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Hydrodynamic and morphological processes associated with wood accumulation patches

Applicant Schalko Isabella
Number 184263
Funding scheme Early Postdoc.Mobility
Research institution Dept. of Civil and Environmental Engineering Massachusetts Inst. of Techn.
Institution of higher education Institution abroad - IACH
Main discipline Civil Engineering
Start/End 01.04.2019 - 30.09.2020
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All Disciplines (2)

Discipline
Civil Engineering
Fluid Dynamics

Keywords (4)

Flow structures; Large wood; River restoration; Sediment transport

Lay Summary (German)

Lead
Weltweit wurden in den letzten Jahrhunderten zahlreiche Flüsse begradigt und weisen heute einen schlechten ökomorphologischen Zustand auf. Gemäss der revidierten Schweizer Gewässerschutzgesetzgebung sollen rund 4'000 Flusskilometer bis 2090 ökologisch aufgewertet werden. In den nächsten Jahren wird somit die Nachfrage an Revitalisierungsprojekten stark zunehmen.Holz ist neben Sediment ein wichtiger Bestandteil eines Flusses und dient vor allem für Fische als bedeutsamer Lebensraum. Um einen Fluss zu revitalisieren, wird dem Fluss immer häufiger Holz zugegeben, da es eine sehr kostengünstige Massnahme ist. Für Revitalisierungsprojekte mit Holz ist es massgebend, die Wechselwirkungen zwischen Strömung, Holz und Sediment zu kennen. Es gibt bereits Feldstudien zur ökologischen Beurteilung von Holzverklausungen (Ansammlung von 10-20 Hölzern), jedoch fehlen vor allem in der Schweiz Richtlinien für eine erfolgreiche Verwendung dieser Massnahme.
Lay summary

Das Ziel dieses Forschungsprojektes ist, die optimale Platzierung von Hölzern abzuleiten, um nachhaltige Revitalisierungsprojekte zu ermöglichen. Mit Hilfe von physikalischen Modellversuchen sollen (1) die Eigenschaften von Holzverklausungen beschrieben und (2) die Strömungs- und (3) morphologischen Prozesse aufgrund von Holzverklausungen untersucht werden. Basierend auf den Modellversuchen sollen Konfigurationen von Holzverklausungen identifiziert werden, welche die Strömung optimal beeinflussen. Die Ergebnisse sollen mit Daten zu Lebensraumpräferenzen von z.B. Fischen verknüpft werden. Darauf aufbauend können Praxis-Empfehlungen für die Schweiz abgeleitet werden, um zur Revitalisierung der 4'000 Flusskilometer bis 2090 beizutragen. Die Ergebnisse dieses Forschungsprojektes sind für Ingenieurbüros und Schweizer Behörden von Interesse.

Direct link to Lay Summary Last update: 21.01.2019

Responsible applicant and co-applicants

Publications

Publication
Logjams With a Lower Gap: Backwater Rise and Flow Distribution Beneath and Through Logjam Predicted by Two‐Box Momentum Balance
Follett E., Schalko I., Nepf H. (2021), Logjams With a Lower Gap: Backwater Rise and Flow Distribution Beneath and Through Logjam Predicted by Two‐Box Momentum Balance, in Geophysical Research Letters, 48(16), 1-10.
Physical modelling of large wood (LW) processes relevant for river management: Perspectives from New Zealand and Switzerland
Friedrich Heide, Ravazzolo Diego, Ruiz‐Villanueva Virginia, Schalko Isabella, Spreitzer Gabriel, Tunnicliffe Jon, Weitbrecht Volker (2021), Physical modelling of large wood (LW) processes relevant for river management: Perspectives from New Zealand and Switzerland, in Earth Surface Processes and Landforms, esp.5181-esp.5181.
Flow and wake characteristics associated with large wood to inform river restoration
SchalkoIsabella, NepfHeidi, WohlEllen (2021), Flow and wake characteristics associated with large wood to inform river restoration, in Scientific Reports, 11(8644 ), 1-12.
Momentum and Energy Predict the Backwater Rise Generated by a Large Wood Jam
Follett E., Schalko I., Nepf H. (2020), Momentum and Energy Predict the Backwater Rise Generated by a Large Wood Jam, in Geophysical Research Letters, 47(17), 1-10.
How to design wood accumulation patches to increase flow variability and deposition – a flume study
Schalko Isabella, NepfNepf (2020), How to design wood accumulation patches to increase flow variability and deposition – a flume study, in River Flow 2020, DelftCRC Press, London.

Datasets

Dataset: Flow and wake characteristics associated with large wood to inform river restoration

Author Schalko, Isabella
Publication date 06.04.2021
Persistent Identifier (PID) 10.5281/zenodo.4665770
Repository Zenodo


Collaboration

Group / person Country
Types of collaboration
Cardiff University Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Colorado State University United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
River Flow 2020 Talk given at a conference Modeling the effect of wood accumulation patches on flow and morphology 06.07.2020 Delft (Online Conference), Netherlands Schalko Isabella;
AGU Fall Meeting Poster Modeling the effect of wood accumulation patches on flow and morphology 09.12.2019 San Francisco, United States of America Schalko Isabella;


Self-organised

Title Date Place
Special Session for River Flow Conference 2020 on "Instream wood: restoration opportunities, flood-related hazards, and management practices" 06.07.2020 Delft (online), Netherlands

Communication with the public

Communication Title Media Place Year
Media relations: print media, online media MIT researchers highlight the impacts of logjams in river restoration projects MIT News International 2020

Abstract

Numerous rivers have been confined and are eco-morphologically impaired, resulting in an increased demand for river restoration projects. Wood placements are a common and inexpensive measure for river restoration. A wood accumulation patch (WAP) is herein defined as an accumulation of less than 20 logs. To plan and evaluate river restoration projects including WAPs, it is important to understand the interactions between flow, wood, and sediment. The number of investigations on the role of wood for restoration projects has considerably increased within the past decades. The majority of the studies were conducted for a specific field site, or focused mainly on engineered log jams. The influence of various flow conditions and bed material on flow and morphological structures in the vicinity of WAPs have not been studied so far. In addition, flow features within an accumulation are still unknown. The main goals of this post-doctoral research project can therefore be described as follows:(1)Quantify flow and morphological structures associated with wood accumulation patches(2)Investigate flow structures within a wood accumulation patch(3)Derive design recommendations for wood accumulation patchesThis project tackles the described goals using physical modeling and is divided into three phases. The objective is to provide data and describe WAP characteristics and respective flow structures that can be linked to desirable river conditions (e.g. fish habitat preferences). These data will allow for a comparison with field and numerical data. For the design recommendations, special emphasis will be put on maintenance and the application for mountain streams. Overall, this project aims to enhance the understanding of hydrodynamic and morphological processes associated with wood accumulations to allow for successful and sustainable river restoration projects.
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