Precipitation and temperature will change in future climates, presenting new challenges and opportunities for Norwegian hydropower. We anticipate an increase in the frequency, duration, and severity of extreme events such as floods, droughts, and high water temperatures. The research project ReAdapt aims to study how we can adapt the hydropower system to a new climate focusing on extreme events. The goal is to maintain or increase hydropower production while preserving biodiversity in well-functioning ecosystems.
Freshwater ecosystems are adapted to historical climate conditions. Hydropower has a recognised impact on freshwater ecosystems, but we have good knowledge of both the effects and mitigation measures. Increased frequency and severity of extreme events may worsen the conditions, but river regulation also provides an opportunity to offset negative climate changes.
ReAdapt will employ ten different scenarios for how climate and extreme events may develop. Hydrological models will be used to calculate inflow, discharge, and water temperature. Power system models will then be used to determine future energy production, electricity prices, and operation of reservoirs and power plants.
We are focusing on salmon in ReAdapt because it responds relatively quickly to changes in physical conditions. There is a lot of relevant knowledge about how salmon reacts to various climatic conditions, which we will use in combination with experimental studies at the NINA research station in Ims. There, we will observe how salmon responds to different flow and water temperature conditions, which will, in turn, be used in models for salmon growth and development. Together with models for climate, hydrology, and power production, we can predict how extreme climate events affect salmon and, furthermore, how we can adapt hydropower and implement mitigating measures to ensure both power production and salmon survival in the future climate.
In WP1, study areas and scenarios were selected in collaboration with industry partners Statkraft, Eviny, and Å Energi. Climate analyses are based on RCP4.5, using results from 10 GCM/RCM models to assess effects on hydrology, biology, hydraulics, and the energy system. The partners have also identified relevant measures to reduce negative climate impacts, with further clarifications made continuously. The choices are documented in the report “Valg av studieområder og utvikling av scenarier i ReAdapt” (NTNU 978-82-8289-215-5), which is updated as decisions are clarified.
In WP2, future climate runoff was simulated for the periods 2041–2070 and 2071–2100. The runoff data has been prepared for use in the hydropower models FanSi and SDPM. A routing model has been established for Follsjø and Gråsjø to assess flood mitigation, and an analysis of runoff was performed to extract extreme values for floods and low flows. Water temperature simulations have been initiated. For Bergsdalsvassdraget, future runoff was simulated for all subcatchments, while the hydrological model has been established in Mandal and climate simulations have been carried out for an unregulated catchment.
Data from WP2 was received and reviewed in spring 2025 and is used in WP3 for model runs in FanSi and SDPM, with the 2050 baseline dataset from KSP HydroConnect ready. Climate scaling is applied to air temperature, while solar and wind power are not adjusted due to high uncertainty. Implementation of climate scaling factors in FanSi is ongoing, but progress has been slower than planned, and the first model runs with adjusted data are scheduled for December 2025. SDPM results are postponed to 2026 due to maternity leave, with initial focus on the Trollheim/Surna case.
WP4 (Ecological impact analyses on a key indicator species) is divided into three sub-tasks. Task 4.1 examines how extreme episodes in the past have affected salmon in regulated rivers, using Surna as a case study and Nausta as a reference. Hydrological and biological data are combined and analyzed with various statistical models; work is ongoing. Task 4.2 tests the effect of future climate warming and hydropower operations on juvenile salmon in semi-natural channels, and analysis of experimental data has begun. A protocol to measure telomere length as a biomarker for climate stress is being tested. Task 4.3 (mathematical modeling of future consequences) will start in 2026.
WP5 will start in 2026.
ReAdapt will generate research-based knowledge about how hydropower can optimize and re-adapt sustainable operations in future climates. The focus will be on extreme events, and how they can be accommodated with strategic investments and measures, to minimize uncertainty, and maintain or increase hydropower production. At the same time, we will investigate impacts to ensure a well-functioning aquatic ecosystem by adapting hydropower operations and suggest mitigation measures for the key species Atlantic salmon.
ReAdapt will identify a set of compound scenarios combining multiple climate pressures and other stressors that pose risks to hydropower production and the ecosystem. By the use of hydrological modelling and ten downscaled and bias-corrected climate scenarios for emission scenarios RCP4.5 and RCP8.5, we will characterize extreme events of flow and water temperature for the scenarios. We will then use power system models to analyse how these scenarios will impact total power system costs, electricity prices, energy production, reservoir management and environmental flow releases at national and local scales.
Atlantic salmon is an ideal model organism to study ecological effects of extreme climate events because it is a key indicator species used to assess ecological conditions in rivers. We will analyse historical data to understand how extreme episodes have affected salmon. By using a combined experimental, and genetical approach, we will test ecological impacts of projected extreme water temperatures and flow conditions at NINA’s Research Station Ims. Results from future scenarios on hydrology and power system models will feed into a mechanistic individual-based model, to simulate salmonid response to impacts of extreme events.
Finally, we will show how extreme events impact the ability for hydropower plants to comply with revised terms of licenses, total power system costs, and energy production while maintaining sustainable ecosystems.
