Session K.pdf - Clarkson University

Fig. 4. Simulated and measured water temperature at Tjelmane, and measured water temperatureat SuldalsosenThe water temperatures from the tributaries have been measured, but the contribution isgenerally of no importance, except in flood episodes and at discharges below 10 m 3 /sfrom Suldalsosen. To simplify the model, we entered all the tributaries at the upper end.That introduces an error since the actual inflow points are at several points down alongthe river. We partly corrected that error from measurements of the actual temperatureincrease/decrease. The standard deviation in the error became just slightly higher than atSuldalsosen (≈1 o C) since the major error came from the input temperature.REGULATED FLOWSuggested regulation regimesThe water in Suldalslagen could have been led through Hylen hydro power station instead. In a way, the water in Suldalslagen is a loss for the power company. The problemis to find the optimal amount of water, giving sufficient provision for life in the riverand sufficient money to the power company. One exciting combination is to lower thedischarge in the spring and early summer to raise the water temperature. On the otherhand, this increases the power production. We have simulated the water temperatureswith three different strategies of water release through the dam at Suldalsosen;FR1: 12 m 3 /s in the winter time, but 7 m 3 /s i shorter periods. Three short floods inMay/June up to 130 m 3 /s. Weekly pulsing in the summer between 42 and 55m 3 /s. Two short autumn floods up to 220 m 3 /s. Same release every year, butthe periods with 7 m 3 /s may come in a cold period.FR2: Low discharge, 6 m 3 /s, from October to mid June. Three small and shortfloods in the spring up to 30 m 3 /s. Weekly pulsing in July-September between40 and 70 m 3 /s. One autumn flood in the end of October up to 180 m 3 /sDR: 23 % of calculated unregulated flow. Limited to never above 250 m 3 /s andnever below 6 m 3 /s.362