Section 1: Introduction
Canada’s natural environment produces an abundance of freshwater that sustains ecosystems and supplies many benefits to people. This freshwater provides vital supplies of drinking water, supports food and timber production, dilutes and carries our wastes, and allows for a myriad of other activities such as hydro-electric production, manufacturing, mining, transport and recreation. Water is also an integral part of aquatic ecosystems, providing habitat for fish and other organisms.
The amount and quality of freshwater supplied to ecosystems varies from year to year, but also according to seasons and across the different regions of the country. This freshwater supply function can be altered and degraded by human activities—for example, climate and land cover change influence aspects of the water cycle (Textbox 1.1), while runoff and wastewater discharge from urban areas and from agriculture, forestry, mining and other activities will affect water quality.
Human Activity and the Environment 2016: Freshwater in Canada provides up-to-date statistics on freshwater supply and demand and includes maps, charts and tables for each of Canada’s 25 drainage regions. It also provides data on some of the factors that influence the supply and quality of freshwater. The report relies on hydrometric data tracking streamflow, survey data on drinking water plants, industrial and agricultural water use, as well as data drawn from numerous other sources to characterize some of the pressures affecting the provision of freshwater.
The report is organized as follows:
Section 2: Freshwater supply and demand provides updated statistics on water yield, water quality and water use.
Section 3: Drainage region profiles provides highlights, maps, tables and charts characterizing water supply, demand and various factors affecting the provision of freshwater for each of Canada’s 25 drainage regions.
Appendices: include a glossary of water terminology, methodology information, equivalences and comprehensive data tables.
The annual Human Activity and the Environment publications bring together data from many sources to present a statistical portrait of Canada’s environment, with special emphasis on human activity and its relationship to natural elements—air, water, soil, plants and animals. Each issue provides accessible and relevant information on an environmental issue of concern to Canadians.
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The hydrological cycle describes the continuous movement of water between the earth and the atmosphere (Figure 1.1). Water evaporates from surfaces, sublimates from snow or ice or is transpired by plants. The water vapour rises through the air, cools and condenses, forming clouds. When the water droplets in clouds combine and grow heavier, they fall to the earth as precipitation—rain, snow or hail. Water is also supplied to ecosystems as dew and fog. It is stored as snowpack and in glaciers, runs overland into streams, rivers and lakes, infiltrates into the soil where it becomes soil moisture, or travels downward through the soil to the water table, becoming groundwater. Groundwater flows slowly underground and is discharged back to surface water systems through wells, springs and seepage into streams, rivers, lakes and oceans. Groundwater can also be stored in aquifers for hundreds or even thousands of years.
Most water is found in the oceans—freshwater makes up less than 3% of water on earth. This freshwater is found in glaciers, ice and snow, in streams, lakes, rivers and wetlands and as groundwater and soil moisture.
Renewable freshwater refers to the water that regularly replenishes our rivers, lakes and aquifers. Non-renewable freshwater describes water that is stored in deep aquifers, ice caps and glaciers that have a negligible rate of recharge on a human time scale. Some freshwater in the Great Lakes and other major water bodies can also be considered non-renewable since the renewal rates are very low.
The water yield is an estimate of renewable freshwater. It is derived from data on the unregulated flow of water in rivers and streams in Canada. Although the water yield provides an estimate of renewable freshwater, it can include some water that is considered non-renewable (e.g., melt water from receding glaciers).
Where possible, data are aggregated and presented by drainage region, which groups 974 sub-sub-drainage areas representing all land and interior freshwater bodies into 25 drainage regions (Map 1.1)Note 1. These drainage regions can be further grouped according to their outflow into one of five ocean drainage areas: the Pacific Ocean, Arctic Ocean, Gulf of Mexico, Hudson Bay or Atlantic Ocean. This geography is a variant of Statistics Canada’s official classification of drainage areas, the Standard Drainage Area Classification (SDAC) 2003.
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