Water Resources : Water is the ii in constituent of hydrosphere. It is renewable resource and covers four-fifths of the earth surface.
Distribution : Water is present all around us, as vapour in the air even In dry deserts It is present under our feet in the soil. There is some 1.4 billion cubic kilometer (km) of water in the hydrosphere. Of this about 97 percent is ocean water, which is unsuitable for human use. Only 3 percent is available as fresh water. About 77.2 percent of the fresh water is locked in
Ice caps and glaciers and 22.4 percent is ground water and soil moisture. The remaining about 0.36 percent is distributed in rivers, lakes, streams and swamps.
Types : Water resources of two types : fresh water resources and Ocean or marine water resources.
Fresh Water Resources
Fresh water resource is essential for life on land and survival of human race. Fresh water is exhaustible, but it is renewed by oceans through “hdrological cycles. About 90 percent of water evaporating from the oceans turns to the latter and the remaining 10 percent fall on the land surface to port natural and man-made ecosystems. Fresh water occurs in ponds, ;, streams, rivers and underground pools. India receives about 2.75
million cubic kilometers of fresh water through an average rainfall of about 110 cm per year. Out of it 0.6 million cubic kilometer seeps into ground, while rest flows into rivers. The ground water reserves of India is about 27 million cubic kilometer or ten times of annual rainfall.
Human Uses : Man obtains fresh water from rivers, lakes, ponds and und. The fresh water is used for following purposes.
(1) It is used for drinking, cooking, bathing and washing.
(2) It is used for disposal of human excreta through sewers.
(3) It used in industries and for construction works.
(4) Water falls and river currents are used to generate electricity.
(5) It is used for raising fish and aquaculture i.e. raising of useful aquatic plants. India with about 1.6 million hectares of inland water has a vast potential for aquaculture. Inland fisheries provides about 40 percent of the total fish production in the country.
(6) Water is also used for navigation and recreational activities like swimming, boating and yatching.
Water Problem A rapid rise in population and expansion in industry and agriculture have increased the demand for water manifold. The average per capita consumption of water in modern society is 350 to 700 liters per day. The demand for usable water.is increasing rapidly. It is becoming difficult to cope with the rising demand for water. Certain factors also confront with the limited resources of usable water and add to the problem. The most important of these are given below.
(1) Deforestation in the catchment areas in the recent past has greatly reduced the absorption of rain water. This has led to soil erosion and wastage of water by way of floods.
(2) Misuse and abuse of fresh water in many residential houses and industries. The disposal of waste or used water is still another problem.
(3) Large scale burning of fossil fuels make the rain water acidic and make the same unfit for use.
(4) Water seeping through soil dissolves a large number of salts and becomes hard. Hardness of water shortens the life of utensils, water heaters, boilers and turbines. Water containing salts more than 3.5 gm per liter is not fit for irrigation.
Conservation of Water : Though water renews itself through hydrological cycles, still an increasing demand for water needs its conservation. Following measures can be adopted for this purpose:
(1) Treatment of used water before passing it into irrigational channels or rivers.
(2) Prevention of wastage of water in irrigation through brick lining of channels and subsurface and sprinkler techniques.
(3) Prevention of water wastage in industries and homes.
(4) Prevention of water pollution by not all allowing raw swage and industrial effluents to pass into water bodies.
(5) Building of dams up streams to store flood water for use during dry periods.
(6) Afforestation and reforestation of hill slopes and catchment areas to hold water and prevent its loss through floods.
(7) Building of tanks and ponds to retain rain water for later use in areas, where perennial sources of water are not available.
Ocean or Marine Resources
The ocean resources are of two types, biotic and abiotic. The abiotic type of ocean resources are used for the following purposes:
(1) Common salt is prepared from sea water by concentration in salt pans in coastal areas.
(2) Sea water and Ocean bed are rich in many minerals. Sodium Chlorine, bromine and magnesium are extracted from the sea. A number of nearly pure mineral concentrates in the form of nodules occur in sea bed.
These mineral nodules are a rich source of manganese, copper, nickel and cobalt. They occur in Pacific Ocean between Hawaii and Mexico as well as along our coast.
(3) Ocean tides are used to generate electricity.
(4) Oceans provide extensive surface for navigation.
(5) Oceans serve heat banks for coastal regions by absorbing and heat.