Beach Transformation After Nourishment: Case Study of Palanga, Lithuania

Beach nourishment, as one of the most widely and effectively used coastal management measures recently, inevitably changes the coastal environment. This study aims to assess how the coastal profile is transformed during repeated beach nourishments with coarser-than-native sand in the Palanga recreational zone, Lithuania, Baltic Sea, using field survey data from the last three decades. When the granulometric composition of the sand is artificially changed during nourishment, the beach adapts to environmental changes by adjusting its morphometric parameters. These changes can be perceived as an intensification of coastal erosion, and, at the same time, a failure of the project. However, the results of this study show that these changes are associated with the transformation of the beach towards a morphologically adjusted state under the new sediment characteristics. In the Palanga case, the coarser-than-native sand used for nourishment led to narrower and steeper beaches compared to the pre-nourishment beaches composed of finer sand, and these characteristics persisted five years after nourishment. Therefore, the wide and low-slope beaches created during beach nourishment could not maintain the formed morphometric features with the coarser sand. For this reason, when implementing a replenishment project, it is important to predict the cross-shore profile that will develop for a given grain-size composition and quantity of the nourishment sand.