Printable Version

Hydropower Supporting Research and Testing

Supporting Research and Testing (SR&T) contributes to the development of advanced hydropower technology by providing a scientific basis for engineering designs or analyses. For example, this research fills significant gaps in the scientific understanding of fish response to the physical stresses experienced in passage through turbine systems. Other research under this activity includes studies of cumulative effects on fish of passage through the several hydropower projects and the effects of hydropower projects on downstream aquatic systems.

Objectives

Researchers are pursuing three complementary research approaches to develop a better understanding of the effects on turbine-passed fish and the modifications needed to reduce those effects:

• Performing laboratory studies of the biological response of fish to the physical stresses experienced during passage through turbines

• Developing new instruments and monitoring technologies to measure the physical conditions inside turbines in the field

• Applying advanced computational techniques to describe the full range of hydraulic environments in turbines under different operating conditions

Technical Challenges

The ability to redesign turbines to improve fish passage survival is constrained by a limited understanding of the severity of potential fish injury mechanisms, e.g., pressure changes, strike, shear stress, and turbulence. The program has supported laboratory studies of several of these injury mechanisms, and expects to develop biocriteria for all in the coming years.

Turbulence in the lower zones of hydropower plants is suspected to be a source of injury and mortality to downstream-migrating fish. Several projects are under way to develop a better understanding of what is happening to fish in draft tubes and tailraces of hydropower facilities. Computer modeling complements field and laboratory studies and improves overall understanding of the hydraulic environment experienced by fish.

Probably the most difficult scientific gap in understanding the effects of hydropower projects is related to predicting the cumulative mortality that results from exposure to multiple stressors. In later years of the hydropower program, this challenge will be addressed in new studies of cumulative effects of multiple, sublethal stressors (i.e., combinations of supersaturated gas, high temperature, and physical trauma) on the health and condition of juvenile salmonids like those migrating downstream in the Columbia River system. As a measure of overall fish health, a variety of bioindicators of physiological stress will be measured during and following a progression of exposure scenarios.

Research

The Hydropower Program is pursuing four specific research activities under SR&T:

• Biological Design Criteria
• Computer and Physical Modeling
• Instrumentation and Controls
• Environmental Analysis

Biological Design Criteria

As conceptual designs for advanced turbines were developed in earlier phases of the program, it became clear that there were significant gaps in the understanding of how fish respond to physical stresses experienced during turbine passage. The potential injury mechanisms affecting turbine-passed fish were first described for the Hydropower Program in the 1990s. The Technical Committee reviewed these and recommended that supplemental laboratory studies were needed to develop biological design criteria (biocriteria) for turbines.

Many of these recommended studies were completed in the 1990s. Turbine manufacturers used design criteria developed from the studies to design the advanced turbines to be installed in two large turbine testing projects.

Several research projects contribute to understanding the effects of physical stresses associated with turbine passage on fish and improving the environmental performance of hydropower technology. Laboratory tests simulating fish passage through pressure regimes and conditions of shear thought to occur inside the turbine environment have been completed. Results provide specific biocriteria for turbine design and operation. Techniques have also been developed for evaluating the potential for indirect mortality based on susceptibility to predators. Initial phases of research to define changes in rapid, reflex escape behaviors resulting from exposure to sublethal stresses have been completed. These behavioral changes, all of which have the effect of reducing a fish's ability to escape a predator, may be a useful indicator of the level of indirect mortality associated with downstream passage.

Future activities will focus on resolving the forces and stresses that cause injury and integrating the results of laboratory and field tests with computational fluid dynamics modeling. Researchers are also developing protocols for biological testing to quantify the effects of turbulence and strike on fish. Methods for quantifying indirect mortality resulting from turbulence have been developed in the laboratory and in future years these techniques will be applied at field sites in order to validate their usefulness and begin to make comparisons of the relative importance of direct and indirect fish mortality. These studies will provide new biocriteria and establish biologically based operating rules for hydroturbines. Laboratory research is also planned to examine the potential for delayed mortality due to cumulative effects of multiple stressors.

Computer and Physical Modeling

Computer simulation and physical models are essential research tools for studying phenomena that are difficult to observe directly, such as the hydraulic environment in turbines and the fate of fish in that environment. Models are being used to complement field and laboratory studies and to improve overall understanding of the hydraulic environment experienced by fish.

A variety of modeling approaches are being carried out to extend our knowledge about the physical environment inside of turbines, ranging from describing hydraulic conditions to predicting the resulting effects on turbine-passed fish. For example, researchers are studying a 1:25 scale physical model turbine to characterize large-scale turbulence that occurs in full-sized turbines. Computational models are being developed to predict and visualize time-varying, turbulent flow fields inside turbine systems. The relationships between fish orientation, fluid velocities, pressure conditions, and fish injury mechanisms are being explored using both experimental and computational tools.

Instrumentation and Controls

Several unique R&D efforts are leading to increased understanding of the fate of fish inside turbines. The sensor fish device has provided knowledge of both acceleration and pressure time histories for passage through turbines, sluiceways, and spill environments at several hydroelectric projects on the Columbia River. The sensor fish device also provides a means to link exposure conditions that fish experience during passage with laboratory studies and computer models. Researchers are evaluating new technologies for visualizing the path of fish through complex hydraulic environments, like those found in a turbine intake, including a "mini-camera" and pulsed laser high-speed videography. Another area involves testing of multiple acoustic Doppler velocimeters (ADV) for acquisition of data on turbulent velocity fields inside full-scale turbine systems.

The sensor fish device has undergone several design changes including a smaller version that will be implantable in live fish. Future activities include use of this device to evaluate the performance of advanced turbine designs for comparison with older turbine designs being replaced by industry. Imaging systems will continue to be evaluated for examining fish behavior, including interactions with stay vanes, wicket gates, and the draft tube. Testing of alternative acoustic pulse schemes and signal processing algorithms will be conducted to improve ADV performance in the field.

Environmental Analysis

The Environmental Analysis activities aim to develop general approaches for estimating both the ecological impacts of hydropower operation and the beneficial effects of mitigation measures.

Environmental performance testing (EPT) is a conceptual framework for testing turbines at field sites that identifies the assessment tools needed, how they would work together, and how they should be applied to any particular hydropower project. The EPT framework will guide the testing that DOE will support during field verification tests and could be used to evaluate the hazards of alternative routes of downstream passage at other dams.

Environmental performance testing tools will be applied and refined as large turbine testing gets underway.

Future R&D in this area would include an examination of ecological indexes, e.g., the Index of Biotic Integrity (IBI), to rivers altered by hydropower operations. Research conducted under the Ecohydraulics of Reservoirs project will test the hypothesis that fluctuating discharges cause hydraulic instability in reservoirs that negatively influence fish migration.