3 rd INTERNATIONAL CONFERENCE ON CARTOGRAPHY AND GIS 15-20 June, 2010, Nessebar, Bulgaria GIS ASSESSMENT OF GLOBAL CHANGE IMPACTS ON THE DYNAMICS OF THE SREBARNA LAKE ECOSYSTEM Mariyana Nikolova, Rumiana Vatseva, Valentin Nikolov Dr. Mariyana Nikolova Institute of Geography, Bulgarian Academy of Sciences Acad. G. Bonchev Str., Bl. 3, 1113 Sofia, Bulgaria Phone/Fax: +3592 870 0204; E-mail: mknikolova@bas.bg Dr. Rumiana Vatseva Institute of Geography, Bulgarian Academy of Sciences Acad. G. Bonchev Str., Bl. 3, 1113 Sofia, Bulgaria Phone/Fax: +3592 870 0204; E-mail: rvatseva@gmail.com Valentin Nikolov Geological Institute, Bulgarian Academy of Sciences Acad. G. Bonchev Str., Bl. 34, 1113 Sofia, Bulgaria Phone: +359885541262; E-mail: valnvaln@yahoo.com Abstract The changes in Srebarna Lake ecosystem, which occurred in the last thirty years, are analyzed in this study considering both anthropogenic and natural stressors. Comparative analyses were performed with GIS and remote sensing data in order to assess the lake evolution after its designation as a protected area, and following global changes that have occurred in the last decades. The recent evolution of the lake ecosystem presents evidences of both human induced and natural changes. Natural events, namely the wet deposition regime, regulate riverine floods and drought periods influencing the lake hydrology. The Danube river management as well as water uses in its watershed have similar impacts. The challenge for the future is to assess the dynamics of the Srebarna Lake ecosystem using geoinformation technologies for ensuring the future maintenance of the lake in its present status. Keywords: Environmental change, GIS, Remote Sensing, Land use/cover change, Srebarna Lake INTRODUCTION The earliest written reports on Lake Srebarna were published by the Austrian naturalist Eduard Hodek in 1882. After him, Lake Srebarna had also been described in the works of Kalbermatten (1891), Lorenz-Liburnau (1893), Reiser (1894). At the same time Felix Kaniz described Srebarna in his travel notes as “El Dorado of wading birds”. The first Bulgarian publication about the lake was that of Prof. St. Petkov, who published information on certain Srebarna plants in 1911. Since then more than 273 research papers, reports, reviews, ecological assessments, etc., on Srebarna were published until 1998 (Management…, 2001). During the last century the Srebarna Lake was designated first as a Breeding ground for wading birds in 1942 and later as Natural protected area (1948), Ramsar site (1975), UNESCO biosphere reserve (1977), Monument of World Cultural and Natural Heritage (1983) and Important Bird Area (1990). Threatened species as Pelicanus crispus, Phalacrocorax pygmeus and Aythya nyroca are breeding in the reserve. Since 2001 the lake management is in accordance with the Management Plan for the Srebarna Managed Natural Reserve. The regular annual penetration of the lake by floodwater from the Danube is a very important factor for its existence. During the last 60 years the lake ecosystem underwent significant changes towards strong eutrophication and anthropogenically speeded-up succession because of the interrupted natural connection with the Danube water due to both natural and man-made factors. The most important of them were the dike built in 1948 and demolished in 1979, the hydro-technical complex “Zhelezni Vrata 1 and 2” built in 1970, the dry period between 1984