Horizontal channel development on the upper Jizera and the upper Vltava Rivers between 1938 and 2012
Abstrakt
Through the use of orthophotomaps from 1938 and 1952, this paper examines the development of horizontal channels of selected rivers in mountain areas of the Bohemian Massif. Two study sites in northern and southern part of Bohemian Massif were analysed in order to evaluate changes in river channels under similar natural conditions.
Developments on the Upper Jizera River and its tributary, the Jizerka River, were investigated for the time period of 1938-2012. The Upper Vltava (Moldau) river, along with its tributaries, was studied in regards to developments taking place over the period of 1952-2012.
Historical orthophotomaps were georeferenced and river banks were subsequently determined through the use of ArcGIS software. Both sites are situated in wide valleys with a low gradient, representing an exceptional relief in generally mountainous regions.
Channel changes are documented via fluvial lakes, paleomeander remnants and meander cut-offs. Together with high precipitation rates in both basins, periods of extreme floodings seem to have a significant influence on channel development and transformation.
Lateral erosion is somewhat less intense when compared to other rivers in similar natural environments across Central E urope. The estimated maximum lateral erosion in the Upper Jizera River basin is 0.5 m/year, whereas in the Vltava River basin, the lateral erosion reaches up to 1.1 m/year.