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Pool and Chute Fishways
Presented to: Pacific Northwest Fish Screening & Passage Workshop, 2006 Yakima, WA Presented by: Patrick D. Powers P.E. September 13, 2006
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What is a Pool and Chute Fishway?
Hybrid type fishway that operates in two flow regimes, plunging and streaming flow
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Background Carpenter Creek – Pool and Weir Fishway
Rainbow Creek – Pool and Weir Fishway WDFW Model Study Town Dam Pool and Chute Construction California
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Pool and Chute - Definition
Side Walls Baffle Baffle Weir Port Floor
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Pool and Chute - Cross Section
W Xpc d Pb b Pw
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Pool and Chute – Profile – Plunging Flow
SoL Pw So L
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Pool and Chute – Profile – Streaming Flow
Pb So L
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Equations Flow over a weir Open channel flow Chezy Eq.
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Research on streaming/plunging flow regimes
Rajaratnam, N. and Katopodis C Plunging and Streaming Flows in Pool and Weir Fishways. Journal of Hydraulic Engineering 114:
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Streaming/Plunging Flow Regimes
Transition Plunging Streaming
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Streaming/Plunging Flow Regimes
High Flow - Flood Streaming
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Streaming transition flow calculations
Example: b = 2 ft L = 6 ft So = 10% Qst = 4 cfs So = 15% Qst = 6 cfs So = 20% Qst = 8 cfs
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Case Studies - Parameters
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Case Studies - Results
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Fairchild Trib Q = 44 cfs D = 1.75 ft Qt = 5.3 cfs Chezy C = 31.5
Xpc = 1.2 EDF = 2.4 Passage Rating Fair
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Fairchild Creek Q = 27 cfs D = 1.65 ft Qt = 5.3 cfs Chezy C = 20.5
Xpc = 1.6 EDF = 2.1 Passage Rating Good
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Percival Creek Q = 24 cfs D = 1.5 ft Qt = 5.3 cfs Chezy C = 22.3
Xpc = 1.5 EDF = 1.3 Passage Rating Fair
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Fairchild Comparison – 12 Foot Wide
44 cfs: EDF = 2.4 29 cfs: EDF = 2.1
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Chezy C vs Qst
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Design Criteria Xpc = Fish Passage Corridor - 0 to 2 ft EDF = 2 to 3
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Design Process Calculate Qfp Select: W, baffle slope, drop, L, b, Pw
Calculate: Qst Select d and C Trial and error until Q = Qfp Check: EDF, Xpc
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Benefits Reduced or No false attraction (small streams)
Self cleaning (gravel/small cobbles) Diverse passage routes for adult and juveniles Pool sizes can be reduced
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Limitations Number of weirs fishway length Alignment Roughness values
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Existing Design Guidelines
Draft in Progress - Pool and Chute Fishways Discussion and Design Process Revised September 11, 2001 By: Patrick D. Powers, P.E. Design Spreadsheet
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