Some of the world's sources for groundwater could be depleted before the year 2050, new research has found.

Groundwater in parts of India, southern Europe and the United States is at risk of depletion because of human consumption, research presented at the American Geophysical Union fall meeting on Thursday shows.

New modelling found the aquifers in the Upper Ganges area of India, southern Spain and Italy could be depleted between 2040 and 2060.

Aquifers in California's Central Valley, Tulare Basin and southern San Joaquin Valley could be depleted by 2030, while other aquifers in Texas, Oklahoma and New Mexico could reach their limit between the 2050s and 2070s, the new research shows.

"While many aquifers remain productive, economically exploitable groundwater is already unattainable or will become so in the near future, especially in intensively irrigated areas in the drier regions of the world," researcher Inge de Graaf, a hydrologist at the Colorado School of of Mines, said in a news release.

Groundwater is the largest freshwater resource around the world, but as demand is increasing, availability is decreasing.

It's imperative to know the limits of groundwater resources, de Graaf said, because billions of gallons of groundwater are used daily for drinking water and agriculture.

By 2050 as many as 1.8 billion people could live in areas where groundwater is fully or nearly depleted, she said.

"When water tables decline, pumping costs will increase and also it will cost more money to maintain the wells," de Graaf said.

The decline will also reduce discharge into rivers, which could result in rivers running dry, she said.

Forecasting aquifer capacity

The research, conducted with Utrecht University in the Netherlands, used data on aquifer structure, water withdrawals and interactions with surrounding water to simulate groundwater depletion.

The simulation was used to forecast when and where world aquifers could reach their limits, or below the reach of modern pumps.

The research found that heavily irrigated regions in drier climates, including the U.S. High Plains, and the Ganges basin, faced the greatest threat of depletion.

De Graaf explained the modelling used in her research looked at lateral groundwater flow, making it more realistic than past groundwater research.

The new estimates look at groundwater on a regional scales, but scientists still lack complete data about aquifer structure and capacity so it's not exactly known how much groundwater remains in the world's aquifers.

"We don't know how much water there is, how fast we're depleting aquifers, or how long we can use this resource before devastating effects take place, like drying up of wells or rivers," de Graaf said.