| Περιγραφή Τόπου |
The freshwater lake Voulkaria is situated in the centre of the Sterna peninsula, at the north-western part of Aitoloakarnania prefecture and southwards of the entrance to the Amvrakikos Gulf. It covers an area of approximately 940 ha. This area shows strong water level fluctuations depending on the annual rainfall. Voulkaria is a shallow lake with maximum depth of 2.5 m. It is developed on a tectonic graben and is considered to be the result of combined action of: 1) tectonics, 2) karstification, and 3) sedimentation of clastic materials (gravel, sand, clay). Later some Neogene sediments of lacustrine or coastal origin, were deposited in the area, and covered by alluvial deposits. The wider area of the lake consists mainly of Mesozoic limestones and dolomites, Neogenic sediments (marls, sandstones, conglomerates), as well as alluvial deposits (Leontaris, 1972). The greatest part of the plain surrounding the lake comprises mainly a series of streams and smaller water courses with varying deposits. Peat formation takes place in wetland areas where no agricultural activities are present. The lake has a large drainage basin, which to the west comprises the eastern part of Asprochorto hill and on the other sides a plain area with extensive agricultural fields. Voulkaria has vague marshy sides and is connected to the sea by an artificial ditch with a length of 1400 m. This ditch (named "Agios Nikolaos" or "Kleopatra") is at the western part of the lake and empties into Agios Nikolaos bay. During the winter, when the lake overflows, a flow of water from the lake to the sea is observed, while during the summer the opposite flow is encountered. This summer flow resulted in the increase of salinity of the lake, which strongly influenced agricultural activities within the surrounding area. This problem has already been confronted since 1964 by controlling the entrance of sea water by closing the ditch during the summer. Near the ditch, water ponds and marshes with grassy vegetation including Carex vulpina, C. divisa, Eleocharis palustris, Juncus heldreichianus, Equisetum telmateia, and Oenanthe silaifolia, etc. occur. In the middle of the infralittoral zone of this side, the species Nympaea alba, and Potamogeton nodosus are observed, while in the lower infralittoral zone the species Myriophyllum spicatum and Potamogeton lucens predominate (Koumpli-Sovantzi, 1983). The water has a pH of 6.5 and in several places the species Hydrocharis morus-ranae is present (Economidou, 1981). At the littoral zone of the lake the herbs predominate forming extensive grasslands, while shrubs (Vitex agnus-castus, Rubus ulmifolius, Paliurus aculeatus, Myrtus communis, Tamarix sp. etc.) and riparian trees (Salix, Ulmus, Fraxinus etc.) occur sporadically forming clusters mainly at the south-eastern side of the lake (near Fraxias). A characteristic feature is that within the upper infralittoral zone, the species Phragmites australis, grows in an almost continuous zone of considerable width. In the extensive reed beds, the species Typha domingensis, Carex vulpina, Pulicaria dysenterica, Cladium mariscus, Lythrum salicaria, Lycopus europaeus, Eupatorium cannabinum, Calystegia sepium, Samolus valerandi, Mentha aquatica, etc., exist. To the west of the lake the rocky hill of Asprochorto exists, where shrubby vegetation along |
