The lake Sevan catchment basin covers an area of some 3 649km2 giving a ratio of 2.45 with the lakes surface area of 1 242km2. This catchment basin to lake surface area ratio is very small when we consider that on average this ratio is normally around 10:1.
The young geological structure of the catchment basin is characterised by a diversity of landscapes originating from basalt lava and different volcanic formations. Indeed, the basin is dominated by the surrounding 400km long Geghama, Vardenis, Aregunyats and Sevan mountain ranges which were formed in the Trias period by intense volcanic activity. These mountains vary in altitude from between 2 200 and 3 800m above sea level. Due to the areas peculiarities its vegetation has a well-expressed mosaic like nature and a number of diverse ecosystem types are represented.