Artificial Beach as a Structure for Protecting a Seacoast from Storm Surge Impact (Based on the Example of the Eastern Gulf of Finland)

Аннотация

A model of an artificial beach is proposed for protecting a seacoast subjected to erosion under significant storm surge impact. The beach profile properties are based on the Dean equilibrium profile. It is shown that coarser sand yields a greater total beach width, but requires a greater volume of berm material. At the same time, this results in decreased loss of material to longshore sediment transport. The results of applying the model to three sectors of eroded coast in the Kurortny District of St. Petersburg (eastern Gulf of Finland) recommend the use of medium-grained 0.3–0.5 mm sand to construct the artificial beach. In this case, the width of the dry beach section would be about 80–140 m, while the volume of berm material would be (1.3–3.2) × 10² m³ per one meter of coast length depending on the sediment deficit for a given coastal sector. To minimize the relative loss of material, it is suggested to construct a beach no less than 1 km in length; in this case, more than half the initial beach volume would be retained even after 30 years. Modeling of extreme storm impact leads to the conclusion that the designed beach profiles are only slightly deformed and can retain their resources for many years.