On Sunday 15 August India is expected to join China as the only other nation on Earth with a billion people.

But, on present projections, India looks set to overtake China by 2045.

A report by the Worldwatch Institute, based in Washington DC, says the birth of the billionth Indian "is not a cause for celebration".

It says half of India's adults are illiterate, more than half of its children are undernourished, and a third of its people live below the poverty line.

Barely keeping pace

In the last 50 years India has tripled its grain harvest, with new high-yielding crops and a tripling of the irrigated area.

Calcutta's pavements get more crowded by the day

Even so, the report says, food production has barely kept up with population.

Now the rise in grainland productivity is slowing, as it is in many other countries. And the amount of land available to each Indian is shrinking.

In 1960 there was an average of 0.21 hectares of grainland for every citizen.

That has fallen to 0.1 ha today, and by 2050 is likely to have fallen further, to 0.07 ha.

Food production is also threatened by falling water tables.

The International Water Management Institute estimates that India is using its underground water reserves twice as fast as they are being replaced.

Unable to respond

That is serious in a country where irrigated land produces 55% of the grain harvest, and where most irrigation water comes from underground.

The Worldwatch Institute says the Indian Government, "overwhelmed by sheer numbers, is suffering from democratic fatigue", and is unable to respond properly to new crises.

India spends 3.5 times more on the military than on health

And it believes that means the worsening environmental problems are likely to have a grim outcome.

"If this decrease in water supplies causes food production to drop, death rates are likely to increase."

In some ways, the report says, India is now paying the price for developing nuclear weapons.

"As a result, it now has a nuclear arsenal capable of protecting the largest concentration of impoverished citizens on Earth."

Different priorities

Comparing India's use of 2.5% of its GNP for military expenditure with the 0.7% it spends on health, the report's verdict is stark.

"Unless India can quickly reorder priorities, it risks falling into a demographic dark hole, one where population will begin to slow because death rates are rising.