With Niagara falls going as hard as it has for as long as it has, where does all of that water come from?
Edit: My first gold! Thank you kind stranger. Also, thank you for all of the kind and informative responses to such a silly question. Definitely helped a lot!
In: Geology
A waterfall is just a vertical gap in a river. A higher part of the river runs into cliff and the falls off, then starts flowing again. So to simplify your question it might be “why do rivers keep flowing and not dry up?”.
A river flows from a high elevation area to a lower area. The water at the higher level comes from rain from humidity in the atmosphere caused by evaporation over the oceans. In a place with consistent rainfall the river will never dry up as the lakes above it keep getting filled. Places with more rain tend to have larger rivers that move more water.
In some parts of the world there are definite rainy and dry seasons, so some waterfalls will be gushing during one part of the year and a tiny trickle at another part of the year, depending on how much rain has been falling upstream.
Seriously curious…. why do you see a distinction between Niagara Falls and just any other river? Flow rates of Mississippi or amazon river are pretty impressive also. Why does going over a waterfall make it harder to believe that the water flow doesn’t run out? Is it because the waterfall makes the sheer volume of flow more tangible? Is it because other waterfalls in your experience may have been artificial and pump-fed? Dunno, just made me really curious. Cheers
The key is that rain from a huge area all goes over those falls. Check out this image: [https://upload.wikimedia.org/wikipedia/commons/d/d4/Sub-basins_Great_Lakes_Basin.png](https://upload.wikimedia.org/wikipedia/commons/d/d4/Sub-basins_Great_Lakes_Basin.png)
This is the great lakes watershed. That means all of the land where rain will flow into a river that will flow into one of the great lakes. Then, the water in each lake flows into the next lake from west to east. Niagra falls is between Lake Eire (yellow) and Lake Ontario (red). That means *all rain* that falls in the pink, blue, green, and yellow areas accumulates and goes over the falls.
So the waterfall has to get the water from somewhere right? This can be from ice, a river, a lake, etc. Niagara Falls gets its water from a few of the Great Lakes. So now the question is why doesn’t the source run out. Well either the source is infinitely large (impossible) or somehow it gets refilled. The refill is done through the water cycle. That’s right; Evaporation, Condensation, Transportation, and Precipitation. The biggest replenishing action comes through rain. It is true that if the source does not get refilled fast enough, it and/or the waterfall will dry up
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