A GIS for the assessment of the spatio-temporal changes of the Kotychi lagoon, western Peloponnese, Greece

Abstract

Kotychi lagoon, located at the northwestern coast of Peloponnese, Greece, is a biotope of great ecological and financial importance,protected by the Ramsar International Convention. Kotychi lagoon hasbeen severely degraded and transformed during the past 50 years, due to agricultural activities in the surrounding areas and watercourse alterations after the construction of Pinios river dam in the late 60's. Restoration works (dredging of a hibernation basin and five radial submerged channels) in the period 1989–1992, resulted in the improvement of the lagoon conditions and provided better conditions for the protection of the ecosystem. In this article, a Geographical Information System has been developed to quantify and spatially characterize the temporal changes on lagoon morphology and surface area for the period from 1945 to 1993. The vector database model of the ARC/INFO has enhanced for the handling the temporal changes of the spatial data. Spatial and thematic information concerning the surface area, topography, and the major cover types of the lagoon for years 1945, 1960, 1987 and 1993 was obtained from aerial photographs and land surveys of the area, and was stored in the GIS database. From the spatio-temporal analysis of the stored data, using as a reference surface the lagoon surface at the year 1945, the following conclusions can be drawn. A permanent decrease of the water surface of the lagoon has been observed between the years 1945 and 1987 (from 97.8 to 40.3% of the lagoon reference surface). In 1987 the surface of the lagoon covered by land or swampy areas reached its maximum (59.7% of the reference surface), while in 1993, after the restoration works, the water surface reached the 48.4% while the land and swampy areas decreased to 51.6% of the reference surface.