Description of the hydrometric and meteorological data for the eastern part of Hudson Bay

Catherine GuayChercheuse – HydrologieUnité Mécanique, métallurgie et hydroéolienDirection scientifique1800, Lionel-Boulet (P-55)Varennes (Québec) J3X 1S1Tél. : 450 652-8082guay.catherine@ireq.ca

1 IntroductionThis document is a short description of the hydrometric and meteorological data available at Hydro-Québec for the eastern part of Hudson Bay, including James Bay. It is intended to accompany data provided by Hydro-Québec’s research institute in the context of the BaySys project.

2 Hydrometric dataFigure 1 shows a map of the watersheds of rivers flowing into eastern Hudson Bay for which hydrometric data is available. The eastern part of Hudson Bay in Québec is a vast territory populated mostly by isolated natives’ communities. Hydro-Québec operates two large hydroelectric complexes on this territory: the La Grande complex, and the Eastmain-1-A-Sarcelle-Rupert complex. Throughout the years, many hydrometric stations were installed by the CEHQ1, but for limited time spans only. These stations provide streamflow time series based on water level gauges and rating curves and are represented by green circles in Figure 1. Another source of hydrometric data is the net basins supplies (NBS) calculated at each Hydro-Québec power plant (or dam), represented by blue circles in Figure 1. Note that the sub-basin contours of the Eastmain-Rupert complex are not shown in Figure 1 for better overall visualisation, but are depicted in Figure 2. These NBS are computed with the following equation:

NBS=∆S+ I−O

Where ΔS is the change in storage, I is the inflow from the upstream power plant, and O is the outflow from the current power plant. The change in storage is determined from reservoir water level measurements, and the inflows and outflows are calculated from the electric output and characteristic curves of turbines in the plants. NBS are subject to greater error than conventional streamflow measurements because of the incertitude associated with (1) the measurement of

1 Centre d’expertise hydrique du Québec, Ministère du Développement durable, de l’Environnement et de la Lutte contre les changements climatiques. The CEHQ is in charge of collecting the hydrological and hydraulic data needed by the Ministère for managing Québec’s water resources.

water levels in large reservoirs, (2) the modelling of storage based on water levels, and (3) the modelling of flow through a turbine based on the electric power produced. For these reasons, the time series of the La Grande complex are particularly noisy in the post-impoundment decades. Nonetheless, NBS are useful to calibrate hydrological models as they represent the natural flows from a watershed, without the influence of dam regulation.

Table 1 provides a description for each station in Figure 1 and other characteristics of the watershed (basin area, type of measurement, years with data). For every station in Table 1, the data is available at a daily time step.

Figure 1 Map of the watersheds with available hydrometric data (Google Earth Enterprise)

Table 1 Description of the hydrometric stations

STATION ID RIVERAREA (km²) DESCRIPTION TYPE START END

080104 Turgeon 11200 14,3 km upstream of the Harricana River Streamflow 1969 2004

080701 Nottaway 57201 Head of Soscumica Lake Streamflow 1961 1981

080801 Broadback 17100 1,6 km downstream of the Ouasouagami River Streamflow 1962 1981

081002 Rupert 40748 11,4 km downstream of the Nemiscau Lake Streamflow 1964 2004

081101 Pontax 5980 60,4 km from outlet in Hudson Bay Streamflow 1975 2012

090601 Eastmain 44241 Head of Basile Gorge Streamflow 1960 1979

093302 Anistuwach 4551 At the outlet of the Pistinikw Lake Streamflow 1982 1992

093801 Grande Riviere de la Baleine 34282 30,6 km upstream of the Denys River Streamflow 1962 2014

093804 Denys 4650 26,9 km upstream of the Grande Rivière de la Baleine River Streamflow 1962 2014

095002 Nastapoca 12879 29,0 km from the outlet in Hudson Bay Streamflow 1975 1992

096101 Innuksuac 11155 15,3 km from the outlet in Hudson Bay Streamflow 1976 1983

094206 Petite Riviere de la Baleine 7496 6,8 km upstream of the Ancel canal Streamflow 1964 2002

948160 La Grande Riviere 30991 At LG-2 power plant Net basin supply 1960 2014

948064 Laforge 9104 At Laforge power plant Net basin supply 1961 2014

948103 La Grande Riviere 28493 At LG-3 power plant Net basin supply 1961 2014

948076 La Grande Riviere 27976 At LG-4 power plant Net basin supply 1961 2014

948034 Caniapiscau 37794 At Brisay Net basin supply 1963 2014

953998 Eastmain 14403 At La Sarcelle power plant (Opinaca Lake) Net basin supply 1960 2014

953997 Eastmain 25857 At Eastmain-1 power plant Net basin supply 1960 2014

948191 La Grande Riviere 2132 At LG-1 power plant Net basin supply 1960 2014

954043 Rupert 1977 Upstream the Tommy-Neeposh tunnel Net basin supply 2004 2014

954044 Rupert 891 Downstream the diversion canals Net basin supply 2006 2014

954045 Rupert 10262 At Mesgouez Lake Net basin supply 2000 2014

954046 Rupert 18211 At Mistassini Lake Net basin supply 2000 2014

2.1 The La Grande complex and Eastmain-Rupert diversion

2.1.1 Description of the tributaries to the La Grande complexThe La Grande complex, shown in Figure 2, drains a vast territory using a large network of dikes, dams, canals and tunnels. Total or partial streamflows from the Caniapiscau, La Grande, Eastmain and Rupert rivers ultimately converge to the LG-1 power plant.

The Caniapiscau and Eastmain rivers were diverted during the first phase of the La Grande project, in the late 1970s and early 1980s. The Caniapiscau River initially flowed northward, and the Eastmain River (shown in blue in Figure 2) flowed westward. After the diversions, the headwaters of the Caniapiscau River flowed towards LG-4 through the Fontanges and Laforge rivers (not shown explicitly in the Figure). The Eastmain River was diverted towards the LG-2 power plant. Between 2002 and 2012, approximately 50 % of the total flow of the Rupert River (shown in yellow in Figure 2) was diverted towards the Eastmain River. The data from the 090601 station (1959-1980) and the 081002 station (1964-2004) thus represent the natural configuration of the Eastmain and Rupert rivers prior to the diversion.

Figure 2 Close-up on the Eastmain-Rupert diversions and the La Grande complex

2.1.2 Net basin suppliesNet basins supplies from the La Grande complex consist of the natural contribution of the watershed comprised between two power plants (or dams). The NBS at one station thus does not include the flow from the upstream watershed. For instance, the NBS at LG-3 (948103)

doesn’t include the flow from LG-4 (948076), nor does LG-4 include the flow from Laforge-1 and 2 (948064), and so on. In order to obtain the total outflow from the La Grande complex, NBS along the complex (including the Eastmain-Rupert diversion) must be summed/routed. On a daily time step though, the transit time of water must be taken into account. At the time of the redaction of this short report, the equations needed for routing the flows were not readily available, but a request has been made to obtain them.

2.1.3 Regulated outflows to Hudson BayThe regulated outflows from the LG-1 power plant are also available for the period 1995-2014 on a daily basis. Since these outflows consist of the actual amount of water exiting the power plant, they do not follow the hydrological cycle, but are rather influenced by power production and reservoir management rules. These data can be provided with the signature of a confidentiality agreement.

3 MeteorologyThe meteorological data consists of basin averages of the daily minimum and maximum temperatures and total precipitation. Basin averages are computed from the interpolated gridded data produced by NRCan (Hutchinson et al., 2009; McKenney et al., 2011) at a resolution of 10 km x 10 km. The data currently delivered range from 1971-2010. They shall be updated to include 2011-2013 and subsequent years as the observations are processed and made available by NRcan.

4 References

Hutchinson, M. F., McKenney, D. W., Lawrence, K., Pedlar, J. H., Hopkinson, R. F., Milewska, E., & Papadopol, P. (2009). Development and Testing of Canada-Wide Interpolated Spatial Models of Daily Minimum–Maximum Temperature and Precipitation for 1961–2003. Journal of Applied Meteorology and Climatology, 48(4), 725–741. http://doi.org/10.1175/2008JAMC1979.1

McKenney, D. W., Hutchinson, M. F., Papadopol, P., Lawrence, K., Pedlar, J., Campbell, K., … Owen, T. (2011). Customized Spatial Climate Models for North America. Bulletin of the American Meteorological Society, 92(12), 1611–1622. http://doi.org/10.1175/2011BAMS3132.1