HYPE model simulations for non-stationary conditions in European medium sized catchments

1. Göran Lindström & Chantal Donnelly, SMHI, Sweden IAHS, 2013-07-23, Göteborg, Sweden. Hw15 - Testing simulation and forecasting models in non-stationary conditions HYPE model simulations for non-stationary conditions in European medium sized catchments After the Gudrun storm January 2005 Photo: H.Alexandesson

2. Outline Objectives • Simulate non-stationary conditions, for this workshop. • Evaluate effects of the Gudrun storm in 2005. Modeled basins • Garonne (France, increase in temperature, decrease in discharge) • Durance(France, increase in temperature, decrease of glacier) • Lissbro (Sweden, forest loss due to Gudrun storm)

3. HYPE modelHydrological Predictions for the Environment • Simulates daily fluxes and turn-over of water, Nitrogen & Phosphorus • Integrated soil- and groundwater, substances follow water flow paths • Developed for large-scale applications • Routing in rivers & lakes (incl. regulation) • Parameters are linked to soil type or land-use, and calibrated • Each combination of soil type and land-use is modeled separately • First version was developed in 2005-2007, and continuously developed • Potential evaporation by air temperature with seasonally varying factor

4. Soil/Land Use classes (SLC)Most parameters coupled to soil or land-use Soil types + Land use SLC

5. HYPE in the world

6. Durance and Garonne – Taken from the E-HYPE pan-Europeanapplicationof the HYPE model • 35000 subbasins • Median size 215 km2 • Used for hindcasting, operationalforecasting and futureclimatepredictions, Q, Nitrogen and Phosphorous • For Durance and Garonne: • Local model taken from E-HYPE (subbasin delineation, landuse, soil-type, lakes, glaciers, irrigation etc) • Used the local forcing data (but with height adjustment to height of each subbasin in catchment for temperature) • Calibrated to given Q data by adjusting ’super-parameters’ (also Precip correction where required)

7. Trends over data period: Observed Trends: Simulated vs Observed Trends: Modeled decrease slightly too weak

8. Durance Catchment area: 2170 km²

9. Garonne Catchment area: 9980 km² • HYPE underestimated the decrease in discharge • Temperature increase not the only cause of decreasing discharge? • Temperature increased by ~1.2 ºC (whole period) • Precipitation decreased by ~8% (whole period) • Data uncertainties? • Regulation, irrigation?

10. Does glacial melt in the Durance catchmentexplain non-stationarity? Glacier = 8 % of area Glacier = 1 % of area

11. S-HYPE model for Sweden Runoff and discharge • For support to implementation of EU WaterFrameworkDirective, forecasting etc. • ~ 35000 subbasins, ~15km2 subbasin resolution Interpolation Cal/Eval at 400 stations

12. Gudrun storm, January 2005 • About 70 M m3 of trees were blown down. • 18 people died (in Sweden) • Three worst storms in Sweden: 1902, 1969 and 2005 • In a region affected by a summer flood in 2004 • Worries about increased flood risk after loss of forest • Also known as Erwin storm

13. Gudrun storm January 2005 • In the worst hit areas ~8 %of trees were blown down. Lissbro Loss offorest (m3/ha) Max wind speed (m/s)

14. Lissbro97 km2, 81% forested, 1 % lakes 2004 summer flood The 10 yearsbefore Gudrun

15. Previous HBV studyofclearfellingBrandt et al. (1988), small-scale experiments, central Sweden Discharge: +165-200 mm/year

16. Lissbro, Reference (no change in model)4 key parameters adjustedtoLissbro data

17. Lissbro,Simulatedclearfelling8% of the forestconvertedtoclearfelling Change in SLC classes

18. Lissbro, DecreasedPotEvapForest PET ~15% higherthanopen areas (8% forest loss) Change in PET parameter

19. Conclusions • Trends in discharge were fairly well captured by the HYPE model for the two French basins (but modeled discharge decrease was too weak in Garonne). • Glacier development had negligible effect in Durance. • The effects of the Gudrun storm on discharge in Lissbro were very small (within the uncertainty in the model calibration period).