Isabella Schalko

Isabella Schalko
Massachusetts Institute of Technology | MIT · Department of Civil and Environmental Engineering

Dr. sc. ETH Zurich

About

34
Publications
6,424
Reads
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288
Citations
Introduction
I am a Senior Research Assistant at ETH Zurich and a Research Affiliate at MIT (Nepf Lab) studying the interaction of flow, sediment, and wood in rivers. I integrate physical modeling and field observations to analyze transport processes in rivers and their implications regarding river restoration efforts and flood risk assessments.
Additional affiliations
April 2019 - present
Massachusetts Institute of Technology
Position
  • PostDoc Position
November 2018 - March 2019
ETH Zurich
Position
  • PostDoc Position
September 2015 - October 2018
ETH Zurich
Position
  • Research Assistant
Education
September 2015 - September 2018
ETH Zurich
Field of study
  • Environmental Engineering

Publications

Publications (34)
Article
Full-text available
Link: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018WR024649 Transported large wood (LW) in rivers may lead to accumulations at natural or artificial obstructions. The hydraulic and geomorphic conditions change due to these accumulations. Backwater rise as well as scour can evolve in the vicinity of such an accumulation. In this first co...
Article
Large wood (LW) transport can highly increase during floods, leading to accumulations at river infrastructures. To mitigate the potential flood hazard, racks are a common method to retain LW upstream of endangered settlements or infrastructures. The majority of LW retention racks consists of vertical bars and, therefore, disrupt bedload transport....
Article
Full-text available
Plain Language Summary Logjams generate important riverine habitat by increasing the upstream water surface elevation, creating an upstream pool with slower, deepened water. Prediction of the change in upstream water surface elevation from the shape of logs and fine material (branches and leaves) within the jam and river discharge is necessary to u...
Article
Full-text available
Wood is an integral part of a river ecosystem and the number of restoration projects using log placements is increasing. Physical model tests were used to explore how the wood position and submergence level (discharge) affect wake structure, and hence the resulting habitat. We observed a von-Kármán vortex street (VS) for emergent logs placed at the...
Article
Full-text available
Logjams with a gap at the bed form naturally in small channels and are used in engineering practice to maintain river connectivity at base flow. Limited understanding of a jam's effect on backwater rise and flow velocity limits assessment of geomorphic and ecological impacts of natural logjams, design of river restoration interventions, and repr...
Conference Paper
Large wood (LW) can be transported in rivers during both small and large floods. To manage LW transport in Alpine rivers, racks have been installed to retain LW upstream of settlements or infrastructures. Such racks are commonly designed to span the river and consist of vertical poles. Due to this setup, they effectively retain LW, however, they al...
Article
Full-text available
Large wood (LW) can be defined as logs with a length of ≥1 m and a diameter of ≥0 [...]
Article
Full-text available
For rivers or streams with waterfalls, water withdrawal for multiple uses can lead to potential conflicts of interest. The question arises to what extent water withdrawal impairs the appearance and acoustics of waterfalls. A data set was analyzed of 15 waterfalls of different morphological types in Switzerland, Austria, and Norway. It comprises dis...
Article
Full-text available
Transported large wood (LW) in rivers may block at river infrastructures such as bridge piers and pose an additional flood hazard. An improved process understanding of LW accumulations at bridge piers is essential for a flood risk assessment. Therefore, we conducted a field study at the River Glatt in Zurich (Switzerland) to analyze the LW accumula...
Article
Full-text available
In forested mountain catchment areas, both bedload and large wood (LW) can be transported during ordinary flows. Retention structures such as sediment traps or racks are built to mitigate potential hazards downstream. Up to now, the design of these retention structures focuses on either LW or bedload. In addition, the majority of LW retention racks...
Article
In the last 30 years, work on large wood (LW) has expanded and matured considerably, and river scientists, managers and practitioners now have a better appreciation of the role of LW in maintaining ecosystems, forming or stabilising riverine landforms, and interacting with river morphodynamics. We have gained a better understanding of the hazards p...
Article
Full-text available
Semi-permeable sediment traps are designed to retain sediment during large floods and enable sediment transport continuity during ordinary floods by combining two barriers with a guiding channel. During floods, not only sediment but also large wood (LW) can be transported, that may block the inclined bar screen (mechanical barrier) and inhibit sedi...
Article
Full-text available
Water-related problems affect several billion people’s lives and represent an annual challenge assessed at multitrillion US dollars, which substantiates their core role in the UN Sustainable Development Goals. Preventing direct and indirect impacts associated with water excess or water scarcity events requires expert judgement based on reliable inf...
Article
Full-text available
Bridges with and without piers are prone to large wood (LW) accumulations during floods, possibly resulting in an upstream backwater rise, local scour, or destabilization of the structure. To reduce the flood hazard, measures are required that decrease the accumulation probability p of LW. This paper presents a literature review on existing measure...
Poster
Full-text available
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. To plan and evaluate river restoration projects including wood placements, it is important to understand the interactions between flow, wood, and sediment. Fl...
Article
River infrastructures like bridges are prone to accumulations of transported large wood (LW) during floods. To contribute to an improved risk evaluation, the prediction of LW accumulation probability (AP) is crucial. Previous studies on LW AP focused mainly on the influence of a bridge deck. In the present study, flume experiments were conducted to...
Article
Wasser Energie Luft 111(2): 63-70 Link: https://issuu.com/swv_wel/docs/wel_2_2019 Während Hochwasserereignissen können Schwemmholzverklausungen vor allem an Brückenbauwerken auftreten. Um kritische Brückenquerschnitte zu identifizieren, ist die Vorhersage der Verklausungswahrscheinlichkeit von massgebender Bedeutung. Frühere Untersuchungen wurden...
Article
Wasser Energie Luft 111(2): 71-77 Link: https://issuu.com/swv_wel/docs/wel_2_2019 Während Hochwasserereignissen kann Schwemmholz an Engstellen wie Brücken oder auch bewusst bei Schwemmholzrechen zu Verklausungen führen. In beiden Fällen führt eine Verklausung zu einem Aufstau infolge des blockierten Fliessquerschnittes. Im Rahmen einer Doktorarbei...
Article
Full-text available
Link: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019WR024789 In this second companion paper, hydraulic model tests were conducted to analyze local scour due to natural spanwise large wood (LW) accumulations. Spanwise accumulations were modeled using a vertical barrier, similar to a LW retention rack in prototype. The flume experiment...
Article
Bei Hochwasserereignissen kann es durch den Transport von Schwemmholz zu Verklausungen an Bauwerken wie Brücken oder Wehren kommen. Diese Verklausungen führen zu einem zusätzlichen Aufstau des Wassers und eventuell zu einer Überschwemmung der umliegenden Gebiete. Auch an Rechenbauwerken, die Schwemmholz gezielt zurückhalten sollen, ergibt sich ein...
Thesis
Full-text available
During floods, transported large wood (LW) may accumulate at river infrastructures or is retained intentionally at retention structures. In both cases, LW accumulation results in backwater rise and local scour. Especially the 2005 flood in the Alpine regions in Europe demonstrated the hazard potential of transported and accumulated LW. Despite rece...
Article
https://ascelibrary.org/doi/abs/10.1061/%28ASCE%29HY.1943-7900.0001501 During flood events, transported large wood (LW) may accumulate at river infrastructures or is retained intentionally at retention structures. In both cases, the accumulation results in backwater rise upstream of the clogged cross section. Previous studies determined various go...
Article
Full-text available
Large wood (LW) in rivers increases the flow variability and provides habitats for various species. During flood events, transported logs can accumulate at river infrastructures and increase the flood hazard. LW accumulations result in an upstream backwater rise and may increase local scour, for instance at bridge piers. Consequently, estimates of...
Conference Paper
During flood events, transported large wood (LW) can accumulate at river infrastructures, reduce the flow cross-section, lead to backwater rise and eventually to flooding of the adjacent area. In addition, LW accumulations can damage the river infrastructure itself. To predict the risk of LW accumulations, the estimation of the accumulation probabi...
Conference Paper
Full-text available
Large wood (logs with a diameter ≥ 0.1 m and a length ≥ 1.0 m) in rivers improves the diversity of morphological structures and flow conditions. It may be transported as single logs or in a bulk, forming a log jam or an accumulation at an obstruction. In a natural river, large wood (LW) accumulations create heterogeneous hydraulic gradients and inc...
Article
Wasserfälle sind besondere Landschaftselemente. Bei Gewässern mit Wasserfällen kann eine Wasserentnahme, z. B. zur Wasserkraftnutzung, zu einem Konfliktpotenzial zwischen den Nutzungsinteressen und den Anliegen des Natur- und Landschaftsschutzes führen. Im Rahmen von drei Masterarbeiten wurde an der Versuchsanstalt für Wasserbau, Hydrologie und Gla...
Conference Paper
Full-text available
Despite the positive contributions of Large Wood (LW) to river ecosystems, LW may also induce risks for human populations, particularly at critical sections such as bridges and weirs. Therefore, the challenge of a better large wood management strategy is to maintain the equilibrium of good ecological and hydromorphological conditions of rivers, and...
Conference Paper
During flood events, transported driftwood may lead to accumulations at river infrastructures, such as bridges or weirs. These accumulations cause backwater rise and may lead to a flooding of the nearby area. Similarly, the accumulation at a driftwood retention structure results in a backwater rise. For both cases, the estimation of the backwater r...

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Projects

Projects (2)
Project
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. To plan and evaluate river restoration projects including wood accumulations, it is important to understand the interactions between flow, wood, and sediment. Using physical modeling, this project aims to quantify flow and morphological structures associated with different wood accumulation setups. This project is funded by the Swiss National Science Foundation.
Archived project
Despite the positive contributions of instream large wood (LW) to river ecosystems, LW may also induce risks for human populations, particularly at critical sections such as bridges and weirs. Therefore, the challenge of a better large wood management strategy is to maintain the equilibrium of good ecological and hydromorphological conditions of rivers, and analyze and manage potential risks. This is the aim of the WoodFlow project (Schwemmholz Management Projekt), which will contribute to the development of a federal management strategy in Switzerland and will help to evaluate and modify established protection concepts. The project is founded by the Swiss Federal Office for the Environment (FOEN-BAFU), it started in September 2015 and will finish in 2019. The project consortium is formed by: Dendrolab.ch (Institute for Environmental Sciences, University of Geneva), Swiss Federal Research Institute (WSL), Laboratory of Hydraulics, Hydrology and Glaciology (VAW-ETH) and the School of Agricultural, Forest and Food Sciences (HAFL-BFH) of the Bern University of Applied Sciences.