1. Integrated hydrological modelling with selected climate scenarios for assessment of future changes in groundwater levels and runoff in coastal areas Torben O. Sonnenborg Department of Hydrology Geological Survey of Denmark and Greenland (GEUS)

2. Content Scenarios and climatic changes Challenges Hydrological impact –Groundwater –Stream discharge –Flooding Conclusions

3. Climate-scenarios (IPCC) A2B2 2071 - 2100

4. Challenges Distribution of climate model results Spatial resolution The model predicts rain almost every day

5. Geographical distribution of precipitation

6. Spatial resolution Resolution –Climate model: 10 – 50 km –Hydrological model: 50 – 1000 m

7. Frequency distribution of rainfall Time Discharge (m 3 /s) Stream discharge

8. Challenges Max precipitation located at coast Spatial resolution The model predicts rain almost every day  Difficult to use climate model results directly

9. Delta Change Method Transformation of precipitation Requires assumption of same dynamics 1961199020712100 Control periodFuture period Time

10. Calculated precipitation Precipitation in mm/day Month Delta value

11. Calculated reference evapotranspiration ET in mm/day

12. Model area Surface elevation (m) Western Jutland Zealand Net precipitation (mm/year)

13. Hydrological model – MIKE SHE

14. Western Jutland - Recharge to the groundwater table Måned Nedsivning (mm) Pr A2 B2 Recharge (mm) Month

15. Western Jutland - Groundwater level (change) B2A2

16. Western Jutland - Groundwater level Hydraulic head (m)

17. Effect of sea level rise (1 m) Change in water level

18. Western Jutland - Stream discharge Pr A2 B2

19. Flooding in Storaa river catchment

20. Flooding in Holstebro New elevation model (laser measurements) Improved description of cross sections and stream valleys Holstebro Width app. 600m 25 30 m 28 27 26 29 31 Elevation (m)

21. Water level in Holstebro Future (A2) Present 7 8 9 10 11 Water level (m) Year

22. Flooding in Holstebro (max.)

23. STOP at red light the path is closed because of flooding

24. Adaptation!

25. Conclusions Winter –Increasing groundwater level –Increasing stream discharge –Increasing flooding risk More dynamic hydrological system –Groundwater recharge and level –Stream discharge Uncertainties –Climate results –Extremes (delta change method) –Coupling between hydrology and atmosphere