Eli5- How does the source of a river not run out of water?

Question

How does a rivers source constantly have water.

In: 262

Answer 1

If you want a sad story with the bonus of answering your question look for a video about the death of the aral sea, there a few out there.

Here goes my eli5:
1. Glacier is melting into river.
2. River flow into lake.
3. Sun makes lake evaporate water into air.
4. Water in air turns to snow when hits mountain.
5. Snow falls on glacier.