eli5: Why does there continue to be water in a river, even though it doesn’t rain all the time in the upper parts?

Question

eli5: Why does there continue to be water in a river, even though it doesn’t rain all the time in the upper parts?

In: 29

Answer 1

It can be from a lake and flows to the ocean. Of course, without rain, the lake will start to dry up slowly. So long as it rains sometimes, the water will stay until the lake fills up with silt or sand.

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