Concerns about the effects of hydropower operations on downstream environmental resources continue to prompt searches for ways to minimize adverse impacts while maintaining high levels of energy production. As part of the Water Use Optimization Toolset (WUOT) Project, a project funded by DOE's Office of Energy Efficiency and Renewable Energy, EVS researchers in collaboration with researchers from Argonne’s Energy Systems Division and from Sandia National Laboratories and Pacific Northwest National Laboratory, have developed an analytical approach and software tool to evaluate how well discharge regimes meet ecosystem management goals downstream of hydropower facilities and assist in the planning and optimization of hydropower operations. The tool, referred to as the Index of River Functionality (IRF) tool, was one of several hydropower planning tools developed for the project.
The IRF tool calculates an overall environmental score based on user-identified environmental objectives and is intended to assist facility operators, natural resource managers, and other stakeholders with the management of water resources. It provides an interface that assists users with input parameters based on the environmental objectives of interest. Under the developed approach, site-specific environmental objectives are identified, along with metrics for characterizing the degree to which those objectives are met.
The environmental objectives are defined using relationships between the metrics and hydropower-influenced flow characteristics (e.g., discharge, velocity, depth, water temperature) and consideration of seasonal timing, duration, and return frequency requirements for the environmental aspect associated with the metric. The IRF tool is capable of integrating information for disparate environmental objectives in multiple downstream locations when appropriate time-series for flow conditions for the various locations are provided. There is also the potential for developing basin-wide environmental performance scores using objectives and time-series of flow conditions for different subbasins.
The IRF tool can be used as a standalone evaluation method or integrated with other software tools developed for operational planning to facilitate prioritization and optimization among environmental performance, hydropower generation, and power revenue goals. It can also be used to support adaptive management by using the results of research and monitoring to refine the way environmental objectives are defined.
Tests of the WUOT for the Bureau of Reclamation's Aspinall Unit (a cascade system of three dams - Blue Mesa, Morrow Point, and Crystal on the Gunnison River in Colorado) and the California Department of Water Resources' Oroville-Thermalito Complex (a combination of pump-storage and conventional hydropower generating units on the Feather River) demonstrated that the WUOT could identify realistic operational scenarios capable of increasing the value of generated hydropower as compared to historic operation while maintaining or improving the ability to meet environmental objectives.