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Pierre Dupuis, ing. Canada J.Dumas, D.Messier, S.Weyman 7th International Conference on Hydro informatics HIC 2006 Nice, France Impacts Assessment of the.

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Presentation on theme: "Pierre Dupuis, ing. Canada J.Dumas, D.Messier, S.Weyman 7th International Conference on Hydro informatics HIC 2006 Nice, France Impacts Assessment of the."— Presentation transcript:

1 Pierre Dupuis, ing. Canada J.Dumas, D.Messier, S.Weyman 7th International Conference on Hydro informatics HIC 2006 Nice, France Impacts Assessment of the Rupert River diversion on Rupert Bay Estuary Hydrodynamics

2 Plan Eastmain 1A – Rupert river diversion project Eastmain 1A – Rupert river diversion project –Impacts assessment study required 2D modeling of Rupert Bay hydrodynamics 2D modeling of Rupert Bay hydrodynamics –Strategy for this study –Data acquisition and analysis –Input to model –Productivity tools used for impact assessments –Results Conclusion Conclusion

3 Eastmain-1-A Project Province de Québec, Canada Montréal Hudson Bay James Bay Great Lakes Rupert Bay La Grande Hydroelectric Complex Eastmain-1-A Powerhouse

4 Diversion Rupert Bay Diversion Eastmain-1-A La Sarcelle La Grande-2-A La Grande 1

5 Eastmain-1-A Project Estimated cost: millions € Estimated cost: millions € Added Power : 768 MW MW Added Power : 768 MW MW Added Annual Energy: 8,5 TWh Added Annual Energy: 8,5 TWh Diversion: 452,6 m 3 /s mean annual flow, max: 800 m 3 /s Diversion: 452,6 m 3 /s mean annual flow, max: 800 m 3 /s Less fresh water inflow in Rupert Bay Less fresh water inflow in Rupert Bay In commission: 2011 In commission: 2011

6 Objectives and constraints Rupert Bay hydrodynamics Get a good understanding of the bay actual hydrodynamic conditions Get a good understanding of the bay actual hydrodynamic conditions Assess the impacts of less freshwater inflow into the bay Assess the impacts of less freshwater inflow into the bay Make sure the study is credible and will be well received by the public and govern- mental agencies (federal and provincial) Make sure the study is credible and will be well received by the public and govern- mental agencies (federal and provincial) Proceed according to an established time frame and within budget! Proceed according to an established time frame and within budget!

7 Rupert bay & Waskaganish James Bay Rupert Bay Stag Rock Waskaganish Cree Native community 17,5 km Stag Island

8 Waskaganish

9 Rupert Bay Characteristics Covers 825 km 2 Covers 825 km 2 Width of the bay varies from 10 to 18 km Width of the bay varies from 10 to 18 km Channel depth varies from 5 to 8 m Channel depth varies from 5 to 8 m Tidal amplitude: 2 m Tidal amplitude: 2 m Salinity of ‰ in James Bay Salinity of ‰ in James Bay

10 Zones Maritime Maritime Mixing Mixing Freshwater Freshwater Pontax Rupert Broadback Nottaway

11 Cabbage Willows – Tidal Flats

12 Modeling Numerical modeling is required Numerical modeling is required –Huge area, low depth, bathymetry Hydro-Québec chose Mike21™ from DHI (Danish Hydraulic Institute) Hydro-Québec chose Mike21™ from DHI (Danish Hydraulic Institute) –Accepted within the scientific community –Well mixed estuary –Modules HD and AD Strategy: Simulation of 7 weeks in summer Strategy: Simulation of 7 weeks in summer –Natural conditions –Post diversion conditions Simulation of 4 weeks in winter Simulation of 4 weeks in winter

13 Required input data Bathymetry Bathymetry Downstream boundary tidal signals Downstream boundary tidal signals Fresh water inflows Fresh water inflows

14 Bathymetry Parallel lines every 200 m Parallel lines every 200 m GPS positioning GPS positioning –Correction for tidal influence –Crosscheck with perpendicular lines Vertical precision estimated at 10 cm Vertical precision estimated at 10 cm Very shallow waters and tidal flats: Airborne Laser Very shallow waters and tidal flats: Airborne Laser Took 2 summers to complete work Took 2 summers to complete work Cost: € Cost: €

15 Final result Rupert Broadback Nottaway James Bay Warm colors: shallow depth Many channels within the bay Pontax

16 Tidal gauges Boundaries Boundaries –Mesaconane –Strutton Within Within –Gushue Island –Stag rock –Rupert river –Lemoyne

17 June July 3 2 m 0 m -2 m 1 m -1 m Boundary conditions for calibration

18 Tidal signals 3 m 0 m -2 m August 7 th 2003October 20 th Tidal signal at downstream boundary for modeling Super storm of August 22, 2003

19 Fresh water inflow in summer total: 2500 to 3000 m 3 /s (summer 2003) Nottaway Pontax Broadback Rupert post diversion Rupert natural state August 1 October m 3 /s 800 m 3 /s 0 m 3 /s

20 Data acquisition costs ( € ) Bathymetry: € Bathymetry: € Oceanography: € Oceanography: € Stations (material & install) € Stations (material & install) € Maintenance (5 years) € Maintenance (5 years) € Helicopters € Helicopters € Total : €

21 Domain Cell: square 162 m Cell: square 162 m Grid Grid –625 rows –370 columns Chézy coefficient for calibration Chézy coefficient for calibration –Tidal range –Signal deformation Time step: 90 s Time step: 90 s Output: 15 minutes Output: 15 minutes

22 Calibration Winter : 35 Winter : 35 Summer : 65 Summer : 65

23 Validation Rupert River Km 2,5Km 4,2

24 Impacts assessment 2 Output files of 15 Gb to work with 2 Output files of 15 Gb to work with –NTFS file system required to store and access output data –Special C++ module for retrieving data –Read directly from binary output files (Mike21 output file of type *.dfs2) –Can work on matrices (matrix operators) 15Gb was a workable up limit for file size 15Gb was a workable up limit for file size

25 Tools Subtractions and comparisons Subtracts post diversion from natural at any given time step Subtracts post diversion from natural at any given time step Do water level variation for a given cell over a given time period and compare to field data – Quick for validation purposes Do water level variation for a given cell over a given time period and compare to field data – Quick for validation purposes

26 Tools Extrema Public and policy makers cannot always be in front of the screen Public and policy makers cannot always be in front of the screen Example: Example: Maximum speed modulus for a five weeks period for pre and post diversion conditions Maximum speed modulus for a five weeks period for pre and post diversion conditions

27 Tools Virtual probe Set start date and location Set start date and location Monitors current speed, depth, time Monitors current speed, depth, time Helps to: Helps to: –understand circulation patterns –Zones affected by each stream

28 Impact of diversion White: Natural White: Natural Black: Post diversion Black: Post diversion Less lateral flow pressure from Rupert River Less lateral flow pressure from Rupert River Flow from Nottaway and Broadback will shift toward the East. Flow from Nottaway and Broadback will shift toward the East.

29 Time of residence Before diversionAfter diversion 8 days 12 days Start

30 History of a virtual probe Before diversionAfter diversion Duration in days 0-30Duration in days 0-25 Travel distance km Travel Distance km 1,4 m/s 0 m/s Speed Azimuth

31 Salinity - Modeling Time step reduced from 90 to 45 s Time step reduced from 90 to 45 s Salinity was set constant at 20 ‰ at downstream boundaries Salinity was set constant at 20 ‰ at downstream boundaries Fresh water threshold : 0,5 ‰ Fresh water threshold : 0,5 ‰ Advection-Dispersion coefficient set to 130 Advection-Dispersion coefficient set to 130 Results showed very good agreement with measurements at Stag Island and Stag Rock Results showed very good agreement with measurements at Stag Island and Stag Rock

32 Fresh water front Samples taken from helicopter to follow front Samples taken from helicopter to follow front For large and small tides For large and small tides Used for calibration Used for calibration

33 Salinity - Model Extreme incursion and excursion From Sept 1 st to October 11 th 2003

34 Salinity Impacts Translation of the freshwater front upstream due to diversion Translation of the freshwater front upstream due to diversion Translation estima- ted to be 4 to 5 km Translation estima- ted to be 4 to 5 km Waskaganish is still in the fresh water zone Waskaganish is still in the fresh water zone Before diversion

35 Winter - Ice field and flux

36 Impact at Waskaganish Imbricated model Imbricated model Cell: 54 m Cell: 54 m Water levels Water levels Flats (low tide) Flats (low tide) Currents Currents

37 Conclusion - 1 Study constrained by cost and time schedule Study constrained by cost and time schedule Data requirements to be planned in advance Data requirements to be planned in advance –Stations carefully located and justifications well explained to project administrator –Types of instruments, number of stations, location and purpose well documented –Stations maintenance and checkup to be included in costs –Modeler has to go to the site to get a feel of the system and must be part of the data gathering team Real conditions simulated over a long time period are well received by the public and governmental agencies Real conditions simulated over a long time period are well received by the public and governmental agencies

38 Conclusion - 2 Tools are needed to synthesize and represent results in a suitable form for other scientists and the public Tools are needed to synthesize and represent results in a suitable form for other scientists and the public Interaction between the modeler and specialists led to development of numerical tools to address their specific demands Interaction between the modeler and specialists led to development of numerical tools to address their specific demands Once created, these tools helped in producing final results in a short time span when all field measurements were available (near the project deadline) Once created, these tools helped in producing final results in a short time span when all field measurements were available (near the project deadline)

39 This PowerPoint presentation can be downloaded from this site in the near future

40 Broadback River channel

41 Salinity Impact

42 Salinity – Measurements Stag Rock (moored station) Depth 4,0 – 6,5 m Salinity ‰ Conductivity 0 – 6 Current speed 0,0 – 0,8 m/s Current direction Julian day

43 Impacts - Summer Fresh water inflow will drop by 20 to 25% Fresh water inflow will drop by 20 to 25% Fluvial circulation will shift toward the north-east (less pressure from Rupert River) Fluvial circulation will shift toward the north-east (less pressure from Rupert River) Residency time in the freshwater zone is one to two days longer in summer time Residency time in the freshwater zone is one to two days longer in summer time Salinity front will translate ≈ 4-5 km southward Salinity front will translate ≈ 4-5 km southward Salinity changes from 0,5 ‰ to 1,0 ‰ in the vicinity of Stag Rock Salinity changes from 0,5 ‰ to 1,0 ‰ in the vicinity of Stag Rock No perceptible variations within the bay as for water levels (in terms of mm) and velocity from a user standpoint No perceptible variations within the bay as for water levels (in terms of mm) and velocity from a user standpoint Piston like effect in James bay moves water within the bay toward the West Piston like effect in James bay moves water within the bay toward the West

44 Impacts - Winter Fresh water inflow will drop by 20 % Fresh water inflow will drop by 20 % Time of residence is much longer Time of residence is much longer Effects from diversion are of lesser importance Effects from diversion are of lesser importance Incursion-excursion of fresh water front is within the limits established for summer Incursion-excursion of fresh water front is within the limits established for summer Corroborates the findings of Ingram (1977) Corroborates the findings of Ingram (1977) Possible explanation System is in a dormant state in winter System is in a dormant state in winter –More friction –Less fresh water inflow –Tidal amplitudes of lesser magnitude


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