NCERT Class 12 Geography of India Chapter 6 Water Resources YouTube Lecture Handouts Part 1

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NCERT Class 12 Geography of India Chapter 6: Water Resources | CBSE | English

Title: Water Resources

  • Approximately, 71 per cent of the earth՚s surface is covered with it but fresh water constitutes only about 3 per cent of the total water. In fact, a very small proportion of fresh water is effectively available for human use. The availability of fresh water varies over space and time. The tensions and disputes on sharing and control of this scare resource are becoming contested issues among communities, regions, and states.
  • Water Dispute – Indus Water Treaty; Super Dam in Tibet
  • Drinkable Water is a real scarcity
    • 2.45 % world՚s surface area
    • 4 % world՚s water resources
    • 16 % world՚s population
  • Total water from rain 4,000 cubic km
  • Surface & replenishable groundwater is 1,869 cubic km
  • 60 % is put to beneficial uses
  • Total utilizable water resource is only 1,122 cubic km
  • Surface and Ground water Resources are main resources
    • Rivers
    • Lakes
    • Ponds
    • Tanks
  • There are four major sources of surface water. These are rivers, lakes, ponds, and tanks. In the country, there are about 10,360 rivers and their tributaries longer than 1.6 km each. The mean annual flow in all the river basins in India is estimated to be 1,869 cubic km. Only about 690 cubic km (32 per cent) of the available surface water can be utilised. Water flow in a river depends on size of its catchment area or river basin and rainfall within its catchment area. India has very high spatial variation, and it is mainly concentrated in Monsoon season.
  • Given that precipitation is relatively high in the catchment areas of the Ganga, the Brahmaputra and the Barak rivers, these rivers, although account for only about one-third of the total area in the country, have 60 per cent of the total surface water resources. Much of the annual water flow in south Indian rivers like the Godavari, the Krishna, and the Kaveri has been harnessed, but it is yet to be done in the Brahmaputra and the Ganga basins
  • The total replenishable groundwater resources in the country are about 432 cubic km. Ganga and the Brahamaputra basins, have about 46 per cent of the total replenishable groundwater resources. The level of groundwater utilisation is relatively high in the river basins lying in north-western region and parts of south India.
  • The groundwater utilisation is very high in the states of Punjab, Haryana, Rajasthan, and Tamil Nadu. However, there are States like Chhattisgarh, Orissa, Kerala, etc. , which utilise only a small proportion of their groundwater potentials. States like Gujarat, Uttar Pradesh, Bihar, Tripura and Maharashtra are utilizing their ground water resources at a moderate rate.
Basinwise Ground Water Potential and Utilisation in India

Basinwise Ground water Potential and Utilisation in India (Cubic Km/Year)

India River Basins
  • India has a vast coastline - lagoons and lakes have formed. The States like Kerala, Orissa 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.
  • India has traditionally been an agrarian economy, and about two-third of its population have been dependent on agriculture. Hence, development of irrigation to increase agricultural production has been assigned a very high priority in the Five-Year Plans, and multipurpose river valleys projects like the Bhakra-Nangal, Hirakud, Damodar Valley, Nagarjuna Sagar, Indira Gandhi Canal Project, etc. have been taken up. In fact, India՚s water demand at present is dominated by irrigational needs
    • Surface Water – 89 % agriculture, 9 % domestic & 2 % industrial use
    • Ground water – 92 % agriculture, 3 % domestic and 5 % industrial use
  • In agriculture, water is mainly used for irrigation. Irrigation is needed because of spatio-temporal variability in rainfall in the country. The large tracts of the country are deficient in rainfall and are drought prone. North-western India and Deccan plateau constitute such areas. Winter and summer seasons are more or less dry in most part of the country. Hence, it is difficult to practice agriculture without assured irrigation during dry seasons. Even in the areas of ample rainfall like West Bengal and Bihar, breaks in monsoon or its failure creates dry spells detrimental for agriculture. Water need of certain crops also makes irrigation necessary.
  • Water requirement of rice, sugarcane, jute, etc. is very high and can be met only through irrigation. Provision of irrigation makes multiple cropping possible. It has also been found that irrigated lands have higher agricultural productivity than unirrigated land. Further, the high yielding varieties of crops need regular moisture supply, which is made possible only by a developed irrigation system. In fact, this is why that green revolution strategy of agriculture development in the country has largely been successful in Punjab, Haryana and western Uttar Pradesh.
  • In Punjab, Haryana and Western Uttar Pradesh more than 85 per cent of their net sown area is under irrigation. Wheat and rice are grown mainly with the help of irrigation in these states. Of the total net irrigated area 76.1 per cent in Punjab and 51.3 per cent in Haryana are irrigated through wells and tube wells. This has led to groundwater depletion – has led to declining water table and increased concentration of fluoride and arsenic in waters.
  • Water quality refers to purity of water, or water without unwanted foreign substances. Water gets polluted by foreign matters such as microorganisms, chemicals, industrial and other wastes. Such matters deteriorate the quality of water and render it unfit for human use. When
  • toxic substances enter lakes, streams, rivers, ocean and other water bodies, they get dissolved or lie suspended in water. This results in pollution of water whereby quality of water deteriorates affecting aquatic systems. Sometimes, these pollutants also seep down and pollute groundwater. The Ganga and the Yamuna are the two highly polluted rivers in the country
  • In plains, river water is used intensively for irrigation, drinking, domestic and industrial purposes. The drains carrying agricultural (fertilisers and insecticides) , domestic (solid and liquid wastes) , and industrial effluents join the rivers. The concentration of pollutants in rivers, especially remains very high during the summer season when flow of water is low.

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