Palaeoenvironmental reconstruction of Kalamas river delta plain-NW Greece

Sea level rise is a worldwide phenomenon affecting most of the coastal areas of the Mediterranean. Delta plains are among the most vulnerable coastal areas to sea level fluctuations, mainly due to their low relief and their unconsolidated sediments which are commonly developed extensively along their deltaic setting. This makes river deltas one of the best cases for assessing a number of implications associated with the anticipated future sea-level rise.

Kalamas River, one of the longest rivers in Greece, has a delta plain which covers an area of around 70 km² and has been extensively influenced by sea level fluctuations during Holocene. The greater area of the plain can be considered both economically and socially important, as it hosts significant farming activities, protected wetland habitats and is also surrounded by well-developed urban areas. Examination of aerial photographs and satellite images, taken in various years, revealed that the old southern mouths of the river has been facing severe inundation problems due to sea level rise, while the northern currently active mouths appears to have been progradating towards the sea. 

This study deals with the geomorphological investigation and paleoenvironmental reconstruction of the delta plain of Kalamas river, based on a multidisciplinary approach, including mineralogical, sedimentological and geochemical analysis as well as absolute dating of twenty six core sediments, collected from four different boreholes along the delta plain. The derived data were incorporated into different chronological-palaeoenvironmental simulation models to reconstruct the evolution of the delta plain during the Holocene, but also predicts changes for future sea level rise scenarios. Digital mapping of the evolutionary changes (including future scenarios) taken place in the plain are then depicted using GIS.

This study revealed that geomorphological changes in the delta plain are directly associated with human interferences (construction of a dam, modifications of channels as well as river diversion). Delta progradation is mainly observed in the greater area of the currently active river mouths, while the older (currently inactive) mouths are now retreating. It could be suggested that the predicted sea level rise will greatly affect the delta plain (especially its current shoreline), causing extensive adverse socio-economic and environmental impacts.

This research was supported by the project “ Study, forecasting and modeling of the effects of climate change on the deltaic coastline of Kalamas River” (MIS 5006050) funded by NSRF 2014-2020.