Uncertainty in projected streamflow for better future large infrastructure design and transboundary water management

The Nelson-Churchill River basin provides a significant source of water to support hydropower generation in the province of Manitoba, and exports to the USA. The province of Manitoba resides on the downstream end of the continental scale watershed, with two other Canadian provinces and many users upstream. In order to appropriately design large infrastructures and manage transboundary water in this expansive and data sparse region, resource planning is required.  Streamflow projections under climate change, necessitating an evaluation of input data uncertainty on long-term water supply projections will be produced and provided to the client. 


Issue to be addressed

The impacts of climate change in the Nelson-Churchill River basin, spanning the Canadian Prairies, have already been felt. Five of the top six Canadian floods in history have occurred within this basin with four in the past two decades. Climate change in unpredictable though in this region as a result of the water-limited nature of the Canadian prairie region and small changes in the net basin water supply can cost millions of Canadian dollars in flood damages, lost hydropower revenue, losses in the aquatic fisheries of Lake Manitoba and Winnipeg, or in tourism and navigation of waterways.
Manitoba Hydro owns and operates eight hydropower stations within this basin, and is mostly reliant on run-of-the-river water supply for hydropower generation for the province of Manitoba and export agreements.  Large hydroelectric infrastructure licensing requires a 100 to 500 year time horizon, and therefore necessitates consideration of potential water futures and water security on a long-term.

Decision support to client

This case study contributes to an initiative undertaken by The Global Water Futures (GWF) Institute, to develop an Integrated Modelling Programme for Canada (IMPC). The results, namely the quantification of uncertainty in projected streamflow available for hydropower generation resulting from input data forcing hydrologic scenarios will be communicated by the GWF to Manitoba Hydro to inform their long-term planning of resource and generation capacity under future climates.

Temporal and spatial scale

Simulations will be derived for, and assessed over three specific periods: historic (1981-2010), near future (2021-2040), and far future (2041-2070). For long-term planning of Manitoba Hydro, a combined future period will also be assessed from 2021-2070 given decision-making time horizons are on the order of 50-100 years. Though the historic reference period is from 1981-2010, simulations will be run from 1961-2015 for model calibration and validation. 
The spatial domain is the Nelson-Churchill River basin (~1.2 million km2), a regional-scale of national importance due to its influence on the freshwater regime of Hudson Bay. It is the primary water supply for Manitoba Hydro and one of the key basins of interest for the IMPC initiative. 

Knowledge brokering

Annual general meetings for the IMPC initiative are held in the form of a two- to three-day workshop where stakeholders (e.g., Manitoba Hydro) interact with knowledge providers under the GWF umbrella, including through this case study.  Regular collaboration between researchers occurs on a bi-weekly to monthly basis via WebEx online meetings, and in-person meetings with various stakeholders (e.g., Manitoba Hydro) as model outcomes are made available.
Various stakeholder-purveyor interactions are facilitated by the IMPC, depending on the knowledge, experience and availability of the stakeholders. Some are directly involved in the research, and others as end users of the resulting tools and technology only. Technology transfer and dissemination of any knowledge is achieved through annual workshops and hands-on training provided by purveyors and their highly qualified personnel.