Water ResourceUPSC Past papers
India accounts for about 2.45 per cent of world’s surface area, 4 per cent of the world’s water resources and about 16 per cent of world’s population. The total water available from precipitation in the country in a year is about 4,000 cubic km. The availability from surface water and replenishable groundwater is 1,869 cubic km. Out of this only 60 per cent can be put to beneficial uses. Thus, the total utilisable water resource in the country is only 1,122 cubic km.
RIVER SYSTEM IN INDIA
The Indus River Systems:
The Ganga River System
The Brahmaputra Rivers System:
• Brahmaputra rises in Tibet, east of Mansarovar Lake very close to the sources of the Indus and the Sutlej.
• In Tibet, it is known by the name, Tsang Po.
• It is slightly longer than the Indus, and most of its course lies in Tibet.
• It flows eastwards parallel to the Himalayas to its south.
• When it reaches mountain peak of Namcha Barwa (7757 m), it takes a ‘U’ twin and makes a 5500 m deep gorge.
• Then it enters India in Arunachal Pradesh through a gorge. Here it is called the Dihang and it is joined by the Dibang, the Lohit, the Kenula and numerous other tributaries to form the Brahmaputra in Assam.
• In Tibet Tsang Po river carries a smaller volume of water and less silt as it is a comparatively dry and hard rocked area.
• In India it passes through a region, which receives a huge amount of rainfall. The result is that the river carries a large volume of water and considerable amount of silt.
• The Brahmaputra has a braided channel in its entire length in Assam, with numerous riverine islands.
• Every year during the rainy season, Brahmaputra River floods its banks and causes widespread devastation in Assam and Bangladesh.
• The river also shifts its channels during rainy season every year.
Peninsular River system
The drainage systems of the Peninsular and extra Peninsular regions differ from each other. The main differences in their drainage systems are given below:
DATA ON DIFFERENT WATER RESOURCES OF INDIA
Surface Water Resource
• The main source of surface water is precipitation.
• About 20 percent part of the precipitation evaporates and mixes with the environment.
• The large part of surface water is found in rivers, riverlets, ponds and lakes. Remaining water flows into the seas, oceans. Water found on the surface is called surface water.
• About two-third of the total surface water flows into three major rivers of the country – Indus, Ganges and Brahmaputras. The water storage capacity of reservoirs constructed in India so far is about 17,400 billion cubic metres.
• The storage capacity of usable water in the Ganges basin is the maximum, but in spite of maximum annual flow, the storage capacity of usable water is the least in Brahmaputras basin.
• The storage capacity in Godavari, Krishna, Mahanadi and Indus is sufficient.
• If storage capacity of usable water is seen in terms of ratio, then of Tapi river basin is 97 percent.
Ground Water Resources
• The total Annual Replenishable ground water resources of the Country have been estimated as 431 billion cubic meter (BCM).
• Keeping 35 BCM for natural discharge, the net annual ground water availability for the entire Country is 396 BCM.
• The Annual ground water draft is 243 BCM out of which 221 BCM is for irrigation use and 22 BCM is for domestic & industrial use.
• The groundwater utilisation is very high in the states of Punjab, Haryana, Rajasthan, and Tamil Nadu.
• However, there are States like Chhattisgarh, Odisha, Kerala, etc., which utilise only a small proportion of their groundwater potentials. States like Gujarat, Uttar Pradesh, Bihar, Tripura and Maharashtra are utilising their ground water resources at a moderate rate.
• If the present trend continues, the demands for water would need the supplies. And such situation, will be detrimental to development, and can cause social upheaval and disruptions.
Lagoons and Backwaters
• India has a vast coastline and the coast is very indented in some states.
• Due to this, a number of lagoons and lakes have formed.
• The States like Kerala, Odisha and West Bengal have vast surface water resources in these lagoons and lakes.
• Although, water is generally brackish in these water-bodies, it is used for fishing and irrigating certain varieties of paddy crops, coconut, etc.
Inland Water Resources
• Inland water resources include streams (rivers), canals, lakes, ponds and wet lands.
• These resources’ offer several services to man which include:
1. Domestic water supply:
• Inland water resources cater to the domestic needs of man for drinking, cooking, bathing, cleaning, watering plants, and crops.
• The water should be pure, free from bacteria and other contaminants (salts, sediments, etc.), taste, smell, and colour.
2. Industrial water supply:
• Industrial plants require water in more quantities than for domestic purposes. Water is needed in-industries for producing steam, for condensing steam, for solution chemical, for humidifiers and refrigerators, for cooling hot Metals, for washing coke; for the manufacture of acids and alkalies in chemical industries, and for washing and dying of hides, etc.
• Water often gets contaminated when it comes from mining areas.
• Rivers, lakes and ponds are sources of inland fishery.
• The Ganga, Sutlej, Mahanadi, etc. in India and many other rivers provide fish for local consumption.
4. Irrigation of Crops:
• In India, various means of irrigation-Canals, wells and tube wells, tanks, are extensively used.
• Selection of crops is largely determined by the availability of water for irrigation.
• Navigation in rivers, canals and lakes is determined by a number of factors including : (i) the direction of river flow, (ii) geographical location of water bodies, (iii) extent of the water body, (iv) amount of water in rivers or lakes, (v) depth and width of water, (vi) meandering of rivers, (vii) swift flow of the stream, (viii) rocks, sand bars etc. in the river channels, (ix) rapids and waterfalls on the rivers, (x) weather conditions and floods, (xi) shifting of river channels, (xii) landing places.
6. Generation of Steam Power and Hydro-electricity:
• Steam power is generated from water to drive machines of plants and locomotives. This steam power is used to generate thermal electricity for plants.
• Hydro-electricity is the cheapest and the cleanest of all the sources of power.
• Besides, it is a renewable and inexhaustible resource.
• A major advantage of hydro-electricity is its utility in decentralization of industries, while the use of coal favours the centralization of industries which creates ninny adverse environmental effects.
7. Availability of minerals:
• Some lakes provide minerals such as salts, potassium etc.
• The Sambhar Lake, the Pachpadra Lake and the Lunkaransar in Rajasthan are sources of salt production in India.
Irrigation in India
• Indian agriculture depends on the monsoon for its water requirement. Even if the monsoon is normal all the places need not get sufficient rainfall, some place may get high rainfall, or some places get very low rainfall as in Rajasthan, Punjab, Haryana, etc.
• The early or delayed withdrawal of monsoon affects the cropping pattern. In the dry period after monsoon, crops cannot be raised without irrigation.
• So irrigation becomes indispensable in India as many people directly or indirectly still depends on agriculture for their subsistence.
• The sources of irrigation can be divided into four categories viz. Canals, Wells, Tanks and other Channels.
• Wells: Wells and tube wells account about 55.9% of the total irrigation, derives water from underground sources, so it is a widely distributed source of irrigation. The major states where well irrigation is utilised are Punjab, UP, Rajasthan, Gujarat, Maharastra, MP and TN.
• Canals: Canals account 31.7% of the total irrigation, it uses surface water from rivers and becomes a principal source of irrigation in India. UP has a good network of canals followed by Punjab, Haryana and Andra Pradesh.
• Tanks: Tanks account 5.9% of the total irrigation, mainly found in peninsular India, most of them are small in size and due to high evaporation, it supplies water only for one crop in year. TN, Karnataka, AP and Orissa tops in tank irrigation.
• Other sources: The other sources of irrigation include as small dams like ahars and pynes in Bihar, spring channels of TN, water holes in flood plains, etc account for 6.4 of the total irrigation.
Distribution of Irrigated Areas
a) The percentage of irrigated land varies from state to state. It varies from state to state with lowest being in Mizoram (6.4 per cent) and highest in Punjab (92.9 per cent).
b) Punjab is at the top in proportion of irrigated area followed by Haryana, U.P., Bihar, Jharkhand, Jammu and Kashmir. Manipur in the north east region irrigate more than 40 per cent of their net cropped area.
• For the better utilization of the total potential the irrigation schemes have been divided into-
(1) Major Projects: Cultivable command area of more than 10,000 hectare, (including canal irrigation).
(2) Medium Project: Cultivable command area between 2000 and 10000 hectare.
(3) Minor Projects: Cultivable command area less than 2000 hectare, include mainly well-irrigation.
(4) Micro Projects: Drip irrigation and the use of sprinklers.
Major Dams of India