Bugajny, N. and Furmańczyk, K., 2017. Comparison of short-term changes caused by storms along natural and protected sections of the Dziwnow Spit, southern Baltic coast.
This paper focuses on a comparison of changes caused by weak storms (significant wave height [Hs] <2.5 m) along a dune coast on a nontidal sea. Repeated observations were made along two 2 km long sections of the southern Baltic coast; one section is a natural coast, and the other features protective structures. Several real-time kinematic GPS surveys were carried out in 2012. The surveys included cross-shore profiles measured from the dune foot to a water depth of 1 m. The profiles were spaced at constant 100 m intervals. In addition, offshore wave data and water level data were collected. Using statistical methods, three types of hydrodynamic conditions were identified and the data grouped accordingly; these groups had different effects on the coast. The coastal changes that occurred along the natural and protected sections of the coast were compared using two parameters: shoreline displacement and volume changes. The net, total, and maximal values and means of shoreline displacement and beach volume changes were calculated and are discussed in this paper. The analysis confirms that both natural processes of erosion and accumulation take place in relation to the location of shoreline displacement and the volume changes under all hydrodynamic conditions on both the natural and protected coasts. The proportion of these changes depends on the hydrodynamic conditions and the type of coast. The accumulative effect of the groynes is particularly seen under the hydrodynamic conditions of group 2. The ratio of volume changes to shoreline displacement exhibits stronger correlation for the natural coast (group 1, R = 0.82; group 2, R = 0.75; group 3, R = 0.80) than for the protected coast (group 1, R = 0.79; group 2, R = 0.74; group 3, R = 0.61), while the slope of regression is greater for the natural than for the protected coast.
