Dynamics of Foredune Parameters of the Curonian Spit (Lithuanian Coast) since 1999

Abstract

Foredune is naturally formed in the west of protective coastal dunes up to the slope of the sand transported by the Baltic Sea wave emissions and prevailing western winds. The sand up to the foot of the slope is reformed by wind to embryonic dunes, and the resulting merger is a foredune. It is described by three basic dimensions - length, width and height. In summer of 1999 from the foot of Kopgalis dune to the Lithuanian state border with the Karaliaucius region, with minor interruptions along the eastern part of the sea beach, the foredune made up a 50 km long belt. Average relative width of a foredune was 7.6 m, its absolute average width being 7.95 m, the height varied from 0.5 m to 1.85 m, while the eastern slope merged with the western dune slope. Plant projection cover was evaluated by 1-13%. On the foredune pioneer plant species Honckenya peploides (L.) Ehrh., Cakile baltica Jordan. were growing in small groups. Pobeda ex. Rootstock grasses Ammophila arenaria (L.) Link. and Leymus arenarius (L.) Hochst. dominated among the other grass on the foredune surface. Hurricane Anatoly which hit the Lithuanian seaside in early December of 1999 destroyed the foredune, and narrowed the top of protective dunes by 2 meters. During the observations of 2003 spring the foredune was partially recovered in some protective dunes of the western slope foot areas. Then its relative mean width was 3 m and the absolute width - 7 m. The observation repeated in 2005 spring, after the devastating storm Ervin showed that the relative average width of the foredune was 2.6 m, and the absolute width - 7 m. In 2006 winter storms bypassed the Lithuanian seaside, in spring the relative average width of the foredune increased up to 5 m, and the absolute average width to 8.4 m. The winter of 2007 was stormy and it greatly influenced the foredunes dimensions. In spring its relative average width was only 2 m, and the absolute average width - 5.3 m. In spring of 2008 the foredune continued to diminish, its relative average width being just 1.5 m, while its absolute average width increased up to 8 m. As observations have indicated the foredune accreted with rootstock grass species can better withstand storms, the western slope of a protective dune suffers less.. The way out of this problem is either artificial formation or natural growth of a foredune of an optimal size at the western slope foot with artificial planting of green rootstock herbaceous plant species.