water composition in school
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Introduction
Water is derived from various sources. Rivers, lakes, seas, oceans and rain are known to be some of the main sources of water. This free flowing and readily available colourless, odourless substance is needed for domestic, agricultural as well as industrial use.
Sources of Water
The sources of water are mainly divided into two categories – Surface Water and Ground Water. Rain water pours and collects on earth in the form of surface water as well as ground water. Here is a brief look at both these sources of water:
Surface Water: It is found in rivers, lakes, reservoirs, streams, seas and other such sources. The water in lakes and rivers comes from rain and the melting of snow. The river water flows into the sea.
Ground Water: It is found under the land. Water travels under the surface of the land by way of soil on the non-porous rocks and fills the opening in these rocks. The rocks that store and send out groundwater are known as aquifers. At times, the water stored in these rocks bursts in the form of springs due to high pressure. Ground water is also extracted by digging wells and tube wells.
Water Available for Human Use
Our planet is rich in water with around three-fourth of its surface being covered with water. However, only a small part (just about 2.7%) of the total resources of water is available for the human use.
Around 97.3% of water on earth forms a part of the oceans. It is salty and cannot be used for the purpose of irrigation or any other agricultural use. It is not even good for industrial or domestic use. Out of the 2.7% fresh water available on earth, the inland surface water that is the water available from sources such as rivers, lakes and ponds accounts for just about 0.02%. This water is crucial for the growth and survival of all forms of