Session K.pdf - Clarkson University

viation of the error was on a daily basis between 0.4 and 0.6 o C for the five years, indicatingthat the physical process is understood.16.00Water temperature [ o C]14.0012.0010.008.006.004.002.000.00Kvilldal observedSuldalsosen observedSuldalsosen simulated01.05.9915.05.9929.05.9912.06.9926.06.9910.07.9924.07.9907.08.9921.08.9904.09.9918.09.9902.10.9916.10.9930.10.99Fig. 6. Simulated and observed temperatures at Suldalsosen in May-Oct 1999. Also the watertemperatures in the discharge water from Kvilldal hydro power station is shownWater temperature at the suggested regulation regimesWe manipulate between the different regimes by changing the discharge in Hylen. If wewant higher outflow to the river, we lower the discharge in Hylen, and visa versa. Tocalculate the water temperatures at different regulation regimes we have to assume thatthe conditions upstream Suldalsporten is unchanged. This is fulfilled for short termchanges, but may not be true with considerable changes over a long period. We calculatedwater temperatures in the same way as explained in the previous chapter. An increasingdischarge therefore releases water from a thicker layer since the thickness isequal to the square of the discharge.Again we used RICE to model the water temperature changes down Suldalslagen, Fig. 7shows the average water temperature differences from the unregulated case, at the upperend (Suldalsosen) and at the lower end (Tjelmane). The differences have been smoothedwith a sliding 30 day average. The simulation shows that the water temperature can besubstantially manipulated by regulating the release of water from Lake Suldalsvatn. Atemperature of several degrees will have large impacts on life in the river.We have used the water temperature simulations as an indicator for ice production in theriver. The water temperature was never below zero at the upper end, but in cold periodsit reached the freezing point on its way down to Tjelmane.364