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Title: Hydroacoustic evaluation of the Bonneville Dam prototype surface collector in 1999
Authors: Ploskey, Gene R.
Lawrence, L. R.
Johnson, Peter N.
Schilt, Carl R.
Nagy, William T.
Patterson, Deborah S.
Skalski, John R.
Keywords: Bonneville Dam (Or. and Wash.)
Fish guidance efficiency
Fixed-aspect hydroacoustics
Hydroacoustic detectability
Juvenile salmon
Prototype surface collector
Publisher: Engineer Research and Development Center (U.S.)
Series/Report no.: Technical Report (Environmental Laboratory (U.S.)) ; no. ERDC/EL TR-01-1
Abstract: This research effort had two primary objectives: (a) to test hydroacoustic sampling proposed for the year-2000 evaluation of the prototype surface collector (PSC); and (b) to evaluate a split-beam deployment upstream of a PSC slot and determine whether it provides reasonable estimates offish passage relative to estimates from in-turbine transducers. For in-turbine passage, two pairs of up- and downlooking single-beam transducers mounted on trashracks in each of the three slots in Unit 5 were used to estimate the number of juvenile salmon passing under and into the PSC. Each opposing pair of transducers was fast multiplexed at a rate of20 pings per second (10 each) for a 2-min period before switching to another opposing pair. All in-turbine counts of fish were spatially expanded based upon the ratio of one-half of the intake width to the diameter of the hydroacoustic beam at the midrange of the detected fish. Fish passage into and fish behavior in front of the PSC were monitored with three pairs of up- and down-looking split-beam transducers mounted on a steel frame and placed upstream of the PSC trashrack at turbine intake Sb. Two of the transducer pairs were located 2 m to either side of the middle of the slot to sample fish on the north and south sides of the PSC entrance. The third pair was placed in the middle of the slot to sample fish near the center of the entrance. Each pair of opposing transducers was fast-multiplexed at 10 pings per second each for 20 min per hour. Twenty-three hours of hydroacoustic data were collected per day for a total of 36 days in the spring and 40 days in the summer. In-turbine counts of fish passing through the PSC were not reliable during 20-ft (6-m) slot treatments because of dense acoustic noise created by turbulence within the PSC. During 20-ft (6-m) slot treatments, large volumes of entrained air were concentrated in the upper water column of the turbine intake, and high densities of echoes from the air reduced the ability to distinguish fish from noise with the up-looking, in-turbine beams. Fortunately, split-beam transducers immediately upstream of the PSC openings provided counts that were highly correlated with in-turbine counts during 5-ft (1.5-m) slot treatments in spring and summer. Consequently, split-beam counts were substituted to estimate numbers of guided fish for 20-ft (6-m) treatments in both seasons. Spring: Efficiency of the PSC (guided fish/guided + unguided fish) with a 20-ft slot (85 percent) was significantly higher (Pr ;::: 0.004; N = 9) than with a 5-ft slot (70 percent). The 20-ft slot yielded significantly higher numbers (Pr ;::: 0.004; N = 9) of guided fish than the 5-ft slot. We detected no difference in numbers of unguided fish among 20-ft and 5-ft slot treatments. PSC effectiveness (proportion of fish collected relative to the proportion of flow passed) was significantly higher (Pr ;::: 0.008; N = 9) during 5-ft treatments than during 20-ft treatments. Entrance efficiencies (proportion of fish entering the slot relative to number passing within about 3 m of the opening) were significantly higher (Pr;::: 0.008; N = 9) with 20-ft slots (32 percent) than with 5-ft slots (30 percent). Entrance efficiencies with split-beam transducers may be low and biased because fish that passed through the beam in lateral or upstream directions may be counted more than once while fish passing toward the opening less than 1 m away are unlikely to be counted more than once. Eighty percent of the fish during 5-ft treatments and 93 percent of the fish during 20-ft treatments detected by the split-beams and moving in a downstream direction were distributed above the elevation of the PSC floor. Summer: Efficiencies did not differ among slots (70 and 67 percent for 20- and 5-ft slots, respectively). No difference was detected in numbers of guided or unguided fish among 20-ft and 5-ft slots. Five-foot treatments resulted in significantly higher PSC effectiveness (Pr;::: 0.002; N = 10) than for 20-ft treatments. Entrance efficiencies were significantly higher (Pr;::: 0.002; N = 10) with 20-ft slots (36 percent) than with 5-ft slots (30 percent). Eighty percent of the fish during 5-ft treatments and 92 percent of the fish during 20-ft treatments detected by the split-beams and moving in a downstream direction were distributed above the elevation of the PSC floor. To determine spatial coverage for sampling of the PSC in 2000, differences of guided and unguided fish passage among and within turbine intakes of Unit 5 were tested by slot treatment. Comparisons of guided fish for 20-ft treatments are not reported due to the previously mentioned noise problems. In spring, no differences in guided fish passage for 5-ft treatments or unguided fish passage for either treatment were detected among the three intakes when passage data were summed by day (N = 18). Summertime amongslot comparisons yielded significant differences (P = 0.0001; N = 20) in guided fish passage with 5-ft slots and unguided fish passage with both slot-width treatments. Within-slot comparisons resulted in detection of significant differences among north and south guided fish passage estimates for 5-ft and unguided fish passage with 5- and 20-ft slot treatments for both seasons. Detected differences in passage estimates among intakes suggest that every intake should be sampled in 2000. Smaller differences among positions within intakes may be most efficiently addressed by stratified random sampling of transducer positions rather than deploying 36 transducers to sample all positions. Given noise limitations of sampling guided fish in turbines during 20-ft slot treatments and the high correlation between split-beam and in-turbine estimates during 5-ft slot treatments, using in-turbine sampling to estimate unguided fish passage and splitbeam counts to estimate guided-fish passage are proposed.
Description: Technical Report
Gov't Doc #: ERDC/EL TR-01-1
Rights: Approved for public release; distribution is unlimited
Appears in Collections:Technical Report

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