If rivers flow from land and into the ocean, then where does that water come from?

Question

I’m essentially asking how a river “starts”, since I generally know that rivers mostly ends flowing into the ocean.

If you could, please use the Yangtze river as an example.

In: Physics

Answer 1

Rivers have a source. These typically start in higher elevations and are fed from melting snow/ice and rain. It could be a lake or stream or the like. The tributaries (streams or smaller rivers) combine and create larger rivers. The Yangtze’s source is tributaries in the Tibetan Plateu fed by glaciers melting and snow melts.