eli5 if deserts used to be wet where did all the water go?

Question

and why is there still a little bit in oases

In: 8

Answer 1

Underground, which is why it can still be found in oasises. which are very low-lying areas where the water can reach the surface.

Give it enough time all water that falls on land will eventually either flow into the ocean, settled down into the ground, or evaporated away.