Abstract
An analysis of streamflow characteristics (i.e. mean annual and seasonal flows and extreme high and low flows) in current and future climates for 21 watersheds of north-east Canada covering mainly the province of Quebec is presented in this article. For the analysis, streamflows are derived from a 10-member ensemble of Canadian Regional Climate Model (CRCM) simulations, driven by the Canadian Global Climate Model simulations, of which five correspond to current 1970–1999 period, while the other five correspond to future 2041–2070 period. For developing projected changes of streamflow characteristics from current to future periods, two different approaches are used: one based on the concept of ensemble averaging while the other approach is based on merged samples of current and similarly future simulations following multiple comparison tests. Verification of the CRCM simulated streamflow characteristics for the 1970–1999 period suggests that the model simulated mean hydrographs and high flow characteristics compare well with those observed, while the model tends to underestimate low flow extremes. Results of projected changes to mean annual streamflow suggest statistically significant increases nearly all over the study domain, while those for seasonal streamflow show increases/decreases depending on the season. Two- and 5-year return levels of 15-day low flows are projected to increase significantly over most part of the study domain, though the changes are small in absolute terms. Based on the ensemble averaging approach, changes to 10- and 30-year return levels of high flows are not generally found significant. However, when a similar analysis is performed using longer samples, significant increases to high flow return levels are found mainly for northernmost watersheds. This study highlights the need for longer samples, particularly for extreme events in the development of robust projections.
Highlights
Reliable information about various streamflow characteristics in a changing climate is critical for planning of adaptation measures, for energy and agriculture sectors
According to the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) (2007), global mean precipitation and evaporation rates are projected to increase in future climate, or in other words an intensification of the global hydrological cycle is to be expected in future warmer climate
Northeastern Canada, the region considered in this study, has an excess of precipitation over evaporation, with mean annual precipitation of the order of 800 mm according to the 1980–2010 normals based on the Global Precipitation Climatology Centre (Rudolf et al 2010), and average annual evaporation of the order of 200 mm according to the 1980–2010 normals calculated using the European Centre for Medium-Range Weather Forecasts (ECMWF)’s ERA interim reanalysis data (Berrisford et al 2009)
Summary
Reliable information about various streamflow characteristics in a changing climate is critical for planning of adaptation measures, for energy and agriculture sectors. According to the Global Climate Models (GCMs) participating in AR4 (IPCC 2007), the mean annual precipitation rate for this region is projected to increase by 0.4–0.5 mm/day, while mean annual evaporation and runoff increase by 0.1–0.2 and 0.1–0.3 mm/day, respectively, in the future 2080–2099 period with respect to the 1980–1999 period. This northeastern part of Canada with its large number of hydroelectric power generation stations plays a very important role in the economy of the provinces located in the region, the province of Quebec. Information on projected changes to various streamflow characteristics and associated uncertainties would be beneficial for better management of these mega-projects, including the ‘‘Plan Nord’’ recently initiated by the Government of Quebec (http://plannord.gouv.qc.ca)
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