Analysis of the longitudinal profile of the Morávka and Mohelnice Rivers in context of morphological and lithological conditions
Published online: 30 September 2016Abstract
The longitudinal profile characterizes average stream slopes for the entire watercourse of the river. The main parameter of longitudinal profile is the channel slope. It illustrates especially the energy of flowing water and subsequent processes which influenced the morphology of a channel.
The main hypothesis of this paper is to analyse longitudinal profiles through a commonly used gradient of the longitudinal profile and SL index and their subsequent correlation in the context of morphological conditions of the channel and lithological conditions. This analysis was realized in the Morávka River basin, namely on the Morávka River and its left tributary the Mohelnice River (Fig. 1). Lithological condition of the Morávka River basin is characterized by Carpathian flysch lithology in the channel bedrock especially with various occurrences of the sandstone layers which are more resistant to water erosion, and claystone layers that present little resistance to water erosion.
Analyses of Morávka and Mohelnice longitudinal profiles showed that incised and regulated reaches indicated increased values of the parameters of longitudinal profile gradient and SL index (see Tabs 2 and 3). On the other hand, channel reaches with lower values of these indices demonstrated absences of incision processes (see Tabs 2 and 3). The combination of the longitudinal profile analyses and existing lithology demonstrated e.g. that the occurrence of resistant Těšín-Hradiště Formation in the Morávka channel bedrock prevent backwards erosion from the reach downstream (see Fig. 2). Using these two methods of the analysis of the longitudinal profile can demonstrate the potential to identify the causes of erosion/accumulation processes and human impact on river beds. Therefore, longitudinal profile of the watercourse can be a suitable tool for the analysis of processes occurring in the basin.