The Hydro-Chemical Changes of Lake Sevan Water After the Artificial Lowering of the Water Level

Abstract

The paper is aimed to show the influence that the dynamics of artificial lowering of a lake water level has on the hydro-chemical regime and the lake itself, on the example of Lake Sevan. Lake Sevan is one of the world's largest high-altitude fresh-water lakes. Studies of chemical composition of its water were launched at the end of the 19th century, and the first salt balance was determined in the 1930s. According to routine observations, one liter of the lake's water contains about 0.7 g salts. Almost all the ion concentrations have been changed by about 5–10% as a result of the lake level drop. There have also been changes in the general mineralization of the lake that are related to the drop of the lake level and the magnitude of its flow. In 1928–1930, well before the artificial change in lake level, total mineralization was 718,4 mg/l, while today it is 673 mg/l (1999– 2002). The decrease of total general mineralization of the lake water is strongly related to the massive outflow of salty water, removing the salts, which had been accumulating in the lake for ages. In conclusion, it must be noted that the drop of the lake level, and the economic development in the basin brought about the change in the hydro-chemical regime of the lake.