1. Hydrological response surfaces in the Nordic Region for use in probabilistic assessment of climate change Phil Graham Sara-Sofia Hellström Fredrik Wetterhall Swedish Meteorological and Hydrological Institute, Norrköping

2. Our contribution to workpackage objectives Hydrological rainfall-runoff models to investigate impacts of climate change on stream discharge Using the climate change signal from RCMs

3. Our contribution to workpackage objectives Response surfaces for selected applications Direct use of multiple regional model projections Comparison of outcomes from the two methods

4. What have we achieved since Lund? In Lund, we showed some preliminary response surfaces Now, we have produced many more In Lund, we discussed the question of seasonality Now, we have investigated the details of representing seasonality

5. Response Surfaces – Annual Runoff no seasonality Lake Vänern

6. Response Surfaces – Annual Runoff with seasonality Lake Vänern

7. RS – Representing Seasonality Method 1 TemperaturePrecipitation

8. RS - Extended Period with Maximum Discharge Current regulation rules Lake Vänern

9. RS - Extended Period with Maximum Discharge Current regulation rules Lake Vänern

10. RS - Extended Period with Maximum Discharge with Modified Regulation Modified regulation can help reduce risk of high discharge Lake Vänern

11. Response Surfaces – Monthly Runoff Lake Vänern

12. Response Surfaces – Annual Runoff Lake Mälaren

13. Response Surfaces – Annual Runoff seasonality 1 Lake Mälaren

14. Response Surfaces – Annual Runoff seasonality 2 Lake Mälaren

15. RS – Representing Seasonality Method 2 Precipitation method 1 Precipitation method 2

16. RS – Lake Levels Low levels Lake Mälaren

17. RS – Lake Levels, seasonality 1 Low levels Lake Mälaren

18. RS – Lake Levels, seasonality 2 Low levels Lake Mälaren

19. Response Surfaces – Monthly Runoff Lake Mälaren

20. Monthly Runoff – compared to previous results Lake Mälaren

21. Some Conclusions Seasonal differences not so apparent for annual runoff Shows up in monthly results, and even more for thresholds, although not all basins are equally sensitive Different methods for representing seasonality have an impact Representation of evapotranspiration is problematic (as usual!)

22. Coming Work Contribution to del. 6.7 (RS Report) Not too much more on response surfaces before data starts coming Next major effort will be to work with direct modelling of RCM simulations (the Matrix, as soon as they are available)

23. Questions for Discussion Critical thresholds, we use experience from critical past events, better ideas? What if there is widely differing seasonality from the climate models? What will we actually get from the climate models (i.e. probabilistic info.) ? How many simulations will be available (perturbed vs. RCM results) ?