Andreas Schumann Ruhr- Universität Bochum Lehrstuhl für Hydrologie, Wasserwirtschaft und Umwelttechnik

Transkript

1 Das Augusthochwasser 22 im Osterzgebirge und dessen statistische Bewertung The extreme flood in August 22 in the eastern part of the Ore Mountains and its statistical assessment Andreas Schumann Ruhr- Universität Bochum Lehrstuhl für Hydrologie, Wasserwirtschaft und Umwelttechnik

2 The extreme flood in August 22 in the eastern part of the Ore Mountains and its statistical assessment 2 The hydrological event Statistical evaluation of the flood event How realistic is the statistical assessment?

3 The extraordinary level of the flood 22 in relationship to flood peaks of the past (since 1771) at an old building in the city of Grimma at the Mulde River in Germany 3

4 Meteorological reason for the floods in August 22 - Vb- Circulation Pattern 4

5 Spatial Distribution of the extreme precipitation from August 1 to August 13, 22 in the German part of the Ore Mountains 5

6 PMP and measured rainfall maxima in August 22 Region Area in sq.km Duration 24 hours Duration 72 hours Station Zinnwald 1 to 25 km 2 35 mm 312 mm 5 mm 46 mm Region Zinnwald 1. km 2 3 mm 45 mm Part of the Elbe River Basin 5. km 2 2 mm 275 mm Watershed Upper Elbe 12. km 2 16 mm 25 mm Precipitation between August 11 and 13, 22 in mm PMP with a duration of 12 hours for watersheds with 5 km 2 in size in summer (June to August)

7 7 Areal precipitation values from August 1 to for watersheds in the Ore Mountains 45 4 Area Precipitation Watershed Size km2

8 Temporal distribution of the precipitation from August 11 to 13 for different river basins in Saxonia Pegel Göritzhain/ Chemnitz Pegel Niederschlema/ Zwickauer Mulde Pegel Cotta/ Verein. Weisseritz Pegel Nossen/ Freiberger Mulde 25 2 Pegel Nossen/ Freiberger Mulde 15 Pegel Cotta/ Verein. Weisseritz 1 5 Pegel Niederschlema/ Zwickauer Mulde Pegel Göritzhain/ Chemnitz ,13: ,16: ,19: ,22: ,1: ,4: ,7: ,1: ,13: ,16: ,19: ,22: ,1: ,4: ,7: ,1:

9 Temporal distribution of runoff from August 11 to 14, 22 for different river basins in Saxonia Pegel Niederschlema/ Zwickauer Mulde Pegel Göritzhain/ Chemnitz Pegel Nossen/ Freiberger Mulde Pegel Cotta/ Verein. Weisseritz Pegel Cotta/ Verein. Weisseritz Pegel Nossen/ Freiberger Mulde.5 Pegel Göritzhain/ Chemnitz Pegel Niederschlema/ Zwickauer Mulde ,13: ,17: ,21: ,1: ,5: ,9: ,13: ,17: ,21: ,1: ,5: ,9: ,13: ,17: ,21: ,1: ,5: ,9: ,13: ,17:

10 Linear regression between direct runoff (in mm) and area precipitation for the flood in August Qsum = *Psum Qsum 2 1 R- (adjusted for d.f.) = 87,8 percent Psum

11 Polynomial regression between direct runoff (in mm) and area precipitation for the flood in August Qsum = *Psum *Psum^2 Qsum 2 1 R-(adjusted for d.f.) = 89,4 percent Psum

12 SBE 19 p Qsum = *Psum *SBE Impact of the soil storage capacity SBE in mm and the total sum of precipitation PSUM on the direct runoff Psum

13 Runoff coefficients in relationship to sum of precipitation 13 Runoff Coefficient.9 Dam sites.8 Gauges measured Gauges computed Psum in mm

14 The extreme flood in August 22 in the eastern part of the Ore Mountains and its statistical assessment 14 The hydrological event Statistical evaluation of the flood event How realistic is the statistical assessment?

15 15 Characterisation of the inflow flood peaks in August 22 in relationship to the assumed 1. and 1. yrs flood for 7 reservoirs in Saxonia Reservoir Catchment size in km 2 Assumed Design Flood 1 HQ(1.) m 3 /s Assumed Design Flood 2 HQ(1.) m 3 /s Max. Inflow in August 22 m 3 /s Max. Release during the flood in August 22 m 3 /s Precipitation in mm within 48 h Max. Inflow / 1. yrs flood Max. Inflow / 1. yrs flood Lehnmühle Klingenberg Malter Altenberg Lichtenberg Saidenbach

16 Return Period of flood peaks in August 22, estimated on the basis of time series ending 21 16

17 Uncertainty of statistical assessments of flood risks showing at the example of the flood in August 22 in Saxonia Lichtenwalde / Zschopau Jahres-HQ-Werte AEV Jahres-HQ-Werte Reihe T=5a 7 Standardisierte Zufallsvariable y(t)=-ln(ln(1/pu))

18 Uncertainty of statistical assessments of flood risks showing at the example of the flood in August 22 in Saxonia Lichtenwalde / Zschopau Jahres-HQ-Werte AEV Jahres-HQ-Werte Reihe T=5a 7 Standardisierte Zufallsvariable y(t)=-ln(ln(1/pu))

19 Uncertainty of statistical assessments of flood risks showing at the example of the flood in August 22 in Saxonia 19 2 Lichtenwalde / Zschopau T=5a Standardisierte Zufallsvariable y(t)=-ln(ln(1/pu))

20 2 Modification of the flood statistics at the gauge Hainsberg 1/ Rote Weisseritz HQ in m3/s Reihe Reihe T=2 a T=5 a T=1 a T=2 a T=25 a T=5 a T=1 a T=2 a T bis 21 mit T=5 a 1. T=1 a y(t)=-ln(ln(1/pu))

21 The extreme flood in August 22 in the eastern part of the Ore Mountains and its statistical assessment 21 The hydrological event Statistical evaluation of the flood event How realistic is the statistical assessment?

22 22 Yearly flood values at the gauge Dohna/ Mueglitz River Return Period T Jahres-HQ- Wert Sommer-HQ- Wert Risk of 3 events in 16 years 1 1: :78 1: HQ Jahr

23 23 Evidence of record-breaking floods (Vogel et al. 21) Yearly flood observations Counting of the highest flood peaks from the begin of observation with a yearly extension of the series Number of record breaking floods in a series of n years Probability of r record-breaking floods in a series of n years with S- Stirling s numberl Approximation for n>2 yrs

24 Number of record breaking floods dependent on the starting point of the series in the Mulde River basin Wechselburg1 Anzahl der bisher beobachteten Höchstwerte Nossen1 Lichtenwalde Golzern1 Theoretische Anzahl in Abhängigkeit von der Reihenlänge Reihenbeginn

25 Wechselburg/ Zwickauer Mulde Golzern Vereinigte Mulde 4 HQ(1) Beginn der Reihe Effect of random samples on flood statistics, Dependency of the 1 yrs- flood from the starting point of the flood series HQ(1) Lichtenwalde/ Zschopau Nossen/ Freiberger Mulde Beginn der Reihe

26 35 3 Pegel Golzern/ Vereinigte Mulde, Reihenbeginn1911 Pegel Wechselburg/ Zwickauer Mulde, Reihenbeginn HQ(1)- Wert Pegel Nossen/ Freiberger Mulde, Reihenbeginn 1926 Endpunkt der Beobachtungsreihe Effect of random samples on flood statistics, Dependency of the 1 yrsflood from the ending point of flood series HQ(1)- Wert Pegel Lichtenwalde/ Zschopau, Reihenbeginn Endpunkt der Beobachtungsreihe

27 Flood Levels since 1771 at an old building in the city of Grimma at the Mulde River in Germany, differentiated between winter and summer flood events 27

28 28 Seasonal Distribution of Catastrophic Floods in the history of the City of Zwickau between 1291 and 1835 Zwickau - Häufigkeitsauswertung historischer Hochwasser der Zwickauer Mulde gemäß Angaben aus der Stadtchronik (Zeitfenster: 1291 bis 1835) 25 2 Monate 15 1 Altstadt überflutet Häuser beschädigt Brücken beschädigt ohne Bauwerksschäden 5 Jan Feb Mär Apr Mai Jun Jul Aug Sep Okt Nov Dez Anzahl der Hochwasser

29 Example for a seasonal flood statistics Gauge Lichtenwalde/ Zschopau Pegel Lichtenwalde/ Zschopau Jahres-HQ- Werte bis 21 Sommer-HQ unkorrigiert Winter-HQ unkorrigiert

30 Example for a seasonal flood statistics Gauge Lichtenwalde/ Zschopau 3 14 Pegel Lichtenwalde / Zschopau 12 Jahres-HQ- Werte bis 21 Sommer-HQ korrigiert Winter-HQ korrigiert

31 Example for a seasonal flood statistics Gauge Lichtenwalde/ Zschopau Pegel Lichtenwalde / Zschopau Jahres-HQ- Werte bis 21 Sommer-HQ korrigiert Winter-HQ korrigiert AEV- Winter AEV Sommer

32 Example for a seasonal flood statistics Gauge Lichtenwalde/ Zschopau Pegel Lichtenwalde / Zschopau Jahres-HQ- Werte bis 21 Sommer-HQ korrigiert Winter-HQ korrigiert AEV- Winter AEV Sommer Kombinierte VF WIN-Som AEV- Jahres-HQ-Werte

33 Differences of statistical assessments of a flood peak of 3 times of the mean annual discharge utilizing a combined seasonal based distribution or the distribution of annual flood 33 Pegel Watershed in km 2 Discharge (3 times MQ) in m³/s Annual maxima Return Period T in Jin years Based on winter and summer maxima D.F. of summer maxima D.F. of winter maxima Golzern1/ Vereinigte Mulde Niederschlema/ZwickauerMulde Wechselburg/ ZwickauerMulde Aue1/ Schwarzwasser Goeritzhain/ Chemnitz Lichtenwalde/ Zschopau Streckewalde/ Preßnitz Pockau1/ Flöha Rothenthal/ Natzschung Zoeblitz/ SchwarzePockau Berthelsdorf/ Freiberger Mulde Nossen1/ Freiberger Mulde Wolfsgrund/ Chemnitzbach Niederstrieg/ Striegis

34 34 Return Period of flood peaks in August 22, estimated on the basis of time series ending 22

35 Thank you very much for your attention! Vielen Dank für Ihre Aufmerksamkeit!