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- Title
Daugiamečiai Baltijos jūros Lietuvos paplūdimių morfodinaminiai ypatumai.
- Authors
Jarmalavičius, Darius; Šilinskas, Gintautas; Pupienis, Donatas
- Abstract
Investigations were carried out in order to evaluate changes of the beach profile during the period 1993-2008 and to elucidate the main trends of coastal dynamics. The morphometric indicators (beach width, height and inclination) were measured every year during the study period in 70 measuring stations located along the coastline. It was determined that in 1993-2008 the dynamic shoreline of the mainland receded by 10.2 m and the dynamic shoreline of the Curonian Spit advanced into the sea by 8.3 m. Different morphometric beach indicators changed to varying extents over the period, but a comparison of their values for 1993 and 2008 showed that these changes were small. The average beach width increased by 1.2 m on the mainland coast and by 0.5 m on the Curonian Spit coast. The average beach height also increased negligibly: by 0.5 m on the mainland coast and 0.1 m on the Curonian Spit coast. The average beach slope inclination increased by 0.012 m (from 0.065 to 0.077) on the mainland coast and 0.005 m (from 0.073 to 0.078) on the Curonian Spit coast. The measurements show that, despite being the most dynamic elements in the coastal system, these beaches managed to retain their morphometric indicators almost unchanged during the period of observation. In the coastal sectors with the prevailing accretion processes, beach widening provides favourable conditions for wind transportation of larger sand masses (due to the increased sediment volume in a beach and wind fetch distance) and the formation of a dune ridge closer to the shoreline. Due to dune ridge transgression, the beach morphometric indicators remain only slightly changed. In the coastal sectors with the prevailing erosion processes, the narrowing of beaches allows the waves to erode the dune ridge. Part of material from the regressing dune ridge is accumulated at the beach, resulting in the recovery of beach profile. In such a way, the beach profile retains quasi-stability both in a coast dominated by accretion processes and in a coast with the prevailing erosion processes. Actually, if the essential factors forming the beach -- the wave energy and the composition of beach deposits -- do not change, the beach profile tries to return into equilibrium with the forming factors. The quasi-stability of beaches is revealed only by analysing the average long-term measuring data over long coastal sectors (in this case, the Lithuanian mainland coast and the coast of the Curonian Spit). Analysis of the long-term dynamics of the morphometric indicators of beaches in shorter coastal sectors or in an individual profile has shown that they may vary considerably due to rhythmic topography and rip cells. Changes of morphometric indicators were most significant in the coastal sectors that have a greater morpholithological diversity and anthropogenic loads. This is especially evident on the mainland coast. The measured morphometric indicators are of great value for planning the coastal infrastructure and adaptation to climatic variations.
- Subjects
BALTIC Sea; LITHUANIA; CLIMATE change; MORPHOMETRICS; BEACHES; ENVIRONMENTAL indicators; SHORELINES; METEOROLOGICAL stations
- Publication
Geografija, 2011, Vol 47, Issue 2, p98
- ISSN
1392-1096
- Publication type
Article