system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 How does a desert oasis work?
gpt
There's water under the ground in most places, that's why wells work. In some places, like deserts, it's very deep underground. But sometimes the land dips downwards, and you naturally get to where that water is, forming an oasis.

The water in the oasis often comes from underground, and the rain that feeds it could be hundreds of miles away. The water spreads out underground until it finally reaches the oasis, and replenishes its supplies.