers studied storm overwash at Loe Bar in England using high-tech measurements and a computer model. They found that the type of waves during a storm affects how much water goes over the barrier. Short waves break before reaching the beach, causing small floods, while long waves arrive unbroken and create bigger floods. When waves have two different sizes, the bigger ones cause the most flooding. Understanding these patterns can help predict when barriers might fail during storms.