Water
A watershed is an area of high land that separates one drainage basin from another.
Water that runs off the land through rivers and lakes into oceans is called runoff. Some runoff soaks deep into Earth through soil and layers of sand, gravel, and porous rock. This is called groundwater. Water constantly evaporates into the atmosphere and returns to the Earth's surface as precipitation to evaporate again. This constant circulation of Earth's water is called the hydrologic cycle. Wetlands include swamp, marsh, and bog. They are places where the water table is at ground level. Wetlands account for about 14% of Canada's area and provide habitats for many species of insects, fish, birds, and mammals. The water table is the top of the soil zone in which all pore spaces are filled with water, called the saturated zone. Above the water table, the pore spaces are filled with air. A drainage basin is the area drained by a river and its tributaries. One drainage basin is separated from another by an area of higher land called a watershed. A tributary is a small stream or river that joins a larger stream or river. The amount of water that flows through a drainage basin is known as the discharge rate. We categorize our use of water in two ways. An instream use occurs when water is used without removing it from lakes or rivers. Instream uses include hydroelectric power generation, transportation, waste disposal, recreation, and fisheries. Withdrawal use actually removes water from the water body. Withdrawal uses include thermal power generation and manufacturing, municipal, agricultural, and mining activities. Withdrawal uses usually consume some of the water, that is, they return less water to the environment than they take out. Water Diversion
Canada has taken steps to solve water shortages in some regions by diverting water from one drainage basin to another. The water in these short-distance diversions is used primarily by large hydro-electric generating stations. We do not notice these diversions at present but, we may have need, in the future, to divert larger amounts of water to more populated areas in order to meet their needs.
Discussions have taken place about large-scale schemes to divert water from Canada to the United States. There are pros and cons to such schemes:
Renewable vs. Non-Renewable Resources
A renewable resource is one that replaces itself unless badly mismanaged. For example, trees grow to replace those cut down or lost to fire or disease.
A non-renewable resource is one that can only be used once, e.g., oil or iron ore. Definitions
Acid Precipitation: rain, snow, or fog created after sulphur dioxide and nitric oxides mix with water vapour in the atmosphere. Acid precipitation kills vegetation and turns lakes acidic, causing fish to die and wildlife to disappear.
Canal: waterway dug across land on which boats and ships travel. Discharge Rate: amount of water that flows through a drainage basin. The discharge rate of a drainage basin may vary greatly from season to season depending on the weather conditions. Drainage: is the process whereby water is removed from an area by flowing out of depressions in the land such as lakes and rivers. Drainage Basin: areas drained by a river and its tributaries. One drainage basin is separated from another by an area of higher land called a watershed. Erosion: is the wearing away of Earth's surface followed by the movement to other locations of materials that have been worn away. Eutrophication: phosphorus and nitrogen are deposited into our water system via soaps and fertilizers. The phosphorus and nitrogen encourage the growth of algae. When the algae dies, it decomposes pulling oxygen out of the water. As a result, fish and other aquatic animals suffocate. The added algae also prevents light from penetrating the water surface. Glaciation: is the state of being covered by glaciers or massive ice sheets. Glaciers: are slow-moving masses of ice. Meltwater: the water resulting from the melting of glacier ice and/or snow. Saturated Zone: is the area where crevices in the rock and spaces between the particles of soil, sand, and gravel are filled with water. The top of this zone is called the water table. Water Availability: volume of water in freshwater sources compared with the amount of water we are using. Weathering: breakdown of rock into small particles. Wetlands: swamp, marsh, and bog; places where the water table is at ground level. |
Chapters
36 Water the Most Basic Resource (p. 476-489)
Types of Water Pollution
Impacts of Urban Runoff
Role of Water & Ice in Landform Formation
Canada's 5 Major Watersheds
International Joint Commission
|