6 Science Chapter 14 Water

Chapter Notes and Summary
• Water is essential for life.
• Wells, rivers, or lakes are sources of fresh water.
• Ocean and sea water are not potable because they dissolve large amount of salt in them.
Water cycle : circulation of water between rivers and land is known as water cycle.
(a) change of water into its vapour is known as evaporation.
(b) change of vapour back into water is known as condensation.
(c) Falling of water from clouds is known as precipitation or rainfall.
(d) Run off is process by which rain water returns back to river bodies.
• Clouds are formed during process of condensation.
• Rain, snow, hail, etc. replenish rivers, lakes, and wells and recharge ground water.
• In India, most of rainfall occurs during monsoon season.
• Heavy rain in a short period of time causes flood.
• No rain for a long period causes drought.
• Most of potable water are available for us as ground water.
• As number of tube-wells in an area increases, level of ground water decreases.
• There is an immediate requirement to harvest water. basic idea behind rainwater harvesting is ‘catch water where it falls.’
• In rainwater harvesting method, stored rainwater is used to recharge ground water.
• In rooftop rainwater harvesting system, rainwater is collected from rooftop in a storage tank. It allows water to go into pit through pipes. This water seeps and refills ground water.

Leave a Reply

Your email address will not be published. Required fields are marked *