Author(s): Randi Pytte Asvall

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Abstract: Alta power plant is located in the very north of Norway. A reservoir was established in the water course. Due to the rich salmon fishing in the river the water temperature changes caused by the regulation have been studied. The general effect of a reservoir on the temperatures downstream is well known, but is difficult to quantify. That is done in this work. The influence of the regulation on the water temperature is evaluated in relation to climatic differences and separated from natural changes without water regulation by analyzing water temperature differences between pairs of stations. The power plant discharge have an average temperature in winter of 0.2-0.5°C in an area where the natural water temperature was close to 0°C. This change is noticable some km down the river according to the cooling conditions. Further downstream there is no effect in winter. The actual change caused by the regulation is a decrease in temperature from middle May to middle August with a maximum difference in the order of 2-3°C in middle June. From august there is an increase in temperature, with a maximum difference in the order of 2-3°C in October. The decrease in temperature may be somewhat reduced in warm summers if the upper intake is the only one in use.

DOI:

Year: 1992