Author(s): Isabell Becker; Gregory Egger

Linked Author(s):

Keywords: River restoration measure; Vegetation succession; Succession model; Braided rivers

Abstract: Gravel-bed rivers, and especially braided rivers, are ecologically extremely valuable ecosystems, but are also highly endangered due to human impacts (Tockner et al., 2008). The case study of the Upper Drava river near Kleblach in Austria was used to study the development of an artificial side arm from its inception to the present day. The arm itself can be seen as an example of a braided river reach. Regular monitoring of the study area allows analysis of vegetation development. In addition, the Casimir succession model was used to simulate vegetation development until 2050. A major flood event was integrated into the model to investigate the effects on the vegetation. Two target plant species of alpine pioneer habitats (Myricaria germanica and Typha minima) were used to assess the consequences of vegetation development over the simulation period. The results show that vegetation developed rapidly on the initially open sites in the study area. In 2018, about 15 years after the restoration, about 60% of the study area was covered by stable succession phases. Modelling results showed that even a major flood event in the near future would not be able to reduce the dense vegetation cover. This will prevent the target species from maintaining a stable population in the long term. In general, hydrodynamic and morphodynamic processes are necessary to maintain the natural conditions of braided rivers. If these processes are suppressed by human intervention, most braided rivers will deteriorate. This trend can already be observed on a global scale.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p1721-cd

Year: 2023