Dune coast changes caused by weak storm events in Miedzywodzie, Poland

Abstract

Bugajny, N. and Furmańczyk, K., 2014. Dune coast changes caused by weak storm events in Miedzywodzie, Poland In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 211–216, ISSN 0749-0208.This paper describes the impact of weak storm events on morphological changes of the sandy, non-tidal Southern Baltic coast. It was initially assumed that weak storms do not cause any significant changes on the coast, i.e. dune erosion. For this purpose, 14 RTK-GPS surveys were carried out during June to December 2012, consisting of a cross-shore profile every 100 m along a 2 km stretch of coast. Offshore wave data (WAM model) and water level data (tide gauge) were also collected. The hydrodynamic conditions were grouped into 3 groups by Ward's hierarchical cluster analysis to investigate relationships with morphological changes on the coast. Correlation between volume changes and shoreline displacement for profiles and each group of hydrodynamic conditions were obtained. The correlation coefficient value for profiles ranged from R=0.41–0.91; and for groups R=0.79–0.82. It was found that for the first group (Hs<1 m), accumulation was observed almost in the whole area. For the second hydrodynamic group, some profiles accumulated while others experienced erosion. For the last group, erosion processes were dominant. The study reveals the oscillating nature of the coast within the study area. Volumetric changes between the first and last survey ranged from 0.8 m3/m to approximately −1.2 m3/m and the shoreline changed from rough to smooth.