Groundwater Basics
Table of Contents
What is the hydrologic cycle?
What is groundwater?
How does groundwater become contaminated?
What is water conservation?
Why is water conservation important in Canada?
How can water conservation be implemented?
What are the benefits of conservation?
What types of freshwater aquatic ecosystems do we have in Canada?
How does an Ecosystem work
What is the Hydrologic cycle?
From the beginning of time when water first appeared, it has been constant in quantity and continuously in motion. Little has been added or lost over the years. The same water molecules have been transferred time and time again from the oceans and the land surface into the atmosphere by evaporation, dropped on the land as precipitation, and transferred back to the sea by rivers and groundwater. This endless circulation is known as the "hydrologic cycle". At any instant, about 5 litres out of every 100 000 litres is in motion.
Over time, major cyclic changes in climatic processes have produced deserts and ice cover across entire continents. Today, regional short-term fluctuations in the order of days, months, or a few years in the hydrologic cycle result in droughts and floods.
What is Groundwater?
Two thirds of the world's fresh water is found underground. Even in Canada, there is more water underground than on the surface. This water is found in aquifers and appears at the surface as springs. Very often groundwater is interconnected with the lakes and rivers.
Groundwater occurs in the tiny spaces between soil particles (silt, sand, and gravel) or in the cracks in bedrock, much like a sponge holds water. The underground areas of soil or rock where substantial quantities of water are found are called "aquifers". These aquifers are the source of wells and springs. It is the top of the water in these aquifers that forms the "water table".
The origin and composition of aquifers are varied. Many important Canadian aquifers are composed of thick deposits of sands and gravel previously laid down by glacial rivers. These types of aquifers provide most of the water supply for the Kitchener-Waterloo region in Ontario and the Fredericton area in New Brunswick. The Carberry aquifer in Manitoba is an old delta lying on what was formally Glacial Lake Agassiz. It is well developed as a source of irrigation water. Prince Edward Island depends on sandstone aquifers for its entire water supply. A major glacial outwash sand and gravel aquifer occurs in the Fraser Valley in British Columbia. It is extensively used for municipal, domestic, and industrial water supplies. The Winnipeg and Montreal aquifers that are used for industrial water supply are composed of fractured rocks.
To concentrate only on major (i.e., large) aquifers, however, is misleading. Many individual farms and rural homes depend on relatively small aquifers such as thin sand and gravel deposits of glacial or other origin. Although these aquifers are individually not very significant, in total they make up a very important groundwater resource.
How does Groundwater become Contaminated?
Groundwater becomes contaminated when anthropogenic, or people-created substances are dissolved or mixed in waters recharging the aquifer. Examples of this are road salt, petroleum products leaking from underground storage tanks, nitrates from the overuse of chemical fertilizers or manure on farmland, excessive applications of chemical pesticides, leaching of fluids from landfills and dumpsites, and accidental spills.
Contamination also results from an overabundance of naturally occurring iron, sulphides, manganese, and substances such as arsenic. Excess iron and manganese are the most common natural contaminants. Another form of contamination results from radioactive decay of uranium in bedrock, which creates the radioactive gas radon. Methane and other gases sometimes cause problems. Seawater can also seep into groundwater and is a common problem in coastal areas. It is referred to as "saltwater intrusion".
What is Water Conservation?
Water conservation activities are essentially designed to do two things: (1) reduce the absolute amounts of water we use (less water per person or given product or service) and/or (2) reduce the rate (using water only when we need it) at which we use water in our daily lives - either at home, at work, in business, or in industry. The reduction in water use will not only reduce the volume of polluted water, but will also allow municipal sewage treatment plants to function better because they work best with more concentrated inflow. In all cases, the goal of water conservation is to use our water resources more efficiently. Water conservation allows us to do the same task or job, but with much less water.
Why is water Conservation important in Canada?
Water conservation is important for three reasons. First, some regions of Canada are water-short due to semi-arid conditions. Dry summers place these areas of the country under additional stress. Second, other parts of the country, particularly the rural areas, often rely on groundwater as their sole source of supply. Excessive water use or withdrawals can lower water tables in these rural areas. And, third, in many urban areas in Canada, municipal water utilities are experiencing limits on supply because of infrastructure problems - either due to summer peak demands exceeding system capacities or due to older sewer and water systems that are in need of upgrading or repair.
In all three contexts listed above, water conservation helps by putting less pressure on the existing water supply (and wastewater treatment systems). Recognizing the importance of water resources to all life and reducing the rate at which we use water and/or the absolute amounts we use is the essence of what conservation is all about. It can help us "stretch" our existing reserves without either to serve the needs of future growth (in population or industry) or to serve an existing population for a longer period of time.
How can Water Conservation be Implemented?
There are many water-saving opportunities available to consumers, industry, and governments. Generally, three groups of actions are important - physical measures, economic measures, and social measures. Physical measures refer to alterations that can be made to water using equipment or processes. Domestic examples include the use of low-flow shower heads and water-conserving toilets, laundry facilities that recycle previously used water, and the implementation of universal water metering in communities. Industrial examples include the installation of water-recycling equipment, such as cooling towers, and process changes that lower water use. Economic measures refer to means of altering the ways in which users pay for the right to use water. Examples include revisions to municipal water rates to assure full cost recovery, water changes based on quantities used, and implementation of volume-based charges for self-supplied industries. Social measures refer to broad social policies and actions designed to lower water usage. Examples include revisions to plumbing codes, legal restrictions on water use during drought periods, and campaigns to inform the public about the importance of water.
The last section of the Primer, Water: Do's and Don'ts, provides many examples of actions that individual water users can take to implement conservation and efficiency.
What are the Benefits of Conservation?
In addition to "stretching" available water supplies to meet increasing demands, water conservation has distinct economic advantages. For example, use of water-saving shower heads can not only save the homeowner the cost of water itself but also save over m$100 annually in water-heating costs. Furthermore, conservation retrofitting of an existing building could generate benefits ranging between 15 and 20 times the costs incurred. Finally, water conservation lessens the demands made on a vital natural resource, thereby contributing to the sustainability of the Canadian environment.
What Types of Freshwater Aquatic Ecosystem do we have in Canada?
Canada contains an abundance of freshwater ecosystems, including lakes, ponds, rivers, streams, prairie potholes, and wetlands.
A lake is a sizable water body surrounded by land and fed by rivers, springs, or local precipitation. The broad geographical distribution of lakes across Canada is primarily the result of extensive glaciation in the past.
Lakes can be classified on the basis of a variety of features, including their formation and their chemical or biological condition. One such classification identifies two types of lakes: Oligotrophic and eutrophic. Oligotrophic lakes are characterized by relatively low productivity and are dominated by cold-water bottom fish such as lake trout. Eutrophic lakes, which are shallower, are more productive and are dominated by warm-water fish such as bass. Great Slave Lake (Northwest Territories) and most prairie lakes represent the two types, respectively. Ponds are smaller bodies of still water located in natural hollows, such as limestone sinks, or that result from the building of dams, either by humans or beavers.
Ponds are found in most regions and may exist either seasonally or persist from year to year. Rivers and streams are bodies of fresh, flowing water. The water runs permanently or seasonally within a natural channel into another body of water such as a lake, sea, or ocean.
Rivers and streams are generally more oxygenated swiftly moving waters (e.g., black fly larva and darter fish.). Some of the larger rivers in Canada include the St. Lawrence, Mackenzie, Fraser, Athabasca, North and South Saskatchewan, and Saint John rivers.
Some rivers flow into oceans, the great saltwater bodies that cover 70% of the earth's surface. The tidal areas where saltwater and fresh water meet are called estuaries. These productive ecosystems, found on Canada's coasts, contain unique assemblages of organisms, including starfish and anemones.
How does an Ecosystem Work?
Energy from the sun is the driving force of an ecosystem. This light energy is captured by primary producers (mainly green plants and algae) and converted by a process called photosynthesis into chemical energy such as carbohydrates.
The chemical energy is then used by the plants to perform a variety of functions including the production of plant parts such as leaves, stems, and flowers. The raw materials used for this purpose are nutrients (e.g., nitrogen, phosphorus, oxygen, and calcium): substances necessary for the growth of all plants and animals.
Animals are incapable of photosynthesis. They therefore eat plants, other animals, or dead tissue to obtain their energy and required nutrients. In ecosystems, the transfer of energy and nutrients from plants to animals occurs along pathways called food chains. The first link in a food chain consists of primary producers: green plants and other organisms capable of photosynthesis.
Plant-eating organisms, known as primary consumers: carnivores (flesh eaters) or omnivores (plant and animal eaters). Decomposers such as bacteria and fungi make up the final link in the food chain. They break down dead tissues and cells, providing nutrients for a new generation of producers.
Most organisms in an ecosystem have more than one food source (e.g., fish feed on both insects and plants) and therefore belong to more than one food chain. The consequent overlapping food chains make up food webs: complex phenomena with links that are constantly changing.