Climate change and water resources in Finland

The effects of climate change on water resources in Finland have been evaluated by conceptual watershed models. The central SILMU scenario is used as a climate change approximation for the future. The evaluated water balance terms are areal corrected precipitation, evapotranspiration, lake evaporation, water equivalent of snow, soil moisture, groundwater and runoff. Changes in the mean values and seasonal distributions of river discharges and lake water levels are also presented. The precipitation and temperature increases assumed by the central SILMU-scenario will not essentially affect annual water balance, but will strongly change the seasonal distribution of runoff and other water balance terms. Snow cover will diminish or almost vanish and its duration will be shortened by one to four months in different scenario runs due to warming. The winters will become wetter and snow-free due to increased precipitation and frequent thawing periods. Spring floods will diminish or vanish and winter floods will occur instead. The summers will become drier due to the longer summer season and increased evapotranspiration and lake evaporation.