Anthropogenic Transformation of Lake Ecosystems and Existent Problems (Case Study of Lake Sevan)

This article discusses the impact of artificial lowering of lake water level on water ecosystems using the case study of Lake Sevan. Numerous rivers, lakes and, in general, water bodies have undergone considerable changes under the impact of the economic activity of man. As a result, hydrometrical, hydrological, biological, ecological conditions as well as the morphometrical elements of these bodies have been destroyed. Lake Sevan and its basin may serve as a classical example in this respect in the world limnology, there has been no other case when a lake level would be artificially lowered by 18 meters for 3-4 decades (1930-70 s), and by another 2 meters at the end of 20th century (1990-2000) and the volume of water in the lake decreased from 58 billion m3 to 32 billion m3. it must be noted that the drop of the lake level, and the economic development in the basin brought about the change in the hydrological regime of the lake. The latter caused the disruption of the hydro chemical and hydrobiological regimes of the lake. The quality of the water deteriorated; water turbidity increased. The inner circulation of the water substances, as well as the circulation of the biological substances altered as well.

Keywords:Lake ecosystems; Anthropogenic transformation; Hydrological regime; Hydro chemical regime; Hydrobiological regime; Eutrophication