16 World Heahh • Ju~-August 1992
World Heahh • July-August 1992
Man and water
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17
W
ater is part of a large constantly moving cycle. Simply explained, it evaporates from the surface of the earth, and turns into clouds that produce rain and snow, which fall on the earth's surface. Then through rivers and under- ground water tables it passes to the oceans and lakes, and thus the cycle continues.Climatic changes caused by human activity - like cutting down forests - have reduced the water supply in many parts of the world. As temperature and rain and snow precipitation patterns change, many rivers carry less water. At times they carry too much water, resulting in floods. Trees and other vegetation help to retain water in the soil and prevent land- slides. Chemical substances from industry sometimes pass into the air. One of the results is acid rain, which kills fish and vegetation in many lakes and rivers. Sometimes danger- ous products from industry, agriculture and other human activities enter the rivers, lakes, oceans and underground water, and can contaminate our drinking-water.
At the same time, the demand for water from villages and towns, and from industry and agriculture, is steadily increasing. Water can therefore no longer be considered an unlimited resource, which costs nothing and which can be wasted. In the next century water supplies will certainly be considered a very valued service, and each one of us will have to pay what it costs to have clean water.
