Influence of land use changes on alluviation of Volvi Lake wetland (North Greece)

Abstract

The study deals with Volvi Lake, the second largest natural lake in Greece, where gradual alleviation and a land use change have taken place in the last 60 years. The aim of the study was to estimate the influence of land use changes of the area on sedimentation and alluviation rate. Due to the lack of sediment measurements the Gavrilovic model was used to calculate the mean annual erosion of the two main drainage basins of the Lake for 1945 and 2007. Field research, orthophotographs, and topographic maps dating from 1945, 1971, and 2007 were used to determine the evolution of the vegetation cover and lake shoreline, in order to compare and evaluate the Gavrilovic model results. An increase of 6% of the forested area in combination with the improvement of scrublands quality were enough to cause a 15% decrease of the mean annual sedimentation, according to the Gavrilovic model, as well as a 50% decrease in alluviation rate, according to delta change measurement, comparing the periods 1945-1971 and 1971-2007. The importance of vegetation for soil protection was clearly demonstrated, indicating that reducing the land use and enhancing the vegetation quality could slow down the erosion process.