Facing severe drought as it enters its hottest season, Thailand has launched groundwater extraction operations in its most arid regions to tap sources deep beneath the soil, as it looks at ways to harness future ­supplies.

The groundwater department has sent geologists and more than 80 teams to areas not served by irrigation networks and regions typically hit by shortages as dam water levels are depleted.

In northeast Yasothon province, solar-powered water pumps and tanks have been deployed in one of 25 groundwater stations, among some 937 underground wells in the region.

"The water source on the surface, when it dries up, the only source left is what is underneath us," Natural Resources and Environment Minister Varawut Silpa-Archa said during a visit.

"The amount of groundwater underneath Thailand has been tremendous," he said, estimating 10 percent to 15 percent of Thailand's more than 700 million liters of rainwater was beneath the ground.

Groundwater abstraction has been controversial in some countries, with concern about an over-reliance on underground sources instead of protecting and better managing water resources on the surface.