International Fish Screening Conference Southampton March 2011

Transcription

1 International Fish Screening Conference Southampton March 2011 Downstream bypass facilities for salmon and eel at small hydro power plants in France F. Travade M. Larinier EDF R&D ONEMA 6, quai Watier Institut de Mécanique des Fluides CHATOU Avenue du Professeur Camille Soula TOULOUSE francois.travade@edf.fr larinier@imft.fr

2 CONTENT 1. French context 2. Evaluation of mortalities due to hydropower 3. Devices for juvenile salmon - experimental techniques - surface bypasses - behavioral devices 4. Experiments on adult eel 5. R&D French program on eel and obstruction

3 FRENCH CONTEXT Regulation (1984) Some rivers are classified as «migratory fish rivers» 11 «official» migratory fish species : salmon, sea trout, shad (2), lamprey (2), eel, sturgeon, brown trout, greyling, pike Obligation to insure upstream and downstream fish passage at dams on migratory fish river Hydropower characteristics About 2000 hydropower dams in France Mainly small plants on migratory fish rivers : H<5m ; Q < 50 m3/s Turbine mortality mainly moderate for salmon juveniles : 5-10 % Turbine mortality higher for adult eel : % Experimental studies about downstream migration devices in for salmon and since 2000 for eel

4 CONTENT 1. French context 2. Evaluation of mortalities due to hydropower 3. Devices for juvenile salmon - experimental techniques - surface bypasses - behavioral devices 4. Experiments on adult eel 5. R&D French program on eel and obstruction

5 PASSAGE THROUGH SPILLWAYS and TURBINES Passage through spillways is generally not a problem in France, due to the low head of installations: spillways are the safest way for fish to migrate downstream Passage through turbines juvenile salmonids (15-20 cm) Pelton turbines: very high mortality rate Francis Turbines : range of mortality rate 5-90%, usually: 15-40% Kaplan turbines : range of mortality rate 2-20%, usually: 5-12%. Mainly used on migratory fish rivers in France adult eel: mortality rate 4-5 times higher than that for juvenile salmonids

6 CONTENT 1. French context 2. Evaluation of mortalities due to hydropower 3. Devices for juvenile salmon - experimental techniques - surface bypasses - behavioral devices 4. Experiments on adult eel 5. R&D French program on eel and obstruction

7 DOWNSTREAM MIGRATION DEVICES FOR SALMON SMOLTS Because they are a large number of existing hydro plants in France it appeared difficult to install physical screens to prevent smolt passage through the turbines without resizing the intakes So, in the Eighties and Nineties experiments were conducted to : Quantify mortality among smolts passing through turbines to assess the impact of each hydropower plant Design and test surface bypasses combined to conventional trashracks Test behavioral devices

8 Field experimental techniques to test dowstream devices Mark-recapture PIT tagging Radio tracking

9 CONTENT 1. French context 2. Evaluation of mortalities due to hydropower 3. Devices for juvenile salmon - experimental techniques - surface bypasses - behavioral devices 4. Experiments on adult eel 5. R&D French program on eel and obstruction

10 Downstream bypass for smolts : operating principle and parameters St Cricq (Gave d Ossau) Trashrack : behavioral repelling effect Bar spacing < 3-4 cm Water velocity < cm/s Surface Bypass Location close to the trashrack Discharge 2%-10% Turb. Dis Hydraulic patterns near the bypass: no turbulences no upwellings

11 Characteristics and efficiency for salmonids of some bypasses tested in France m3/s mm % % Dam River Max trashrack turbine bar spacing discharge ( m 3 (mm) /s) Bypass inflow ( m 3 /s) Bypass inflow / turbine discharge (%) Number of entrances Entrance width (m) Evaluation method * Efficiency (%) Evaluation date Soeix Gave d'aspe (last tests) 2 (now) MR + Rad Bedous Gave d'aspe , MR +MD+Rad (mean 55) Camon Garonne MR + Rad (mean 73) St Cricq Gave d'ossau mean 0.65 mean MR + Rad (mean 79) 1996 Baigts Castetarbe Gave de Pau Gave de Pau Guilhot Ariège Las Rives Ariège Crampagna Ariège , Rad 92, Rad , mean , mean , mean MD MD ? MD Las Mijanes Ariège mean MD Halsou Nive MR + Rad mean Poutès Allier Rad

12 Location and discharge effect (Soeix HPP - Gave d Aspe river) 15 m 3.5 m TD : 35 m3/s BPD : 1.8 m3/s 1.5 m upstream trashrack upwelling removal by deflector BPD : 0.8 m3/s 1.5 m upstream trashrack BPD : 0.6 m3/s 6m upstream trashrack Bypass efficiency

13 Bar spacing and BP discharge effect (Baigts Gave de Pau river Bypass 40 m 90 m3/s Good efficiency After changing The trashrack (3 cm) And increasing the Bypass discharge (2.2 m3/s) Low efficiency due to large bar spacing (7 cm) and insufficient discharge in the bypass (0.6 m3/s) Bypass efficiency

14 Hydraulic patterns effect (Camon - Garonne river) High efficiency achieved by removing the upwelling with a submerged deflector plate Bypass included in the Trashrack TD : 85 m3/s BD : 2 3 m3/s Low efficiency due to an upwelling near the bypass entrance Bypass efficiency

15 LOCATION OF DOWSTREAM BYPASSES AT HYDROELECTRIC PLANT INTAKES

16 EXAMPLES AND EFFICIENCY OF SURFACE BYPASSES HALSOU (Nive) POUTES (Allier) LAILHACAR (Gave d Ossau) CASTETARBE (Gave de Pau) Efficiency: from 10% to >80% generally very limited with 5-6 cm spacing (10-20%), 60-70%: with 3-4 cm spacing and good hydraulic conditions 80-90%: with 2.5 cm spacing and good hydraulic conditions

17 CONTENT 1. French context 2. Evaluation of mortalities due to hydropower 3. Devices for juvenile salmon - experimental techniques - surface bypasses - behavioral devices 4. Experiments on adult eel 5. R&D French program on eel and obstruction

18 BEHAVIORAL DEVICES Principle : using stimuli to guide, repell or attrack fish Electric guiding screen 15% efficiency (8-28%) to guide smolts to a bypass with a 20 m long screen (Halsou) Acoustic screen 0% efficiency to guide smolts to a bypass with a BAFF (FGS) : acoustic field combined to an air bubble curtain (Halsou) 0% efficiency to repell smolts from an intake canal entrance by an acoustic screen (FGS) (St Cricq) Night lighting device Low wattage mercury vapor light (50-80 W) at the bypasses entrance increases their efficiency. Very efficient on low velocity intakes (Intakes on lakes / Ex Poutès)

19 CONCLUSIONS for salmonids Surface bypass combined with trashracks can be a simple solution to solve downstream migration problems for small scale power plants where % efficiency is sufficient Some criteria must be respected and several parameters carefully examined before designing a bypass : Bar-spacing at trashracks < mm Water velocity < m/s Flow pattern conditions to determine the location of the bypass No upwelling near the entrance Bypass discharge / turbine discharge = 2-10 % Efficiency can vary strongly in the time if some parameters are modified (ex : flow patterns and velocity with variation in plant operation Pb in France) Behavioral devices (electric, acoustic screns) tested in France have a low efficiency for guiding salmonids to a bypass. Night lighting the surface bypasses entrance by low wattage mercury vapor light can improve the bypass efficiency

20 CONTENT 1. French context 2. Evaluation of mortalities due to hydropower 3. Devices for juvenile salmon - experimental techniques - surface bypasses - behavioral devices 4. Experiments on adult eel 5. R&D French program on eel and obstruction

21 EXPERIMENTS ABOUT DOWNSTREAM MIGRATION DEVICES FOR SILVER EEL Fields experiments conducted to Analyse the eel behaviour near the HPP intakes improve the efficiency of surface and bottom bypasses similar to those used for salmonids

22 Experimental studies radiotracking and transponders (PIT tags) Forebay RE Gave de Pau Intake Trashracks A B C D E TU EX CL Downstream Fish Bypasses Entrances VA OldFishPass MG MT Intake Powerhouse Flap Gate Spill Gate 2 Spill Gate 1 AG Fish Lift ST Tailrace Small Scale Powerhouse

23 HALSOU EXPERIMENTS : m 3.5 m Surface bypass 1.4 m width / 0.6 m3/s 2% TD Bottom bypass 1.3 w x 0.5 h 0.6 m3/s 2% TD Surface gate Discharge Tower

24 HALSOU EXPERIMENTS : % Turbines 32% Fishway 0% Bottom Bypass 48% 30-40% 40-50% Spillwaw 10% Surface Bypass 10% 38 radiotracked eels Combined efficiency of the two bypasses = % (mean value for the 3 years) Bottom Bypass 3 to 4 times more efficient than Surface Bypass

25 BAIGTS Experiments Surface bypass 2004 and deep bypass 2005 Trashrack Surface bypass: test 2004 Efficiency for smolts 90% Qturb = 90 m3/s 40 m 5.5 m Surf. Bypass Forebay Surf. gate POWER Power plant PLANT DAM Gate2 Gate1 Deep bypass : test 2005 Spacing 3 cm width 1.8 m velocity < 0.4 m/s 2.2 m3/s 2.5% TD Fishway Deep entrance : - 7m

26 BAIGTS 2006 Surface bypass and physical screen Qturb = 90 m3/s Surface bypass Bar spacing : 3 cm POWER PLANT DAM Physical screen simulated by using eels with body larger than the bar spacing for the experiment

27 Bypass Efficiency 8% 0% 18% 3% 24% 0% 15% 44% 68% 60% 54% 8% 2004 : surface Bypass Small eels 2005 : deep Bypass Small eels 2006 : surface Bypass large eels Surface bypass less efficient for eel than for salmon Deep bypass less efficient than surface one. Opposite to Halsou Position? Size of the plant? Trashrack has a poor repelling effect compared to smolts Small bar spacing trashrack (physical screen) and small velocities = delay 1 to 14 days before passing by bypass or flood gates

28 Spillways, the best bypass? Passage at the plant occured mainly during peak flow discharges of the river High escapement by the spillways occurs for high ratio of spill flow discharge to total river flow discharge 2006 Spillway Turbine Bypass River Flow 01/11/06 06/11/06 11/11/06 16/11/06 21/11/06 26/11/06 01/12/06 06/12/06 11/12/06 16/12/06 21/12/06 26/12/06 31/12/06 05/01/07 10/01/07 15/01/07 20/01/07 25/01/07 30/01/07 04/02/07 09/02/07 14/02/07 19/02/07 24/02/07 01/03/07 06/03/07 11/03/07 16/03/07 21/03/07 26/03/07 31/03/07 05/04/07 10/04/07 15/04/07 Date River Flow (m 3.s -1 )

29 Spillways, the best bypass? Modelling the escapement Escapement probabilities at the Baigts plant is a function of : Ratio Qspill / Qriver Eel length The effect of eel length is due to the possibilities of passage through the trashrack (3 cm bar spacing)

30 CONCLUSIONS FOR EEL Surface bypass and bottom bypass combined with trashracks are less efficient for silver eel than for smolts mainly because the behavioural repellent effect of the trashrack seems to be low for eel Bypasses combined with a 3 cm bar-spacing may be partially efficient for very small plants with a favourable configuration : % at Halsou On larger plants or on less favourable configurations, this efficiency appears to be very low. One solution could be the use of a smaller bar spacing (< = 2cm) to create a physical barrier The bar spacing has to be determined as a function of the eel size in the local population The use of a physical barrier needs low velocities (<= cm/s?) in front of the trashrack to prevent fish impingement and so, a risk of mortality higher than turbine passage A physical barrier causes delay to find bypasses or to wait for flood gates opening. It could be problematic in case of multiple plants The feasibility of the installation of small spacing trashrack can be problematic for the operation of existing hydro plant but can be possible for the future (small?) plants Escapement by spillways could be important on some plants according to the eel length, the ratio turbine discharge / river discharge and according to the migration rhythms. This escapement has to be evaluated case by case Alternative solutions : behavioural devices (light, sound?) altered generation schedule (turbine shutdown) during the migration peaks Fish friendly turbines Trap and transport

31 CONTENT 1. French context 2. Evaluation of mortalities due to hydropower 3. Devices for juvenile salmon - experimental techniques - surface bypasses - behavioral devices 4. Experiments on adult eel 5. R&D French program on eel and obstruction

32 French R&D program on eel and dams Under progress / Results end of 2011 (1) 1 - Prediction of turbine mortality : statistical analysis of experimental mortality tests (70 experiments around the world) Taux de mortalité (%) [0-100[ [ [ [ [ [ [ Vitesse de rotation (trs/min) 2 Modeling the cumulative mortality due to turbine passage on a river with several hydro plants 3 Migrating behaviour and passage ways of silver eel along a small river (Gave de Pau river) with several hydro plants 4 - Migrating behaviour and passage ways of silver eel along a large river (Rhine river) with several hydro plants % barrage Qdev/Qriv % barrage 5 Test of eel mortality by passing in large turbine : tests on 3 turbines with the HI Z tags technique (Rhine and Rhône rivers)

33 French research program on eel and dams Under progress / First results end of 2011 (2) période effective de pêche CPUE observées CPUE prédites 6 - Prediction of eel downstream migration peaks by using environmental parameters (river Loire eel fishery) 7 Prediction of eel downstream migration peaks by using the bio monitor MIGROMAT on the river Shannon ( ) année test préd. vérifiée = 100% 9 1/10 15/10 29/10 12/11 26/11 10/12 24/12 7/1 21/1 4/ Measurement of eel downstream migration by using a sampling fishery (river Dordogne) 9 Test of an infra sound deterrent device (ProFish) at the intake of two hydro plants (Gave de Pau river) 10 Design of Fish Friendly intakes for HPP

34 French research program on eel and dams Under progress / First results end of 2011 (3) 11 Improvement and test of a the VLH Fish Friendly turbine 12 Financement for the development of the Alden Fish Friendly Turbine (USA)

35 Thank you for your attention

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