Changes in quantitative parameters of active wind dunes on the south-east Baltic Sea coast during the last decade (Curonian Spit, Lithuania)

The Curonian Spit is one of the largest Holocene sand accumulation forms, stretching along the Baltic Sea coast and belonging to the Baltic sand belt. This article deals with the dynamics of the Curonian Spit dunes in the context of global climate change. Investigations were carried out in the environs of two high dunes (Parnidis Dune and Naglis Dune) over a period of 10 years (2003-2014). Levelling of cross-sections was performed using modern geodesic devices. Wind velocities and directions were measured at meteorological stations of Klaipeda and Nida. The wind regime (number of days with winds >15 m/s) was almost at the multiannual average during the study period. Sand moisture was measured in both dunes studied, and groundwater level was measured in the environs of the Naglis Dune by using ground penetrating radar (GPR). The Naglis Dune experienced a more significant lowering (by 4-6 m) compared with the Parnidis Dune over the study period, while sand deficit was greater in the Parnidis Dune (~10,000 m3). Compared with other European sand dune systems, the Curonian Spit dunes have undergone strong degradation. The article highlights possible degradation reasons and indicates the necessity of additional investigations. Only long-term investigations can contribute to disclosing the main processes both as natural background and due to anthropogenic activities, and the devising of protection measures.