Session K.pdf - Clarkson University

All temperatures are compared with unregulated conditions. The regimes FR1 and FR2has fixed values from year to year, regardless of the climate. DR is a dynamic regimethat changes from year to year and is given as a percentage of the natural flow, here23 %. Fig. 5 shows an example from 1999.Discharge [m 3 /s]25020015010050FR1FR2DR001.01.9901.02.9901.03.9901.04.9901.05.9901.06.9901.07.9901.08.9901.09.9901.10.9901.11.9901.12.99Fig. 5. The discharge at Suldalsosen in 1999 with the three regulation regimesOutflow At Suldalsporten and SuldalsosenThe introduction of Kvilldal hydro power station 5 km upstream Suldalsporten changedthe hydraulic situation in the lower part of Lake Suldalsvatn. In the unregulated situationthe normal situation was transport of “surface” water out through the shallowSuldalsporten. Today frequent changes in the water temperature indicate that the waterthat passes Suldalsporten periodically comes from deeper layer in lake Suldalsvatn. Thisis confirmed with hourly measurements from the upper 50 m. The water from Kvilldalmay come from deep layers in reservoirs (cold in summer) and may come from surfacecreek intakes (warm in summer). The water temperature, and hence the density, governsthe depth that the discharge water is buffered in Lake Suldalsvatn. The excess of waterin this layer sets up a pressure that pushes water from this depth across the threshold atSuldalsporten. From Suldalsporten the water temperature may change to Suldalsosenwhere we have our measurements.Since we have measurements from the lake upstream Suldalsporten, and from Kvilldal,we may calculate the water temperature at Suldalsosen:• Calculate the storage depth by comparing the Kvilldal temperature with the measurementsfrom the lake.• Assume that the transport is at the maximum at this depth and decreases to zero at adistance above and below this depth. The transport height depends on the discharge andis assumed to equal the square root of the discharge. Calculate the mean temperature ofthese water masses passing Suldalsporten.• Use QUAL2E to calculate the changes down to Suldalsporten.Fig. 6 compares the calculated values and the observed values at Suldalsosen in 1999.We had sufficient data in the five years 1996, 1998-99 and 2001-02. The standard de-363