Saudi Arabia is maintaining its air offensive in Yemen, and Houthi rebels continue to stage assaults. A humanitarian crisis appears imminent.

But another crisis is raging in Yemen that could pose an existential threat to one of the world’s most troubled nations.

Experts predicted in 2010 that Yemen could be the first country to run out of water. Today, half of Yemen’s population–about 13 million people–struggles to secure sufficient supplies of water.