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


How does a rivers source constantly have water.

In: 262

It’s kind of misleading that we call a certain place ‘the source’ of a river because that’s not where the water is literally coming from. Rather, the water for a river is typically collected over a very large area where rain collects in many small rivulets until it builds up into a large stream. We just call one place ‘the source’ of the river because that is the point where we can say okay, this is definitely the river. Often this point is actually a spring – water collects on mountainsides and seeps into the ground, following underground channels until it emerges and forms a spring which feeds into a river. Or, it might be another feature like a glacier – snow collects in mountain valleys and slowly melts at one end, forming a glacial lake that then feeds a river.

I guess that only partially answered the question. The real answer then is that the river doesn’t run out of water because is being replenished all the time by rainwater or melting snow.

A river’s source is constantly replenished via rainfall or snowmelt. It may pass through an underground aquafer first, or though smaller rivulets, but precipitation is the ultimate answer.

Water evaporates from the ocean. This forms clouds who drift back over land. Rain from those clouds then replenishes underground water reservoirs, which feed stream sources.

Rain water or melting ice higher up the hill or mountain is constantly trickling through the soil providing more water, eventually in dry spells the amount of water is reduced and the flow of the river can slow dramatically or even stop completely.

Many smaller rivers nearly run dry in California during our dry season. They come back after it rains in the winter