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Title: Explaining fish guidance characteristics of mesh and bar screens: The relative pressure signature hypothesis

Hydropower dams on the Columbia River block migration of anadromous fishes. Extensive bypass facilities have been installed to guide migrating fishes around the dams. The first component of such systems encountered by out-migrating smolts is submerged bypass screens of one of two major design alternatives. Screens are constructed of either relatively fine woven mesh (traveling screens) or closely spaced bars (bar screens). Using underwater videoimaging, we quantified the relative fish impingement characteristics of each screen design at McNary Dam and The Dalles Dam. Each design was operated under a variety of deployment alternatives and turbine discharges. Video images of the screen surface were obtained from 5-6 cameras distributed on the screen centerline from the screen top (nearest the deck or intake) to the screen bottom. Over 4000 smolt-screen interactions were imaged, processed, and analyzed. A selection of hydraulic and behavioral variables was collected from each recorded image. Screen type had a significant effect on fish impingement and near-screen flow fields. These findings, in conjunction with the known influence of background noise levels on ability of fish to detect specific underwater signals, suggest that guidance effectiveness of a specific screen design may be partially determined by characteristics of the pressure fieldmore » that the screen generates relative to background turbulence patterns - the Relative Pressure Signature Hypothesis.« less
Authors:
;
Publication Date:
OSTI Identifier:
220012
Report Number(s):
CONF-9507190--
TRN: 96:000708-0094
Resource Type:
Conference
Resource Relation:
Conference: Waterpower 1995: international conference, San Francisco, CA (United States), 25-28 Jul 1995; Other Information: PBD: 1995; Related Information: Is Part Of Waterpower`95. Volume 1-3; Cassidy, J.L. [ed.]; PB: 2869 p.
Publisher:
American Society of Civil Engineers, New York, NY (United States)
Country of Publication:
United States
Language:
English
Subject:
13 HYDRO ENERGY; HYDROELECTRIC POWER PLANTS; FISH PASSAGE FACILITIES; ANADROMOUS FISHES; MIGRATION; COLUMBIA RIVER