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Water : A Precious, ie ey, , , , , , , , , living things on Farth. Itisan essential, , i yall, Water is vital fo water is an, , natural resource. Availability of potable, important issue in urban areas and villages. Planning for, optimal use and conservation of water resources Is @, subject of great interest and concern for us. India should, consider itself blessed, as it is one of the wettest countries, of the world with an average rainfall of above 1000mm, per year. However, what we do with our resources needs, much better planning and implementation., , , , HOW MUCH WATER |S AVAILABLE?, , About 71% of Earth's surface is covered with water. About 97.4% of the total water is saline water (in seas, and oceans). This is not fit for human use. About 3% is fresh water which is present in the frozen form in, glaciers ice caps and permanent snow, again not available readily. The amount of water which is roughly, 0.006% of all the water is available for our use., , USES OF WATER, (i) We need water daily for our personal needs such as ot,, drinking, bathing, washing, cooking and cleaning Think SEYON? &, , our houses and utensils., * 22nd March is celebrated as the World Water Day., , (ii) Nearly 60% of our population depends on Year 2003 was observed as the international year, , agriculture for living. There is an increase in of fresh water to make people aware of this, , agricultural activities day by day because of the dwindling natural resource. ;, , increase in population. As rain is often * The amount of water recommended by the United, , unpredictable, therefore, in India about 70% of the Nations for drinking, washing, cooking and, , total available water is used for agriculture, maintaining proper hygiene is a minimum of 50, (ii) Water provides a medium for all biochemical vee Per Parser cy,, , reactions taking place inside our bodies, |, (iv) Water is essential for 8ermination of seeds and, , (v) Most industrial activities need w,, ater. Industries such i ili, drugs, dyes and heavy chemical industries require Sia: traps « Petroleu lariat ee, ntities., , nimals,, , — Hy, , growth of plants., , (vi) Water provides habitat for severa| Plants anda
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xc. water changes to ice. While, a ter { » Most substa, ig, weaker expands at nces, rE floats its freezing temperature ice is be dan 2, anne e ats On water. In severe winters dense than, ors the water warm below it. Thus, the it acts as a protective coat, . aquatic life can eas, ly survive, , sh The s, , d form, snow and ice, 'S present, gota? snow covered mountains and glaciers. @S ice caps at the poles of, , , , Solid state of water, , Liquid State, , water remains in the liquid form between O°C and 100°C. This is a very, mportant factor which enables sustenance of life on Earth. This is also a, ynique property of water as most of the other substances do not occur in their, form at ordinary temperature., , Liquid state of water, Gaseous State, When the liquid water changes into ice on cooling, it is called freezing. By, absorbing heat, solid form of water that is ice changes into liquid form. This, orocess is called melting. On heating water up to 100°C, it changes to vapour,, , a gaseous form. This process !s called boiling, , interchangeability of states of water, The states of water can be changed from one, the temperature, , Liquid water changes to ice on cooling, on #, water can be converted into vapour on further heating. Water vapours convert into liquid water on, , , , state to the other by changing Water boiling on the fire, , increasing the temperature, ice changes to water. Similarly, liquit, cooling., , heating heating, — —<== Water vapour (gas), , p 001, cooling (iquid) cooling, , , , SOURCES OF WATER, , There are mainly two sources of water :, , 1. Surtace water. z. Underground water, Surface Water, , The water present on the surface of the Earth is called the surface water. It is of three types:
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(a) Rain Water The first, , Rain water is the, shower contains dust and oth, , (b) River and Lake Water, , The water in rivers and lakes, snow. It contains clay, sand, solub!, , of, purest form of natural wate, , er impurities, , piting of, comes from rain and melting ¢, le salts and other, , impurities, (c) Sea Water, , Water from rivers, lake!, water contains various soluble salts an, , therefore it is very salty., , 5 and streams flow into the sea. Sea, id other impurities,, , , , Underground Water, , Apart of the rain water percolates into the soil and gets, collected there, it is called the underground water. It, is derived from springs or wells., , The water that is collected above the rocks exerts, pressure, and comes out from an opening in the Earth., It is called spring water, while the water that is _— Tat, collected above a rock is called the well water. 7 an, , , , far, , Composition of Water, , Water is a compound. It is made up of two elements, i.e., hydrogen and oxygen in, the ratio of 2:1 by volume and 1:8 by mass., , WATER CYCLE, The water molecule ., , The constant circulation of water from the water, bodies to the atmosphere and again back to the, water bodiesis known as the water cycle. The, water in the seas, rivers, lakes, ponds or any other, sources evaporates because of the heat of the sun, , Plants also give out large amount of water from, heir leaves. The water vapour rises up and, ondenses into the atmosphere to form clouds and, omes down as rain or snow by precipitation ;, , , , ie rain water enters the Seas, rivers, lakes, pond, ’ 1 S, , id streams and then evaporat :, les aga, iter cycle in nature goes on, gain. Thus, the, , , , Water cycle
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wey PRACTICE SESSION-1, , the following :, , word, , «eon, jected above rock., , water col, . ant circulation of wai er fi : ., , 1 Const . -_ ter from water bodies to atmosphe ., conversion of solid ice into liquid water. phere and again back to water bodies, , of, , A compound in which the ratio of hydrogen and oxygen is 1, ygen is 1:8,, , write T for Truc oF F for False for the following statement, * pnts +, , b 7 Seawater is the purest form of natural water., , 3, The flowing water is used for generating electricity. F, , 3, 22nd March is celebrated as the world water day, ' ’, , 4, The three forms of water are not interchangeable, , E, , pepLeT’ 1ON OF WATER TABLE, jnour country, the availability of surface water is limited. It varies from place to place and from time to time., Hence, mostly, we depend on ground water for irrigation, industry and domestic use. This has put a great, , stress on the water table. Water table is going down every year., Depletion of Water Table is Caused by the following Reasons:, , Increasing population., , Water requirements for sewage disposal., More of constructional activity of houses, Increasing industries to meet consumer demands., , for increasing population., , aor wp:, , Increasing deforestation, e of rain water into the, , In most cases, groundwater is replenished by the seepagt, from the nearby lakes and rivers. The process of seeping of water into the ground is called infiltration. The, groundwater thus gets recharged by this process. It is stored between layers of hard rock below water table, , rface water resources and industric, , This is known as an aquifer. Scanty rainfall, deforestation, drying of the su, ble is continuing unabated and, , pollution affect water table. Under these circumstances, depletion of water ta, time may come when w h sufficient water, even for domestic use. Before we come to fa, , e will not be left wit!, this situation, we should take resto conserve water., , all possible measu, SCARCITY OF WATER, ilable drinking water has led to its, , Overuse and misuse of avai, id. Water is wasted in almost, , acute shortage all over the :, all human activities such as domestic, agriculture oF, , industrial., Pollution of river and other water bodies is another major, factor that makes water unusable for human beings., , te, , , , Waterfall Flowing nver, , a —
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fficient to meet the fresh water requirement otter, ‘ich, , Causes of Water Scarcity, rain is su, , Although, the water that falls on the anon, there is scarcity of water due to the follow, (a) Uneven Distribution of Water k, ll on the Earth. om, some places receive plenty of len, some do not receive any rain. Almost a 3, half of the Earth's land area does not gi, , There is uneven rainf, , sufficient rains., (b) Lack of Conservation Facilities, Facilities to store water are not sufficient, and adequate. As a result, the rain water, runs off into the sources like rivers and, streams and further into the sea. This can, otherwise be stored by constructing small, or big dams, reservoirs, artificial lakes and, other storage facilities., Pollution of Water, The water has been polluted to a, considerable extent by human and, industrial activities. Careless dumping of, sewage water into a source of water has, caused pollution of the fresh water, sources,, , Effects of Water Scarcity, , The main condition that results due to scarcity of water is drought. Ad there rainfall, 1 . A drought, in an area fora quite long time. ; eeisieenii a, , (c, , , , , , Drought results in :, * Acute shortage of water for everyone. * Drying up of Pumps and lakes., * Failure of crops leading to shortage of food. * Death of people and animals, , Drought condition can be i, harvesting system . Prevented by encouraging people to conserve rain water by constructing rain water, , * Convert wastelands to forest lands win a |, * Use water judiciously. Se alternative crops in drought condition. |, WATER CONSERVATION Avoid wastage and pollution of water., , Water iS a precious resource ang in mal |, : order, conserve it today. Somestepstacone oe —— easily available for the future generations, e hat, , air)
