Ladislava Řezníčková

Fluctuations of floods of the River Morava (Czech Republic) in the 1691- 2009 period: interactions of natural and anthropogenic factors

Abstract Floods from the middle part of the River Morava (eastern Czech Republic) are considered over the course of the past three centuries, the study being based on data derived from documentary evidence (1691–1880), measured peak water stages, Hk (1881–1920) and peak discharges, Qk (1916–2009), evaluated with respect to their N-year return period (HN and QN ). Changes in land use and water management (water reservoirs, channel modifications) are discussed, as are factors influencing runoff conditions in the Morava catchment. Decadal synthesis of flood series identifies the highest flood activity in the decades of 1911–1920 and 1961–1970 (11 floods each), 1831–1840, 1891–1900, 1901–1910 and 1931–1940 (10 floods each). Uncertainty in this series is related to some incompleteness of documentary data in the pre-1881 period. Very low flood frequency occurred in the 1990s–2000s, although the most disastrous floods were recorded in this particular period (July 1997 at Q 100 and March/April 2006 at Q 20–Q 50). Changes in flood frequency correspond partly to long-term changes in temperature and precipitation patterns. Citation Brázdil, R., Řezníčková, L., Valášek, H., Havlíček, M., Dobrovolný, P., Soukalová, E., Řehánek, T. & Skokanová, H. (2011) Fluctuations of floods of the River Morava (Czech Republic) in the 1691–2009 period: interactions of natural and anthropogenic factors. Hydrol. Sci. J. 56(3), 468–485.

Floods and floodplain changes of the River Morava, the Strážnické Pomoraví region (Czech Republic) over the past 130 years

Abstract The development of the River Morava floodplain has been influenced by several natural and anthropogenic factors. This paper focuses on variations in flood activity and channel changes of the River Morava in the region of Strážnické Pomoraví (southeastern Czech Republic). Floods are analysed in terms of measured peak water stages, Hk (Rohatec, 1886–1920) and peak discharges Qk (Rohatec/Strážnice, 1921–2010) evaluated with respect to their N-year return period (H N or QN ). The frequency of floods with Qk ≥ Q 2 reaches a significant maximum in March, followed by July. According to flood series compiled from 1881 onwards, their frequency peaked in the 1961–1970 decade with the most severe events occurring in July 1997 (Q 100), March 2006 and June 2010 (Q 50). During the study period the natural dynamics of the original anabranching channel patterns were significantly modified by human intervention, such as the abandonment of some anabranching channels, channel straightening, enlargement of the main channel, flood-dike construction, and the creation of the Baťa shipping channel. These changes resulted in decreased frequency and a reduction in the extent of floodplain inundations compared to the period prior to channel modifications in the 1930s. Citation Brázdil, R., Máčka, Z., Řezníčková, L., Soukalová, E., Dobrovolný, P. & Matys Grygar, T. (2011) Floods and floodplain changes of the River Morava, the Strážnické Pomoraví region (Czech Republic) over the past 130 years. Hydrol. Sci. J. 56(7), 1166–1185.

Windstorm of the eighteenth century in the Czech Lands: course,extent, impacts

This paper addresses the course, extent, and impacts of a windstorm that occurred on 20–21 December 1740, in the Czech Lands. The analysis is based on documentary data included in chronicles, “books of memory”, memoirs, damage reports, urbaria, and cadastral records, as well as secondary sources. The windstorm started with a thunderstorm in the afternoon of 20 December, continued during the night, and was followed by a flood. It also appeared in documentary data from Bavaria, Thuringia, Saxony, Silesia, Slovakia, and Hungary. The event may be related to a cyclone north-west of the Czech territory moving to the east with an intense western flow over central Europe. The storm did great material damage to houses, farm buildings, churches, and forests and is recorded in various documentary sources for 85 places in the Czech Lands. The windstorm had a significant influence on the development of local plantation forestry (discussed in greater detail). Judging by territorial extent and damage done, this windstorm, compared to other similar events, has been classified as “the windstorm of the eighteenth century” in the Czech Lands. This contribution demonstrates the potential of documentary evidence for the elucidation of heavy windstorms in the pre-instrumental period in Europe.

Climate variability and changes in the agricultural cycle in the Czech Lands from the sixteenth century to the present

This contribution analyses the influence of long-term climate variability on changes in the agricultural cycle in the Czech Lands over the course of the past five centuries. Series of crop- and grape-harvest (for wine) dates were compiled from rich documentary evidence for the periods of 1517–1542, 1561–1622, 1770–1815, 1871–1910 and 1971–2010. Two model areas were selected: the Louny region in north-west Bohemia and the Elbe region in central Bohemia. Fluctuations in selected agricultural series are compared with those expressed in temperature, precipitation and Standardised Precipitation Evapotranspiration Index (SPEI) series for various combinations of months. The basic statistics for the agricultural series are presented, and these are correlated with climatic variables. The earliest starts for harvests occurred in the recent 1971–2010 period and the 1517–1542 period. Harvest dates were comparatively delayed in the three remaining periods. Air temperature, also combined with the drought effect as expressed by SPEI, played a significant role in the agricultural cycle in all periods analysed except 1871–1910, in which temperatures were notably dominant as quite wet patterns prevailed. Summer precipitation played a significant role in the first three periods analysed. Correlation coefficients of agricultural series with temperatures indicate increasing weight for this factor over the course of the centuries. Possible effects of uncertainties in agricultural and climatic data in the results obtained are discussed, as well as the relationship of the agricultural cycle to climate variables and its broader context.

Past locust outbreaks in the Czech Lands: do they indicate particular climatic patterns?

Outbreaks of locusts, probably Locusta migratoria, were once relatively frequent phenomena in Central Europe. Documentary evidence reaching back as far as the fourteenth century provides information about these events in the Czech Lands. The stages of morphological development of locusts are influenced by a number of natural conditions, including climate. The question remains as to the extent to which the occurrence of locusts may be attributed to particular weather/climatic patterns in a given year (period) in Central Europe. Available documentary sources recording locust outbreaks in the Czech Lands are presented. The chronology thus created shows their occurrence peaked in the seventeenth century, followed in severity by the eighteenth and sixteenth centuries. Some of the largest outbreaks recorded (1338, 1474–1475, 1542–1546, 1693, 1712 and 1748–1749) are analysed in detail. Seasonal temperature and precipitation patterns in Central Europe during the years in which the locust outbreaks took place show no particular climatic features compared with the years without them, with the exception of cooler and wetter springs and wetter summers.