Environmental impacts of future operating conditions (Task 2.3)

This is a research project within the NRP 70, led by Paolo Burlando (ETHZ-HWRM) under the SCCER-SoE umbrella project “Hydropower and Geo-Energy”. The project aims at providing new and advanced methods for the analysis of medium-to-long term trade-offs between hydropower production and eco-hydrological dynamics in Alpine catchments under current and projected climate.

This is a research project within the NRP 70 led by Anton Schleiss (EPFL-LCH). It aims at predicting, quantifying, and monitoring the consequences of adaptive flow management and other restoration actions for floodplains as centres of biodiversity and ecosystem goods and services.

This is an applied research project supported by the Federal Office for the Environment (FOEN). It is a follow-up of the project “Integrated River Management”. The project aims at developing and evaluating methods for an effective and ecologically sound bedload transport, and for the restoration of the dynamics in floodplain

This project, led by Matteo Facchini (ERHZ-VAW), aims at investigating the sediment dynamics downstream of a recently installed sediment bypass tunnel at a hydropower dam.

Freshwater ecosystems are exposed to a multitude of anthropogenic stressors, such as overexploitation, water pollution, hydro-morphological alteration and hydropower operations. Further, it is very likely that there will be a global surge in the construction of small to medium-sized hydropower plants located in mountainous regions. The impact of such small hydropower plants are most obvious in the downstream river reaches, which experience reduced flows and sediment inputs below the water takes. The resulting deterioration of the in-stream habitat within these residual flow reaches has been shown to impact on fish density and condition, invertebrate and fish community composition and ecosystem functioning such as organic matter breakdown and retention. However, there currently is a lack of understanding of the underlying mechanisms affecting food-web structure and dynamics. Therefore, this project investigates in-stream conditions and the structure and functioning of food-webs along the river reaches impacted by small run-of-river hydropower plants. The gained knowledge will then help designing efficient mitigation measures.

As most of the potential for large hydropower reservoirs is already exploited, future development focusses on small run-of-the-river hydropower plants (SHP). Being considered a relatively environment-friendly electricity source, investment in SHP is promoted through subsidies. However, SHP can have a significant impact on riverine ecosystems, especially in the Alpine region where residual flow reaches tend to be long. An increase in hydropower exploitation will therefore increase pressure on ecosystems. While it is inevitable that some ecosystems are compromised by hydropower plants, the context of these impacts within a river network should be considered when selecting suitable sites for SHP. From an ecological point of view, the diversity of habitats, and therefore the diversity of species, should be maintained within a river basin. Within this project, trade-offs between multiple objectives regarding environmental impacts, electricity production and economic valuation are established using a multi-objective evolutionary algorithm. Objectives that go beyond lumped parameters of hydrological alteration, but also consider habitat diversity and the spatial configuration will be developed. Trade-off curves between different objectives can help decision makers to define policies for licensing new SHP and for defining minimum flow requirements.

The goal is to develop and study the performances of innovative water intake operational rules for redistributing the water between the environment and the hydropower. It will be shown that non-proportional redistribution is a more efficient solution than proportional and static ones, as it results in increased both ecological and economic benefits for water exploitation of Alpine rivers."

The technique of replenishment of sediments consists on supplying these by bypassing them directly from the reservoir or collecting grains from other close sites. This technique was already adopted in a few Japanese and German rivers. The results, so far from these experiences, indicate that the replenishment helps maintaining a stable bed and mitigating bed armoring. The goal of this research is to improve the procedure to be applicable in the alpine sites aiming at developing adequate morphology for restoration of suitable habitats conditions downstream dams in order to ensure fish reproduction. Hydrodynamics around river replenishment geometries and erosion evolution of these will be assessed