Long-term coastal changes of Varna bay caused by anthropogenic influence

Abstract. This research aims to explore coastline alterations and changes to the beaches of Varna Bay, North Bulgarian Black Sea coast, between 1908 and 2007. A large number of different types of port and coast-protection structures have been constructed along the coast of the study area, over a 100-year period. As a result of human activities i.e. building of harbour, navigational channels, coastal dike and solid groin system, the coastline of study area and adjacent beaches have been significantly modified. Various sources of shoreline position data were used to detect long-term coastal changes: the historical map of Varna Bay at a scale of 1:10 000, from 1908; and the modern satellite image from 2007. Data processing and analysis were performed in GIS environment, as both map and satellite image were preliminary geo-referenced. An indicative segmentation by landform units (beaches/cliffs) and technogenous units (port/coast-protection structures) of both historical and current coastlines was produced to identify changes caused by anthropogenic influence. On the basis of coastline segmentation, an assessment of technogenous impact on the study area, both in 1908 and 2007, was done to quantify the increased extent of human intervention. The results clearly indicate that the long-term coastline/beach changes could be mainly considered as human-induced. Furthermore, at many sites the coast was irreversibly modified.