Author(s): Mahmoud O. M. Awadallah; David F. Vetsch; Robert M. Boes; Erik Van Rooijen; Davide Vanzo

Linked Author(s): David Vetsch, Davide Vanzo, Robert Boes

Keywords: Morphological changes; Hydraulic units; BASEmeso; Habitat changes; Hydrodynamic modelling

Abstract: Riverine ecosystems are highly susceptible to disturbance events, such as flood events, which can induce significant geomorphic restructuring and alter the physical and biological characteristics of river systems. Understanding the impact of floods on habitat dynamics is essential for effective river restoration, yet remains a complex task. This study investigates the temporal and spatial variations of habitat dynamics resulting from floods at Moesa River, an Alpine reach in Switzerland, during the period December 2018 to January 2020. Using the mesoscale habitat tool BASEmeso, hydraulic units were delineated based on depth and velocity distributions and classified into four physical habitat types. These habitats were evaluated at different discharges (1,5, and 15 m3/s), and spatial metrics were used to analyze the resulting changes in habitat configuration and distribution. Results indicate that morphological changes have a greater impact on habitat changes at lower discharges. The direction of this effect (increase or decrease) varies depending on the habitat type and on the discharge. Longitudinal distribution of the habitats showed to be affected by the floods, the spacing between shallow habitats showed to increase, and the number of habitats per cross section decreased at higher discharges. This spatially explicit approach to physical habitat assessment is crucial for understanding the impact of disturbance events on biota in the context of river restoration.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0831-cd

Year: 2023