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

Abstract

Freely meandering (quasi)natural reaches of lowland rivers represent a rare phenomenon in Central Europe. Increasing attention is currently being paid to the dynamics of quasi-natural (arti cially in uenced) meandering rivers as this attention represents the basic prerequisite for the development of appropriate restoration strategies on regulated rivers. This study focused on a 5.5 km long reach of the Morava River in the Strážnické Pomoraví region, Czech Republic that is characterised by quasi-natural evolution after substantial engineering adjustments were made in the rst decades of the twentieth century. Based on Geographic Information Systems (GIS) analysis of aerial photographs, the spatio-temporal dynamics of bank erosion and accretion rates were quantitatively described and variables that control channel migration rates were identi ed. High rates of lateral shifts were localised in high sinuosity segments (sinuosity 1.17-2.37), whereas segments with very low rates were straight or formed into slightly curved bends (sinuosity 1.05-1.18). As a key factor, engineering works that in uenced local river bed slope and induced a dramatic increase in bank erosion rates were identi ed. River engineering works induced a dramatic increase in bank erosion rate (2.19 m/year for 1938-53 and 1.47 m/year for 1953-63). An interval of approximately 25 years was needed before the erosion rates dropped back to values documented before river regulation (0.35-1.09 m/year for 1841-1938). Other important controlling variables included radius of curvature, frequency and magnitude of oods and, locally, river bank material properties and oodplain land cover.

Detailed assessment of spatial and temporal variations in river channel changes and meander evolution as a preliminary work for effective floodplain management. The example of Sajó River, Hungary

“…Our results have shown some similarities with other European rivers. Ondruch and Máčka (2015), who worked on the Morava River (Czech Republic), found that the correlation between the duration of discharges was equal or higher than the effective discharge and the bank erosion rates, reaching 0.57. However, they investigated only a 5.5 km long reach and the meandering reaches showed a correlation of only 0.26, while along the Sajó River, it was 0.59, 0.61 and 0.59 regarding the total reach, the natural and the artificial reaches, respectively (Suppl.…”

Issues of Meander Development: Land Degradation or Ecological Value? The Example of the Sajó River, Hungary

“…Morphological changes allow registering high rates of bank erosion, which in similar investigations in other European rivers, was also calculated [3,73,74]; however, the extent of arable lands lost by lateral erosion is not an outstanding value compared to other rivers with similar geomorphological patterns [75]. In this way, it would be a great opportunity to include in future investigations the correlation between these morphological alterations, the changes in the biodiversity and the bank erosion rates.…”