Publishing House of the Slovak Academy of Sciences

PUBLISHING HOUSE OF THE SLOVAK ACADEMY OF SCIENCES

Publication of the Slovak Committee for Hydrology – NC IHP UNESCO Monograph No. 12

This monograph is a contribution of the Slovak Committee for Hydrology (SCH) to the International Hydrological Programme (IHP) of UNESCO, phase VIII Focal Area 1.5 - Improve scientific basis for hydrology and water sciences for preparation and response to extreme hydrological events, and to the Regional co-operation of the Danube countries in the framework of IHP UNESCO. Particularly it contributes to the project No. 9 Flood regime of rivers in the Danube River basin within the Regional co-operation of the Danube countries.

Editorial board of the monograph series Chairman: RNDr. Pavol Miklánek, CSc. Members: Prof. Ing. Ján Szolgay, PhD. Ing. Dana Halmová, PhD. Prof. RNDr. Miriam Fendeková, CSc. RNDr. Katarína Holubová, PhD. Ing. Jana Poórová, PhD.

Translation: authors

Reviewed by: RNDr. Gabriela Babiaková, CSc. Doc. Ing. Silvia Kohnová, PhD.

PAVLA PEKÁROVÁ PAVOL MIKLÁNEK MARIÁN MELO DANA HALMOVÁ JÁN PEKÁR VERONIKA BAČOVÁ MITKOVÁ

Flood marks along the Danube River between Passau and Bratislava

Bratislava, 2014

This work was supported by the Science and Technology Assistance Agency under contract no. APVV-0015-10. Printing of the monograph was supported by the Slovak Commission for UNESCO.

ISBN 978-80-224-1408-1

CONTENTS

Preface ...... 8

1 Description of the Danube River Basin ...... 9 1.1 Climatic conditions ...... 12 1.1.1 Temperature ...... 12 1.1.2 Precipitation ...... 13 1.1.3 Runoff ...... 17 1.2 Flood regime along the Danube River ...... 21

2 The Danube flood marks between Passau and Bratislava ...... 26 2.1 The Danube floods in the middle age ...... 26 2.2 The Danube floods within the 1501–1876 period ...... 28

3 Flood marks in Bratislava before instrumental period ...... 45 3.1 Summer floods in Bratislava ...... 45 3.1.1 Flood of 1501 and 1670 ...... 45 3.1.2 Flood of October and November 1787 ...... 51 3.2 Ice floods in Bratislava ...... 51 3.2.1 Flood marks from the year 1775 ...... 52 3.2.2 Flood marks from the year 1809 ...... 53 3.2.3 Flood marks from the year 1850 ...... 57

4 Flood marks at Bratislava during the 1876–2013 period...... 62 4.1 Summer floods ...... 68 4.1.1 Flood of August 1897 ...... 69 4.1.2 Flood of September 1899 ...... 70 4.1.3 Flood of July 1954 ...... 72 4.1.4 Flood in the year 1965 ...... 73

5 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

4.1.5 Flood of August 2002 ...... 74 4.1.6 Flood of May / June 2013 ...... 76 4.2 Winter and snowmelt floods ...... 78 4.2.1 Flood of the year 1876 ...... 78 4.2.2 Comparison of the 1895 and 2006 Danube floods ...... 80 4.2.2.1 Maximum annual discharge at Bratislava and Orsova ...... 83

5 Flood frequency analysis with historical information ...... 89 5.1 Flood regime analysis of the Danube River at Bratislava .... 89 5.2 Catastrophic flood scenario ...... 92

6 Conclusions ...... 96

7 References ...... 98

6 Flood marks along the Danube River between Passau and Bratislava

ACKNOWLEDGMENT

This monograph summarizes results of long-term research of the Institute of Hydrology of the Slovak Academy of Sciences within the Regional co-operation of the Danube countries in the framework of the IHP UNESCO, and project APVV-0015-10 Identification of changes in hydrological regime of rivers in the Danube River Basin. Publication of the monograph was supported by the Slovak Commission for UNESCO. Part of data used in this monograph were obtained from the database of the project No. 9 „Flood regime of rivers in the Danube River Basin“ of the Regional co-operation of the Danube countries in the framework of IHP UNESCO.

This publication is the result of the project implementation ITMS 26240120004 Centre of excellence for integrated flood protection of land supported by the Research & Development Operational Programme funded by the ERDF.

7 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Preface

Floods on the Danube occurred through the whole history. Floods belong to the extreme natural phenomena, which have their place in the Danube Basin. The first records of floods are known from the year 1012. During the last 1000 years there are known at least 5 floods (in 1012, 1210, 1501, 1670 and 1787), which probably did exceed the discharge of 11 500 m3s-1 at Bratislava (Neweklowsky, 1955; Kresser, 1957; Szlávik, 2002). In the instrumented period, since 1876, the highest discharge of 10 870 m3s-1 was observed on 17 September 1899 at the water stage of 970 cm at Bratislava gauge. The highest water level of 1 034 cm was recorded during the May/June flood in 2013 with discharge of 10 640 m3s-1. Measured hydrological data series on the Danube River are limited. Instrumental data can be completed by documentary data from historical sources from different archive documents (Bel, 1735; Neweklowsky, 1955; Kresser, 1957; Szlávik, 2002; Horváthová, 2003; Rohr, 2005, 2007; Brázdil and Kundzewicz, 2006; Kiss, 2009; Kiss and Laszlovszky, 2013; Munzar et al., 2006; Przybylak et al., 2010; Kiss, 2011; Pišút, 2011; Stankoviansky and Pišút, 2011; Brázdil et al., 2010; Brázdil et al., 2012; Elleder et al., 2013; Melo and Bernáthová, 2013; Pekárová et al., 2013). Most of the presented information about historical floods in the Upper Danube area has its origin in flood marks, in newspaper articles, chronicles, official letters, books, maps and photos. Flood marks contain a brief description of a flooding event with indication of peak flood water level. In cities located along the Upper Danube (e.g. Passau, Linz, Mauthausen, Grain, Ybbs, Melk, Krems, or Hainburg an der Donau), there can be found more flood marks of the historical floods, even since the year 1501. In this monograph we focused on the history of floods and extreme flood frequency analysis of the Upper Danube River at Bratislava. We describe the flood marks found on the Upper Danube River from Passau up to region of Bratislava, Slovakia. Then, we analyse the annual maximum discharge series for the period 1876–2013, including the most recent flood of June 2013. Finally, we compare the values of T-year design discharge computed with and without incorporating the historical floods (floods of the years 1501, 1682, and 1787 into the 138-years series of annual maximum discharges).

8 Flood marks along the Danube River between Passau and Bratislava

1 Description of the Danube River Basin

The Danube River Basin is the Europe's second largest river basin, with a total area of 817 000 km² (Fig. 1.1). It is the world's most international river basin. In January 2008 the Danube Basin included the territories of 19 countries. Its river basin is situated between the headwater regions of the Rhine and the Dnieper River. The bee-line distance between the springs of the Danube in the Black Forest Mountains and its embouchure into the Black Sea is 1 630 km (Domokos in Brilly, 2010). The Danube River has a total length of 2 857 km. About one third of the Danube River Basin is mountainous. The highest points in the Danube Basin are Piz Bernina (4 052 m a.s.l.) in the southern reach and Peak Kriváň (2 496 m a.s.l.) in the northern reach (Fig. 1.2). The average altitude of the Danube catchment is 475 m a.s.l.

Regensburg Pfeling Hoffkirchen Ingolstatd Achleiten Krems Berg Bratislava Linz Wien Nagymaros

a Mohac D Bezdan Ceatal Reni Bogojevo Pancevo Orsova

Veliko Zimnicea Gradiste

Fig. 1.1 The Danube River Basin scheme, stations along the Danube River.

9 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Fig. 1.2 The Danube River Basin scheme, orography.

The Danube Basin can be subdivided into three main parts (Fig. 1.3), and the Danube delta: • the Upper Danube region, between the springs and the Devín Gate (Porta Hungarica), (133 m a.s.l., 1 880 rkm, 131 338 km2, 2 051 m3s-1); • the Central Danube region between the Devín Gate and the Iron Gate (60 m a.s.l., 930 rkm, 444 894 km2, 5 585 m3s-1 at Turnu Severin/Orsova gauge); • the Lower Danube region, between the Iron Gate and the Danube’s embouchure into the Black Sea (1 m a.s.l., 72 rkm, 230 768 km2 , 6 499 m3s-1 at Ceatal Izmail gauge); • the Danube Delta. There are 34 major tributaries of the Danube River (Figs. 1.3 and 1.4). The Tisza River Basin is the largest sub-basin in the Danube basin (157 186 km2). It is also the Danube’s longest tributary (966 km). According to flow volume, it is the second largest after the Sava River. The Sava River is the largest Danube tributary by discharge (average 1 564 m3s-1) and the second largest by catchment area (95 419 km2). The Inn is the third largest by discharge and the seventh longest Danube tributary (Fig. 1.4).

10 Flood marks along the Danube River between Passau and Bratislava

Morava er Upp be Danu Prut

Inn C Tisza

e Siret

n t

Drava r

a l

Mures

Sava be nu Da Vel. Lower Morava

Fig. 1.3 The Danube River Basin scheme, main subbasins in the Danube River Basin.

Fig. 1.4 The Danube and its tributaries, discharge.

11 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

1.1 Climatic conditions

The Danube Basin extends from the western regions of the Upper Danube with high Atlantic influence, to the eastern territories affected by continental climate. In the Upper and Central Danube region, especially in the Drava and Sava basins, the climate is influenced by the Mediterranean. This basic character of the climate is varied and modified into natural regions by the great mountain systems, influenced by the elevation above the sea level and the relief features (exposure, leeward and windward position), too (Stančík and Jovanovic, 1988).

1.1.1 Temperature

The pronounced air temperature differences are also determined by the extensive area and elongated character of the Danube Basin from west to east. Average annual air temperature within the basin ranges from -2 °C to +12°C. The lowest value originates from Sonnblick, the highest mean annual temperature was observed in the northern part of the Hungarian Lowland and at the Black Sea coast. In the entire Danube Basin, July is the warmest month, and January is the coldest one (Stančík and Jovanovic, 1988). In the upper reach of the Danube Basin the winter period usually lasts from December to February. The average January temperature is -0.8 to -3°C in the plains, and -6 to -13°C in the mountains. Summers are warm and last here from June to August. Mean July temperatures are 17–20°C, the mean July isotherm in the high mountains being 0°C at heights of about 3 500 m a.s.l. In the Central Danube region the winter only lasts for 1.5–2 months, the mean January temperatures being -0.3 to -2°C in the lowlands and about -l0°C at the highest points, but in some places even lower. In July the average air temperatures rise to 20–23°C in the valleys in the middle reach of the Danube Basin, but they are only 4–5°C in the higher mountain regions.

12 Flood marks along the Danube River between Passau and Bratislava

7000 3 -1 6000 Q[m s ] 5000 Danube: Turnu/Orsova

4000 1770 1790 1810 1830 1850 1870 1890 1910 1930 1950 1970 1990 2010 12.3 T[°C] Budapest 9.5 11.3 8.5 10.3 Bratislava 7.5 9.3 Wien Prague T[°C] 8.3 6.5 Hohenpeissenberg 7.3 5.5 1770 1790 1810 1830 1850 1870 1890 1910 1930 1950 1970 1990 2010

Fig. 1.5 Courses of the filtered mean annual discharge of the Danube at Orsova and annual air temperature, HP-filter lambda=50. Budapest, Bratislava, Praha: Klementinum, Wien, and Hohenpeissenberg stations, 1780–2004 period.

The winter period of the Lower Danube Region usually begins 2 weeks later than in the most western parts of the Danube River Basin and lasts from the second half of December to the end of February. Mean January temperatures fluctuate within the range -1.2 to -3°C, and -8 to -9°C in the mountains. Summer starts in late May and ends in September with maximum monthly temperatures of 22–24°C in July (Stančík and Jovanovic, 1988). In Fig. 1.5, the mean annual discharge of the Danube at Orsova and the mean annual temperature series are plotted. The two driest periods of the Danube flows of the instrumental era occurred in different temperature conditions. During the period 1860–1870 the temperatures were lower, as during 1985–1995.

1.1.2 Precipitation

Average annual precipitation fluctuates between 2300 mm in the high mountains and 400 mm in the delta region. On Fig 1.6, the annual precipitation totals from Hurbanovo station are presented (period 1871–2010). The driest decade in the history of the precipitation observations at the Hurbanovo station (South Slovakia) was the period 1981–1990.

13 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

From the analysed long precipitation series observed at the nearby meteorological stations (Mosonmagyarovar, Vienna, and Brno) we can see lower precipitation depths before the year 1871 than those in decade 1981–1990. The best example of precipitation long-term trend is visible in the series from the meteorological station at Brno. The time period between 1803 and 1830 was most likely exceptional in terms of precipitation in the Danubian lowland region. We approximated the long-term trend by a polynomial of the 4th degree. Markedly drier periods occur every 120–140 years.

650 Hurbanovo 570 P [mm]

490

680 Mosonmagyarovar 590 P [mm] 500

730 Vienna

640 P [mm]

550

620 Brno 530 P [mm]

440

1803-1810 1821-1830 1841-1850 1861-1870 1881-1890 1901-1910 1921-1930 1941-1950 1961-1970 1981-1990 2001-2010 Fig. 1.6 10-years average of precipitation at Hurbanovo (1871–2010), Mosonmagyarovar (1861–2009), Vienna (1841–2009), and Brno (1803–2010).

The regional variation of the annual precipitation in the Danube River Basin is shown in Fig. 1.7, where the mean annual values are interpreted for the time period 1961–1990 (Petrovič et al., 2006). The Upper Danube River Basin shows a remarkably variable character of precipitation. In the high Alpine regions the values of 2 000 mm are sometimes exceeded, the mountain marginal belts being extraordinarily rich in precipitation.

14 Flood marks along the Danube River between Passau and Bratislava

Fig. 1.7 Mean annual precipitation in the Danube Basin, 1960–1990, Authors: Kostka, Z. and Holko, L. in Petrovič et al. (2006).

The increment of mean annual precipitation values amounts to about 50 mm per 100 m height in the northern Alpine slopes and in the Alps. A further contribution is the distant influence of the mountains, affecting precipitation on windward slopes and increasing precipitation on approach to the mountains. Thus, the lines of uniform precipitation follow the contours of the mountains. In the northern Alpine foothills the amount of precipitation decreases in this way from about 1 500 mm per year on the periphery of the mountains to 700 mm per year in the Danube valley. About 1 500 mm of precipitation per year also falls in the Danube source area, in the Schwarzwald Massif and in the higher regions of the Bavarian and Bohemian Forests. Other territories show average precipitation values 600–1 000 mm, the valleys and basins being relatively dry with about 700 mm. The intermountains valleys are also relatively dry (Stančík and Jovanovic, 1988). In the Central Danube region the highest values of mean annual precipitation occur on the outskirts of mountains surrounding the lowlands. The highest precipitation values above 2 000 mm occur on the southern-oriented mountain chains of the Julian Alps and the Dinaric system, which are exposed to the effect of humid-warm air masses coming from the Mediterranean. In the Carpathians the mean precipitation values vary

15 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V. between 1 000 and 1 500 mm. In the shelter of those mountains, in the east Bohemian-Moravian Uplands, as well as in the Carpathian foothills, the average precipitation amounts are in the range from 600 to 1 000 mm. In the southern part of the central Danube Lowland the annual precipitation falls to 600–800 mm, in Alföld to 550 mm and in the region of the central Tisza to 500 mm. This dry climate regime increases in the central Danube Lowland in the northerly and easterly directions. In the plains of the Lower Danube River Basin, the precipitation is only 500–600 mm, though the lowest precipitation values of less than 400 mm are recorded within the Danube estuary. In some years there is no precipitation over the summer period. Because of the low precipitation and high summer temperatures, the region of the Danube estuary may be considered as a region with a steppe climate. When the annual distribution of the precipitation is studied, it can be seen that the maximum occurs regularly in the summer months. This is especially true in low-lying parts of the Danube River Basin, where convective precipitation constitutes a considerable contribution to the total precipitation (Stančík and Jovanovic, 1988). In those regions the maximum is shifted with increasing continentality from July to June or May, since in mid-summer the low air humidity is not sufficient for the development of the showers. The minimum precipitation occurs there in February and sometimes in January in mid-winter when the Asiatic region of high pressure blocks the transfer of Atlantic air masses to the east. The conditions are different in mid-mountain and high-mountain ranges under the influence of a maritime climate. They usually have their maximum in summer but due to the orography enabling precipitation in the winter months of December and January, they frequently show a secondary maximum, in some places even an absolute maximum of the precipitation activity, as for instance in the Bavarian and Bohemian Forest. A deviation from this basic pattern is shown in regions influenced by the Mediterranean, where the months of October–December show maximum precipitation and the summer is relatively dry. The number of days with snow cover, duration and thickness of the snow cover increase with altitude. The shortest duration of snow cover (9–12 days) is on the Black Sea coast. The snow cover lasts for only 20–30 days in the Central Danube region, 40–60 days in the Upper Danube River Basin and the mean proportion of the snow in the total annual precipitation is about 10% (Stančík and Jovanovic, 1988).

16 Flood marks along the Danube River between Passau and Bratislava

1.1.3 Runoff

According to Horváthová (2003), the first water stage observations started on the river Danube at Komárno in 1805, then at Vienna in 1821, and at Bratislava in 1823. In this work we used mean daily discharge data from the database of the project “Flood regime of rivers in the Danube River Basin”. In Table 1.1, there is the list of the selected water gauges along the Danube with altitude of the gauge zero (recalculated into the Baltic system) and long-term daily discharge series (Fig. 1.8 a–b).

Table 1.1 List of selected water gauges along the Danube River Qa – long-term average annual discharge (1931–2005)

Coun River Altitude Discharge River Water gauge Area try km Baltic Qa

[ km2 ] [m a.s.l.] [ m3/s ]

Danube Berg GE 4 047 2 613 489.48 38.0 Danube Ingolstadt GE 20 001 2 457 359.97 313.0 Schwabelweis/ Danube Regensburg GE 35 399 2 376 324.06 444.0 Danube Pfelling GE 37 757 2 306 307.73 468.8 Danube Hofkirchen GE 47 496 2 257 299.17 640.0 Danube Achleiten GE 76 653 2 223 287.27 1 428.0 Danube Linz/Aschach AT 79 490 2 135 247.06 1 464.0 Kienstock ( station moved Danube from Stein-Krems AT 96 045 2 003 193.32 1 892.0 Danube Wien-Nussdorf AT 101 731 1 934 157.0 1 920.4 Devin (station moved Danube from Bratislava SK 131 338 1 869 132.86 2 050.0 Danube Nagymaros HU 183 534 1 695 99.37 2 336.0 Danube Mohács HU 209 064 1 447 79.19 2 354.0 Danube Bezdan SR 210 250 1 426 79.29 2 357.0 Danube Bogojevo SR 251 593 1 367 76.11 2 893.0 Danube Pancevo SR 525 009 1 153 65,98 5 320.0 Danube Veliko Gradiste SR 570 375 1 060 60.83 5 560.0 Orsova (station moved Danube from Turnu Severin RO 576 232 955 44.76 5 602.0 Danube Zimnicea RO 658 400 554 16.06 6 001.0 Danube Reni UKR 805 700 132 0.2 6 563.0 Danube Ceatal Izmail RO 807 000 72 6 415.0

17 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

500

400 Berg 1884 1868 300 1646 Hainburg, Hainburg, Bratislava, Budapest, 200

100

Elevation[m a.s.l], Baltic 0 3000 2500 2000 1500 1000 500 0 Rive r k m [k m ] a) 10000

8000 Qa Ceatal ] s Zimnicea -1 Orsova Pancevo s 6000 3

4000 Mohacs Qa [m Qa Linz Wien Bratislava Nagymaro Krems 2000 Passau Regensbur 0 Berg 3000 2500 2000 1500 1000 500 0 river km b) Fig. 1.8 a) Elevations of the water gauge datum of the selected stations along the Danube River (Baltic system). b) Long-term average annual discharge at the stations along the Danube, period 1931–2005).

Long-term average annual runoff varies from 50 mm per year up to 1 600 mm per year in the Danube Basin (Fig. 1.9).

Fig. 1.9 Mean annual runoff in the Danube River Basin, 1960–1990, Authors: Kostka, Z. and Holko, L. in Petrovič et al. (2006).

18 Flood marks along the Danube River between Passau and Bratislava

440 ] -1 .s 3 350 [m a Q Inn: Wasserburg 260 1821 1841 1861 1881 1901 1921 1941 1961 1981 2001

2740 ] Bratislava -1 .s 3 2070 [m a Q

1400 1821 1841 1861 1881 1901 1921 1941 1961 1981 2001

] 7800 Ors ova -1 .s 3 5600 [m a Q

3400 1821 1841 1861 1881 1901 1921 1941 1961 1981 2001

9800

] Re ni -1 .s 3 6700 [m a Q

3600 1821 1841 1861 1881 1901 1921 1941 1961 1981 2001

Fig. 1.10 Average annual Danube discharge in selected stations (points), deviations from double 5-years moving averages (bold line).

For analysis of the long-term multi-annual variability of the mean annual Danube Basin discharges, we used the four longest so far available discharge time series. The first one is from the Austrian water gauge on Inn at Wasserburg (1828–2007). The second one is from the Slovak water gauge at Bratislava (1876–2006). The third one originates from the Romanian water gauge Turnu Severin/Orsova (1840–2006). The water gauge was originally at Turnu Severin, and since 1970 it is at Orsova. The last one is from the Ukrainian station Reni, according to Mikhailova et al. (2012). In Fig. 1.10, there are the time series of the deviations of individual mean annual discharges from the double 5-years moving averages of the mean discharge.

19 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

8000

Ceatal 7500 Danube, discharge [m3s-1] Reni 7000

6500 Zimnicea

6000 Orsova

5500 Gradiste

5000

Pancevo 4500

3500 Bogojevo Bezdan

3000 Mohacs Nagymaros

2500 Bratislava

Wien 2000 Stein Linz 1500 Achleiten Hofkirchen 1000 Pfeling Regensburg 500 Ingolstadt

0 Berg 1870 1890 1910 1930 1950 1970 1990 2010

Fig. 1.11 The double 5-year moving averages of average annual discharge at 20 stations along the Danube River.

It is evident from the Fig. 1.11, that these time series include the multi-annual cycles of the dry and wet periods. Very wet period occurred during the World War II on the Danube River and the driest period was around the year 1863 (Pekárová et al., 2003; Pekárová and Pekár, 2006; Pekárová, 2009). From the long-term point of view, the annual discharges of the Danube River are constant.

20 Flood marks along the Danube River between Passau and Bratislava

1.2 Flood regime along the Danube River

In the last fifteen years, several big floods occurred in the Danube Basin, e.g. on the Upper Danube in June 2013, in August 2002, and on the Central and Lover Danube in March–April 2006, and in 2014 (Fig. 1.12). The highest discharge on the Upper Danube during the instrumental period occurred at Krems/Kienstock, 11 900 m3s-1 in 2013, the second highest was 11 306 m3s-1 in 2002 and the third one 11 200 m3s-1 in 1899. At Bratislava the highest peak discharge was in the year 1899. At the Danube delta Bondar a Panin (2001) evaluated the discharge of 20 940 m3s-1 during the flood in July 1897. The assessment of long-term trends in Qmax series is very complex and questionable with respect to the quality of the assessment of the maximum annual discharges Qmax in the past. The period 1840–1899 was influenced by several catastrophic floods in the Upper Danube area (Fig. 1.12). In contrast, the period of 1901–1953 was relatively quiet in terms of flood risk. The period after 1953 is disquiet. In the middle Danube area at Orsova / Turnu Severin a long-term linear trend in Qmax series is almost constant. On the lower reaches of the Danube, there is no station with a sufficiently long series of Qmax. Catastrophic floods on the Upper (from the Danube source to Bratislava gauge), the Central, and the Lower Danube (from the Orsova gauge to the river outlet), usually do not occur simultaneously. At Hofkirchen the highest floods were in years: 1845, 1862, 1882, 1954, 1999, and 2013. Between Passau city and Bratislava, the highest floods during the observation period were in years 1830, 1862, 1897, 1899, 1954, 2002, and 2013. The same phenomena occurred in the middle course in 1838, 1893, 1897, 1938, 1940, 1941, 1954, 1956, and 2006. According to Bondar (2003) the highest floods in the lower part of watershed were in 1845, 1853, 1888, 1895, 1897, 1907, 1914, 1919, 1924, 1932, 1940, 1941, 1944, 1947, 1954, 1955, 1956, 1958, 1962, 1965, 1970, 1975, 1980, 1981, and 1988. A part of these floods occurred also due to ice jams along the Danube in the winter-spring season. In the years 1897, 1965, or in 2006, the floods occurred in the whole Danube Basin (Fig. 1.13).

21 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

4500 Hofkirchen -1 s 3 2500 m

500 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000 2020

11000 Kienstock/ Stein Krems 8000 -1 s 3

m 5000

2000 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000 2020 11000 Bratislava 8000 -1 s 3

m 5000

2000 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000 2020 17000 Orsova/Turnu Severin 14000 -1

s 11000 3 m 8000

5000 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000 2020 20000 Reni 17000

-1 14000 s 3 11000 m 8000 5000 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000 2020 Fig. 1.12 Maximum annual discharge in selected stations downstream the Danube.

We consider as high floods at Bratislava on the Upper Danube the periods, when the water discharge exceeds the value of 5 000 m3s-1. At Central Danube at Turnu Severin/Orsova the threshold is 11 000 m3s-1 (Pekárová et al., 2009). Due to the long propagation distance (over 950 km to the Black Sea) a certain attenuation of the high floods occurs downstream. The duration of high floods at Bratislava is 5–10 days, on the Lower Danube section the high floods generally exceed 40 days, but exceptionally the duration may reach 200 days (e.g. in the year 1965).

22 Flood marks along the Danube River between Passau and Bratislava

20000 1954 ]

-1 15000 s 3 Zimnicea Orsova Linz Bratislav Krems Ceatal Passau Nagymaro 10000 Mohacs Budapest Qmax [m Regensbur 5000 Wien Berg

0 3000 2500 2000 1500 1000 500 0 a) river km

20000 2006 ]

-1 15000 s 3 10000

Qmax [m 5000

0 3000 2500 2000 1500 1000 500 0 b) river km

Fig. 1.13 The 1954 and 2006 Danube flood peaks along the Danube River length.

20000 1501 1897 Krems Linz 15000 p99 ] -1 Bratislava s 3 p50 10000

Qmax [m 5000

0 3000 2500 2000 1500 1000 500 0 river km Fig. 1.14 Percentiles of the maximum annual discharge in selected stations downstream the Danube in the period 1876–2006. p99-, p50- percentiles and historical floods 1501 and 1897.

In Fig. 1.14, there are the percentiles of the maximum annual discharge in selected stations downstream the Danube River and reconstructed discharge during the historical flood in 1501. According to Kresser (1957) the peak discharge in 1501 was 11 000 m3s-1 at Linz, and 14 000 m3s-1 at Stein Krems.

23 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

2250 Passau 2200 Achleiten

2150

2100 Ybss 2050 1899 Kienstock 2000 Stein Krems 2002 1950 1954 Vienna

1900 Bratislava 1850 River station [rkm]

1800

Komárno 1750 1897 2013 Sturovo 1700 Nagymaros 0 153045607590105120135150165180195 Travel time [hrs] Fig. 1.15 Travel times of the highest floods between Passau and Nagymaros.

The travel time of the flood waves between Hofkirchen (2 257 rkm) and Passau (2 226.7 rkm) is 25 hrs, with an average celerity of 30 km/day. The travel time of the wave between Passau (2 226 rkm) and Bratislava (1 869 rkm) was 96 hours in 2002 (wave celerity of 89 km/day), in 1954 it was 130 hours (wave celerity of 66 km/day). The travel time of the highest floods between Bratislava (1 869 rkm) and Orsova (955 rkm) is around 16 days, with an average celerity of 57 km/day. For example the travel times of the important floods in the reach Passau– Nagymaros are presented on Fig. 1.15. According to Bondar (2003) the time difference between the high floods at Orsova and Black Sea mouth is of 15–20 days, when the high flood wave travels along the Danube River with an average celerity of about 53 km/day (Fig. 1.16).

16000

12000 Ceatal ] -1 s

3 8000 Turnu Severin

Q [m 4000 Bratislava 0 123456789101112 1940 Fig. 1.16 Daily discharge of the Danube River at three water gauges: Bratislava, Turnu Severin/Orsova and Ceatal Izmail, year 1940.

24 Flood marks along the Danube River between Passau and Bratislava

35 35 Achleiten Bratislava 30 30 1901-2005 1901-2005 25 25 20 20 15 15 10 10 5 5 0 0

t t r t r t n h r y e y v c n h r y e y v c l g l g c c b p b p a c p a n o e a c p a n o e u u u u e r e e r e J u O J u O A A J N D J N D M A M A a a F S F S J J

M M

35 35 30 Ors ova 30 Ceatal Izmail 1901-2005 1931-2005 25 25 20 20 15 15 10 10 5 5 0 0

t r t t r t n h r y e y v c n h r y e y v c l g c l g b p c b p a c p a n o e a c p a n o e u u u u e r e e r e J u O A J u O J N D A M A J N D a M A F S a J F S J

M M

Fig. 1.17 Frequency of occurrence of the maximum annual discharge in individual months in selected stations downstream the Danube.

Finally, we assessed the occurrence of maximum annual discharge in four Danube stations in order to make basic comparison of the flood regime in individual parts of the river basin (Pramuk et el., 2014). The floods occur most frequently in June–August in the Upper Danube River Basin, in April in the Central part, and in April–May in the Lower Danube River Basin (Fig. 1.17).

25 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

2 The Danube flood marks between Passau and Bratislava

The aim of this chapter is to analyse the occurrence of the floods in the Upper/Central part of the Danube River, based on historical archive information (period 1000–1875), historical flood marks, and measured discharge series at Bratislava station (period 1876–2013).

2.1 The Danube floods in the middle age

The analysis of historical floods occurrence on the upper Danube is in the first part of the chapter. It is based on the historical flood marks in Passau, Linz, Mauthausen, Ybbs, Melk, Spitz, Krems, Hainburg, Bratislava, Štúrovo, and Budapest. The oldest evidence of floods on the Danube goes back to 1012. Other floods with severe consequences, as documented in historical annals, occurred in 1051, 1060, 1086, 1173, and 1210.

The occurrence of the Danube medieval floods on its Austrian–Slovak– Hungarian stretch has been described in detail by Kiss (2011) in her dissertation. As very high summer floods were denoted those in years 1235, 1316, 1402, 1414, 1432, and 1490 (Fig. 2.1). In general, the 15th century is known by a high flood occurrence. The Danube floods history at Bratislava was in centre of attention of Horváthová (2003). In her publication, she described the flood occurrence based on analysis of the archive materials. From the 15th century, there are preserved mainly the references about the Bratislava ice floods (ice jams, ice barriers) damaging the bridge.

26 Flood marks along the Danube River between Passau and Bratislava

These floods damaged seriously also the city buildings by ice floes. For example, Sigismund of Luxemburg, the Hungarian, the Czech, and the Roman king, ordered in 1426 to repair the protective flood bank levees, damaged by the preceding floods. In 1430, Sigismund ordered to construct the bridge across the Danube at Bratislava. Its part was supported by piers and other part was laid on large boats (pontoons). Records on damage of this bridge can be considered as proofs of the high floods occurrence in the first half of the 15th century. For example, the flood washed away one pontoon on 20 March 1439, three bridge fields were washed out on 30 July 1440, and the flood damaged the whole bridge completely on the Good Friday (Easter) 1443.

15000 ]

-1 13000 s 3 11000

9000

Qmax [m 7000

5000 1000 1100 1200year 1300 1400 1500

Fig. 2.1 The Upper Danube (to Budapest) incidence since the year 1000 up to 1500 according to Kiss (2011) (red columns - summer floods, blue columns – ice floods).

Mathias Corvinus, the Hungarian king, ordered to build another bridge over the Danube at Bratislava in 1472. Its construction was similar to the previous one. On beginning of September 1478, a flood damaged three of the bridge fields, on the New Year 1482 and in the spring 1485, the bridge was damaged by the ice floes. At the end of July 1485, the bridge was damaged again by flood, and a following wave on the 1 September 1485 demolished it completely. According to information in chronicles, many people perished in Bavaria during the August 1485 flood. In 1486, the bridge at Bratislava was damaged again by ice floes, and the king Mathias Corvinus forced the city of Bratislava to repair it. High floods occurred also in the years 1490 and 1499.

27 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

2.2 The Danube floods within the 1501–1876 period

The water level marks of the highest Danube floods (after 1500) remained on historical buildings in Germany and Austria. Such examples are shown on following photos (Figs. 2.2a–m) from cities located close to the river (Vilshofen, Passau, Linz, Mauthausen, Ybbs, Melk, Emmersdorf an der Donau, Dürnstein, Spitz, Schönbühel, Stein–Krems, Hainburg and Budapest). These marks make it is possible to imagine a real Danube water level elevation, and to compare them each against the others. It should be taken into attention that the Danube river channel morphology changed several times in course of the centuries. It also happened, that during building reconstructions, the reconstructed marks were not located correctly, or the old data were corrected (Fig. 2.2b– b’). Moreover, not each of the significant floods must have been marked on the particular location. For these reasons, it is necessary to follow also other archive sources. As shown in the photos, so far the highest flood, reliably and authentically marked on the Danube River stretch between Passau and Bratislava, occurred in August 1501 (Kresser, 1957; Rohr, 2005). The peak discharge at Linz was estimated up to 12 000 m3s-1, and at Vienna it was 14 000 m3s-1. Discharge of 11 000 m3s-1 at Ybbs was exceeded probably by the summer floods on 25 June 1682, on 31 October 1787 and by a “rain” flood on 3 February 1862.

Economic impact of the “millennium flood” of 1501 can be reconstructed in a great detail: carpenters and other craftsmen worked from August to December 1501, and again several months later in 1502, with the aim to repair the bridge (Rohr, 2005). Numerous meadows and orchards along the riverside were destroyed and their owners were changed. Perhaps the former owners perished during the flood or moved away.

28 Flood marks along the Danube River between Passau and Bratislava

Fig. 2.2a The Danube flood marks, Vilshofen. (Photo, Creative Commons 2010).

29 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Fig. 2.2b The Danube flood marks, Passau. (Photo Miklánek left 2010; right 2014). After the June 2013 flood the flood mark of 1501 was increased.

30 Flood marks along the Danube River between Passau and Bratislava

Fig. 2.2b’ The Danube flood marks, Passau. (Photo, left - Daneček, 2010; right - Lešková 2014; down - Robert Lesti, http://www.flickr.com/photos/45224155@N06/7793930312 ).

31 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Fig. 2.2c The Danube flood marks, Linz 1501, 1954 and 1787. (Photo: up - Christian Wirth http://www.linzwiki.at/wiki/Datei:Linz_Urfahr_Hochwasserstand_1501.jpg/; down - http://commons.wikimedia.org/wiki/File:Linz_PA_Hochwasser1501_Gedenkstein_Glei%C 3%9Fnerhaus.jpg).

32 Flood marks along the Danube River between Passau and Bratislava

Fig. 2.2d The Danube flood marks, Mauthausen. (Photo Miklánek, 2010).

33 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Fig. 2.2e The Danube flood marks, Ybbs. (Photo Miklánek, 2010).

34 Flood marks along the Danube River between Passau and Bratislava

Fig. 2.2f The Danube flood marks, Melk. (Photo Miklánek, Pekárová, 2014).

35 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Fig. 2.2f’ The Danube flood marks, Melk, detail. (Photo Miklánek, Pekárová, 2014).

36 Flood marks along the Danube River between Passau and Bratislava

Fig. 2.2g’ The Danube flood marks, Emmersdorf an der Donau. (Photo Alexander Szep, 2014, http://www.panoramio.com/photo/106599261).

37 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Fig. 2.2h The Danube flood marks, Dürnstein. (Photo Pekárová, 2014).

38 Flood marks along the Danube River between Passau and Bratislava

Fig. 2.2i The Danube flood marks, Spitz. (Photo left: http://dswarthout.blogspot.sk/2014/05/danube-bike-trip-day-5.html right: Miklánek, 2014).

39 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Fig 1.3j Building with the Danube flood marks in Schönbühel. (Photo Pekárová, 2010).

40 Flood marks along the Danube River between Passau and Bratislava

Fig. 2.2k The Danube flood marks, Stein-Krems. (Photo Pekárová, 2014).

41 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

2013

Fig. 2.2l The Danube flood marks, the Hainburg water gauge. (Photo Pekárová, 2011, 2014).

42 Flood marks along the Danube River between Passau and Bratislava

1809 1876

1899 1897 1787

Fig. 2.2l’ The Danube flood marks, Hainburg. (Photo Pekárová, 2011).

43 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Fig. 2.2m The Danube flood marks, Budapest. (Photo Pekárová, 2011; Nagy, 2014).

44 Flood marks along the Danube River between Passau and Bratislava

3 Flood marks in Bratislava before instrumental period

At Bratislava, the Danube formed many arms in the past. After high floods; it changed its river bed regularly. In the 13th century, one of these arms flew along the old city walls over the today’s Hviezdoslav square. During catastrophic floods, the Danube waters and the groundwater flooded even the old city centre (Fig. 3.1a).

3.1 Summer floods in Bratislava

Serious flood thread to Bratislava present the summer floods caused by extensive rainfall systems moving through the Danube River Basin from west to east. The floods of August 1501, July 1670, June 1682, and November 1787 belong among such floodings.

3.1.1 Flood of 1501 and 1670

The oldest flood marks on the territory of Bratislava were from the beginning of the 16th century (Pekárová and Miklánek, 2012). One was situated on the Vydrická brána (Vydrická Gate) third pier, and the other one was on the border pole between Zuckermandel and Vydrica (Bel, 1735). The Vydrická Gate was located in the old city south-western part, where the routes started to Vienna and Rusovce (Fig.3.1a). Location of this gate is denoted in Fig. 3.1b by year 1501. The Vydrická Gate was demolished in 1778. Drawings in Fig. 3.2 show this gate prior to 1777, and the photo down shows it at present.

45 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

old city

The Vydrická gate The Danube River

b) Fig. 3.1 a) The Danube River arms and the old Bratislava in year 1291 (according to V. and D. Mencl adjusted by J. Hanák (Hanák, Kopuncová, 2007)). b) Flood marks in the old Bratislava city: Yellow colour – flood marks still existing, Red colour – flood mark not existing today, Blue colour – only photos of the flooded area are available.

46 Flood marks along the Danube River between Passau and Bratislava

Fig. 3.2 The Vydrická Gate from the year 1563. (left up - part of the king Maximilian coronation picture, Dvořák, 2007); right up - painting according to K. H. Frech (Benyovszky, 2001); down - rest of the former Vydrická Gate (Photo Pekárová, 2011).

This oldest flood marks description was presented by Matej Bel in his fundamental work (Bel, 1735), as shown in Fig. 3.3a. Dating of this flood is not unambiguous. Matej Bel lived at the time when the Vydrická Gate has not been yet demolished (it happened in 1778). So he could have seen it by his own eyes. However, he does not notice its year of origin. According to historian Holčík (2011), it is probable, that if this year would have been graved on the Gate’s cross, Bel would notice it. Similar flood marks from the 1501 flood, with cross sign, you can find in Passau (Fig. 3.3b). The Vydrická Gate flood mark was described also by the Bel’s followers - Korabinský (1786) and Windisch (1780). They date it to the year 1516 (Fig. 3.4a–b). According to Čičo (2012), Korabinský (1786) described this flood mark in another way: “In the 18th century in front of the warehouse gate there stood the well and one very old statue of the bishop facing the river with the marked 1516 year, and inscription Quod Istri vis hic diruit hoc rursus est exstructum, Anno 1670 on the rear side, together with the city coat-of-arms”. In his Notitia, Bel (1735) gives also information on another 1516 Danube flood mark. It was located on the stone column with a cross sign, on the limit

47 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V. between Zuckermandel and the Vydrica, close to the Danube in front of the Kings arsenal building (Fig. 3.1 - point 1501, 1670, Fig. 3.5).

b) Fig. 3.3 a) Bel(1735), page 634, translation - …Inside of this Gate, on third of columns supporting the vault, there is a doubled cross carved into the stone, which should retain memory on Danube flood, which says that it flooded this gate to water height more than four feet. b) Similar flood marks with cross sign from the 1501 flood in Passau (Photo: http://commons.wikimedia.org/wiki/Category:Flood_level_signs_in_Passau ).

b) Fig. 3.4 Notice on the Vydrická Gate Danube flood mark a) according to Korabinský (1786), translation: … 1516, big flood which was marked on the Vydrická Gate…, b) according to Windisch (1780), translation: ….Under this Gate there was on the third pier a doubled cross carved, reminding a large Danube flood from the 1516 year, …

48 Flood marks along the Danube River between Passau and Bratislava

Fig. 3.5 Bel (1735), page 638. Translation: …As limit between two peripheries the mark rises of cross located on a rock column…1670. What was destroyed by a wild Danube, has been reconstructed again……The cross was displaced, perhaps by the ice flood, and lastly renewed again on account of the municipality. On the column part facing river, take notice of the memorial groove, reminding that during the 1516 year flood, water rose up to one and a half of fathom over the river banks.

In Fig. 3.6 we can see the column together with the statue in front of the King’s arsenal as engraved on a copperplate from 1730–1735, and the arsenal photo from the year 1935. The mentioned column and statue were lost. It is possible that they were demolished by some of the ice floods in Bratislava in years 1775, 1809, or 1850. Taking into account the flood marks in surrounding cities, we suppose that the Vydrická Gate flood mark flagged the 1501 flood highest water level. The documents from the 6 May 1503 also confirm the occurrence of the 1501 flood in Bratislava. According them, the Czech and Hungarian king Vladislaus II. Jagellon confirms liberation of Bratislava from paying contributions and charges to the Esztergom archbishop (Horváthová, 2003). He also ordered not to exact debts of the Bratislava inhabitants, because the flood (probably that of August 1501) has caused them large damages. At beginning of July 1670 the flood inundated a large part of the Žitný ostrov (Rye island) between Bratislava and Komárno. During this flood, about 500 people perished, and approximately 4 thousands of cattle were lost (Horváthová, 2003). As already mentioned, this flood was reminded in Bratislava by a cross on column located on the city limit between its parts Zuckermandel and Vydrica (Bel, 1735).

49 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Fig. 3.6 Detail of the King’s arsenal at Podhradie extramural settlement, (up: Werner, copper plate engraving 1735, GMB- Bratislava City Gallery, down: aerial photo from the year 1935).

50 Flood marks along the Danube River between Passau and Bratislava

3.1.2 Flood of October and November 1787

The most severe flood in the 18th century – which became to be known as the All Saint’s Flood – occurred at the end of October and beginning of November 1787. The peak discharge at Vienna reached 11 800 m3s-1 according to the historical annals of the Austrian Hydrographic Service. Detailed description of this flood on the Bratislava territory was presented by Pišút (2011). The Danube water level was rising since 28 October 1787. On 1 November 1787 water broke the right (Petržalka bank) protective bund with the Vienna road (built on direct Maria Teresia command only few years prior to this flood, in years 1773–1774). Water flooded the whole Petržalka up to Rusovce community. A large lake arose here which served immediately as large polder. Consequently, thanks to Vienna road breach in length of 406 meters, the water rise was stopped in the old Bratislava city. In spite of that, water flooded the quay and broke also into courtyards and cellars of the inner city. High Danube water levels in Bratislava lasted from 26 October to 6 November 1787 (Preßburger Zeitung, No. 88, 89). The flood peaked on 3 November 1787 in Bratislava with the discharge over 11 800 m3s-1. Would not the Vienna Road protective bund breach, the flood peak would reach 12 200 m3s-1, such as at ice floods of the years 1809 and 1850 (Pišút, 2011). Close to Bratislava, a mark to this flood has been preserved in Hainburg (Horváthová, 2003). According to Preßburger Zeitung No. 88, the 1787 flood water level exceeded that of the large ice flood in 1775, marked by groove on the military Water barracks (Pišút, 2011). During this flood, large erosion of the Danube banks occurred, as well as a huge sediment transport through the river channel.

3.2 Ice floods in Bratislava

The Danube ice floods of the local importance occurred quite often during the small ice age (17th through 19th centuries). In winter the ice barriers have been formed often in the Danube River channel, which in consequence swelled up the water endangering the neighbouring land. At present, they do not represent such threat as in the past. Freezing up of the Danube water surface does not occur frequently anymore due to the river channel

51 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V. morphology corrections, warming of the air, and possibility of the Danube water level artificial change. The large ice flood of 1526 is the first one documented in the municipal archives of the Bratislava city (Horváthová, 2003). The 1526 flood occurred unexpectedly overnight, with an aftermath of 53 fatalities. Other ice floods in Bratislava followed in years 1721, 1775, 1784, 1809, 1813, 1847, 1850, 1895.

3.2.1 Flood marks from the year 1775

Historical documents from the 18th century include a reference to two flood marks in Bratislava, which recorded the water level of the Danube River from February 1775 (Melo et al., 2014). These flood marks were located on the buildings of the former Water Barracks (Fig. 3.7a) and the former Bathhouse (Lower Spa) (Fig. 3.7b). Neither of these marks has survived until present day. The first flood mark was probably destroyed during the demolition of the southern wing of the Water Barracks, and the second one disappeared probably during rebuilding of the house of former spa or during its demolition. Therefore at the present stage of research, other details about the two marks, especially their location in terms of elevation above ground level, remain unknown. It can be concluded that the 1775 flood on the Danube River must have been severe at Bratislava since water flooded the inner town (originally located inside the historical city walls); this can be also supported by information about the discovery of a flood mark in a building of the former Bathhouse (Lower Spa) at the crossing of Laurinská street and Rybná gate.

Fig. 3.7a Flood in year 1899 near the building of Water barracks (behind) with flood mark from 1775. (http://www.bratislavskerozky.sk/sk/Databaza-bratislavskych-pohladnic.html).

52 Flood marks along the Danube River between Passau and Bratislava

Fig. 3.7b The corner of Rybná gate and Laurinská street in 1926. (Bratislava municipality archive, AMB 05271).

A more detailed overview of the February 1775 flood was established based on reports published in the contemporary local press (Preßburger Zeitung). The Danube flooded mainly area of Blumentál (eastern part of Bratislava) and some villages (Prievoz, Vrakuňa, Vajnory). Catastrophic consequences of the flood were reported especially from the lower part of the Danube River (Vác, Pest, Óbuda, Buda, and Ráckeve) in Hungary.

3.2.2 Flood marks from the year 1809

Very clear and detailed description of the 1809 Bratislava flood was elaborated by Pišút (2002, 2008, 2009). In 1809, the Danube River breached the right hand bunds and its waters flooded the city suburb Petržalka. Memorial flood mark on this flood can be found there, close to the horse race course on the old historical Kotešova gamekeeper’s lodge (Fig. 3.8a). In the front of the gamekeeper´s lodge, there is a stone cross with inscription: “Zur Errinerung an 1809 von den Burgern Pressburgs 1869” (In memory of 1809, from citizens of Pressburg, 1869). According to what people say, the big flood of 1809 brought a wooden cross to this place. Because nobody appealed to the cross, it was erected in front of the gamekeeper’s lodge. As time passed, it mouldered, and on its place, a stone cross was erected in 1869 (Fig. 3.8b). Nearby, there is a pedestal with the evening bell.

53 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Fig. 3.8a Old gamekeeper’s lodge in Petržalka (Koteš’s lodge, later pub.) Stone cross from the year 1869, built on place of the 1809 wooden cross (photo about 1947 Bratislava municipality archive, AMB).

The most damaged parts on the left bank in the Bratislava city were: Zuckermadel, Vydrica, Gorkého St., Jesenského St., and Laurinská St., as well as Grösslingova St. A mark of this flood was located on building in the Lodná St. (Photo 3.8c). The 1809 ice flood belongs to the most extreme floods among the ice floods. The reason is that it influenced not only the Danube–Komárno river stretch close communities, but it also hit those located at the lower section of the Morava River. This flood demolished 35 houses in Vysoká pri Morave, and 30 houses in a close Zohor village. In Komárno, on 2 February 1809, water swelled up by the Danube ice barrier breached the protective bund, and demolished 400 houses.

54 Flood marks along the Danube River between Passau and Bratislava

1809

1850

Fig. 3.8b Overall view on the little chapel with cross from the year 1909, built at occasion of the 1809 flood centennial anniversary, and the gamekeeper’s lodge with memorial plates today (Photo Pekárová, 2011). The detail of the 1809 flood memorial plate, and the 1850 flood mark on the gamekeeper’s lodge in Petržalka (Photo Pekárová, 2011), right.

55 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Fig. 3.8c Flood mark from the 1809 flood at Lodná St. in Bratislava, (Photo from 1947- Bratislava municipality archive, AMB).

56 Flood marks along the Danube River between Passau and Bratislava

3.2.3 Flood marks from the year 1850

During the flood of 1850 (on February 5), the streets of Bratislava were under water again. Flood marks on old buildings in the downtown are still showing the height of the water level during this flood (Fig. 3.9–3.10). The water stage was the highest in the water level measurement period at Zuckermandel (140.7 m a.s.l. according to Piffl, 1967). It is possible to find five preserved marks of the ice flood in 1850 at Bratislava. The development of this flood was described by Horváthová (2003). After creating ice jams, the water level of the Danube surged and on 5 February 1850 the water flooded the streets of Bratislava city to the level

Fig. 3.9 Zuckermandel - Neumann Inn at the corner of the Ballus St. and Podhradie embankment –flood mark of the flood on 5 February 1850. (Photo: archive of Jozef Hanák – Bratislava municipality archive, AMB).

57 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

1850

1899

Fig. 3.10 Zuckermandel – Neumann Inn at the corner of the Ballus St. and Podhradie embankment –flood in 1899 and flood mark of the flood on 5 February 1850. (Photo: archive of Jozef Hanák – Bratislava municipality archive, AMB). corresponding to water level of 1 123 cm (elevation 139.66 m a.s.l.) at the current water gauge according to the Slovak Water Management Enterprise (SVP, 2007). According to contemporary press 6 people have been killed, several houses have been destroyed, ice floes broke windows, and tore down the walls. One such sign is located on the Old Town Hall (Main Square) with the inscription 5 Febr 1850, but currently the year 1850 is only visible, which according to SVP (2007) refers to the culmination at 139.656 m a.s.l. (Fig. 3.11). The other preserved flood mark can be found on the Primate's palace (Uršulínska St.) with the inscription 1850 Febr 5 and with the line indicating 139.660 m a.s.l. according to SVP (2007) (Fig. 3.12). The third one is placed 182 cm above the pavement at the corner of Laurinská and Uršulínska streets with the inscription 5.Feber 1850 and with the line indicating 139.650 m a.s.l. according to SVP (2007) (Fig. 3.13). Another one is the plate placed on the house No. 9 (Laurinská St.) with the inscription 5. Feber 1850 and with the line indicating 139.130 m a.s.l. according to SVP (2007). It is supposed that it was placed in wrong height during the reconstruction works in the past (Fig. 3.14). The fifth preserved mark can be found on the building of the SNG (in the court at the entrance to the former Water barracks) with the inscription 5.Feber 1850 – výška vody

58 Flood marks along the Danube River between Passau and Bratislava

(translation: water level) and with the line indicating 139.720 m a.s.l. according to SVP (2007) (Fig. 3.15).

Fig. 3.11 Flood mark on the building of the Old Town Hall in Bratislava. (Photo Melo, 2012).

Fig. 3.12 Flood mark on the building of the Primate's Palace in Bratislava. (Photo Melo, 2012 and Pekárová, 2014).

Fig. 3.13 Flood mark on the house at the corner of Laurinská and Uršulínska streets in Bratislava. (Photo Melo, 2012).

59 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Fig. 3.14 Flood mark on the house at Laurinská St. No. 9 in Bratislava. (Photo Pekárová, 2014).

Fig. 3.15 Flood mark on the building of the former Water barracks, now the building of the Slovak National Gallery (SNG) in Bratislava. Blue dashed line - water level during the 1850 flood. (Photo Pekárová, 2012, 2014).

60 Flood marks along the Danube River between Passau and Bratislava

Fig. 3.16 The 1850 flood mark on the gamekeeper’s lodge in Petržalka (Photo Pekárová, 2011, 2014, see Fig. 3.8b as well).

As mentioned earlier, one flood mark is preserved also in Petržalka city district (Fig. 3.16). From the above analysis it follows, that within the period from 1500 to 1876 (beginning of the Danube discharge evaluation at Bratislava), in average a summer flood occurred once in 100 years with the peak over 11 800 m3s-1 (1501, 1670, 1682, 1787, 1862). In addition, city was often flooded by the ice floods. The occurrence of the large Danube floods between the years 1000 and 1876 is shown in Fig. 3.17 (red columns - summer floods, blue columns - ice floods). We processed this picture with accounting the floods described by various authors in cities close to Bratislava, like Kresser (1957), Horváthová (2003), Neweklowsky (1955), Pišút (2011), and Kiss (2011), or in historical studies (Bel, 1735), and in the old volumes of the newspaper Pressburger Zeitung.

1501 ] 15000 1012 -1 1210 1670 1787 s 3 10000

5000 Danube [m

max 0 Q 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 year Fig. 3.17. Occurrence of the large Danube floods between the years 1000 and 1876 (red columns - summer floods, blue columns – ice floods).

61 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

4 Flood marks at Bratislava during the 1876–2013 period

The first water stage measurements on the Danube River at Bratislava (1 868.8 rkm, catchment area 131 338 km2) were made in 1823. After 1876 the average daily river stages were recorded in Hungarian yearbooks Vizallasok (1890). The gauge datum was at 131.08 m J (Adriatic system). The historical water gauge is shown on photo Fig. 4.1a and compared to the current water gauge on photos 4.1b and 3.15. In 1942, the Bratislava gauge datum has been lowered by two meters, down to 129.08 m J (Adriatic system). After 1964, the gauge datum was determined at 128.43 m Bpv (Baltic system). The water gauge in Bratislava in 2007 and 2012 is shown on Figs. 4.2 and 4.3. The water gauge in Devín in 2011 is shown on Fig. 4.4. The first discharge observations at Bratislava, based on measurements of flow velocities, were available as early as 1882 (Mitková et al., 2005; Pekárová et al., 2007a; Svoboda et al., 2000). Water stage measurements on the Danube River at Bratislava have been routinely processed since 1901. In 2003, the staff of the SHMI (Slovak Hydrometeorological Institute) extended the average daily discharge series by adding data from 1891–1900. In our previous works we extended the average daily flow records by adding 15-years of daily water level observations 1876–1890 according to historical rating curve (Škoda and Turbek, 1995; Pekárová et al., 2007a–b, 2008; Pekárová, 2009, 2010). After commissioning the Gabčíkovo works, flow rates are evaluated according to Devin gauge (Fig. 4.4). Average daily discharge characteristics of the Danube River at Bratislava (1876–2013) are presented in Table 4.1. Table 4.1 Average daily discharge characteristics of the Danube at Bratislava (1876–2013). Mean Min Max 330-day 30-day cs cv Q (m3 s–1) 2 059 580 10 810 1 040 3 440 1.7 0.48 q (l s–1 km–2) 15.7 4.4 82.2 7.9 26.2 R (mm) 494.3

62 Flood marks along the Danube River between Passau and Bratislava

a) 1870

b) 2007 Fig. 4.1 a) Water gauge in Bratislava in 1870. (Photo Korper, 1870) b) Water gauge in July 2007. (Photo Pekárová, 2007).

63 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

a) 21 July 2007

b) 8 February 2012 Fig. 4.2 a) Water gauge in Bratislava in 2007. (Photo Pekárová, 21 July 2007) b) Water gauge in 2012. (Photo Pekárová, 8 February 2012).

64 Flood marks along the Danube River between Passau and Bratislava

Fig. 4.3 Left - water gauge in Bratislava in 2007. (Photo Pekárová, 21 July 2007) right - water gauge in 2012. (Photo Pekárová, 8 February 2012).

Fig. 4.4 Water gauge in Devín in 2011. (Photo Pekárová, 21 March 2011).

65 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

12000 3000 10000 2500 ]

-1 Danube - Bratislava

s 8000 2000 3 6000 1500 4000 1000 Qd [m 2000 500 0 0 01.01.1850 03.01.1860 04.01.1870 06.01.1880 07.01.1890 9/Jan/1900 11/Jan/1910

12000 3000 10000 2500 ] -1

s 8000 2000 3 6000 1500

Qd [m 4000 1000 2000 500 0 0 2-Jan-1900 1-Jan-1910 1-Jan-1920 1-Jan-1930 1-Jan-1940 1-Jan-1950 1-Jan-1960

12000 3000 10000 2500 ] -1

s 8000 2000 3 6000 1500

Qd [m 4000 1000 2000 500 0 0 1-Jan-1960 1-Jan-1970 1-Jan-1980 1-Jan-1990 1-Jan-2000 1-Jan-2010 1-Jan-2020

Fig. 4.5 Variability of the average daily discharge of the Danube River at Bratislava during the period 1876–2013; light blue line – five years moving averages.

9000 P 99 8000 P 90 7000 P 50 6000 P 01 ] -1

s 5000 3 4000

Qd [m 3000 2000 1000 0 01-Jan 01-Apr 01-Jul 01-Oct Fig. 4.6. Long-term percentiles of the daily discharges, Bratislava gauge, 1876–2013.

On Figure 4.5, there is depicted the time series of the average daily discharge, and on Fig. 4.6 there are the percentiles of the daily discharges during the 1876–2013 period. Average annual discharges vary between 1 419 m3s–1 (in 1934) and 2 910 m3s–1 (in 1965) with long-term average 2 059 m3s–1 (Table 4.2, Fig. 4.7).

66 Flood marks along the Danube River between Passau and Bratislava

Table 4.2. Average annual discharge characteristics of the Danube River at Bratislava.

Qa qa Qmin Qmax cs cv Med. Trend (m3s–1) (ls–1km–2) (m3s–1) (m3s–1) (–) (–) (m3s–1) 1876–2013 2 059 15.7 1 420 2 910 0.31 0.16 2 042 -0.0251

3000

] Danube: Bratislava y = -0.0251x + 2060.8 -1 .s 3 2200 [m a Q

1400 1870 1890 1910 1930 1950 1970 1990 2010

Fig. 4.7 Variability of the average annual discharge of the Danube River at Bratislava during the period 1876–2013.

In Table 4.3, there are statistically processed the maximum annual discharges Qmax at Bratislava for the period after 1876. This time series is depicted on Fig. 4.8. Several of the greatest floods at Bratislava during the instrumental observation period occurred in the last quarter of the 19th century (1876–1900). Five floods with peak discharge exceeding 10 000 m3s–1 occurred during the 1876–2013 period: once in June (2013), July (1954) and September (1899), and twice in August (1897, 2002). This data correspond to the data published in Blöschl et al. (2013), and Blaškovičová et al. (2006, 2013).

Table 4.3. Annual maximum discharge characteristics of the Danube at Bratislava.

Qmax qmax Min Max cs cv Med. Trend (m3s–1) (ls–1km–2) (m3s–1) (m3s–1) (–) (–) (m3s–1) 1876–2013 5 866 44.7 3 000 10 870 0.86 0.28 5 604 2.112

10500 ] Danube: Bratislava/Devín -1 .s

3 8500

[m 6500 max

Q 4500

2500 1870 1890 1910 1930 1950 1970 1990 2010 Fig. 4.8 Variability of the annual maximum discharge of the Danube River at Bratislava during the period 1876–2013.

67 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

4.1 Summer floods

The largest floods of the rainfall origin occur typically in summer months from June to September on the Danube River. The largest summer floods at Bratislava were observed in 1897, 1899, 1954, 2002, and 2013.

10000 1897

] 8000 -1 s

3 6000 4000 Q [m 2000 0 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

10000 1899

] 8000 -1 s

3 6000 4000 Q [m 2000 0 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

10000 1954

] 8000 -1 s

3 6000 4000 Q [ m 2000 0 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

10000 2002

] 8000 -1 s

3 6000 4000 Q [m 2000 0 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

10000 2013

] 8000 -1 s

3 6000 4000 Q [m 2000 0 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- 01- Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Fig. 4.9 Observed daily discharge at Bratislava in 1897, 1899, 1954, 2002, and 2013.

68 Flood marks along the Danube River between Passau and Bratislava

4.1.1 Flood of August 1897

The flood culminated on 4 August 1897. According to Angelini (1955), the peak water level was 940 cm and mean daily discharge 10 140 m3s-1 (Fig. 4.10). The flood is documented by the historical photo from the Bratislava city (Fig. 4.11). Large areas of the Western and Central Europe were hit by precipitation. E.g. on 29 July 1897, the meteorological station in the Jizera Mountains (Nová Louka), measured 345 mm of precipitation per 24 hours which is an European record (Munzar and Ondráček, 2010). 12000 1897 peak 4.08.1897 10000

] stage 940 cm -1 8000

s 3 -1

3 Qd 10 140 m s 6000 4000 Qd [m 2000 0 24-Jul 03-Aug 13-Aug 23-Aug

Fig. 4.10 Hydrograph of the August 1897 flood at the Bratislava water gauge.

Fig. 4.11 Flood 1897 in the Bratislava city (Photo: Bratislava City Museum).

69 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

4.1.2 Flood of September 1899

The flood culminated on 17 September 1899, and reached 11 200 m3s-1 (water stage 972 cm) at the Krems water gauge; and 10 500 m3s-1 at the Vienna water gauge. According to Angelini (1955), the peak water level at Bratislava was observed on September 19, with a stage of 970 cm (10 870 m3s-1) (Figs. 4.12–14). This flood was the consequence of a flash- flood on the Inn River, a tributary emptying into the Danube River at Passau (Kresser, 1957). 12000 1899 peak 19.09.1899 10000

] stage 970 cm -1 8000

s 3 -1

3 Qmax 10 870 m s 6000 4000 Qd [m 2000 0 08-Sep 18-Sep 28-Sep 08-Oct

Fig. 4.12 Hydrograph of the September 1899 flood at the Bratislava water gauge.

Fig. 4.13 Flood 1899 at Bratislava (Photo: http://www.bratislavskerozky.sk/sk/Databaza- bratislavskych-pohladnic.html.

70 Flood marks along the Danube River between Passau and Bratislava

Fig. 4.14 Flood 1899 at Bratislava (below) and the area at normal situation (above). (Photo: http://www.bratislavskerozky.sk/sk/Databaza-bratislavskych-pohladnic.html.)

71 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

4.1.3 Flood of July 1954

The flood of July 1954 was the highest flood on the Danube River at Bratislava in the 20th century (Angelini, 1955). In the middle Danube section it exceeded the 1899 flood values. The flood peaked at Bratislava on 15 July with a water stage of 984 cm and discharge of 10 400 m3s-1 (Figs. 4.15–16). Due to heavy rainfall, the Danube started to rise on 9 July in Bavaria. The Danube tributaries from the Alps have peaked earlier (8–9 July), and the Inn culminated on 10 July, so it coincided together with the rising Danube.

12000 1954 peak 15.07. 1954 10000 stage 984 cm ]

-1 8000 Qmax s

3 3 -1 6000 10 400 m s 4000 Qd [m 2000 0 01-Jul 11-Jul 21-Jul 31-Jul

Fig. 4.15 Hydrograph of the July1954 flood at the Bratislava water gauge.

Fig. 4.16 Flood 1954 at Bratislava, left wharf, right – the Bratislava water gauge. (Photo: Bratislava municipality archive, AMB).

72 Flood marks along the Danube River between Passau and Bratislava

4.1.4 Flood in the year 1965

This flood was of a different character. It originated as consequence of the long-lasting heavy rains, mixed with snowmelt, causing high soil saturation in the Upper and Central Danube Basin. Rainfall activity culminated on 9 to 12 June 1965 in the upper Danube River Basin, as well as in basins of tributaries from Czechoslovakia (Figs. 4.17–18). In Bratislava, the flood situation lasted from March to July. Flood was formed by six waves and this flood is first of all remarkable by its volume. In 1954 and 1965 the Danube bunds in the Slovak-Hungarian reach were broken in some parts, and the peak flows were therefore lower in downstream gauging stations (Komárno, Štúrovo, Nagymaros, Budapest).

12000 1965 peak 16.06.1965 10000 stage 918 cm 3 -1

] Qmax 9 225 m s -1 8000 s 3 6000 4000 Qd [m 2000 0 01.V 11.V 21.V 31.V 10.VI 20.VI 30.VI 10.VII

Fig. 4.17 Hydrograph of the 1965 flood at the Bratislava water gauge.

Fig. 4.18 Flood in 1965 in Petržalka, (Photo: Archive local library in Petržalka).

73 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

4.1.5 Flood of August 2002

Two floods, one smaller in March, and a larger one in August, occurred in the year 2002 on the Danube River at Bratislava. During the second flood (5–16 August 2002), two waves with discharges of about 6 800 and 10 370 m3s-1, respectively, were recorded at the Bratislava water gauge (Fig. 4.19). The peak water stage was 993 cm on 15 August. The Danube bunds in the Slovak-Hungarian reach were not broken. Height of flooding in the Danube floodplain forest is shown in Fig. 4.20. 12000 2002 peak 15-16. 08. 2002 10000 ]

-1 8000 stage 993 cm

s 3 -1 3 Qmax 10 370 m s 6000 4000 Qd [m 2000 0 04-Aug 14-Aug 24-Aug 03-Sep

Fig. 4.19 Hydrograph of the August 2002 flood at the Bratislava water gauge.

Fig. 4.20 August 2002 flood traces near Medveďovo, Kľúčovec. (Photo Bezák, 2002).

74 Flood marks along the Danube River between Passau and Bratislava

For comparison of the flood situation in the centre of Bratislava city in 1954 and 2002, there are two historical photos in Fig. 4.21. Near Bratislava the flood of 2002 is only documented by flood mark at Devín (Fig. 4.22).

Fig. 4.21 Flood 1954 – left, 2002 – right.

Fig. 4.22 Flood marks 2002 and 2013 at Devín. (Photo Pekárová, 2012).

75 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

4.1.6 Flood of May / June 2013

Extreme flooding in the Central Europe began after several days of heavy rain in late May and early June 2013. This extreme hydrological situation started on 29 May 2013 based on heavy rains in the upper part of the Danube River Basin. May 2013 was one of the three wettest months of May in the past 150-year in this part of the Danube River Basin. Heavy precipitation occurred mainly in sub-basins of the rivers: Isar, Inn, Traun, Enns, and Ybbs. The Bavarian basin, for example, had 120 mm of precipitation in average, the basins of Inn, Salzach, Traun, Enns and Ybbs had 150 mm of precipitation, per four days (29 May–2 June 2013). The sub- basin of the Danube River between Ybbs and the Morava River had 60 mm of precipitation (SHMI, 2013). Blöschl et al. (2013) described the June 2013 flood in the Upper Danube Basin, and compared it with the 2002, 1954, and 1899 floods. They described local atmospheric and meteorological conditions, and runoff generation of the 2013 flood. Considering that heavy precipitation did not occur only in the German part of the Danube River Basin, but also in the Austrian part of the Danube River Basin, water levels started to increase almost simultaneously. The Bavarian Danube and the Inn join at Passau. For example, the water level in the Passau-Ilzstadt water gauge already started to rise on 30 May from the water level of 553 cm to the level of 1 102 cm. After the confluence of the Bavarian Danube and Inn, the flood wave travelled downstream the Austrian Danube changing the shape and shifting the timing. Recorded flows from the Austrian part of the Danube were high, caused by heavy precipitation in basins of the rivers Traun, Enns and Ybbs. The culminations in the Austrian water gauges Ybbs and Kienstock started on the evening of Thursday 4 June 2013. The Danube River in Slovakia started to increase on Friday 31 May 2013. Due to temporary interruption in precipitation; the water level also temporarily did not rise. Water levels began to rise again from Sunday 2 June 2013 to Thursday 6 June 2013. The culmination of the Danube River occurred on Thursday 6 June 2013 (at 3:15 p.m.) at the Devín water gauge (974 cm, 10 640 m3s-1) and about two hours later at the Bratislava water gauge (1 034 cm, 10 641 m3s-1) (Figs. 4.23–24). During the flood in 2013 (similar to flood in 2002 and 2006) the breakage of dams did not occur on the Slovak-Hungarian section of the Danube (Konecsny and Nagy, 2013). Therefore, the peak flows of these floods were

76 Flood marks along the Danube River between Passau and Bratislava

not reduced downstream and the series of maximum annual flows Qmax continues to show an increasing trend at the Nagymaros station (Fig. 4.25).

12000 2013 peak 06. 06. 2013 10000

] stage 1034 cm -1 8000 3 -1 s

3 Qmax 10 640 m s 6000 4000 Qd [m 2000 0 25-May 04-Jun 14-Jun 24-Jun

Fig. 4.23 Hydrograph of the 2013 flood at the Bratislava water gauge.

Fig. 4.2 Flood 2013 at the Bratislava water gauge. (Photo Pekárová, 6 June 2013)

10000

] Danube: Nagymaros

-1 8000 .s 3 6000 [m 4000 max Q 2000 1870 1890 1910 1930 1950 1970 1990 2010

Fig. 4.25 Variability of the maximum annual discharge of the Danube River at the Nagymaros water gauge during the period 1893–2013.

77 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

4.2 Winter and snowmelt floods

4.2.1 Flood of the year 1876

Winter and spring floods belong to mixed floods from rainfall and snowmelt. In 1876, as a result of warming, the water level of the Danube raised after heavy rainfall that began in the second half of February. It rained the whole month until mid-March, so the flood had long duration and big volume (Fig. 4.26). It was the largest flood at Budapest until the flood in 2013. On the territory downstream of Bratislava the consequences were catastrophic. Totally 58 000 ha of Žitný ostrov (Rye Island) were flooded and 40 villages were destroyed (Fig. 4.27).

10000 1876

] 8000 -1 s

3 6000 4000 Q [m 2000 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Fig. 4.26 Hydrograph of the Danube at the Bratislava water gauge, year 1876.

Fig. 4.27 Flood 1876 at Štúrovo.

78 Flood marks along the Danube River between Passau and Bratislava

There exists till now the flood mark from this flood on the Marchegg Viaduct (Fig. 4.28a-c) over the Morava River at Devínska Nová Ves (Paulík, 2014).

b) Fig.4.28 a) Water gauge at Devínska Nová Ves, the Morava River. (Photo Miklánek, 2011); b-c) The 20 February 1876 flood mark on the Marchegg Viaduct over the Morava River. (Photo Paulík, 2011).

79 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

4.2.2 Comparison of the 1895 and 2006 Danube floods

In the year 2012 we have discovered an unreferenced flood mark of the 1895 flood in the old city of Bratislava (Pekárová and Miklánek, 2012; Pekárová et al., 2012). This flood mark was found in the garden on the wall of the Holy Trinity church on Žižkova St. No.3 (Fig. 4.29) in the former quarter called Zuckermandel (below the Bratislava castle).

Fig. 4.29 The 1895 flood mark in the garden of Holy Trinity Church in Bratislava. (Photo Miklánek, 2012).

80 Flood marks along the Danube River between Passau and Bratislava

The flood mark indicates the water level dated 1895 below the Hungarian inscription “VIZRAJZI MAGASSÁGJEGY” (translation: “hydrographic level mark”). The flood in spring 1895 was one of the biggest floods in the Lower Danube Basin. However, there exist no descriptions of the flooding occurrence in year 1895 at Bratislava in the official documents of the hydrographic service. In these paragraphs we summarize information on the 1895 Danube flood based on the study of the historical records (Melo et al., 2012, 2014). Later on the 1895 and 2006 floods are compared on base of the observed Danube daily discharge data from five stations along the Danube. It is surprising how similar are the both floods - in their meteorological and hydrological origin aspect, particularly their peak discharges, or their flood wave travel times. Major damages due to flood in 1895, upstream of Bratislava, were not known or reported. At Bratislava itself, according to „The New York Times“ newspaper (Fig. 4.30), the flood manifested itself by „devastating effects“. The following report, with the title “Blue Danube Fatal at Pressburg”, was published on 16 April 1895 by a Vienna correspondent. The headline of this report is not very precise, because the report mostly relates to Hungary and not only to Bratislava (at that time, Pressburg).

Fig. 4.30 Report on the 1895 Danube flood at Pressburg (Bratislava) in the newspaper “The New York Times”, 16 April, 1895.

81 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

We studied the newspaper articles of the Preßburger Zeitung and Wiener Zeitung (the time period from the end of February till the end of April 1895) trying to find any information on the flood on the Danube and its tributaries in 1895. Further two flood marks were discovered on our territory at Iža and Komárno. New information was also found in archive of the weekly „Komáromi Lapok“ journal. The information about flooded municipalities in the surroundings of Komárno is given in this source, but without reporting major damages.

The 1895 Danube flood manifested itself particularly on the lower river reach, the southern Hungary had been flooded at that time, and on its tributaries (e.g. Tisza River). On territory of the today northern Serbia (in Vojvodina), this flood peaked app. at the beginning of April 1895. In the east of Serbia and over the west of Romania (in Orsova, at the Iron Gate), it peaked app. in the middle of April 1895 (Mikhailov et al., 2008). At that locality, it became even the highest Danube flood since the beginning of the observation period. It was exceeded much later, in the year 2006. The 1895 flood confirms frequent occurrence of floods in the Slovak Danube River section in last decade of the 19th century. This flood did not manifest itself strongly in the upper Danube reach in March and April 1895. Some serious manifestations of this flood are known in the central Danube River Basin, and later on and downstream the Danube, it grew up to one of the most significant Danube River floods in its history. However, so far, more detailed studies of this flood are missing.

The 1895 March flood at Bratislava apparently was an ice one. It started on the 26 to 27 March 1895. It is interesting to compare this historical 1895 flood with that of the year 2006. The similarity of these two floods confirms our assumption, that the structural river channel interventions (river regulations), changed the flood wave travel times only in cases of the minor floods. In the case of the high floods, with vast inundation areas flooded, the flood wave travel times have not been changed. The 1895 and 2006 Danube floods are compared using the discharge data from the water gauges Bratislava, Turnu-Severin/Orsova, and Ceatal Izmail. In Fig. 4.31 there is the mean daily discharge in selected stations in 1895 and 2006. In other stations there are no data available for the year 1895. In 1895 at Bratislava the flood wave culminated on 31 March 1895 with discharge of 6 979 m3s-1, and in 2006 the flood wave culminated on 31 March 2006, as well, with discharge of 7 824 m3s-1.

82 Flood marks along the Danube River between Passau and Bratislava

16000

12000 ] -1 s

3 8000 Turnu Severin

Q [m 4000 Bratislava 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1895 16000 Ceatal 12000 ] -1 s

3 8000 Turnu Severin

Q [m 4000 Bratislava 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 2006

Fig. 4.31 Mean daily discharge hydrographs of the Danube, gauging stations Bratislava, Turnu Severin/Orsova, and Ceatal Izmail, (years 1895, 2006).

At Turnu-Severin the flood wave in 1895 culminated on 14–18 April (about 16 days later than at Bratislava) with discharge of 15 200 m3s-1, and in 2006 the flood wave culminated at Orsova on 15–18 April (also about 16 days later than at Bratislava) with discharge of 16 258 m3s-1. There are no differences in the travel times of both floods. Even when the smaller flood waves have shorter travel times due to channel training at present, it is not valid for larger floods. The travel time of the large flood is the same as 111 years ago. The development of the flood waves is remarkably similar in 2006 and 1895 (Fig. 4.31).

4.2.2.1 Maximum annual discharge at Bratislava and Orsova

In this part we concentrated on assessment of the 1895 flood significance at stations Danube: Bratislava, and Danube: Orsova. We used the log- Pearson type III distribution for assessment of the flood significance. The maximum annual discharge series at stations Bratislava, Nagymaros and Orsova are shown in Fig. 4.32. The return period of the flood at Bratislava station was about 5–10 years (Fig. 4.33), at Orsova station it was the biggest flood ever measured with the return period of about 80–100 years.

83 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

It is an interesting fact, that also such catastrophic Danube flood can fall into oblivion after 111 years. Instigation to search for this flood information was an incidental discovery of the flood mark from 1895, in garden of the Bratislava (under the castle) Holy Trinity church, when searching for flood marks from the other years. After the first reading of it, we thought that it had been only fixed in 1895, reminding one of the much older flood events on the Danube at Bratislava. When studying and reviewing the flood regime at present, it is necessary to pay due attention to historical hydrology and to the data in archives. It is still possible to find out new information on flood history over our territory, enabling us to better evaluate the flood peak exceedance probabilities (T-year flood peaks). Ice flooding occurred on the Danube at Bratislava also in the years 1900/01, 1929, 1947, 1956, 1963, what is documented on historical photographs (Figs. 4.34–38).

11000

] Danube: Bratislava/Devín -1

.s 9000 3 7000 [m

max 5000 Q 3000 1870 1890 1910 1930 1950 1970 1990 2010

11000

] Danube: Nagymaros -1

.s 9000 3 7000 [m

max 5000 Q 3000 1870 1890 1910 1930 1950 1970 1990 2010

16000

] Danube: Turnu/Orsova -1 14000 .s 3 12000

[m 10000

max 8000 Q 6000 1870 1890 1910 1930 1950 1970 1990 2010

Fig. 4.32 The Danube maximum annual discharge time series. Years 1895 and 2006 are marked by the circle at Bratislava (above), Nagymaros (middle), and Turnu Severin / Orsova (below).

84 Flood marks along the Danube River between Passau and Bratislava

20000 ] -1 s 3 Danube River: Orsova Q [m

10000

8000

6000

5000 Danube River: Bratislava 4000

3000

99.99 99.8 99 98 95 90 80 70 60 50 40 30 20 10 5 2 1 0.5 0.1 0.01 probability

Fig. 4.33 Empirical and theoretical exceedance probability curves of the Danube maximum annual discharges at Bratislava and Orsova, from the whole observation period. q(5) and q(95) are the probability confidence limits, the log- Pearson type III probability distribution.

Fig. 4.34 Ice on the Danube in 1901, (from the book A. Balaz: Hriešna Vydrica. Bratislava City Gallery, archive of J. Hanák).

85 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Fig 4.35 The frozen Danube at Bratislava in winter 1928/29. (Archives of the City of Bratislava, Photo Hofer).

86 Flood marks along the Danube River between Passau and Bratislava

Fig. 4.36 The frozen Danube at Bratislava on 20 February 1956. (Photo: TASR, File Name: 558667-110160601, http://tvnoviny.sk/sekcia/spravy/regiony/v-bratislave-bola- pred-55-rokmi-taka-zima-ze-zamrzol-dunaj.html).

87 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

Fig. 4.37 Flooded Bratislava, city district Prievoz, 1947 (source: Bratislavské noviny on 9 February 2006, Photo Alojz Prakeš, 1963).

Fig. 4.38 The frozen Danube at Bratislava in 1963 (source: Bratislavské noviny on 9 February 2006, Photo Alojz Prakeš, 1963).

88 Flood marks along the Danube River between Passau and Bratislava

5 Flood frequency analysis with historical information

Based on the analysis of the observed Danube water levels at Hainburg (and at Bratislava), we estimated the Bratislava historical peak water levels of floods in years 1501, 1787 and 1862 (Fig. 5.1). The significant flood water levels we determined also using the today not existing flood marks in Bratislava. Summary of significant flood water levels estimated in such ways for the today Bratislava water gauge is shown in Fig. 5.2.

1100 Stein - Krems 1050 Nußdorf Hainburg 1000 Bratislava 950

H [cm] 900

850

800

750 1501 1787 1862 1897 1899 1954

Fig. 5.1 The Bratislava water gauge levels based on those from Hainburg, for Danube floods in years 1501, 1787 and 1862.

5.1 Flood regime analysis of the Danube River at Bratislava

From the 138-years mean daily discharge time series of the Danube River at Bratislava (period 1876–2013), we counted all floods over 4 000, 5 000,

89 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

6 000, 7 000, 8 000, 9 000, and 10 000 m3s-1. Totally we analysed 350 flood waves in this period. In Table 5.1, there are listed the numbers of floods in individual classes within the whole 138-years period. Columns in Fig. 5.3 show number of floods in those classes, and in individual months of the year. The floods at Bratislava occur in May–July most frequently. Five floods with peak discharge exceeding 10 000 m3s-1 occurred during the 138-years period (Fig. 4.8). The extreme flood occurred once in June (2013), July (1954), September (1899), and twice in August (1897, 2002).

winter/spring summer 140.03 1160 floods floods

139.83 29.01.1809 1140

05.02.1850 139.63 1120

20. 02. 1847 139.43 1100

01.11.1787 139.23 1080 27. 03. 1895

139.03 1060

138.83 1040 06.06.2013

138.63 16. 02. 1775 1020

138.43 1000 16.08.2002 15.07.1954 138.23 980 19.09.1899

138.03 960

04.08.1897 137.83 940 14.03.1947 16.06.1965 137.63 07.03.1956 920

137.43 900 05.07.1975 17.02.1923 880 137.23 27.02.1880 06.01.1883

06.08.1991 137.03 860 21.02.1876 08.09.1890

136.83 840 04 Bpv. [m] Water level [cm]

Fig. 5.2 Measured and estimated water levels of significant floods at Bratislava gauge. Left column (blue points) – ice floods, right column (red points) – summer floods. (Photo: Pekárová, 2012).

90 Flood marks along the Danube River between Passau and Bratislava

Table 5.1. Number of floods in selected classes (over 4 000 m3s-1), Danube River, the Bratislava water gauge Period 4 000- 5 000- 6 000- 7 000- 8 000- 9 000- above Total 4 999 5 999 6 999 7 999 8 999 9 999 10 000 1876–2013 198 76 45 14 10 2 5 350

Based on historical sources, we set up series of significant historical Danube River floods (since 1501) upstream from Bratislava. In this river section, there are known about ten summer floods before the year 1876 (Fig. 5.4). Out of these, floods in years 1501, 1682, and 1787 peaked probably at discharge higher than that of the 1899 year. From these data it does not follow, that the high flood frequency would change during the last 500 years. The highest flood frequency in this river section during the instrumental observation period, occurred in last quarter of the 19th century (1876–1900).

10000 40 9000 8000 7000 30

N 6000 5000 4000 20

0 I IIIIIIVVVIVIIVIIIIXXXIXII Fig. 5.3 Number of floods in selected classes and in individual months at Bratislava, period 1876–2013.

15000 ] 1501 1897

-1 2013 1682 1787 1954 s 1862 1899 3 2002 10000

5000 Danube [m Danube max

Q 0 1500 1600 1700 1800 1900 2000 year Fig. 5.4 Historical Danube River floods in river section Kienstock–Bratislava since 1500 up to 1876 (red columns - summer floods, blue columns - winter floods); since 1876- the observed annual peaks Qmax at the Bratislava water gauge.

91 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

5.2 Catastrophic flood scenario

The EU flood directive requires from the EU member states to elaborate the flood threat and flood risk maps, for floods of a very small exceedance probability, for return periods T of 500–1000 years (catastrophic flood scenario, Directive, 2007). For a correct extreme flood peak estimation, it is necessary to include as much as possible historical information from the archive sources into the statistically processed data series (Merz and Blöschl, 2008a,b; Blöschl and Merz, 2008; Elleder, 2010; Gaál et al., 2010; Kjeldsen et al., 2014). In this chapter we present an example of such T-years flood peaks for the Bratislava water gauge on the Danube River. In general, severity of a flood, with respect to its peak flow, is expressed as the probability of its occurrence or exceedance. We used the annual maximum discharge time series Qmax (Fig. 5.4) of the Danube for the period 1876–2013, together with 3 historical floods (from the years 1501, 1682, and 1787) (Pekárová et al., 2013). Firstly, we chose type of the theoretical probability distribution curve. We tested several models to achieve a good fit to flood-flow data (Bačová Mitková et al., 2014). In case of the log-normal distribution, the probability p of the individual empirical annual maximum discharge exceedance probability Qmax was estimated according to: p= (m-0.3)/(n+0.4), (1) where: m - serial number of the element in decreasing order; n - number of elements. The relationship between the probability of exceedance p of a certain annual discharge Qmax and the return period T, is generally given as p=1/T. The following formula is used in Slovakia historically (Szolgay et al. 2007): p = 1 – e-1/T , (2) which is based on peak over threshold (POT) method. In Fig. 5.6 return period of the Danube River floods is shown, where T is calculated according to formula:

T = –1/(ln(1-p)). (3)

92 Flood marks along the Danube River between Passau and Bratislava

16000 3 -1 14000 Qmax [m s ] observed log-Pearson 12000 log-normal 10000 8000 6000

4000 2000 0 0.0010 0.0100 0.1000 1.0000 probability

Fig. 5.5 Qmax return periods drawn for two types of the distributions: log-Pearson type III, and log-normal.

On the Figure 5.5, the return periods of the Qmax are drawn for two types of the distributions: log-Pearson type III, and log-normal ones. From the results it follows, that choice of the distribution curve type has substantial effect on estimate of the T-year discharge, particularly for the higher return periods. For example, the 1000-year discharge according to log-normal distribution on the Danube River at the Bratislava water gauge is 13 977 m3s–1, and according to log-Pearson type III distribution it is 14 188 m3s–1. We recommend using the log-Pearson type III distribution in flood frequency investigations. In the next step, we included the historical floods from the years 1501, 1682, and 1787 into the 138-years series of annual discharge maxima (Fig. 5.6). The calculated T-year maximum discharge of the Danube at Bratislava for the period 1876–2013 without and with estimates of historical flood discharges are listed in Table 5.2a–b. A consistent increase in the T-year discharge can be seen when the three floods from the pre- instrumental period are included.

3 -1 Table 5.2a. T-year peak flow Qmax [m s ], log-Pearson type III distribution; CL- confidence limits; the Danube at Bratislava, 1876–2013, without historical floods T in years 1000 500 200 100 50 20 10

Qmax 13 893 13 015 11 871 11 012 10 153 9 005 8 108 95% CL 12 708 11 969 10 998 10 263 9 522 8 517 7 720 5% CL 15 466 14 392 13 005 11 974 10 955 9 609 8 576

93 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

3 -1 Table 5.2b. T-year peak flow Qmax [m s ], log-Pearson type III distribution; CL- confidence limits; the Danube at Bratislava, 1876–2013, with historical floods T in years 1000 500 200 100 50 20 10

Qmax 14 440 13 470 12 216 11 283 10 359 9 136 8 191 95% CL 13 188 12 372 11 308 10 509 9 711 8 640 7 800 5% CL 16 102 14 914 13 394 12 277 11 180 9 748 8 662

16000 14000

] 12000 -1 s 3 10000 8000

Qmax [m 6000 4000 2000 4.00 6.00 8.00 0.20 0.40 0.60 0.80 2.00 0.10 1.00 20.00 40.00 60.00 80.00

% 10.00 16000 14000

] 12000 -1 s 3 10000 8000 1501 flood 1501 Qmax [m Qmax 6000 flood 1787 1682 flood 1682 4000 2000 0.20 0.40 0.60 0.80 2.00 4.00 6.00 8.00 0.10 1.00 20.00 60.00 40.00 80.00 % 10.00

Fig. 5.6 Empirical and theoretical log-Pearson type III distribution curve of the annual maximum discharge without and with historical floods, 5% and 95% confidence limits, the Danube at Bratislava.

94 Flood marks along the Danube River between Passau and Bratislava

In Fig. 5.7, there is the Bratislava water gauge with indicated water levels during 2002 and 2013 floods, and our water level estimation of the catastrophic flood situation (Qmax with return period T=1000 years). Our evaluations consistently reveal that the log-Pearson type III three- parameter probabilistic model provides a good approximation to flood-flow data in the middle Danube River stretch. Such procedures would be needed and useful not only for other gauging stations on the Danube River, but also for many other gauging stations on the rivers of Slovakia. There, however, is not sufficient attention devoted so far to the historical hydrology.

Fig. 5.7 The Danube River, the Bratislava water gauge, 2002 and 2013 water levels, and estimation of the catastrophic flood scenario. (Photo Pekárová, 2 July 2013).

95 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

6 Conclusions

From the above results it follows, that the frequently expressed hypothesis about the presently more extreme Danube floods has not been confirmed. Neither in cases of the higher and small flood events, no increase of their characteristics has been confirmed in 1876–2013 period. From flood marks along the Danube from Passau to Melk we can clearly see that the flood in 1501 was the largest recorded flood in the Upper Danube for at least the last 500 years. Flood in 1501 affected river basins of the Elbe and the Thaya as well (Daňhelka and Elleder, 2012). Flood protection of Bratislava and other cities in the Upper Danube region was built with respect to this flood. However, we must still be aware of the fact that even greater flood can come in the future. Although the probability of greater flooding is very low, it is not absolutely excluded. Therefore, we must be prepared for such a flood event. The experience of the floods in Moravia in 1997 and on the Vltava River at Prague in 2002 should warn us. After a relatively quiet period, which occurred on the Danube at Bratislava after 1965, when no floods over 10 000 m3s-1 occurred, wetter period had come again. Such alterations of the wet and dry periods have occurred several times in history. In the long term this is not something special. But in terms of the length of a person's life such a catastrophic flood is unique event, which may affect a person's life for many years. In the same time we must be aware of the fact that the runoff conditions are permanently and continuously changing in any river basin including the Danube River Basin. For 110 years there has been an increase in the Danube water levels by more than 60 cm at Bratislava, which is already not insignificant value. It is difficult to answer the question why there is an increase of water levels at stations on the Danube. Likely there will be more causes:

96 Flood marks along the Danube River between Passau and Bratislava

• Reduction of the gauging cross-section area because of dykes and embankments construction, at Bratislava, and above and below the city. • Rise of sediments and gravel accumulations in the river channel near the gauge (Opatovská, 2002). • Another reason is that there was no dyke break in the Slovak/ Hungarian Danube reach in 2002, 2006 and 2013. Therefore the transformation of the flood wave was slower, and the water levels were higher compared to 1894, 1899, 1954 and 1965, when the Danube dykes were broken downstream of Bratislava (Svoboda et al., 2000; Pekárová et al., 2013). • Alluviation of the channel at the middle Danube below Devin Gate is a natural process (Hronec, 1969), resulting from the Danube bottom slope changes.

97 Pekárová, P., Miklánek, P., Melo, M., Halmová, D., Pekár, J., Bačová Mitková, V.

7 References

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Back volumes of SCH Publications

1. Lešková, D. (1997) Selected Statistical and Probability Characteristics of Low Flow. (ISBN 80-900558-8-5) SHMÚ & SVH, Bratislava, 58 pp. 2. Kostka, Z., Holko, L. (1997) Soil Moisture and Runoff Generation in Small Mountain Basin. (ISBN 80-967808-1-6) ÚH SAV & SVH, Bratislava, 90 pp. 3. Hlavčová, K., Szolgay, J., Čunderlík, J., Parajka, J., Lapin, M. (1999) Impact of Climate Change on the Hydrological Regime of Rivers in Slovakia. (ISBN 80-227-1296-5) STU & SVH, Bratislava, 101 pp. 4. Pekárová, P., Miklánek, P., Koníček, A., Pekár, J. (1999) Water Quality in Experimental Basins. (ISBN 80-967808-8-3) ÚH SAV & SVH, Bratislava, 96 pp. 5. Svoboda, A., Pekárová, P., Miklánek, P. (2000) Flood Hydrology of Danube between Devín and Nagymaros. (ISBN 80-967808-9-1) ÚH SAV & SVH, Bratislava, 96 pp. 6. Solín, Ľ., Cebecauer, T., Grešková, A., Šúri, M. (2000) Small Basins of Slovakia And Their Physical Characteristics. (ISBN 80-968365-2-8) GgÚ SAV & SVH, Bratislava, 77 pp. 7. Kohnová, S., Szolgay, J., Solín, Ľ., Hlavčová, K. (2006) Regional Methods for Prediction in Ungauged Basins – Case Studies. (ISBN 80-87071-02-6) KEY Publishing, Ostrava, 112 pp. 8. Szolgay, J., Hlavčová, K., Kohnová, S. et al. (2007) Climate and Land Cover Impact on Runoff in the Hron River Basin. KEY Publishing, Ostrava, 120 pp. 9. Pekárová, P., Onderka, M., Pekár, J., Miklánek, P., Halmová, D., Škoda, P., Bačová Mitková, V. (2008) Hydrologic Scenarios for the Danube River at Bratislava. (ISBN 978-80-87071-51-9) KEY Publishing, Ostrava, 158 pp. National report 2008 of the IHP UNESCO project 2.4 Methodologies for integrated river basin management. 10. Kohnová, S., Hlavčová, K., Szolgay, J., Horvát, O. (2012) Scenario Based Modeling of Hydrological Change: Case Studies in Slovak Basins. (ISBN 978- 80-7418-169-6) KEY Publishing, Ostrava, 89 pp. National report 2012 of the UNESCO “IHP-VII FA 1.2 Climate change impacts on the hydrological cycle and consequent impact on water resources”, and “IHP-VII FA 2.4 - Managing water as a shared responsibility across geographical & social boundaries”. 11. Szolgay, J., Danáčová, M., Šúrek, P. (2012) Multilinear Flow Routing Using Travel-Time Discharge Relationships. (ISBN 978-80-7418-172-6) KEY Publishing, Ostrava, 94 pp. National report 2012 of the UNESCO “IHP-VII FA 1.3 - Hydrohazards, hydrological extremes and water-related disasters”.

PUBLICATION of the Slovak Committee for Hydrology 12

Flood marks along the Danube River between Passau and Bratislava

RNDr. Pavla Pekárová, DrSc. RNDr. Pavol Miklánek, CSc. RNDr. Marián Melo, PhD. Ing. Dana Halmová, PhD. doc. RNDr. Ján Pekár, CSc. Ing. Veronika Bačová Mitková, PhD.

Cover desing: Ing. Arch. Andrej Znášik

Published by VEDA and the Slovak Committee for Hydrology - National Committee for the International Hydrological Programme of UNESCO (SVH - NC IHP UNESCO)

First edition.

Vytlačila VEDA, vydavateľstvo Slovenskej akadémie vied, v Bratislave v roku 2014 ako svoju 4092 publikáciu. Strán 104.

ISBN 978-80-224-1408-1