ECOSED_TT
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TOWARDS AN EFFICIENT DESIGN OF RIVER CONFLUENCES TO MANAGE INTENSE SEDIMENT IMPACTS FROM TRIBUTARY TORRENTS

 

Funding

Autonomous Province Bozen-Bolzano

Applicant

  • Assoc.-Prof. DI Dr. Bernhard Gems
    Unit of Hydraulic Engineering, University of Innsbruck (UIBK)

Partners

  • Faculty of Science and Technology
    Free University of Bozen-Bolzano (UNIBZ)

Staff

  • Assoc.-Prof. DI Dr. Bernhard Gems (project coordinator, UIBK)
  • DI MThèo St.Pierre OStrander (UIBK)
  • BSc. Maria Gorfer (UIBK)
  • Prof. Dr. Francesco Comiti (UNIBZ)
  • Ass.-Prof. Dr. Andrea Andreoli (UNIBZ)
  • MSc. Johannes Holzner (UNIBZ)

Project duration

     10/2020 - 12/2022

 

Project description

Confluences of torrent channels and receiving waters are a neuralgic spot in the context of torrential hazards and flood risk. Recent events revealed that damage-causing processes often develop due to local constraints or insufficient capacities in confluence zones. Bed-load deposition patterns at confluences are thereby crucial: (i) damming of the torrent channel due to high discharges or low bed-load transport capacities in the receiving water cause regressive deposition and lead to overbanking; (ii) massive sediment loads from the tributary cause damming in the receiving water and inundations upstream; (iii) high stream power in the receiving water mobilizes large amounts of torrential sediments in the confluence zone and thus intensifies downstream flood risk.

Project ECOSED_TT focuses on fluvial hazard processes in confluences of torrents and receiving waters. Thereby, extreme conditions which exceed the present water course capacities are also considered. With a large, adaptable scale model analyses on the capacities of confluences, on bed-load deposition patterns and on the effects of technical and ecologically valuable protection structures are accomplished. Effects of different parameters as channel gradients, widths and bed structure, confluence angle, process type and intensities (fluviatile, debris floods, debris flows; grain size) are in the focus. 2D-morphodynamic and 3D-hydraulic software applications are further accomplished to analyse up- and downstream effects of massive sediment inputs in the confluence zone on a larger spatial scale. Experiments and numerical modelling are related to field studies and geomorphological analyses of natural hazard processes at existing confluences in South-Tyrol and Tyrol. Studies of historic hazard events and confluence geometries as well as bathymetry surveys and case-study-based analyses of sediment availability and connectivity are performed.

The project findings extend knowledge on morphodynamic patterns in river confluences and provide new insights about extreme hazard processes related to steep torrent channels. Guidelines for the design of confluences and related flood protection measures are developed, helping to achieve a sufficient protection against fluvial natural hazards and thereby to maintain ecologically valuable conditions in the water courses. Since prospective extreme fluvial hazards events will occur more frequently this is highly valuable information for operational flood risk management in mountain regions.

The project is conducted by researchers from University of Innsbruck (UIBK, lead partner) and Free University of Bozen-Bolzano (UNIBZ). According their specific research expertise UIBK leads the works on experimental and numerical modelling. UNIBZ leads field studies and geomorphological analyses.

Apart from publications and conference contributions, an international workshop at UNIBZ is organized to discuss project findings with science community and practitioners.


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