Population and Water

In one line

The quantity of water India receives does not change, so per capita availability falls as population rises, and the gap has been met by pumping groundwater faster than it recharges.

In the wording a student can write in an exam: per capita water availability falls as population rises against an essentially fixed annual precipitation. The National Water Policy 2012 records that India has more than 18 per cent of the world's population but only 4 per cent of the world's renewable water resources and 2.4 per cent of the world's land area. The shortfall has been met principally by groundwater, which is now over-extracted across large parts of the north-west and the peninsula, and which is the least regulated water resource in Indian law.

The two problems

Quantity. Total renewable water is essentially fixed by precipitation, and it is unevenly distributed in time, falling largely in a few monsoon months, and in space, with very different availability by basin. Per capita availability therefore falls arithmetically as population rises, and the classification of a country as water stressed or water scarce is made by reference to per capita availability.

Quality. Contamination reduces the usable quantity, so a pollution problem is also a scarcity problem. The Central Pollution Control Board's list of polluted river stretches, and the fluoride, arsenic, nitrate and salinity problems in groundwater, all reduce what is available for use.

A candidate should keep them apart, because the legal instruments differ: quantity is allocation and is a State subject, and quality is regulated by the Water Act 1974.

Groundwater

The most important part of this chapter, and the part most answers omit.

It is the source that met the gap. Surface irrigation reached a limit; the tubewell did not. The expansion of groundwater irrigation from the 1970s is what allowed the food production of the previous chapter, and it is why the water table has fallen.

It is legally the least protected resource in India. Historically, groundwater has been treated as an incident of ownership of the land above it, so that a landowner might extract without limit, and there is no general Indian statute regulating extraction.

And free power is the driver. The marginal cost of pumping is close to zero where electricity for agriculture is free or heavily subsidised. No regulation of extraction can operate against that incentive, which is why the recommendation in the chapter on food is to price the power.

The Central Ground Water Board's assessment, which classifies units as safe, semi-critical, critical or over-exploited, is the source to cite.

The National Water Policy 2012's answer. Its paragraph 2.2 proposes that water, and particularly groundwater, be managed as a community resource held by the State under the public trust doctrine. That is the doctrine of module I applied to the resource under the greatest pressure, and it would require legislation to operate.