PARIS — Water shortages and inefficient irrigation threaten the world’s ability to feed a growing population, said David Molden, deputy director-general for research at the International Water Management Institute.

The grain-growing regions of northern China, India and Australia’s Murray Darling Basin, as well as farming areas in the western United States, Mexico and Pakistan, face “really tight” water situations, Molden said.

Agriculture and irrigation methods must change for the world to produce enough food, Molden said. More precise water delivery and boosting crop yields can make irrigation more efficient while water rationing and pricing may prod farmers to reduce consumption, he added.

“Our food security is based on unsustainable water practices,” Molden said in Montpellier, France. “I don’t think people have quite realized that. The next 10 years are going to be tough as we deal with water shortages.”

Food production will have to expand by 70 percent in the next four decades as the global population expands to 9.1 billion and rising incomes boost meat consumption, according to the United Nations’ Food and Agriculture Organization.

Agriculture accounts for 70 percent of water withdrawals from rivers worldwide, and reduced river flows are degrading water quality and damaging wetlands, Molden said. Groundwater reservoirs, which supply half of the irrigation water in India and China, are being depleted, he added.

Egypt, northern China, Pakistan and India’s states of Punjab and Haryana are among water “hot spots” that are using the resource “up to its limit,” according to Molden.

Molden spoke at the Global Conference on Agricultural Research for Development, where he received an award for his work in water research.