Abstract:

Korissia lagoon located in the southwest end of Corfu separated from the open Ionian Sea by a narrow (<250 m) stip of land. It has a surface of 4,2 km2 and depths <2m, communicating with the sea via an artificial-dredged channel. The bed of the lagoon consists of fine-grainned sediment (sandy silt – silty sand). Its drainage basin covers an area of 16 km2 and is characterized by low relief. It receives the freshwater inputs form a low relief (maximum elevation 319 m) of the drainage basin. The influx of fresh water is surficial includes also an underground flow, as indicated by the presence of a phreatic aquifer and a large number of wells at its nearby surrounding area. The water budget of the lagoon is characterised by a wet (October-March) and a dry (April-September) period. During the wet period the incoming volume of fresh water (5,3x106 m3 ) is much larger than its total volume (2,5 x 106 m3 ); this implies an outflow of lagoonal waters whilst lagoonal waters are characterised by relatively lower salinity values (<20 ppt) compare to those of the Ionian Sea (38 ppt). In contrast, during the dry period, the fresh water influx (1,2 x106 m3 ) is smaller than the volume of the lagoon; this induces an influx of sea water, which in association with the high levels of evaporation moduled hyper-saline (>50 ppt) hydrologic conditions within the lagoonal basin.