Water is available on earth in two different forms
Surface Water
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- This form is available on earth in form of river, lakes, ponds, canals, etc.
- Of these, rivers comprise the most important source of surface water
- India is blessed with a large number of major, medium and small size rivers
- The mean annual flow in all the river basins in India is estimated to be 1,869 cubic km
- However, due to topographical, hydrological and other constraints, only about 690 cubic km (32 per cent) of the available surface water can be utilised
- As many as, 13 of them are classified as major rivers whose total catchment area is 252.8 million ha
- Of the major rivers, the Ganga-Brahmaputra-Meghna system is the biggest with catchment area of about 110 million ha
- The other major rivers with catchment area more than 10million ha, are those of the Indus, Godavari, Krishna and Mahanadi
- The catchment area of medium rivers is about 25 million ha
- About 40% of utilizable surface water resources are in the Ganga-Brahmaputra-Meghna System
- This form is available on earth in form of river, lakes, ponds, canals, etc.
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Ground Water
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- A part of the rain water percolates in the rocks and soils and is available to us as ground water
- As per the latest assessment, the annual replenishable ground water resource of country has been estimated as433 billion cubic meter(bcm), out of which 399 bcm is considered to be available for development for various uses.
- Of these, the Ganga and the Brahamaputra basins, have about 46% of the total replenishable groundwater resources
- The main items of supply to ground water reservoir are:
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- Precipitation infiltration to the water table
- disposal Natural recharge from streams, lakes and ponds
- Recharge from irrigation, reservoirs and other schemes
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- The items of from ground water reservoir are:
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- Evaporation from capillary fringe in areas of shallow water table, and transpiration by vegetation
- Natural discharge by seepage and spring flow to streams, lakes and ponds
- Groundwater outflow
- Artificial discharge by pumping or flowing well/drains
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- The level of groundwater utilisation is relatively high in the river basins lying in north-western region and parts of south India
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- 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
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- Also, most of the peninsular plateau area is composed of hard rocks and is not much favorable for exploitation of ground water resources
Water Demand and Utilisation
- India has traditionally been an agrarian economy, and about two-third of its population have been dependent on agriculture
- Presently, India’s water demand is dominated by irrigational needs
- Agriculture accounts for most of the surface and ground water utilisation, it accounts for 89% of the surface water and 92% of the groundwater utilisation
- While the share of industrial sector is limited to 2% of the surface water utilisation and 5% of the ground-water, the share of domestic sector is higher (9%) in surface water utilisation as compared to groundwater
