Climate Change Impacts on Water Resources and Lake Regulation in the Vuoksi Watershed in Finland

The impacts of climate change on hydrology and water resources in the Vuoksi watershed in eastern Finland were studied in order to assess the possibilities to adapt lake regulation to the projected changes. A conceptual watershed model and several climate scenarios were used to estimate the effects of climate change on three lakes in the Vuoksi watershed for 2010-2039, 2040-2069 and 2070-2099. The adaptation possibilities were studied by using alternative regulation strategies. In Lake Pielinen the impacts of these water level changes on social, economic and ecological indicators were assessed with two different outflow strategies. According to the results, climate change will alter snow accumulation and melt and therefore cause large seasonal changes in runoff and water levels. Runoff and water levels will decrease during late spring and summer and increase during late autumn and winter. In some lakes current calendar-based regulation practices and limits, which have been developed based on past hydrology, may not be appropriate in the future. Modifying the regulation practices and limits is a necessary and effective way to adapt to climate change.