Downstream Passage Research Articles

DOWNSTREAM MIGRATION: PROBLEMS AND FACILITIES

Downstream fish passage technology is much less advanced than it is for upstream fish passage facilities. This is simply due to the fact that efforts to re-establish free movement for migrating fish began with the construction of upstream fish passage facilities, and that downstream migration problems have only been recognised and addressed more recently. It is also because it is much more difficult and complex to develop effective facilities for downstream migration. This situation is not restricted to France, since as yet, no country has found satisfactory solutions for downstream migration problems, especially where large installations are involved (EPRI, 1994).

The Development of Advanced Hydroelectric Turbines to Improve Fish Passage Survival

Recent efforts to improve the survival of hydroelectric turbine-passed juvenile fish have explored modifications to both operation and design of the turbines. Much of this research is being carried out by power producers in the Columbia River basin (U.S. Army Corps of Engineers and the public utility districts), while the development of low-impact turbines is being pursued on a national scale by the U.S. Department of Energy. Fisheries managers are involved in all aspects of these efforts. Advanced versions of conventional Kaplan turbines are being installed and tested in the Columbia River basin, and a pilot scale version of a novel turbine concept is undergoing laboratory testing. Field studies in the last few years have shown that improvements in the design of conventional turbines have increased the survival of juvenile fish. There is still much to be learned about the causes and extent of injuries in the turbine system (including the draft tube and tailrace), as well as the significance of indirect mortality and the effects of turbine passage on adult fish. However, improvements in turbine design and operation, as well as new field, laboratory, and modeling techniques to assess turbine-passage survival, are contributing toward resolution of the downstream fish passage issue at hydroelectric power plants.

Influence of Compressor Exit Conditions on Combustor Annular Diffusers, Part 1: Diffuser Performance

In gas-turbine engines, the velocity of air issuing from the compressor must be reduced to permit effective operation of the downstream combustor. This is partly achieved by locating an annular diffuserbehind the compressor outlet guide vanes (OGV) and, in modern systems, the inlet of this diffuser is usually located at the trailing edge of the blade row. The interactions that occur between these components and, in particular, the impact on the measured diffuser performance are studied. A mainly experimental investigation has been undertaken in a fully annular facility that incorporates a single-stage axial-e ow compressor and simulated e ame tube. In addition, a constant-area passage, or diffusers of area ratio 1.45 or 1.60, can be incorporated immediately downstream of the OGV row. The results indicate that, within experimental error, the diffusers have little effect on the e ow within the OGVbladepassages. However,theOGV blade rowproducesa proe lethat, duemainly to thebladewakes,contains a relatively large amount of kinetic energy. Hence, even within the downstream constant area passage a signie cant pressure rise is observed as these wakes mix out. Additional pressure forces are introduced with the downstream diffusers present, but analysis of the experimental data indicates these have a limited effect on the wake mixing process, both in terms of stagnation pressure loss and static pressure rise. Hence, the overall static pressure rise measured, between the inlet and exit of each diffuser, is greater than that predicted using design charts obtained using more conventional axisymmetric inlet conditions. This cone rms previous work where it was thought that wake mixing can enhance diffuser performance.

Semi-volatile organic compounds in the campaspe river system (Victoria, Australia)

The levels of semi-volatile organic compounds (SVOCs) in the Campaspe River system, North Central Victoria, Australia, were monitored from January to September 1995, and the environmental trends and sources of these compounds were determined. The land use within particular catchments dictated the complexity of the SVOCs in run-off water. Run-off from native forest contained the greatest number of SVOCs. Soil and ground litter were shown to contain the greatest complexity of SVOCs, mostly terpenes. However, only a small proportion were leached by run-off with the remainder being tightly bound to the soil or volatilizing to the atmosphere. Under the prevailing drought of early 1995, the rivers contained no detectable SVOCs until the first catchment run-off after significant rainfall in May. The maximum complexity and concentration of the SVOCs coincided with extensive run-off after heavy rainfall in June, effecting a surge of SVOCs with the flood peak. Fatty acids, their amides and hydrocarbons made up the majority of the compounds identified and were in the 1-39μg/l concentration range. The levels then diminished as the catchment was flushed by continual run-off. These results support Lake's 1967 hypothesis that natural floodwaters contain a signature of SVOCs entering from the catchment. The downstream passage of these compounds was obstructed by a man–made storage, Lake Eppalock, with only low concentrations of SVOCs (1–3μg/l) in the outflow, displaying no correlation to run-off.

Recent evaluations of physical and behavioral barriers for reducing fish entrainment at hydroelectric plants in the upper Midwest

Wisconsin Electric Power Company recognized the need to address fish protection options and commenced a proactive applied research program in the late 1980s. Within a few years, the company began evaluation studies of promising physical and behavioral alternatives. Stone and Webster Environmental Services and Alden Research Laboratory, Inc. played significant roles in identifying and evaluating the alternatives. The results from an evaluation of a barrier net installation at the Pine Hydroelectric Project indicated that the technology was effective in preventing downstream passage of a wide variety of species and sizes of fish, but was not as effective in preventing passage of YOY fish. The results of a separate Electric Power Research Institute tailored collaboration study of sound, strobe light, and air bubble behavioral devices were discouraging. None of the devices, either alone or in combination, were effective in significantly reducing entrainment of native riverine fish species at the White Rapids Hydroelectric Project.

Design of Optimum Selective Withdrawal Operation for Temperature Management at Round Butte Dam, Lake Billy Chinook, Oregon

Design of Optimum Selective Withdrawal Operation for Temperature Management at Round Butte Dam, Lake Billy Chinook, OregonAs part of the ongoing efforts to restore downstream anadromous fish passage through Round Butte Dam, modifications to the reservoir operation and withdrawal structure were evaluated. A reservoir temperature model (BETTER) was calibrated, verified, and then applied to evaluate the effects of proposed reservoir modifications on the in-lake and downstream temperatures. An understanding of the effect...Author(s)Curtis DeGasperiTarang KhangaonkarSteven BreithauptKevin MarshallSourceProceedings of the Water Environment FederationSubjectSession 74 - Surface Water Quality and Ecology Symposium I: Total Maximum Daily Loads IIDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2000ISSN1938-6478SICI1938-6478(20000101)2000:7L.196;1-DOI10.2175/193864700784547106Volume / Issue2000 / 7Content sourceWEFTECFirst / last page(s)196 - 211Copyright2000Word count206

Spectroscopic Characterization of Fulvic Acid Fractions of a Contaminated Groundwater

Two fulvic acid (FA) samples taken from a former gas production facility in the Southwest of Germany were characterized using advanced fluorescence techniques. Steady-state fluorescence (fluorescence excitation, synchronous fluorescence) as well as time-resolved fluorescence were applied. Distinct differences between the sample B22 FA taken within the contamination plume and the sample B53 FA taken downstream were found. Comparison with a model compound for metabolites and humic substances revealed that due to the downstream passage the characteristics of the dissolved organic matter became more humic-like. The assignment of single classes of compounds in the sample B22 FA is discussed in terms of their synchronous fluorescence spectra and fluorescence decay time distribution.

The Effect of Inlet Boundary Layer Thickness on the Flow Within an Annular S-Shaped Duct

Experimental and numerical investigations were carried out to gain a better understanding of the flow characteristics within an annular S-shaped duct, including the effect of the inlet boundary layer (IBL) on the flow. A duct with six struts and the same geometry as that used to connect compressor spools on our experimental small two-spool turbofan engine was investigated. A curved downstream annular passage with a similar meridional flow path geometry to that of the centrifugal compressor has been fitted at the exit of S-shaped duct. Two types of the IBL (i.e., thin and thick IBL) were used. Results showed that large differences of flow pattern were observed at the S-shaped duct exit between two types of the IBL, though the value of “net” total pressure loss has not been remarkably changed. According to “overall” total pressure loss, which includes the IBL loss, the total pressure loss was greatly increased near the hub as compared to that for a thin one. For the thick IBL, a vortex pair related to the hub-side horseshoe vortex and the separated flow found at the strut trailing edge has been clearly captured in the form of the total pressure loss contours and secondary flow vectors, experimentally and numerically. The high-pressure loss regions on either side of the strut wake near the hub may act on a downstream compressor as a large inlet distortion, and strongly affect the downstream compressor performance. There is a much-distorted three-dimensional flow pattern at the exit of S-shaped duct. This means that the aerodynamic sensitivity of S-shaped duct to the IBL thickness is very high. Therefore, sufficient care is needed to design not only downstream aerodynamic components (for example, centrifugal impeller) but also upstream aerodynamic components (LPC OGV).

Migration Timing of Atlantic Salmon Smolts Relative to Environmental and Physiological Factors

We determined the migration timing of fry-stocked smolts of Atlantic salmon Salmo salar relative to environmental and physiological factors, by using net weirs and counting fences in three tributaries of the West River, Vermont. Smolt migration began in late April and early May when water temperature was 5°C, peak movements occurred in early and mid-May at temperatures exceeding 8°C, and migration was complete by early June. Within this seasonal window, significant differences in migration timing and gill Na+,K+-ATPase activity occurred among tributaries. In both years of the study, smolts tended to migrate earlier and exhibit greater gill Na+,K+-ATPase activity in the warmest tributary than in the coolest tributary. Smolt migration timing differed most among tributaries in mid-May when (1) water temperatures were more than 8°C, (2) smolts peaked in gill Na+,K+-ATPase activity, and (3) discharge peaked, stimulating smolt migration. Smolts captured after the migratory period had lower gill Na+,K+-ATPase activity than migrating smolts. Relating smolt physiology to migration was crucial for explaining complex interactions among water temperature, discharge, and smolt behavior during both the onset and cessation of migratory activity. Because the period between onset of migration and loss of smolt physiological characteristics may be brief, delays in downstream passage that may occur at dams must be minimized to maximize the successful recruitment of smolts to the marine environment.

The Influence of Downstream Passage on the Flow Within an Annular S-Shaped Duct

Experimental and numerical investigations were carried out to gain a better understanding of the flow characteristics within an annular S-shaped duct, including the influence of the shape of the downstream passage located at the exit of the duct on the flow. A duct with six struts and the same geometry as that used to connect the compressor spools on our new experimental small two-spool turbofan engine was investigated. Two types of downstream passage were used. One type had a straight annular passage and the other a curved annular passage with a meridional flow path geometry similar to that of the centrifugal compressor. Results showed that the total pressure loss near the hub is large due to instability of the flow, as compared with that near the casing. Also, a vortex related to the horseshoe vortex was observed near the casing. In the case of the curved annular passage, the total pressure loss near the hub was greatly increased compared with the case of the straight annular passage, and the spatial position of this vortex depends on the passage core pressure gradient. Furthermore, results of calculation using an in-house-developed three-dimensional Navier–Stokes code with a low-Reynolds-number k–ε turbulence model were in good qualitative agreement with experimental results. According to the simulation results, a region of very high pressure loss is observed near the hub at the duct exit with the increase of inlet boundary layer thickness. Such regions of high pressure loss may act on the downstream compressor as a large inlet distortion, and strongly affect downstream compressor performance.

Morphological controls on the downstream passage of a sediment wave in a gravel-bed stream

Sediment waves in river systems have been widely reported, although few studies have examined the interaction between these waves and the morphology of the reaches through which they pass. This interaction determines how waves are modified as they propagate downstream. This study documents the origin and downstream passage of an avulsion-generated sediment wave through a 374 m study reach of the Allt Dubhaig, Scotland. A nested survey framework was adopted, with volumes calculated from cross-sections spaced between 10 and 40 m apart documenting the origin and downstream passage of the wave. The wave moved through an intensively (c. 1 m cross-section spacing) monitored 120 m stretch (Reach A) within the study reach, allowing assessment of sediment exchanges between the incoming wave and the local morphology. Successive surveys show the movement of the wave through and out of the reach, and also that areas where wave sediment was deposited did not always correspond with areas of subsequent erosion. Reach A was divided into three morphologically distinct sub-reaches (1A, 2A and 3A) within which sediment fluxes and the three-dimensional distribution of erosion/deposition were estimated. Sediment wave input into 1A and 2A (relatively stable sub-reaches) caused forced bar aggradation and erosion of sediment from elsewhere within the reach, which then became part of the wave. The downstream transfer of this sediment into unstable 3A caused aggradation and, in response, widespread erosion which increased the magnitude of the sediment wave as it exited reach A. Sediment exchange between the recipient reach and the wave depends upon local morphological stability and is a crucial process affecting wave magnitude and attenuation. The macroscale sediment wave interacted with, rather than overwhelmed, the recipient morphology. © 1998 John Wiley & Sons, Ltd.

Morphological controls on the downstream passage of a sediment wave in a gravel‐bed stream

Morphological controls on the downstream passage of a sediment wave in a gravel‐bed stream

Effect of Water Acceleration on Downstream Migratory Behavior and Passage of Atlantic Salmon Smolts and Juvenile American Shad at Surface Bypasses

Abstract Behavior and passage rate of smolts of Atlantic salmon Salmo salar and juvenile American shad Alosa sapidissima were compared between a standard (sharp-crested) and a modified surface bypass weir that employs uniform flow velocity increase (1 m·s−1·m−1 of linear distance). Within the first 30 min after release, significantly more smolts passed the modified weir than the standard weir, but no differences in passage rate between weir types were noted for juvenile American shad. More Atlantic salmon smolts and juvenile American shad were passed by the modified weir in groups of two or more than were passed by the standard weir. Mean lengths of passed and nonpassed smolts were not significantly different between weir types, but American shad passed by the sharp-crested weir were significantly smaller than nonpassed fish. Most individuals of both species that passed the modified weir maintained positive rheotaxis and strong swimming throughout the length of the weir. In addition to acceleration, visua...

Optimizing the Return Channel Profile for Multistage Francis-Type Reversible Pump-Turbines. 2nd Report. Effect of Turbining Operation Point on Flow Pattern and Performance.

Flow pattern and performance of a return channel model were investigated experimentally, under various operation points in the turbining mode. The position where the secondary flow conspicuously occurs near the return channel inlet changes gradually from the casing wall to the pressure surface of the return vane, with decreasing the turbine output power. Such a secondary flow induces swirling flow in the downstream passage and makes the through flow under-turning. The features of the hydraulic loss to the change of the turbining peration point are also decided near the return channel inlet, and the loss increases markedly in the low output power range because of the shock loss at the return vane inlet.

A Quasi-Unsteady Study on Wake Interaction of Turbine Stator and Rotor Cascades

Detailed flow measurements were made to study cascade interaction of turbine stator and rotor, using two linear cascades installed in series. The upstream cascade was moved to several places in the cascade pitchwise direction in order to change the relative location between the two cascades, and measurements were made in the downstream cascade. The result shows that the net total pressure loss generated in the downstream cascade becomes maximum when wakes of the upstream cascade pass the suction side of the downstream cascade passage, while the tip leakage loss generated in the downstream cascade does not change with the relative location of the cascades. The upstream cascade wakes interact with the secondary flows and most strongly with the endwall flow in the downstream cascade passage, making the loss distributions in the cascades fairly unsteady.

Status of Fish Passage Facilities at Nonfederal Hydropower Projects

Abstract The status of direct mitigation practices for fish passage was assessed as part of an ongoing, multi-year study of the costs and benefits of environmental mitigation measures at nonfederal hydroelectric power plants. Information was obtained from the Federal Energy Regulatory Commission, hydropower developers and state and federal resource agencies involved in hydropower regulation. Fish ladders were found to be the most common means of passing fish upstream; elevators/lifts were less common, but their use appears to be increasing. A wide variety of mitigative measures, including spill flows, narrow-mesh intake screens, angled bar racks and light- or sound-based guidance measures, is employed to prevent fish from being drawn into turbine intakes. Performance monitoring and detailed, quantifiable performance criteria were frequently lacking. Fifty-two of the 66 projects (82%) with operating downstream fish passage measures had no performance monitoring requirements; 50 of 71 project operators (70%...

Flow through Guide Vanes of Low Specific Speed Mixed Flow Pumps.

Flow structure around a guide vane, installed in a diffuser of a mixed flow pump with low specific speed, was investigated experimentally. The secondary flow along the hub wall, which is caused by the vane camber and runs toward the suction side of the vane, changes to run upstream near the suction surface of the vane. Its flow unites with another secondary flow along the suction surface, which is caused by the meridian curvature and runs toward the hub wall, to form the strong vortex on the hub wall near the suction surface. This vortex induces the downstream flow along the suction surface to run toward the casing wall. This flow also unites with the flow from the leading edge along the suction surface to form another vortex on the suction surface near the casing wall. These vortices induce a circulating flow on the cross section in the downstream passage, and markedly affect the turning angle of the guide vane.

A stochastic, compartmental model of the migration of juvenile anadromous salmonids in the Columbia River Basin

A probabilistic model is developed which describes the juvenile migration of Pacific salmon and steelhead trout ( Oncorhynchus sp.) in the Columbia River Basin in western North America. The downstream passage of smolts through a series of reservoirs or river reaches is modeled as an irreversible particle diffusion process through a series of compartments. The probability of live passage from one compartment to the next t time units after having entered the compartment can be viewed as the product of the probability of having survived to time t, the probability of transiting the compartment in t time units, and the probability of a successful transition between compartments at time t. From this basic premise, a general passage model is developed. Focusing on survival through Columbia and Snake River reservoirs (as opposed to dam-related mortality), a specific model which uses a Poisson death process and a gamma distribution to describe transmit time is presente. Analytical solutions to the single-compartment system are derived with extensions to the multi-compartment system. Empirical data from the Columbia River is used to demonstrate the utility of the model as well as to highlight problems that exist in fitting the model using existing data. Graphical techniques are presented for using the model to assess the effectiveness of management actions that are designed to improve the reservoir survival of smolts.

Particle size, resource concentration, and the distribution of net-spinning caddisflies.

The dimensions of net meshes constructed by hydropsychid Trichoptera vary both within and between species. Despite these catchnet differences, the diets of most Hydropsychidae studied in Utah streams were statistically indistinguishable. There was no relationship between the size of available resources and catchnet construction among species assemblages inhabiting 10 different localities. A particle-size model of caddis communities, suggesting that taxa feed selectively on particle sizes corresponding to the dimension of catchnet meshes, is not supported by these data.Diatom concentration increased regularly with downstream passage in two different drainages. The identity and number of coexisting hydropsychid species and the size of their catchnets were strongly correlated with diatom concentration. Taxa with large catchnet mesh were the only residents at sites where diatom concentration was very low; as resource concentration increased downstream, species with successively smaller mesh joined the coexisting guild. Together, the broad dietary similarities and distributional pattern from Utah streams suggest that resource concentration, rather than particle size, is the basis of community organization among the hydropsychid Trichoptera.

A study on leakage-flow-induced vibrations. 2nd report. Calculations of fluid-dynamic forces acting on the walls of a one-dimensional, narrow passage by the transfer matrix method.

The transfer matrix method is applied to the calculations of fluid-dynamic forces acting on the walls of a one-dimensional, narrow passage when one of them is vibrating harmonically with a small amplitude. First, the fluid-dynamic coefficients in the case of a tapered passage are calculated to check the accuracy of this method. The results show a good agreement with those by theoretical solutions obtained in the first report. Second, fluid-dynamic coefficients in the case of the passage with a step are also calculated. It is found that if the cross sectional area of the upstream passage is smaller than the downstream one, both negative fluid-dynamic stiffness and negative fluid-dynamic damping can occur, and that when the effective pressure loss factor of the passage is nearly equal to unity, the area ratio of the downstream passage to the upstream one, where negative fluid-dynamic damping occurs, decreases with increasing upstream passage length.