Above the water table lies the unsaturated zone. The level below which all the spaces are filled with water is called the water table. Many terms are used to describe the nature and extent of the groundwater resource. In some places, where groundwater has dissolved limestone to form caverns and large openings, its rate of flow can be relatively fast but this is exceptional. Groundwater flows slowly through water-bearing formations (aquifers) at different rates. At greater depths, because of the weight of overlying rock, these openings are much smaller, and therefore hold considerably smaller quantities of water. Much of the earth's fresh water is found in these spaces. The water filling these openings is usually within 100 metres of the surface. It fills the spaces between sand grains (intergranular), in rock crevices (as in igneous rocks), and in solution openings (as in limestone). The illustration shows where groundwater can be found. The manure contaminated the water with the E.coli intestinal bacteria, causing illness and death to some residents and acting as a serious reminder of the importance of what many Canadians take for granted - clean and safe drinking water.Įven where we might not use it directly as drinking water supply, we must still protect groundwater, since it will carry contaminants and pollutants from the land into the lakes and rivers from which other people get a large percentage of their freshwater supply. ![]() In May 2000, a heavy rain storm washed cattle manure into a town well in Walkerton, Ontario. Newspaper reports alerted area residents and helped focus attention on the problem of groundwater pollution. Early in 1990, chemical seepage, caused by the tire fire at Hagersville, Ontario, threatened to pollute groundwater supplies in the region. Media reports about the contamination of wells from leaking gasoline storage tanks or dry cleaning solvents, and about the effects on groundwater of chemical leakage from landfill or industrial waste disposal sites have raised public concerns about groundwater quality. In recent years, a number of events affecting groundwater quality have contributed to a heightened public awareness and concern about the importance and vulnerability of the resource.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |