The influence of natural and anthropogenic factors on grain size distribution along the southeastern Baltic spits

Abstract

The in flu ence of nat u ral and anthropogenic fac tors on the dis tri bu tion of sand grain size along sandy beaches is as sessed, based on study of three spits of the south east ern Bal tic Sea: the Curonian, Vistula and the Hel. 330 sand sam ples were collected from the beach and foredune at 1 km in ter vals. Our find ings show that al though the three spits have some char ac ter istics in com mon, e.g. a pre dom i nance of fine-and me dium-grained ma rine sand on their beaches and foredunes, the grain size dis tri bu tion pat terns of the re cent sed i ments along these spits dif fer sig nif i cantly. The key fac tors de ter min ing the grain size dis tri bu tion in clude the dom i nant hydro meteoro logi cal re gime, anthropogenic ac tiv ity and geo log i cal frame work. Trends in the mean grain size dif fer en ti a tion along the Vistula and Curonian spits di rectly cor re late with the di rec tion of the long shore sed i ment trans port: as the dis tance from sources of the long shore sed i ment trans port in creases, the size of sand par ti cles, both on the beach and the foredune, de creases. By con trast, on the Hel Spit, this pat tern is dis turbed in ar eas of hydrotechnical con struc tion and ar ti fi cial beach nour ish ment. Sand dif fer en ti a tion along the beach can also be pre de termined by the geo log i cal frame work, par tic u larly in lithologically anom a lous sec tions, such as the JuodkrantÅ set tle ment on the Curonian Spit. Key words: long shore sed i ment trans port, hu man ac tiv ity, geo log i cal frame work, lithological anom a lies, shift re gime de tection.

Beach-Foredune Sediment Budget Response to Sea Level Fluctuation. Curonian Spit, Lithuania

“…Meanwhile, in the northern part of the Curonian Spit, this pattern was not observed. In general, permanent sand accretion on the beach in 2002-2019 only took place in the northern part of the spit (the Smiltynė-Alksnynė coastal sector), predetermined by a blockage of the alongshore sediment transport by the Klaipėda port jetties [35,49]. In the southern part (Pervalka-Nida), the variations in beach sand volume followed no definite pattern.…”

“…The alongshore sediment transport from the southern part of the Curonian Spit (Kaliningrad district) is the main cause of this sand accretion. Due to the sand transport being blocked by the Klaipėda port jetties, the most intense accretion takes place in the northern part of the spit [35,49]. The observed rate of sea level rise does not stop the dominant trend of sand accumulation and coastal accretion [43].…”

“…The obtained results showed that if there is a sufficient amount of sand, even a slow sea level rise has a positive effect on the foredune sand budget. This is related not only to the alongshore transport of huge amounts of sediments from the southern part of the spit [35,[47][48][49], but also to small nearshore inclines, which create favorable conditions for sandbar welding to the beach during fair weather conditions [61]. In these circumstances, foredunes that are built up at distal ends of some spits can build upwards despite a sea level rise [62].…”

“…As the tidal range of the South-Eastern Baltic coasts is not significant and barely reaches 3.5-4.0 cm [44,45], the wind-generated waves [46], the prevailing alongshore currents, and accordingly the sand transport from south to north [35,[47][48][49] and the aeolian processes [42] are the main beachforming factors on the Lithuanian Baltic Sea coast. The most significant short-term sea level As the tidal range of the South-Eastern Baltic coasts is not significant and barely reaches 3.5-4.0 cm [44,45], the wind-generated waves [46], the prevailing alongshore currents, and accordingly the sand transport from south to north [35,[47][48][49] and the aeolian processes [42] are the main beach-forming factors on the Lithuanian Baltic Sea coast. The most significant short-term sea level fluctuations near the Lithuanian coast occur due to storm surges.…”

Application of Remote Sensing Methods in Research of Nearshore Sandbars, Curonian Spit, Lithuania

“…Subaerial section of Baltic Sea coast in the Curonian Spit is characterized by beachforedune system. Beaches are 30-80 m wide and foredune height ranges from 6 to 16 m (Jarmalavičius et al, 2015;Žilinskas et al, 2018). Beaches are composed of fine and medium sand.…”