Auswirkungen des Klimawandels auf den Wasserhaushalt in Deutschland:

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1 Auswirkungen des Klimawandels auf den Wasserhaushalt in Deutschland: - am Beispiel der Entwicklung von Extreme Dürren - Luis Samaniego Workshop KliWES Dresden,

2 Droughts in Germany Droughts are long-term regional hydro-meteorological anomalies Major droughts 1904, 1959, 1963, 1971, 1989, 2003, 2007,

3 Droughts in Germany Droughts are long-term regional hydro-meteorological anomalies Major droughts 1904, 1959, 1963, 1971, 1989, 2003, 2007, 2010 Murg at Rastatt, (gettyimages) 1

4 Droughts in Germany Droughts are long-term regional hydro-meteorological anomalies Major droughts 1904, 1959, 1963, 1971, 1989, 2003, 2007, 2010 Level of the Rhine at an all-time low, (MunichRe) 1

5 Droughts in Germany Droughts are long-term regional hydro-meteorological anomalies Major droughts 1904, 1959, 1963, 1971, 1989, 2003, 2007, 2010 Among the costliest natural Losses in the agricultural sector in 2003, COPA-COGECA: 1.5 billion AC Yield -30% disasters Wilhite (2000), Dai et al. (2010) Economic Environmental Social 1

6 Droughts in the press SACHSEN sz-exklusiv Dienstag, 7. Juni 2011 (Sächsische Zeitung) Die schlimmste Trockenheit seit 50 Jahren Auch der mancherorts fallende Gewitterregen bessert die Bilanz kaum. Sachsen muss sich auf häufige Dürren einstellen. 29. Mai 2011, 08:05 Uhr Trockenheit Berlin/Dresden. Der derzeitige Regen ist nur der berühmte Tropfen auf den heißen Stein: So extrem trocken wie in diesem Frühjahr war es seit mindestens 50Jahren nicht mehr in Deutschland. Das jedenfalls sagt der Leiter des Zentrums für Agrarmeteorologische Forschung beim Deutschen Wetterdienst (DWD), Franz-Josef Löpmeier. Die Trockenheit in Deutschland könnte zu Schwierigkeiten bei der Stromversorgung führen. Nach SPIEGEL-Informationen warnt die Deutsche Energie-Agentur vor Kühlwasserengpässen in Kernkraftwerken und Problemen bei Brennstofflieferungen per Schiff. Berlin - Die Deutsche Energie-Agentur (Dena) warnt vor Engpässen in der Versorgung mit Strom, sollte sich die Dürre der vergangenen Monate im Sommer fortsetzen. "Weitere 2 extreme Trockenheit kann auf vielfache Weise die Stromversorgung gefährden", sagt NR. 126 SEITE 7 DlENSTAG, 31. MAl 2011 Trockenster Friihling seit 100 Jahren OFFENBACH, 30. Mai (dpa). Del' Friihling ist in diesem Jahr aubefgewohnlich sommerlich ausgefallen. Es war das sonnigste Friihjahr seit Beginn del' DWD Messungen 1952 und das zweitwiirmste nach 2007, wie del' Deutsche Wetterdienst (DWD) am Montag in Offenbach mitteilte. Del' diesjiihrige Friihling iibertraf mit 699 Stunden Sonnenschein das Soil von 459 Stunden urn gut 50 Prozent. Den meisten Sonnenschein meldete Rheinau-Memprechtshofen bei Baden-Baden mit 802 Stunden. Dafiir fielen in diesem Friihjahr im Durchschnitt nur 88 Liter Regen pro Quadratmeter. 1m langjiihrigen Mittel sind es sonst 186 Liter. Am trockensten war es im siidlichen Rheinland-Pfalz, im nordlichen Baden-Wiirttemberg, in Hessen, in Unterfranken und im siidlichen Thiiringen. 1m Mai waren die Pegel del' meisten deutschen Fliisse so niedrig wie seit etwa 100 Jahren nicht mehr zu diesel' Jahreszeit, wie del' DWD mitteilteo Die Durchschnittstemperatur lag trotz Nachtfrosts bis in den Mai hinein bei 10,1 Grad. Das waren 2,4 Grad mehr als das langjiihrige Mittel von 7,7 Grad. Auch die Landwirtschaft leidet unter del' Trockenheit. Das Getreide ist dieses Jahr im Wuchs zuriickgeblieben. Dafur begann dank del' warmen Witterung die Erdbeerernte nach den Angaben mehr als zwei Wochen fruher als ublich.

7 Research questions Which were the potential triggering mechanisms? 3

8 Research questions Which were the potential triggering mechanisms? How can agricultural drought events be quantified? 3

9 Research questions Which were the potential triggering mechanisms? How can agricultural drought events be quantified? How long, severe, and extensive were the extreme drought events since 1951? 3

10 Research questions Which were the potential triggering mechanisms? How can agricultural drought events be quantified? How long, severe, and extensive were the extreme drought events since 1951? How uncertain are these drought characteristics? 3

11 Long-term hydro-climatic changes: Avg. Temp. Mann-Kendall test p-value = 0.10 Winter T, P Summer T, P Precip. Negative trend No trend Positive trend 4

12 Changes in circulation patterns Absolute frequency Summer Year Dry CPs = Wa, SWa, NWa, HM, BM, HNa, HB, NEa, HFa, HNFa, SEa, SEz, Sa (Hess and Brezowsky, 1969) Wetness index: Samaniego & Bárdossy, JoH

13 Drought indices Meteorological Drought Precipitation SPI MacKee et al., 1995,... Average drought index Precipitation Runoff Soil moisture Year

14 Drought indices Meteorological Drought Precipitation SPI MacKee et al., 1995,... Hydrological Drought Streamflow Average drought index Precipitation Runoff Soil moisture Year

15 Drought indices Meteorological Drought Precipitation SPI MacKee et al., 1995,... Hydrological Drought Streamflow Agricultural Drought Soil moisture VIC Sheffield et al., 2004 SWI Vidal et al., 2010 SMI Samaniego et al, 2011 Average drought index Precipitation Runoff Soil moisture Year

16 Modeling approach mhm Model ẋ t i = f(x t i, u t i, β it, t) + ηi t β = β 0 } β 0 = g(u 0 MPR, γ) u 0 level-0 predictors (e.g. soil, DEM,...) β model parameters β 0 sub-grid model parameters γ global parameters Level-1: 4 km Cell i, time t Samaniego et al. WRR, 2010a, 2010b Kumar et al. JoH, 2010, WRR, 2012 (rev) 7

17 mhm input data Level-2: 1-4 km Meteorological forcings DWD 100 km High resolution DEM BGK DWD 5600 rain gauges 8

18 mhm input data Level-2: 1-4 km Meteorological forcings DWD Level-0: 100 m DEM BGK Soil texture, root zone depth BÜK Hydraulic conductivity HÜK LAI NASA Land cover NASA, CORINE River network, gauged stations GRDC-EWA, EURO-FRIEND Radiation, albedo, emissivity, wind LSA-SAF, NCEP-CFSR 100 km High resolution DEM BGK DWD 5600 rain gauges 8

19 mhm flux validation Soil moisture anomaly [-] EC Tharandt mhm n = r 2 = 0.73 Zink et al # ET [mm/d] Hours since EC Tharandt mhm n = 366 r² = Day of Year 2000 Tharandt EC, Bernhofer et al., FluxNet 9

20 Testing mhm performance 54 N 52 N Ems Weser Saale Elbe Oder Basin NSE-cal NSE-val Neckar Main Danube Weser Ems Saale Mulde Calibration: Validation: Rhine Mulde 50 N Main Neckar Danube 48 N km E 10 E 12 E 14 E 10

21 Testing mhm performance Basin NSE-cal NSE-val NSE-trans Neckar Main Danube Weser Ems Saale Mulde Calibration: Validation: km 10

22 Soil Moisture Index (SMI) Reconstruction of the monthly soil moisture fraction since

23 Soil Moisture Index (SMI) Reconstruction of the monthly soil moisture fraction since

24 Soil Moisture Index (SMI) Reconstruction of the monthly soil moisture fraction since

25 Soil Moisture Index (SMI) Reconstruction of the monthly soil moisture fraction since

26 Soil Moisture Index (SMI) Reconstruction of the monthly soil moisture fraction since 1950 Monthly empirical PDFs for each cell and month Estimate non parametric CDFs SMI Sheffield et al., 2004 Vidal et al., 2010 Samaniego al.,

27 km Soil Moisture Index (SMI) C1 (1) (2) (3) (4) C2 C1 C3 C1 C2 C3 C3 (5) (6) (7) (8) (9) (10) (11) (12) C1 Reconstruction of the monthly soil moisture fraction since 1950 Monthly empirical PDFs for each cell and month Estimate non parametric CDFs SMI Identification of drought events (spatio-temporal clustering) C3 C Sheffield et al., 2004 Vidal et al., 2010 Samaniego al.,

28 SMI uncertainty Ensemble n = precipitation products REGNIE-DWD EDK-UFZ 100 parameter sets for mhm (γ) 12

29 SMI uncertainty Ensemble n = precipitation products REGNIE-DWD EDK-UFZ 100 parameter sets for mhm (γ) 54 N Ems Oder 52 N Weser Elbe Saale Rhine Mulde 50 N Main Neckar 48 N Danube km E 10 E 12 E 14 E 12

30 Ensemble SMI over Saxony n =

31 Trends of the SMI 100 Percentage of ensemble members exhibiting a negative trend (p-value = 5%) 14

32 Predictive uncertainty in major events 100 Drought development ( ) % of Germany area Months since Jan 1951 Samaniego et al., J. Hydrometeorol (in review) 15

33 Predictive uncertainty in major events 100 Drought development ( ) % of Germany area Months since Jan 1951 Samaniego et al., J. Hydrometeorol (in review) 15

34 Predictive uncertainty in major events 100 Drought development ( ) % of Germany area Months since Jan 1951 Samaniego et al., J. Hydrometeorol (in review) 15

35 Predictive uncertainty in major events 100 Drought development ( ) % of Germany area Months since Jan 1951 Samaniego et al., J. Hydrometeorol (in review) 15

36 Predictive uncertainty in major events 100 Drought development ( ) % of Germany area Months since Jan 1951 Samaniego et al., J. Hydrometeorol (in review) 15

37 Predictive uncertainty in major events 100 Drought development ( ) % of Germany area Months since Jan 1951 Samaniego et al., J. Hydrometeorol (in review) 15

38 Predictive uncertainty in major events 100 Drought development ( ) % of Germany area Months since Jan 1951 Samaniego et al., J. Hydrometeorol (in review) 15

39 Predictive uncertainty in major events 100 Drought development ( ) % of Germany area Months since Jan 1951 Samaniego et al., J. Hydrometeorol (in review) 15

40 Predictive uncertainty in major events 100 Drought development ( ) % of Germany area Months since Jan 1951 Samaniego et al., J. Hydrometeorol (in review) 15

41 Predictive uncertainty in major events 100 Drought development ( ) % of Germany area Months since Jan 1951 Samaniego et al., J. Hydrometeorol (in review) 15

42 Predictive uncertainty in major events 100 Drought development ( ) % of Germany area Months since Jan 1951 Samaniego et al., J. Hydrometeorol (in review) 15

43 Predictive uncertainty in major events Losses of the agricultural sector 1.5 billion AC Yield -30% COPA-COGECA 15 Samaniego et al., J. Hydrometeorol (in review)

44 Major drought events since Total drought magnitude : Aug 1971 Jul : Jul 1962 Apr : Feb 1991 Sep 1993 Mean duration (months) : Jul 1975 Nov : Mar 1959 Sep : Apr 2003 Oct : Jan 1989 Nov : Jun 2005 Aug Mean area (% of Germany area) 16

45 Uncertainty analysis 17 Probability density function

46 SMI vs. yield statistics Basin average monthly SMI Basin average monthly SMI Year Year Yield Mt Danube Ems Rhein Elbe Oder Wesser 18

47 Drought persistence km P (SMI(t + 1) 0.20 SMI(t) 0.20) Agricultural suitability 19

48 Acknowledgment BfG German Federal Institute of Hydrology BGR Federal Institute for Geosciences and Natural Resources BKG Federal Agency for Cartography and Geodesy DWD German Meteorological Service EEA European Environment Agency EWA European Water Archive GRDC Global Runoff Data Centre NASA National Aeronautics and Space Administration Destatis Federal Statistical Office of Germany Artwork COPA-COGECA Life Magazine 2007 gettyimages 20

49 21 Appendix

50 imultiscale Parameter Regionalization in mhm State equations ẋ it = g(x it, u it, β it ) + η it Parameterization β = β 0 β 0 = f(u 0, γ) Cell i, time t Level-1 Level-1' Level-0 Level-2 Effective parameter at various modelling scales (level-1, level-1')i'βi1i'<0βi1>βjjupscaling Regionalized β = f (u k, γ)0parameter field at level-0 operator0u j1... Predictor fields at level-0 ju kj0phase 01. Regionalization2. Upscaling Samaniego et al. WRR, 2010a, 2010b Kumar et al. JoH, 2010 WRR Editor s Choice Award 2010 Spatial scale 22

51 Estimation of the soil moisture drought index Estimate monthly PDFs ˆf using the Unbiased Cross-Validation criterium Scott & Sain, 2004 min ˆf(x h) 2 dx 2 n ˆf(x) = 1 nh n ˆf k (x h) k=1 n ( ) x0 x k K h k=1 K(x) = smoothing kernel n = sampling size h = bandwidth Fitted vs. empirical CDF 23