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, 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

The use of taxation records in assessing historical floods in South Moravia, Czech Republic

“…Channel regulation was particularly influential between Napajedla and Rohatec. In the Strážnické Pomoraví region, the natural dynamics of the original anabranching channel patterns of the Morava were significantly modified by human intervention, including the abandonment of some anabranching channels, main channel straightening and enlargement, flood-dike construction, and the creation of a shipping channel for Bat'a Enterprises (Brázdil et al, 2011b). From changes in land use between 1836 and 2006, reflected in the retention capacity of the landscape, it follows that 59.2 % of the entire Morava catchment was once in stable use (mainly forest and arable land).…”

“…Moreover, depending on channel capacity, the river need not even inundate the floodplain and do damage. For example, the modern channel of the River Morava in the area of Strážnické Pomoraví has the capacity to carry a discharge equivalent to a 5-year flood Q 5 (Brázdil et al, 2011b).…”

Channel migration inferred from aerial photographs, its timing and environmental consequences as responses to floods: A case study of the meandering Topľa River, Slovak Carpathians

“…Hence, understanding streambank erosion hazards in response to recent floods calls for analyses of the links between floods and river behaviours at the regional to local scale (Langhammer and Vilímek, 2008;Brázdil et al, 2011). The long-term response to a series of flood events manifests itself first in the inner-channel organisation of landforms.…”

Response of lateral channel dynamics of a lowland meanderingriver to engineering-derived adjustments - an example of theMorava River (Czech Republic)

“…Since the 1920s, discharges have reached Q once, Q twice, Q once, Q six times, Q eighteen times, and Q twentyeight times (Figure 3). Among the highest frequencies of oods are decades 1961-1970, with eleven events, and 2001-2010, with seven events [26]. So far the highest peak discharge at Strážnice, a ow of 901 m s − , was recorded on 10 July 1997, during the ' ood of the 20th century' which exceeded the value of Q .…”

“…The study reach is situated on the former dominant anastomosing arm, which has preserved, according to evidence from old maps, its meandering pattern since at least the second half of the eighteenth century. The current spatial pattern of dynamic and stable segments distribution had already been documented by [26] who employed visual analysis of old maps from the second half of the nineteenth century. While the channel migration rates varied signi cantly in that time and were conditioned primarily by river engineering, the spatial pattern was rather persistent.…”