SUPERVISOR: Stefan SCHMUTZ

PROJECT ASSIGNED TO: Kevin MERL

The European Union aims to improve the ecological status of rivers (WFD - EU Water Framework Directive) and at the same time aims for a reduction in greenhouse gas of 80-95 % by 2050 (European Commission, 2012). These two objectives don’t necessarily go hand in hand. The reduction of greenhouse gas emissions should be achieved through the expansion of renewable energy sources as well as by increasing efficiency and reducing electricity consumption. Renewable energy production by wind and solar is volatile, therefore a way to buffer these fluctuations is needed (European Commission, 2009). Storage power plants and pumped storage hydro power plants (Figure 1) offer a way to store and release the energy when needed (Neubarth, 2017). But these power plants influence the river systems. Most obviously the hydrology and river morphology changes (Vanzo et al., 2015) and, consequently,  the ecology is affected (Bunn & Arthington, 2002; Poff & Zimmerman, 2010).

Figure 1: Scheme of a high-head storage power plant (Greimel et al., 2018)

The thesis is situated in the ÖkoResch – Project which tries to establish the basis for a tolerable ecological condition (“Good Ecological Potential”) in Alpine rivers affected by residual flow and hydropeaking (Greimel, 2020).

One part of the thesis tries to assesses the influence of artificial flow fluctuations (hydropeaking) downstream of the power plant, which are caused by the rapid release of water for energy production – affecting a variety of biotic and abiotic parameters. In the project morphology, hydrology as well as fish and macroinvertebrates are considered. This part of the thesis will focus on the influence of hydropeaking on juvenile fish based on the SuREmMa+ method (Schülting et al., 2021). Juvenile fish are sensitive to hydropeaking because they prefer habitats close to the bank and their ability to swim is not fully developed (Auer et al., 2017; Heggenes & Traaen, 1988; Jensen & Johnsen, 1999; Young et al., 2011). In this study the results of in situ sampling of juvenile fish are compared to the hydropeaking intensity and the morphological characteristics of the river. Experimentally, multiple thresholds for hydropeaking are already established as shown in a review of Moreira et al. (2019). Compared to the study of Schmutz et al. (2015) which tested the response of fish communities to hydropeaking in Austrian rivers this study will focus on the juvenile fish abundance and sample in a higher spatial resolution. This work should underpin the experimental thresholds of the hydropeaking intensities in the field at multiple river systems. Which leads to the research question: “How are juvenile fish abundances affected by hydropeaking intensity parameters (amplitude, frequency, ramping rate) in combination with morphological characteristics (e.g. channel geometry) in various rivers in Austria?”.

The results should build the scientific basis for the establishment of a guideline for assessing the influence of hydropeaking and a means to monitor mitigation measures.

The second part of the thesis is situated in residual flow stretches, where water is stored or abstracted at the weir which is therefore missing in the river downstream. The morphology of a river changes with alterations in hydrology and sediment transport (Gurnell, 1983), which is a rarely researched (Bakker et al., 2018). Based on the morphology of the rivers the effect of the reduction in discharge and sediment transport on the channel form will be investigated. Reference sites above the weir allow a comparison to an un/less impacted state. Also, a combination of morphological and hydrological data will help classify and compare these river systems to each other and other alpine rivers. This leads to the research question: “How is the channel form of residual flow stretches affected by water abstraction and sediment retention in various Alpine rivers in Austria?”.  In addition to assessing the impacts on river morphology, this will also help to interpret the macroinvertebrate data that will also be assessed in the project. Fish are not considered for this part of the thesis because fish do not/rarely occur in the high alpine residual flow sampling stretches.

 

 

Auer, S., Zeiringer, B., Führer, S., Tonolla, D., & Schmutz, S. (2017). Effects of river bank heterogeneity and time of day on drift and stranding of juvenile European grayling (Thymallus thymallus L.) caused by hydropeaking. Science of the Total Environment, 575, 1515–1521. doi.org/10.1016/j.scitotenv.2016.10.029

Bakker, M., Costa, A., Silva, T. A., Stutenbecker, L., Girardclos, S., Loizeau, J. L., Molnar, P., Schlunegger, F., & Lane, S. N. (2018). Combined Flow Abstraction and Climate Change Impacts on an Aggrading Alpine River. Water Resources Research, 54(1), 223–242. doi.org/10.1002/2017WR021775

Bunn, S. E., & Arthington, A. H. (2002). Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity. Environmental Management, 30(4), 492–507. doi.org/10.1007/S00267-002-2737-0

European Commission. (2009). Directive 2009/28/EC on the promotion of the use of energy from renewable sources and amending and subsequently repealing Directives 2001/77/EC and 2003/30/EC. Official Journal of the European Union, 140, 16–45.

European Commission. (2012). Energy Roadmap 2050, Communication, COM(2011) 885/2. EU Energy. ec.europa.eu/energy/energy2020/roadmap/doc/com_2011_8852_en.pdf

Greimel, F. (2020). ÖkoResch - Erreichung des Guten Ökologischen Potenzials in hochalpinen Restwasserstrecken und schwallbelasteten Gewässern. forschung.boku.ac.at/fis/suchen.projekt_uebersicht

Greimel, F., Schülting, L., Graf, W., Bondar-Kunze, E., Auer, S., Zeiringer, B., & Hauer, C. (2018). Hydropeaking Impacts and Mitigation. In Riverine Ecosystem Management (pp. 91–110). doi.org/10.1007/978-3-319-73250-3_5

Gurnell, A. M. (1983). Downstream Channel Adjustments in Response to Water Abstraction for Hydro-Electric Power Generation from Alpine Glacial Melt-Water Streams. The Geographical Journal, 149(3), 342. doi.org/10.2307/634009

Heggenes, J., & Traaen, T. (1988). Downstream migration and critical water velocities in stream channels for fry of four salmonid species. Journal of Fish Biology, 32(5), 717–727. doi.org/10.1111/j.1095-8649.1988.tb05412.x

Jensen, A. J., & Johnsen, B. O. (1999). The functional relationship between peak spring floods and survival and growth of juvenile Atlantic Salmon (Salmo salar) and Brown Trout (Salmo trutta). Functional Ecology, 13(6), 778–785. doi.org/10.1046/j.1365-2435.1999.00358.x

Moreira, M., Hayes, D. S., Boavida, I., Schletterer, M., Schmutz, S., & Pinheiro, A. (2019). Ecologically-based criteria for hydropeaking mitigation: A review. Science of the Total Environment, 657, 1508–1522. doi.org/10.1016/j.scitotenv.2018.12.107

Neubarth, J. (2017). SuREmMa - Technischer Bericht C - Die Rolle der Speicherwasserkraft im österrei- chischen und europäischen Stromversorgungssystem.

Poff, N. L., & Zimmerman, J. K. H. (2010). Ecological responses to altered flow regimes: a literature review to inform the science and management of environmental flows. Freshwater Biology, 55, 1. doi.org/10.1111/j.1365-2427.2009.02272.x

Schmutz, S., Bakken, T. H., Friedrich, T., Greimel, F., Harby, A., Jungwirth, M., Melcher, A., Unfer, G., & Zeiringer, B. (2015). Response of Fish Communities to Hydrological and Morphological Alterations in Hydropeaking Rivers of Austria. River Research and Applications, 31(8), 919–930. doi.org/10.1002/rra.2795

Schülting, L., Zeiringer, B., Leitner, P., Greimel, F., Zoltan, L., Führer, S., Auer, S., Dossi, F., Sumper, R., Pazmandy, J., Haslauer, M., Graf, W., & Schmutz, S. (2021). Technischer Bericht IV - Entwicklung Anwendung des Monitoringkonzeptes zur Durchführung des ökologischen Prä- und Post-Monitorings in Schwallstrecken, Er- gänzung zu Endbericht: SuREmMa+, Forschungsbericht, Wien Seiten. 33.

Vanzo, D., Zolezzi, G., & Siviglia, A. (2015). Eco-hydraulic modelling of the interactions between hydropeaking and river morphology. doi.org/10.1002/eco.1647

Young, P. S., Cech, J. J., & Thompson, L. C. (2011). Hydropower-related pulsed-flow impacts on stream fishes: A brief review, conceptual model, knowledge gaps, and research needs. Reviews in Fish Biology and Fisheries, 21(4), 713–731. https://doi.org/10.1007/s11160-011-9211-0