Water yield variability and response to climate change across Canada

This study generated a water yield dataset for Canada for 1979–2016 by subtracting the land surface evapotranspiration (ET) and water surface evaporation (E0) from precipitation (P). The dataset was validated in Budyko space and compared with streamflow (Q) before the spatial variability and trends were analysed. Results indicate (1) uncertainties of the dataset are generally small; (2) despite the asynchronous inter-annual change, annual water yield varies in a similar temporal pattern to Q; (3) annual water yield varies dramatically across Canada, ranging from about zero on the Canadian Prairies to over 2500 mm on the West Coast; and (4) annual water yield shows no significant changes over the study period in the vast majority (82.4%) of Canada’s landmass. The most significant increasing trend appears in South Central Canada, attributed to increasing P. The most significant decreasing trend appears in Northeast Canada and the Southern Montane Cordillera, attributed to decreasing P and increasing ET.