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

Rain, mainly, flooding off land into small streams which come together to make rivers. There are also rivers from lakes that flow to the sea, with the lakes getting water from surrounding land and rivers going into them.