Comparison of the geochemistry of the regulated Lule River and the unregulated Kalix River, Northern Sweden

Abstract: Hydropower production in Sweden represents nearly 50% of the total electricity production in Sweden. The aim of this study is to evaluate the impact of stream regulation on the geochemistry of the Lule River, northern Sweden, which is the largest and the most important river for waterpower production in Sweden. Impacts of river regulation were evaluated by comparison with the natural geochemical seasonal variations in the pristine Kalix River, which is very close geographically and has comparable watershed with similar bedrock, soil type, climate and vegetation. Seasonal variations of the geochemical constituents in the regulated Lule River have been studied during a whole year cycle (May 2000 to June 2001) at the Boden powerstation near the mouth of the river. Data from the Kalix River were obtained from a previous study realised from 1990 to 1992. Additional data about transport in the Kalix River were achieved from the study of the impact on the Kalix River system of the tailings dam failure at the Aitik copper mine that occurred in September 2000. These results were used to calibrate the parameters of a model that will be developed for geochemical transports in the regulated Lule River.