Hydro:
Impacts related to instream flow releases from conventional hydropower

Conventional Hydropower Instream Flow Needs Assessment

Stakeholders are applying increasing pressure on many hydropower owners to change plant operations such that downstream river flows are more conducive to healthy aquatic biological communities. These changes often result in a move away from peaking operations to run-of-river operations that are less economically valuable, based on the assumption that downstream biological communities will improve under more natural flow regimes. In order to compare and contrast flow regime options and evaluate the level of differences between regulated scenarios and unregulated flows, appropriate analytical methods are needed. Under this subtask, Argonne will identify and evaluate flow metrics suitable for describing how operational objectives (e.g., providing power during peak demand) and environmental regulations (e.g., such as minimizing extreme flow fluctuations) interact to alter the river flow regime at various time scales (e.g., within-day, between day, seasonal, and interannual). Appropriate methods and tools are needed to be able to assess the comparative value of river flow dynamics for both power production and biological resources.

This project will develop an analytical approach that stakeholders can use to characterize flow regimes to better assess their ability to provide efficient power and environmental services.

Argonne will evaluate and develop analytical approaches suitable for evaluating hydropower flow regimes. Tasks to be conducted include:

• Evaluate descriptive flow metrics and determine which are most appropriate for hydropower assessment and mitigation
• Develop new flow metrics for assessing within-day flow variability to address hydropower peaking operations
• Test various multivariate statistical approaches for using simultaneously multiple flow metrics (within-day, among-day, and seasonal) in characterizing existing and potential project hydrographs
• Participate in conference symposia and workshops

March 2012