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, H k (1881-1920) and peak discharges, Q k , evaluated with respect to their N-year return period (H N and Q N ). 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

Abstract. Since the second half of the 17th century, tax relief has been available to farmers and landowners to offset flood damage to property (buildings) and land (fields, meadows, pastures, gardens) in South Moravia, Czech Republic. Historically, the written applications for this were supported by a relatively efficient bureaucratic process that left a clear data trail of documentation, preserved at several levels: in the communities affected, in regional offices, and in the Moravian Land Office, all of which are to be found in estate and family collections in the Moravian Land Archives in the city of Brno, the provincial capital. As well as detailed information about damage done and administrative responses to it, data are often preserved as to the flood event itself, the time of its occurrence and its impacts, sometimes together with causes and stages. The final flood database based on taxation records is used here to describe the temporal and spatial density of both flood events and the records themselves. The information derived is used to help create long-term flood chronologies for the rivers Dyje, Jihlava, Svratka and Morava, combining floods interpreted from taxation records with other documentary data and floods derived from later systematic hydrological measurements (water levels, discharges). Common periods of higher flood frequency appear largely in the periods 1821-1850 and 1921-1950, although this shifts to several other decades for individual rivers. A number of uncertainties are inseparable from flood data taxation records: their spatial and temporal incompleteness; the inevitable limitation to larger-scale damage and restriction to the summer half-year; and the different characters of rivers, including land-use changes and channel modifications. Taxation data have considerable potential for extending our knowledge of past floods for the rest of the Czech Republic, not to mention other European countries in which records have survived.

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, H k (Rohatec, 1886(Rohatec, -1920 and peak discharges Q k (Rohatec/Strážnice, 1921 evaluated with respect to their N-year return period (H N or Q N ). The frequency of floods with Q k ≥ 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 Bat'a 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. Q 50 ). Au cours de la période, les dynamiques naturelles d'écoulement du lit original en tresses ont été profondément transformées par l'intervention humaine: abandon des lits en tresses, redressement et élar-gissement du lit principal, construction de digues contre les crues, et création du canal de navigation Bat'a. Ces changements ont eu pour résultat de réduire la fréquence et la zone d'expansion des inondations dans la plaine par rapport à la situation qui prévalait antérieurement à la canalisation de la rivière dans les années 1930.Mots clefs inondation; transformation de la plaine d'inondation; transformation du lit fluvial; lit anastomosé; région de Strážnicke Pomoraví; Rivière Morava

In central Europe, floods are natural disasters causing the greatest economic losses. One way to reduce partly the flood-related damage, especially the loss of lives, is a functional objective forecasting and warning system that incorporates both meteorological and hydrological models. Numerical weather prediction models operate with horizontal spatial resolution of several dozens of kilometres up to several kilometres, nevertheless, the common error in the localisation of the heavy rainfall characteristic maxima is mostly several times as large as the grid size. The distributive hydrological models for the middle sized basins (hundreds to thousands of km²) operate with the resolution of hundreds of meters. Therefore, the (in) accuracy of the meteorological forecast can heavily influence the following hydrological forecast. In general, we can say that the shorter is the duration of the given phenomenon and the smaller area it hits, the more difficult is its prediction. The time and spatial distribution of the predicted precipitation is still one of the most difficult tasks of meteorology. Hydrological forecasts are created under the conditions of great uncertainty. This paper deals with the possibilities of the current hydrology and meteorology with regard to the predictability of the flood events. The Czech Hydrometeorological Institute is responsible by law for the forecasting flood service in the Czech Republic. For the precipitation and temperature forecasts, the outputs of the numerical model of atmosphere ALADIN are used. Moreover, the meteorological community has available operational outputs of many weather prediction models, being run in several meteorological centres around the world. For the hydrological forecast, the HYDROG and AQUALOG models are utilised. The paper shows examples of the hydrological flood forecasts from the years 2002–2006 in the Dyje catchment, attention being paid to floods caused by heavy rainfalls in the summer season. The results show that it is necessary to take into account the predictability of the particular phenomenon, which can be used in the decision making process during an emergency.

Abstract. Since the second half of the 17th century, tax relief has been available to farmers and landowners to offset flood damage to property (buildings) and land (fields, meadows, pastures, gardens) in South Moravia, Czech Republic. Historically, the written applications for this were supported by a relatively efficient bureaucratic process that left a clear data trail of documentation, preserved at several levels: in the communities affected, in regional offices, and in the Moravian Land Office, all of which are to be found in estate and family collections in the Moravian Land Archives in the city of Brno, the provincial capital. As well as detailed information about damage done and administrative responses to it, data is often preserved as to the flood event itself, the time of its occurrence and its impacts, sometimes together with causes and stages. The final flood database based on taxation records is used here to describe the temporal and spatial density of both flood events and the records themselves. The information derived is used to help create long-term flood chronologies for the Rivers Dyje, Jihlava, Svratka and Morava, combining floods interpreted from taxation records with other documentary data and floods derived from later systematic hydrological measurements (water levels, discharges). Common periods of higher flood frequency appear largely in 1821–1850 and 1921–1950, although this shifts to several other decades for individual rivers. Certain uncertainties are inseparable from flood data taxation records: their spatial and temporal incompleteness; the inevitable limitation to larger-scale damage and to the summer half-year; and the different characters of rivers, including land-use changes and channel modifications. Taxation data has great potential for extending our knowledge of past floods for the rest of the Czech Republic as well, not to mention other European countries in which records have survived.