The Water Yield for Canada As a Thirty-year Average (1971 to 2000): Concepts, Methodology and Initial Results - ARCHIVED
Surveys and statistical programs – Documentation: 16-001-M2009007
In this paper, we present the methodology developed by Statistics Canada to calculate the average annual water yield for Canada. Water yield, for the purposes of this paper, is defined as the amount of freshwater derived from unregulated flow (m3 s-1) measurements for a given geographic area over a defined period of time. The methodology is applied to the 1971 to 2000 time period.
This research was conducted to fill data gaps in Statistics Canada's water statistics program. These gaps exist because estimates of freshwater flow for Canada have not been calculated regularly and have been produced using a variety of methods that do not necessarily generate comparable results. The methodology developed in this study produced results that are coherent through space and time. These results will be used in the future to investigate changes in water yield on a more disaggregated basis.
To achieve the water yield estimate a database of natural streamflow observations from 1971 to 2000 was compiled. The streamflow values were then converted to a runoff depth and interpolated using ordinary kriging to produce spatial estimates of runoff. The spatial estimates were then scaled to create a National estimate of water yield as a thirty-year average. The methodology and results were then validated using a stability analysis and several techniques involving uncertainty. The result of the methodology indicates that the thirty-year average water yield for Canada is 3435 km3.