Development of an inflow‐controlled environmental flow regime for a norwegian river

Hydropower produces 99% of the electricity in Norway, and a large number of rivers are regulated. Currently, static minimum flow regimes are used as a mitigation measure for most of these developments, usually having fixed values for winter and summer flow. Improved knowledge on the importance of variability in flow regimes has led to research on alternative solutions to the static minimum flow regimes. This paper describes the development of an environmental flow regime that is designed to follow the variation in natural inflow. The flow regime is designed using an adaptation of the building block methodology and linked to high, normal and low natural flow conditions. The work is focused on the river Daleelva in western Norway where Atlantic salmon is the key species. The paper also describes how the variable environmental flow regime can be implemented in practice as it pertains to current Norwegian legislation.