Task 2.1: Morphoclimatic controls on future hydropower production

Research Partners: Swiss National Institute of Forest, Snow and Landscape Research (WSL), Center for Climate Systems Modeling (C2SM) at ETH Zurich, Chair of Hydrology and Water Resources Management (HWRM) at ETH Zurich, Laboratory of Hydraulics, Hydrology and Glaciology (VAW) at ETH Zurich

Research objectives
The recent comprehensive study about the impact of climate change on hydropower production (SGHL/CHy, 2011) revealed substantial uncertainties related to the water resources that will be available in 30 to 50 years. With a dedicated effort at leading Swiss research institutes in climate modelling, glacier and snow research, we aim to significantly reduce these uncertainties and provide a more secure basis to hydropower industry to decide on long-term investments.

With the expected climate change, the “natural boundary conditions” for hydropower production will change. Today, we know quite well how water availability for alpine hydropower plants, as well for down-stream run-on-river plants in Switzerland will change on average. Several national and international studies (swisselectric, EU-project ACQWA, NRP 61) agree that:

  • the most significant change will be the temporal shift and overall contribution in spring runoff as a consequence of changing snow availability and melt.
  • glacier melt is currently more abundant than compared to the time when many of the existing power plants were built. This abundance is expected to decrease substantially in the second half of the century.
  • overall the total annual water availability for hydropower production will not decrease dramatically. Large parts of the uncertainty affecting future projections of the water resources are related to uncertainties associated with climate scenarios. with regard to fine sediments and coarse bedload transported towards water-intakes and hydropower reservoirs there is strong evidence that the availability will increase, particularly in periglacial zones. However, this doesn’t necessarily mean that the transport of this material will increase. This will not depend on the future average water flow, but on the occurrence of large rare storm events.

In spite of the comprehensive knowledge gained in recent national and international studies, there are still important knowledge gaps:

  • Current ice volume of glaciers. The spatial extension of the glaciers is well-known, but there is substantial uncertainty about their thickness.
  • Winter-time inflow to hydropower reservoirs and plants. Past studies focused on the water inflow in spring and summer; however, most important for hyddropower production will be the availability of water in winter time.
  • Role of climate change and climate variability. Global and regional climate models as well as statistical and stochastic downscaling methods are continuously being improved. The SCCER-SoE will have access to an updated set of climate change scenarios from a multi-model, multi-greenhouse gas scenario ensemble as well as to very-high resolution climate scenarios (down to 2km resolution) for the first time. Uncertainties in climate scenarios result from emission scenarios, natural climate variability, and climate models themselves. Using an updated set of climate scenarios will allow better exploring the uncertainties and the extreme events affecting future estimates of hydropower resources with a mid- to long-term time horizon.
  • Decadal variability. Climate trends are not steady, but include decadal oscillations. For HP investments with an amortization in the time scale of 10 to 30 years, such decadal variability is of great interest.
  • Sediment flow to hydropower intakes and reservoirs. Measurements of sediment transport above hydropower plants are very scarce worldwide. Therefore, estimations of rates and total volumes of sediment supply to hydropower intakes and reservoirs are still of low reliability.

Current projects

The project assesses how decadal predictions can be used for middle-term forecasts in the hydro-glaciological context. The aim is to support achieving the goals defined in the Swiss Energy Strategy 2050.

Source of funding: Swiss National Science Foundation (SNSF), National Research Programme NRP 70

Research partners: Swiss National Institute of Forest, Snow and Landscape Research (WSL)

Duration: November 2014 to October 2017

Project website

The project HEPS4Power explores the use of extended-range hydrological ensemble predictions systems (HEPS) for improving the operations and revenues of hydropower systems. Monthly to seasonal forecasts will be tested and novel post-processing and verification methods will be developed.

Source of funding: Swiss National Science Foundation (SNSF), National Research Programme NRP 70

Research partners: Swiss National Institute of Forest, Snow and Landscape Research (WSL), Federal Office of Meteorology and Climatology (MeteoSwiss)

Duration: November 2014 to October 2017

Project website

The project OPT-HE has the objective to increase the production of large hydropower plants by hydrological high performance forecasts which allow optimizing the management of the dams and reducing water loss by spillage inside of a complex catchment.

Source of funding: Commission for Technology and Innovation (CTI)

Research partners: Laboratory of Hydraulic Constructions (LCH) at EPFL, Swiss Federal Institute of Technology in Zurich (ETHZ), e-dric.ch, Alpiq, Groupe-e, MeteoSwiss, Romande Energie, Société Electrique des Forces de l’Aubonne (SEFA), SIG

Duration: May 2014 to August 2017

Thesis sheet

 

The main objective of this project is to generate very high-resolution climate scenarios for hydropower projection for the mid and end of the 21th century using state of the art global and regional climate models and greenhouse gas scenario ensemble. For that purpose a new stochastic weather generator is being developed with the aim of formulating a high spatial and temporal resolution (e.g. 1 km x 1 km and 5 min) for simulating key climate variables (e.g. precipitation, temperature, cloud cover, etc.) at local scale and over a raster. This will allow better exploring the uncertainties in the projected climate scenarios at basin scale, which result from emission scenarios, natural-stochastic climate variability, and global circulations models.

Source of funding: Swiss Competence Center on Supply of Electricity (SCCER-SoE)

Research partners: Center for Climate Systems Modeling (C2SM) at ETH Zurich, Chair of Hydrology and Water Resources Management (HWRM) at ETH Zurich

Duration: August 2014 to December 2016

Previous studies on the impact of climate change on water resources provided clear perspectives for annual and spring/summer water availability for hydropower. However, for the water inflow to hydropower plants during the critical winter period, an in-depth analysis is still missing. This project makes use of the available model simulations, as well as of most recent climate change scenarios to highlight the perspectives for water flow to hydropower plants in late autumn and winter throughout the 21st century.

Source of funding: Swiss Competence Center on Supply of Electricity (SCCER-SoE)

Research partners: Swiss National Institute of Forest, Snow and Landscape Research (WSL)

Duration: January 2014 to December 2016

Past projects

Until recently, direct measurements of ice thickness were limited to a few selected glaciers. Supported by the Swiss Geophysical Commission (SGPK) and Swiss Competence Center on Supply of Electricity (SCCER-SoE) an initiative to improve the knowledge of ice volume distribution in the Swiss Alps was started. An important step towards this goal includes the delineation of the glacier bedrock topography using a new approach of ice flux computation. Additional measurements on not yet surveyed glaciers are needed and previous surveys will be completed.

Source of funding: Swiss Geophysical Commission (SGPK), Swiss Federal Institute of Technology in Zurich (ETHZ)

Research partners: Swiss Federal Institute of Technology in Zurich (ETHZ)

Duration: January 2014 to December 2015

Project website