Kabul and its surrounding region are perilously short of water and may not be able to supply a fast-growing, more affluent population, a joint US and Afghan government scientific report has warned.

Rapid population growth and expected temperature rises due to climate change mean the area – which just manages to support 6 million people today – will need six times more water by 2050, the US Geological Survey report says.

More than half the shallow wells people now rely on will dry up if temperatures continue to increase as expected, it warns.

Thousands of wells have been sunk in Kabul in the last decade as the city's population has more than doubled. But the water table has dropped several metres, and many settlements already experience water shortages.

In addition, most of the shared water points and wells are contaminated, leading to illness. According to current United Nations estimates, Kabul's population could reach 9 million by 2050.

The two-year Kabul basin water survey warned that barely exploited deep underground water sources may not be sufficient to provide for all human and farming needs.

Mountain snow, which feeds rivers throughout the basin, is melting earlier each year, leaving less water for use later on, particularly during summer, when it is needed most.

Kabul residents use around 40 litres a day each, far less than most other Asian cities, but demand is expected to soar as communities develop and numbers grow.

The study backs up Oxfam research which shows that competition for water in both rural and urban Afghan communities is increasing, leading to heightened tensions and violence. According to the aid agency, 43% of local conflicts are now over water.

The Oxfam policy officer, Ashley Jackson, said: "Thirty years of war has left sources of water co-opted, stolen and contaminated.

"Oxfam research has found that water is now a major cause of local conflicts. Disputes over these scarce resources lead to violence and even, in some instances, fuel the greater conflict."

Last year, two men were killed after being found trying to steal water from the river Paghman in Kabul province. Families took sides, the row escalated and fights broke out between people armed with knives.

The conflict was only resolved when elders found a new way to channel the river, which provides 20 villages with water.