Effects of watercourse regulation on the local climate

The conference paper discusses the changed condition of local climate caused by hydroelectric power development in Norway. Because of water release from power plants during winter the regulated rivers may not freeze even in cold winters. This results in the formation of steam fog over the river and the adjacent banks. If the water is released into a fjord, either directly or via a river, a shallow layer of fresh water forms on the fjord surface. This layer freezes readily, thereby eliminating the contact between the air and water. The transfer of energy from the water to the air thus becomes greatly reduced, resulting in lower air temperature locally. The height of Norwegian dams may reach 100 m or more. They are often situated in deep valleys and may affect the drainage flow of cold air through the valleys. 12 refs., 5 figs