A quantification and analysis of historical sectoral and regional water withdrawals in Canada

Canada is a water rich country with one of the highest annual water uses per person among developed countries. This study provides a systematic, comprehensive analysis of recent data on this water use at national and subnational scales. It spatially disaggregates surveyed data from Statistics Canada (StatCan) to develop a historical dataset from 2005-2018 for Canadian water withdrawals at provincial and river basin scales for seven water use sectors: domestic use, manufacturing, irrigation, livestock, mining, oil and gas and thermal power generation. Additionally, sectoral water withdrawals are estimated for each province-river basin combination. Sectoral priorities are analyzed at the provincial and river basin scales and historical trends are identified. Water use intensity indicators are calculated and compared between different provinces, and a water stress index is used to identify regions most prone to water shortages. We find that water use decreased nationally over the study years for all sectors except irrigation, mining and oil and gas. Ontario had the highest water use of all provinces, mainly for thermal power generation. Manufacturing and domestic sectors were the dominant users in Quebec and British Columbia while the Prairies had more diversified uses. Domestic water use per capita values in Newfoundland & Labrador and Quebec are higher than the national average and all global values included in the study for comparison. Finally, the irrigation sector withdraws the most water per $GDP nationally while the oil and gas sector withdraws the least. Dataset development faced challenges related to data availability and uncertainties in downscaling assumptions. These challenges are described, and emphasize the need for a systematic and standardized approach to water data gathering and sharing in Canada.

加拿大是水资源丰沛的国家，亦是发达国家中人均年用水量最高的国家之一。本研究针对国家级与次国家级尺度下的近期用水数据，开展系统性、综合性分析。本研究对加拿大统计局（Statistics Canada，StatCan）的调研数据进行空间降尺度处理，构建了2005-2018年加拿大省级与流域尺度的取用水历史数据集，覆盖生活用水、制造业、灌溉、畜牧业、矿业、油气以及火力发电七大用水部门。此外，本研究还针对各省-流域组合分别估算了分部门取用水量。研究在省级与流域尺度下分析了用水部门优先级，并识别了历史演变趋势。计算了用水强度指标并开展跨省份对比，同时利用水资源压力指数识别出最易发生水资源短缺的区域。研究发现，在研究时段内，全国范围内除灌溉、矿业与油气部门外，其余所有部门的用水量均呈下降趋势。安大略省是全加拿大用水量最高的省份，其用水主要集中于火力发电领域；魁北克省与不列颠哥伦比亚省的用水主力为制造业与生活用水部门；而草原三省的用水结构则更为多元。纽芬兰与拉布拉多省以及魁北克省的人均生活用水量高于全国平均水平，同时也高于本研究用于对比的全球所有相关用水数据。最后，从单位GDP取用水量来看，灌溉部门的用水强度最高，而油气部门的用水强度最低。数据集构建过程中面临了数据可用性不足、降尺度假设存在不确定性等挑战。本研究对这些挑战进行了阐述，并强调加拿大亟需建立系统性、标准化的水资源数据收集与共享机制。