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SEDRIVER: Effects of sediment transporting flows on fish habitat in mountain rivers - expected development until 2050 taking into account climate change

Applicant Rickenmann Dieter
Number 125975
Funding scheme NRP 61 Sustainable Water Management
Research institution Swiss Federal Research Inst. WSL Direktion
Institution of higher education Swiss Federal Institute for Forest, Snow and Landscape Research - WSL
Main discipline Geomorphology
Start/End 01.04.2010 - 30.11.2013
Approved amount 512'538.00
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All Disciplines (6)

Discipline
Geomorphology
Civil Engineering
Environmental Research
Hydrology, Limnology, Glaciology
Other disciplines of Environmental Sciences
Ecology

Keywords (5)

sediment transport; brown trout habitat; mountain stream; flood risk; climate change

Lay Summary (German)

Lead
Mehr Hochwasser - mehr Sedimenttransport - weniger Fische? Mit dem Klimawandel werden sich das zeitliche Auftreten und möglicherweise die Stärke von Hochwassern verändern. Auch wird eine Zunahme oder eine saisonale Verschiebung der von den Flüssen verfrachteten Mengen an Kies und Sand erwartet. Massnahmen gegen Hochwasser müssen also angepasst werden. Wie wirken sich Hochwasser und Sedimenttransport auf die Lebensbedingungen der Fische aus?
Lay summary

Hintergrund

Der Klimawandel wird in den kommenden 40 bis 100 Jahren die Hochwasser und somit den Transport von Sedimenten in Gebirgsflüssen beträchtlich beeinflussen. Es wird damit gerechnet, dass sich Anzahl, Stärke und zeitliche Verteilung von Niederschlagsereignissen verändern werden. Dies könnte zu häufigeren und grösseren Hochwassern führen. Zudem wird durch das Abschmelzen der Gletscher und des Permafrostes Schutt freigelegt, der abtransportiert werden kann. Das führt in einigen Gebieten dazu, dass Gebirgsflüsse mehr Kies und Sand transportieren werden. Bei stark erhöhten Sedimentmengen werden bestehende Schutzmassnahmen ihre Funktion nur noch teilweise erfüllen. Die veränderte Verteilung des Materials in den Flüssen wird auch die Lebensbedingungen der Fische beeinflussen. Wahrscheinlich wird sich das Auftreten von Hochwassern im Winter und Frühjahr verändern, was den Erfolg der natürlichen Fortpflanzung beeinträchtigen kann. Die genauen Auswirkungen sind allerdings noch kaum bekannt.

Ziele und Methoden

In diesem Projekt werden die Folgen des Klimawandels für den Sedimenttransport und für die Qualität der Fischhabitate untersucht. Mit einem Modell werden Sedimentbilanzen ausgewählter Flussgebiete berechnet, nämlich für die Kleine Emme, den Brenno und die Hasliaare. Wir vergleichen die Modellberechnungen mit Daten von vergangenen Hochwasserereignissen in diesen Flüssen. Mit Messungen an Gebirgsflüssen wird der Zustand der Fischhabitate erhoben. Wir untersuchen, wie der veränderte Sedimenttransport im Fluss den Fortbestand von Bachforellenpopulationen beeinflusst. Wir analysieren zudem, wie sich Änderungen des Hochwasserabflusses und Veränderungen des Eintrages von Sedimenten zum Beispiel durch den Permafrost-Rückzug auf das Geschiebe in den Gebirgsflüssen und die Hochwassersicherheit auswirken.

Bedeutung

Das Projekt soll dazu beitragen die zeitliche Entwicklung der Geschiebeverlagerungen in Gebirgsflüssen zu quantifizieren, welche als Folge des Klimawandels bzw. von veränderten Abflüssen und Sedimenteinträgen zu erwarten ist. Die Resultate liefern wichtige Grundlagen, um in Gebirgsflüssen einerseits Gefahren zukünftiger Hochwasser mit Geschiebeverfrachtung abzuschätzen, und andererseits die Lebensbedingungen für Bachforellen zu beurteilen. Die entwickelten Methoden werden Behörden und Entscheidungsträger darin unterstützten, mögliche Gefahren im Zusammenhang mit Sedimentverlagerungen bei Hochwassern in Gebirgsflüssen besser einzuschätzen und Konzepte für ein ökologisches und integrales Management von Einzugsgebieten weiterzuentwickeln.

Direct link to Lay Summary Last update: 19.03.2013

Lay Summary (French)

Lead
Augmentation des crues, augmentation des transports de sédiments: moins de poissons?Avec le changement climatique, les périodes propices aux crues, et éventuellement l'intensité de celles-ci, vont changer. On s’attend aussi à une augmentation ou à un décalage saisonnier des volumes de gravier et de sable transportés par les rivières. Les mesures contre les crues doivent donc être adaptées. Quels effets les crues et le transport de sédiments ont-ils sur les conditions de vie des poissons?
Lay summary

Arrière-plan

Dans les 40 à 100 ans à venir, le changement climatique va influencer considérablement les crues, et de ce fait le transport de sédiments dans les rivières alpines. On s’attend à ce que la quantité, l’intensité et la périodicité des précipitations changent. Ceci pourrait conduire à des crues plus fréquentes et plus fortes. De plus, la fonte des glaciers et du pergélisol dégagent des matériaux pouvant par la suite être emportés. En conséquence, dans certaines régions, les rivières alpines transporteront davantage de gravier et de sable. En cas de forte augmentation du volume de sédiments, les mesures de protection en place ne rempliront que partiellement leur fonction. Une modification de la répartition des matériaux dans les rivières influencera aussi les conditions de vie des poissons. La survenue des crues hivernales et printanières va probablement changer, ce qui pourrait nuire au succès de la reproduction naturelle. Les répercussions exactes ne sont toutefois que très mal connues.

Objectifs et méthodes

Au cours de ce projet, les conséquences du changement climatique sur le transport de sédiments et la qualité de l’habitat des poissons seront examinées. A l’aide d’un modèle, le bilan sédimentaire des rivières choisies, soit la Petite Emme, le Brenno et la Hasliaare, sera calculé. Les prédictions du modèle seront comparées avec les crues antérieures de ces rivières. A l'aide de mesures prises dans des rivières de montagne, l’état des habitats piscicoles sera relevé. Nous déterminerons comment les modifications du transport des sédiments dans les rivières influencent la subsistance de populations de truites de rivière. En outre, nous analyserons l'effet produit par les changements des débits de crues et par les modifications dans l'apport de sédiments, par exemple en raison du retrait du pergélisol, sur les matériaux charriés dans les rivières torrentielles et sur la sécurité en cas de crues.

Portée

Le projet doit contribuer à quantifier l'évolution chronologique du charriage dans les rivières torrentielles, à laquelle il faut s'attendre en raison du changement climatique ainsi que des modifications du débit et de la quantité de sédiments. Ces résultats fournissent des bases permettant d’une part d’estimer les dangers liés à de futures crues accompagnées de déplacements de matériaux charriés dans les rivières de montagne, et d’autre part de juger des conditions de vie des truites de rivière. Les méthodes développées aideront les autorités et les décideurs à mieux évaluer les éventuels dangers liés aux matériaux charriés lors de crues dans les rivières torrentielles et à perfectionner les concepts de gestion écologique intégrée des bassins versants.

 

Direct link to Lay Summary Last update: 19.03.2013

Lay Summary (English)

Lead
More floods - more sediment transport - less fish? The frequency and possibly the extent of flooding will change as the climate changes. An increase or a seasonal shift in the amount of gravel and sand that is transported by rivers may be expected. Existing measures against floods need to be adapted. What effects do flooding and sediment transport have on fish environments?
Lay summary

Background
Climate change will considerably affect flooding and sediment transport in mountain streams over the coming 40 to 100 years. It is to be expected that the number, intensity and temporal distribution of rainfall events will change. This could lead to more frequent and larger floods. Also, the melting of glaciers and permafrost uncovers sediment that can be washed away. For this reason, in some areas mountain streams will carry more gravel and sand. If considerably larger sediment volumes are transported, existing protection measures will only partially fulfil their functions. The modified distribution of material in the rivers will also affect the living conditions of fish. Flood occurrence in winter and spring is likely to change and can interfere with the success of natural reproduction. However, the exact repercussions are hardly known yet.

Objectives and methods

In this project, the consequences of climate change on sediment transport and the quality of fish habitat are examined. Using a model, we calculate sediment budgets for three river catchments, i.e. the Kleine Emme, Brenno, and Hasliaare rivers. We compare the model predictions with data from past flood events in these rivers. Habitat conditions for brown trout are investigated with field campaigns. Climate models predict a future shift in the flow regime during winter periods. We examine how the resulting change of sediment transport in the study rivers influences the survival of brown trout populations. We also analyze how changes in flow discharge and increased sediment delivery for example due to permafrost retreat influence bedload transport and flood safety in mountain streams.

Significance
This study will help to quantify the time evolution of sediment transfer in mountain streams in response to climate change, i.e. to changed runoff and sediment input conditions. The results will support the evaluation of future flood hazards with bed load displacement in mountain streams on the one hand, and the assessment of living conditions for brown trout on the other. The developed methods will help authorities and decision makers to evaluate potential flood-related sediment hazards in Alpine mountain river catchments and to further develop sustainable flood protection and river management concepts.

Direct link to Lay Summary Last update: 19.03.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Bedload transport simulation with the model sedFlow: application to mountain rivers in Switzerland
Rickenmann Dieter, Böckli Martin, Heimann Florian U.M., Badoux Alexandre, Turwoski Jens M. (2016), Bedload transport simulation with the model sedFlow: application to mountain rivers in Switzerland, in Koboltschnig Gernot (ed.), International Research Society INTERPRAEVENT, Klagenfurt, Austria, 387-395.
Assessing the impact of climate change on brown trout (Salmo trutta fario) recruitment
Junker Julian, Heimann FlorianU.M., Hauer Christoph, Turowski JensM., Rickenmann Dieter, Zappa Massimiliano, Peter Armin (2015), Assessing the impact of climate change on brown trout (Salmo trutta fario) recruitment, in Hydrobiologia, 751(1), 1-21.
Calculation of bedload transport in Swiss mountain rivers using the model sedFlow: proof of concept
Heimann Florian U.M., Rickenmann Dieter, Böckli Martin, Badoux Alexandre, Turowski Jens M., Kirchner James W. (2015), Calculation of bedload transport in Swiss mountain rivers using the model sedFlow: proof of concept, in Earth Surface Dynamics, 3(1), 35-54.
Erratum to: Assessing the impact of climate change on brown trout (Salmo trutta fario) recruitment
Junker Julian, Heimann FlorianU.M., Hauer Christoph, Turowski JensM., Rickenmann Dieter, Zappa Massimiliano, Peter Armin (2015), Erratum to: Assessing the impact of climate change on brown trout (Salmo trutta fario) recruitment, in Hydrobiologia, 751(1), 23-24.
sedFlow – a tool for simulating fractional bedload transport and longitudinal profile evolution in mountain streams
Heimann Florian U.M., Rickenmann Dieter, Turowski Jens M., Kirchner James W. (2015), sedFlow – a tool for simulating fractional bedload transport and longitudinal profile evolution in mountain streams, in Earth Surface Dynamics, 3(1), 15-34.
Geschiebetransport und Forellenhabitate in Gebirgsflüssen der Schweiz: mögliche Auswirkungen der Klimaänderung
Badoux A. Peter A. Rickenmann D. Junker J. Heimann F. Zappa M. Turowski J.M. (2014), Geschiebetransport und Forellenhabitate in Gebirgsflüssen der Schweiz: mögliche Auswirkungen der Klimaänderung, SWV, Wasser Energie Luft, Baden, Switzerland.
Geschiebetransport-Simulationen mit sedFlow in zwei Gebirgsflüssen der Schweiz
Rickenmann D. Heimann F. Böckli M. Turowski J.M. Bieler C. Badoux A. (2014), Geschiebetransport-Simulationen mit sedFlow in zwei Gebirgsflüssen der Schweiz, SWV, Wasser Energie Luft, Baden, Switzerland.
Timing of brown trout spawning in Alpine rivers with special consideration of egg burial depth
Riedl Christina, Peter Armin (2013), Timing of brown trout spawning in Alpine rivers with special consideration of egg burial depth, in Ecology of Freshwater Fish, 22(3), 384-397.
Rainfall intensity-duration thresholds for bedload transport initiation in small Alpine watersheds
Badoux Alexandre, Turowski Jens Martin, Mao Luca, Mathys Nicole, Rickenmann Dieter (2012), Rainfall intensity-duration thresholds for bedload transport initiation in small Alpine watersheds, in NATURAL HAZARDS AND EARTH SYSTEM SCIENCES, 12(10), 3091-3108.

Collaboration

Group / person Country
Types of collaboration
Prof. P. Burlando, ETHZ Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
NRP 61 Progress Report Meeting 2013 Talk given at a conference Sedriver, Progress report 14.10.2013 Thun, Switzerland Rickenmann Dieter;
9th International Symposium on Ecohydraulics 2012 Talk given at a conference Influence of hydropeaking on brown trout habitat 17.09.2012 Vienna (BOKU University), Austria Peter Armin;
14. JUWI‐Treffen junger Wissenschaftlerinnen deutschsprachiger Wasserbauinstitute in München Poster Geschiebetransport alpiner Fließgewässer – Modellentwicklung sedFlow 25.06.2012 Munich (Germany), Germany Heimann Florian;
NRP61 Progress Report Meeting 2012 Talk given at a conference SEDRIVER, progress report 12.03.2012 Vitznau, Switzerland Rickenmann Dieter; Peter Armin; Heimann Florian;
NRP61 Progress Report Meeting 2011 Talk given at a conference SEDRIVER, Progress Report 31.03.2011 Murten, Switzerland Rickenmann Dieter; Peter Armin; Heimann Florian; Riedl Christina;
River Corridor Restoration Conference 2011 Talk given at a conference Restoration of the river corridor: a fish perspective 13.03.2011 Ascona, Switzerland Peter Armin;


Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved
13. Kongress INTERPRAEVENT 2016 Talk 30.05.2016 Lucerne, Switzerland Badoux Alexandre; Rickenmann Dieter;
EAWAG Peak-Fachtagung “Herausforderungen einer nachhaltigen Wasserwirtschaft” Talk 14.09.2012 Dübendorf, Switzerland Rickenmann Dieter; Peter Armin;
Discussion of bedload transport simulation tool sedFlow Workshop 01.06.2012 Birmensdorf, Switzerland Heimann Florian; Rickenmann Dieter; Turowski Jens Martin;


Self-organised

Title Date Place
Geschiebehaushalt in Fliessgewässern 17.06.2011 Birmensdorf, Switzerland

Communication with the public

Communication Title Media Place Year
Print (books, brochures, leaflets) Auqa & Gas No. 10, 2012, p. 8 German-speaking Switzerland 2012
Video/Film Mehr Hochwasser - mehr Sedimenttransport - weniger Fische? Western Switzerland German-speaking Switzerland 2012
Media relations: radio, television Gefährdeter Forellen-Nachwuchs DRS1, Magazin Einstein German-speaking Switzerland 2011

Associated projects

Number Title Start Funding scheme
132163 Field measurements of sediment-flux-driven bedrock erosion 01.10.2010 Project funding (Div. I-III)

Abstract

Several studies indicate that climate change will affect flooding and sediment transport in mountain catchments in Switzerland over the coming 40 to 100 years. Sediment yield in a catchment is dependent both on the stream’s capacity to transport and on the availability of loose material. Changing atmospheric circulation will affect the regional distribution and amount of precipitation, and thus possibly the number and frequency of extreme events, and their time of occurrence throughout the year. The extent of glaciation and of permafrost zones, and vegetation patterns will respond to changing temperature, with various effects on sediment availability. The expected resulting increase of the sediment load of a given flood will affect both stream morphology and flood risk assessment. The anticipated hydrological changes will have clear consequences for salmonid survival in mountain streams. Brown trout (Salmo trutta fario) is the most important fish species in Alpine rivers and can be used as an indicator species. The main goal of the proposed project is to study the effect of changing climate conditions on flood and sediment transport behaviour in mountain rivers, and to examine the related impact on trout habitat conditions. The modelling of the sediment transport behaviour for future environmental conditions will be accomplished by adapting an existing, cellular automaton based sediment transport model. The findings of this study will serve to formulate recommendations concerning an ecologically sound river management for the fish habitat both for present and future environmental conditions. The model predictions will also be a basis for the evaluation of future potential sediment hazards at the catchment scale. The main expected outcome of the project can be summarized as follows:•Prediction of the impact of climate change on sediment delivery from Alpine basins•Quantification of relevant components of climate change (snowmelt, glacial melt, vegetation cover) which will have the biggest impact on sediment delivery (which will support flood risk mitigation)•Prediction of the influence of climate driven changes in sediment delivery on fish habitats and related consequences for the survival of brown troutOne of the most highly developed cellular automaton model for fluvial environments cur-rently available is the Cellular Automaton Evolutionary Slope And River (CAESAR) model (Coulthard et al., 2007). This model is appropriate to consider the evolution of coarse and fine sediment transfer in Alpine catchments over longer time periods. It can be operated at two different scales (catchment and reach scale), and has been successfully applied in similar sized UK catchments responding to climate change during the Holocene. Recently, the CAESAR model has been applied to an Alpine environment in eastern France, and the simulated sediment transport successfully compared with the sediment record over the period from 1825 to 2005.The project will be organized in four main tasks, namely “CAESAR model adaptation” (T1), “Investigation of the brown trout life cycle” (T2), “Assessing climate change effects on sediment transport and brown trout habitat” (T3), and “Implementation activities” (T4). An important input to the modelling are the expected climatologic conditions (e.g. rainfall, temperature) for the next 40 years. For this purpose we will coordinate our project with related studies which will provide information on climate change effects on flood scenarios, including glacier retreat and forest cover changes. The task T1 “CAESAR model adaptation” aims to quantify the sediment supply and transfer in typical Swiss mountain catchments, including calibration with past flood events. We will identify dominant hillslope processes and methods for sediment delivery, based on previous studies in Alpine headwater catchments. The elements to be modified in the CAESAR model intend to better represent some important processes in the study catchments and include: snowmelt module, glacial meltwater module, hillslope processes component including quantification of hillslope sediment supply, component to account for changing sediment availability, bedload transport equations tested for mountain rivers and torrents. It is then essential to test and calibrate the modified CAESAR model with past flood events including substantial sediment transport. During the last 10 to 15 years, several large flood events occurred in Switzerland that suit this purpose.In task T2 “Brown trout life cycle” we will study the preferred habitat conditions for brown trout with field investigations in 4-5 prealpine and alpine rivers, and model these conditions with CAESAR. The key environmental variables to describe habitat requirements of brown trout in the model PHABSIM and CASiMiR are streamflow velocity, water depth and substrate properties. Brown trout spawning behaviour will be observed and documented, considering variables used in the habitat models, and new variables will be added (burial depth). Trout spawning sites will be characterized and furthermore, eggs will be artificially incubated in the stream bed and the survival will be monitored at different times, until the time of emergence. In addition wild fry survival will be studied. Using the CAESAR model, we will simulate discharge, flow depth, velocity and substrate variables in two dimensions at a high spatial and temporal resolution. The planned observations at the study river reaches will be used to establish habitat preference curves. Hydraulic and ecological observations will be used to assess the suitability of the CAESAR model predictions to predict the key variables that are essential to characterize the trout habitat conditions.In task T3 “Climate change effects” we will model the effects of expected changes in precipitation, flood occurrence and sediment availability/supply to stream channels due to climate change over the next 40 years. Modelling of sediment transport processes with the modified CAESAR version will be made, accounting for the expected climate change effects on rainfall/flood evolution and sediment supply at the catchment scale and at the reach scale. Model runs will be carried out on relatively coarse spatial scale, using a 25 m grid. The model simulations will show how sediment transfer along the channel system will change for different scenarios of flood occurrence and hillslope sediment delivery. The simulation results (catchment scale) at the upstream point of the selected river reaches will form the input condition for the simulations at a finer spatial scale, with a 2-5 m grid. The focus will be on river reaches of several km lengths which are also part of the field investigations on trout habitat conditions. In task T4 “Implementation activities” we will regularly discuss our findings with stakeholders and we will focus on know-how transfer and software tools to practicing engineers and decision makers. We plan to inform the target audience, i.e. the stakeholders at BAFU and cantonal authorities as well as the practitioners in river engineering and ecological consulting companies, of the findings of our project by the following means: reports summarizing best-practice guidelines for integrated river management; publications in applied journals; workshops with stakeholders at FOEN, cantonal authorities, engineering consultants; a symposium to inform the target audience; and a software tool to predict sediment transport and trout habit conditions.With this project we intend to improve the understanding of the effects of climate change on sediment transporting flood flows, the evolution of river morphology and associated flood hazards in mountain catchments. The project will also contribute to a better understanding of disturbances on the salmonid spawning and rearing habitat, which is basic for future salmonid management and spawning habitat remediation.
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