Resilience of beach morphometric characteristics on decadal time scale: a case study from the Lithuanian Baltic Sea

The sandy seashore is a highly dynamic environment where the beach experiences constant change. If the granulometric composition of beach sediment does not change substantially and the sediment circulation is undisturbed, as well as the prevailing hydrometeorological situation does not substantially change, the beach can maintain its morphology quasi-stably on a decadal time scale, even when coastal erosion or accretion processes prevail. In this study, beach width and volume characteristics of coastal segments with prevailing erosion or accretion were assessed based on interannual beach leveling surveys from the Lithuanian Baltic Sea coast in 2002–2023 (72 cross-shore profiles in total). Study results revealed that the beach on both coastal stretches with prevailing erosion processes and coastal stretches with prevailing accretion processes maintains its morphometric characteristics. On coastal stretches with prevailing erosion, the beach maintains its profile by supplementing its sediment budget with the sediment reserves in the foredune, while on coastal stretches with prevailing accretion and seaward shoreline migration, the indefinite increase in beach width is limited by the formation of the incipient dunes at the foredune toe.