Present-day dune environment dynamics on the coast of the Świna Gate Sandbar (Polish West coast)

Abstract

In present day Polish coastal dunes' development, heavy storms and human activity play a significant role. Natural or almost natural dune processes and accumulation of the coast is observed only in a few places, such as the Świna Gate Sandbar (also called barrier). As far as the spit number and morphology of the youngest ridges is concerned, they are different in the western, the middle and the eastern part. In the western part, ridges are smaller and closer to each other, thus depressions between them are narrower. Moreover, beach is widely covered by small hillocks. In the middle part, ridges are higher but narrower. Likewise, depressions between them are wider. The beach is wide and covered by large numbers of plants and dune hillocks. In the eastern part, dunes are also high but tend to be narrow, with steep seaside slope having the most frequent occurrence. Depressions and beach are narrow. The number of plants is not considerable compared with other parts. Since 1997 an increase of the new dune ridge on the still developing beach has been observed. Each year the beach is becoming wider and covered by larger number of plants. Plants lead to the development of new dunes and increase of the sandbar. The new foredune ridge consists of several hillocks joined into irregular ridge. This new first ridge is also shaped by storm waves but still becomes a real ridge. This development may be caused by continuous sand supply and by very strong north and west winds. A lot of different dune psammophyties on the beach are in favour of sand fixing on the increasing beach far from the first ridge. Only on part of spit with a tendency to erosion, accumulation of the dunes is not to be observed. Additionally, human activity stops aeolian accumulation and plant growth on the beach.