Multi-scale analysis of wave conditions and coastal changes in the north-eastern Baltic Sea

Temporal variations of shoreline changes have been analyzed and interpreted in three differently exposed Estonian coastal sections. Using coastline contours that have been recorded frequently over the last twelve years, as well as recently digitized aerial photographs, orthophotos and old topographic maps (some of them daring back to 1900), all overlaid in the Mapinfo software, areal changes over different sub-periods were calculated. To explain the shoreline changes, two different wave modelling approaches were used and mutually compared. Both the BaltAn65+ reanalysis (an ERA-40 refinement) forced SWAN model hindcast (1965-2005) and the point model runs (1966-2012), locally and independently calibrated against extensive wave measurements in these coastal study sites, confirmed specifically higher (and increasing) intensity of coastal processes in the westerly exposed study sites, and a decrease in northerly exposed sites. Some common quasi-periodic cycles with high stage approximately in 1985-1995, and probably also from 2007 can be found. However, the role of a few randomly occurring extreme winter storms (such as in 1967, 2005, 2007 and 2012) was often decisive within the sub-periods.