Study region The study region consists of eight catchments with seasonal snow cover in different parts of Finland representing main catchment types across the country. These include catchments with different size, lake percentages, degree of lake regulation and geographical locations (south to north). Study focus This study evaluates modelled impacts of climate change on extreme high and low flows using a scenario-neutral impact response surface (IRS) approach. We analyse the frequency, timing and magnitude of high and low flows and their sensitivity to incremental changes in temperature and precipitation across contrasting catchment characteristics and regions. High and low flows are calculated using the physically based, national-scale WSFS-P hydrological model for Finland. New hydrological insight for the region Our results indicate that increasing temperatures cause shifts in flow regimes. In northern catchments, the change from snowmelt to mixed flood regime requires more than a 5 °C increase in mean temperature. In currently mixed regimes, increased rainfall and warmer temperatures lead to a higher magnitude and frequency of winter and rainfall-generated floods. The magnitude of annual low flows increases with rising temperatures in northern Finland, where low flows occur in spring before snowmelt, while in southern and mixed flow regimes, summertime low flows are accentuated with increasing temperature. The IRS approach produced outcomes comparable to projections from regional climate models, even for hydrological extremes. In particular, it offers potentially useful information for flood risk and water resource management planning for adapting to changes in flow regimes.
Fazel et al. (Thu,) studied this question.