Water Resources of India

India accounts for about 2.45 per cent of the world’s surface area, 4 per cent of the world’s water resources, and more than 17 per cent of the 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.

Surface Water Resources

There are four major sources of surface water: 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. However, due to topographical, hydrological, and other constraints, only about 690 cubic km (32 per cent) of the available surface water can be utilised.

Water flow in a river depends on the size of its catchment area or river basin and the rainfall within that catchment area. Precipitation in India has very high spatial variation and is mainly concentrated in the monsoon season. Some rivers like the Ganga, the Brahmaputra, and the Indus have huge catchment areas. Given that precipitation is relatively high in the catchment areas of the Ganga, the Brahmaputra, and the Barak rivers, these rivers — although they 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.

Groundwater Resources

The total replenishable groundwater resources in the country are about 432 cubic km. The level of groundwater utilisation is relatively high in the river basins lying in the 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, Odisha, and Kerala which utilise only a small proportion of their groundwater potentials. States like Gujarat, Uttar Pradesh, Bihar, Tripura, and Maharashtra are utilising their groundwater resources at a moderate rate. If the present trend continues, the demands for water would need the supplies, and such a 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. 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.

Water Demand and Utilisation

India has traditionally been an agrarian economy, and about two-thirds 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. Multipurpose river valley projects like the Bhakra-Nangal, Hirakud, Damodar Valley, Nagarjuna Sagar, and Indira Gandhi Canal Project have been taken up.

India’s water demand at present is dominated by irrigational needs. Agriculture accounts for most of the surface and groundwater utilisation — it accounts for 89 per cent of the surface water and 92 per cent of the groundwater utilisation. While the share of the industrial sector is limited to 2 per cent of the surface water utilisation and 5 per cent of the groundwater, the share of the domestic sector is higher (9 per cent) in surface water utilisation as compared to groundwater. The share of the agricultural sector in total water utilisation is much higher than other sectors. However, in future, with development, the shares of the industrial and domestic sectors in the country are likely to increase.

Demand of Water for Irrigation …