Ecologically-based criteria for hydropeaking mitigation: A review.

Area of Science:

• Environmental Science
• River Ecology
• Hydropower Management

Background:

• Hydroelectric power plants cause hydropeaking, rapid downstream water level fluctuations impacting river ecosystems.
• Hydrological alterations from hydropeaking are defined by magnitude, rate of change, frequency, duration, and timing.
• These parameters correlate with environmental impacts, informing mitigation strategies.

Purpose of the Study:

• To review existing hydropeaking targets and thresholds from scientific literature and national regulations.
• To identify knowledge gaps in mitigation strategies for hydropeaking impacts.
• To propose an approach for developing ecologically-based mitigation targets.

Main Methods:

• Extensive literature review of scientific publications.
• Analysis of national regulations concerning hydropeaking in various countries.
• Synthesis of findings to identify common themes and knowledge gaps.

Main Results:

• Few European countries (Switzerland, Austria) have legal hydropeaking flow thresholds.
• US and Canadian legislation can mandate mitigation, but specific thresholds are often lacking.
• Literature primarily addresses salmonid stranding and spawning ground desiccation, with limited data on other species and case studies.

Conclusions:

• Existing hydropeaking mitigation targets are scarce and often species-specific (e.g., salmonids).
• A significant knowledge gap exists regarding mitigation for other fish species and comprehensive case studies.
• Ecologically-based mitigation targets should integrate key species, seasonal/daily variations, life stages, and site-specific characteristics.