By Eng. Thushara Dissanayake
Human civilization began along rivers in the world over, as water is an essential natural resource for people. These early river valley civilizations include the Indus valley, the ancient Egypt near the Nile river, the Mesopotamia civilization along the Tigris and Euphrates rivers, and the Chinese civilization along the Yellow river. Later on, with the increase in population and technological advancements thousands of dams have been built to meet the water needs during dry periods by regulating river flows.
Today, according to estimates there are 59,071 large dams all over the world with a total storage of 16,201 Km3 according to registered data of International Commission on Large Dams (ICOLD). A dam is categorised as large if the height is greater than 15m. A dam of height 5-15 m is also considered as a large dam if its storage capacity is more than 3 MCM. Accordingly, Sri Lanka has around 80 large dams, 270 medium dams and over 10,000 small dams.