Session K.pdf - Clarkson University

17th International Symposium on IceSaint Petersburg, Russia, 21-25 June 2004International Association of Hydraulic Engineering and ResearchWATER TEMPERATURES AT DIFFERENT REGULATIONREGIMES IN SULDALSLAGEN,A NORWEGIAN SALMON RIVERAanund Sigurd Kvambekk 1ABSTRACTSuldalslagen is one of Norway’s best salmon rivers, famous for the large salmons. Since1986 the river has been extensively regulated. Today most of the water is directedthrough a power station and the discharge in the river reduced. A lot of effort has beenmade to find the amount of water needed to sustain the salmon tribe. The water temperaturedepend on the discharge and is an important factor for the growth rate of thefish and also the time they leave the river. We have therefore simulated the water temperaturesunder three possible regulation regimes and even how it would have beenwithout the regulations. A low discharge in winter and spring, reduced from 12 to 6 m 3 /s,may five-double the number of days with ice production and raise the spring temperatureswith 3-4 o C.INTRODUCTIONSuldalslagen is one of Norway’s best salmon rivers, famous for the large salmons.Since 1986 the river has been extensively regulated. Today most of the water is takenaway from the river and directed through the Hylen power station (fig. 1). A lot of efforthas been made to find the amount of water needed to sustain the salmon tribe.Since the water temperature depend on the discharge and is an important factor for thegrowth rate of the fish and the time they leave the river, we have simulated the watertemperatures under several regulation regimes and even how it would have been withoutthe regulations.1 Norwegian Water and Energy Directorate, P.O. Box 5091 Maj, N-0301 OSLO, NORWAY359