co-location, co-location, co-location: enabling an “esk ... · significantly greater...
TRANSCRIPT
Co-location, Co-location, Co-location:
Enabling an “Esk-ape to the country”?
R.A. Noble, J. Dodd, S. Walton, J.D. Bolland
& I.G. Cowx
J. Hateley, P. O’Brien, M. Reid, J. Gregory
A study of the performance of a Larinier fish pass co-located with a low-head hydropower turbine on Ruswarp Weir at the tidal limit of the Yorkshire Esk
Ruswarp Weir – Co-located fish pass & Turbine
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Ruswarp Weir – Co-located fish pass & Turbine
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Before:
Pool-traverse pass
After:
Larinier passLow-head 50 kW HP(max 4 cumec abstraction)
Ruswarp Weir
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Flow
TidalBaulk fish pass
Main Fish pass
Model 290 acoustic tag receiver Acoustic Tracking System
Model 300 mobile hydrophones
Hydroacoustic Technology Inc., Seattle, USA
Study design – post commissioning
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HTi ATS Array
HTi Remote hydrophonesPost Commissioning Monitoring Only
Release site
Model 795LG acoustic tags
All tagging done under Home Office LicencePPL 80/2411
Coarse-scaleFish passage metrics
Fates of tagged fish – post commissioning
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Attraction efficiency?
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“Attraction efficiency”
Post- = 62%
Baseline = 35%
Detected in Array
Not detected in Array
Totals
Baseline 17 31 48
Post- 81 50 131
Totals 98 81 179
Chi-square Test for Independence (Frequency Distributions)
Chi-square = 9.894d.f. = 1p < 0.01
Highly significantly different
Overall passage efficiency?
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“Overall Passage efficiency”
Post- = 47%
Baseline = 35%
Passed Weir (LFP+ BFP)
Did not pass Weir
Totals
Baseline 17 31 48
Post- 61 70 131
Totals 78 101 179
Chi-square Test for Independence (Frequency Distributions)
Chi-square = 1.776d.f. = 1p > 0.05
No Significant difference
“Attraction/Passage Efficiency” – influence of return rate?
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YearBehaviour/Detections 2013 2014 2015n sea trout tagged 46 44 41% First detected in Whitby 26% 25% 49%n later detected at Ruswarp 6 3 3% re-ascending river 50% 27% 15%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
15/10 01/11 18 &22/11
16/10 04/11 10/11 18/11 30/10 9/11 16/11 23/11
2013 2014 2015
% o
f ta
gg
ed fis
h
Batch / Year
Total in Array n logger only n 0 Records
23 13 8 13 9 9 13 12 4 17 8
Attraction/Passage Efficiency – post commissioning
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81 went on to enter the array
Attraction efficiency = 96%
Overall Passage efficiency = 73%
61 ascended the weir via any route
84 tagged sea trout returned to the weir
Fish pass efficiency?
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Fish Pass efficiency
Post- = 67%
Baseline = 100%
Array -LFP
Array (BFP or DNP)
Totals
Baseline 17 0 17
Post- 54 27 81
Totals 71 27 98
Chi-square Test for Independence (Frequency Distributions)
Chi-square (Yates’) = 6.241d.f. = 1p < 0.05
Significant difference
Fish behaviour:
Searching behaviour&
Delay
Time spent searching
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Median total time from first to last array detection:
Larinier Passage2.6 (0.6 – 18.1) hours (n = 54)
Non-passage34.7 (5.8 – 78.3) hours (n = 20)
Baulk Passage9.2 (0.8 – 186.6) hours (n = 6)
Noble’s Yard
Array
Travel time from Noble’s to ArrayMedian 24.7 (19.1 – 39.9) minutesMinimum 4.8 minutes
Number of visits to the array13.6% pass on 1st visit41% had more than 5 visits before passage
~ 195m
Time spent in the array
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Median total time spent in the array by sea trout prior to passage:
Post commissioning26.4 (2.4 – 76.9) minutes (n = 54)
Baseline4.8 (1.5 – 27.8) minutes(n = 17)
(Mann Whitney U-test: Z = 2.237, n = 71, P <0.05)
Duration of individual tracks:Baseline median = 3.6 (1.6 – 9.5) minutes Post-commissioning median = 2.9 (0.8 – 8.2) minutes
Time from first array detection to passage
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The median time from first detection in the array to passagePost- = 2.7 (0.8 – 17.3) hrsBaseline = 0.3 (0.1 – 1.4) hrs
(Mann Whitney U-test: Z = 3.153, n = 71, P <0.01)
0
2
4
6
8
10
12
14
16
Num
ber
of fish
2011 2012
0
2
4
6
8
10
12
14
16
1 2 3 4 5 6 7 8 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
48
72
96
120
>1
20
Nu
mb
er
of fish
Time between detection and H8 (Hours)
2013 2014 2015
Fish behaviour:
Fine-scale behaviour at the pass
2D Tracking Analysis
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FP
HP
FP
HP
FP
HP
Simple –Passage
Simple –Non-Passage
One or more approaches?
FP
HP
FP
HP
Resting –no approaches?
Non-passage –Distraction?
Evidence of attraction to:
HP outflow?
Deeper water?
Is this evidence of distraction or resting/refuge?
Spatial Use of the Pool
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Baseline Post-commissioning
Occupation of the Pool
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Baseline Post-commissioning
Timing of passage in relation to generation
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• Hydropower turbine active for 63% of the time (varied between years)
• Operating at near capacity (abstraction > 3.5 m3s-1) for 19.8% of the time during tracking period
• Sea trout were observed to ascend through the fish pass under most conditions
• Three sea trout passed whilst the turbine was off
• 42% of tagged sea trout passing at turbine flows of greater than 3.5 m3s-1
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
0
10
20
30
40
50
60
70
80
90
100
Hydro
pow
er
flow
m3s
-1
Exceedence %
Hydropower flow 2013 2013 Passages
Hydropower flow 2014 2014 Passages
Hydropower flow 2015 2015 Passages
1/9 - 31/12 flows
Flow & HP abstraction
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0 m3s-1 (Off)n = 37
0.01 to 1.00 m3s-1
n = 41
1.01 to 2.00 m3s-1
n = 62
2.01 to 3.00 m3s-1
n = 74>3.01 m3s-1
n = 76Use of the pool under different HP activity –
River flows <Q25(6.28 m3s-1)
~ Overtopping of weir
Track distribution/duration in relation to flows
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Abstraction > 2 m3s-1
Discharge Q25 to Q15
n = 217
Abstraction > 2 m3s-1
Discharge Q15 to Q10
n = 59
Abstraction > 2 m3s-1
Discharge > Q10
n = 76
Conclusions
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1. “Passage Efficiency” varied greatly between years - no significantdifference after commissioning of the turbine
• Influenced by return rate
• Passage efficiency 73% post-commissioning
• “Passage at the site maintained”
2. “Attraction Efficiency” - significantly higher post-commissioning
• Influenced by return rate
• Attraction efficiency 96% post-commissioning
3. “Fish Pass Efficiency” - significantly lower post-commissioning
• Is 67% passage of sea trout an adequate performance for a Larinier pass at head oftide?
Conclusions
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4. The delay between arrival in the pool and eventual passage, whilst statisticallysignificantly greater post-commissioning, is of little energetic consequencegiven the overall scale and duration of the sea trout migration.
• However, it is possible that longer delays did have consequences for successfulpassage.
5. Some evidence of attraction of fish to the area in front of the hydropoweroutfall screens - most apparent when the turbine was active at flows <Q25.
• Caused by sea trout seeking refuge in deep water or being distracted from the fishpass plume by the outfall from the hydropower screw?
6. No evidence to suggest that any of the changes and variability in the passagemetrics and the delay in passage through the main fish pass can be solelyattributed to the activity of the hydropower turbine.
Thank you