To quantify the detailed mechanisms that cause sedimentation at the tidal inlets and deformation of shore line in the Messolonghi-Aetoliko lagoonal system, the Litpack numerical simulation model was applied. The study focuses on the longshore sediment transport as well as the coastline evolution, with emphasis on the vicinity of two tidal inlets, where the problem is more acute. Based on the numerical predictions, which have been qualitatively corroborated via satellite images from Google Earth, it is shown that the prevailing direction of net sediment transport is from westwards to eastwards. A sandy platform that develops just westwards of the tidal mouths leads gradually to wide erodible areas, just eastwards of the mouths. The numerical results lead to recommendations of soft and relatively cheap solutions with minimum impact to the sandy barrier zone of the lagoon. In this frame the depth at the mouths can be maintained and the coastline and shore face can be kept as natural as possible.
The Messolonghi-Aetoliko lagoon complex, situated in Western Greece and located at N38022' - E21021', is the largest wetland in Greece and one of the largest and most important in Europe, both in ecological and in economic terms. The Messolonghi lagoon covers the main area of the complex, and its waters are shallow and open in the south to the waters of the Gulf of Patras (hereafter ‘Gulf’). The depth ranges from a few cm in the interior regions, up to roughly 2.5 m, while the mean depth is approximately 0.5 m. The lagoon is separated from the Gulf's waters by approximately a 12 km long sand bar, oriented from west to east (AB in Fig.1). The complex consist of a central part, called kentriki limnothalasa (i.e. central lagoon), of 80 km2, which includes the fishing sites of Tourlida, Vasiladi, Komma, Schoinias and Prokopanistos, and a series of peripheral lagoons including Klisova, Diavlos, Aitoliko, Tholi, Paleopotamos. The total area of the lagoon complex is 150 km2 (Koutrakis et al., 2007).