MODELLING HYDROLOGICAL IMPACTS OF CLIMATE CHANGE IN THE LAKE VÄNERN REGION IN SWEDEN
During the autumn and winter of 2000/2001, excessive rainfall occurred over large parts of the Lake Vänern drainage basin and caused floods especially in Lake Glafsfjorden. As a consequence, it was decided within the Swedish Regional Climate Modelling Programme (SWECLIM) to produce water resources scenarios for the Lake Vänern region. The scenarios were based on a combination of global climate models (GCMs), a regional climate model and a hydrological model. The GCMs used were the UKMO HadCM2 of the Hadley Centre in Reading and the ECHAM4/OPYC3 of the Max Planck Institute for Meteorology in Hamburg. The regional climate model used, RCA, was developed at the Rossby Centre of the Swedish Meteorological and Hydrological Institute (SMHI). The differences in meteorological variables between scenario runs and a control run of the RCA model were transferred to an observed database which was used for off-line hydrological modelling with the HBV model. The scenarios indicated a significant change in the seasonal variation of future inflow and water levels in Lake Glafsfjorden and Lake Vänern. The results are discussed in terms of average changes and frequency analysis of maximum values.