Do all rivers run downhill?

The water could also gather up momentum by running down a mountainside, and then run over flat land for a while on that momentum and the pressure of the other water.

And sometimes there is a dropping off effect. That’s called a waterfall, if I’m not mistaken.

If there is a waterfall, does that mean that all the land in the river bed below the waterfall is lower than all the land in the river bed above it?

It is possible for water to build up enough momentum to briefly flow uphill, under certain circumstances.
The overall trend, though, is downhill.

The natural course of rivers is downhill, but if there is pressure applied, such as a narrowing of the river banks, it could force the water to flow upwards for a while. In California, the viaduct is designed to force water up and over the mountains by sending it through increasingly narrower pipes. The pressure does most of the work.

Any “uphill flow” is transient and due to a local upset condition only. Water doesn’t flow uphill. Take that to the bank.

I often agree with @YARNLADY‘s take on relationship issues, but on this topic she is misinformed. The California viaduct system relies on gravity for the downhill flow of water… and pumping stations as required to lift it.

The Mississippi (like most other rivers) doesn’t “cut a deeper channel” as it flows. It’s the surface of the water… the banks and the entire bed… that continue to drop in elevation over the entire course. The general elevation along the Minnesota – Wisconsin border is around 650 feet above sea level (LaCrosse, WI is 669’, per its Wikipedia entry. It’s all downhill from there to the Gulf of Mexico. High spots on the river, such as Vicksburg, MS, are simply “routed around”.

Water won’t flow uphill for longer than it takes to re-establish an equilibrium and find a new way “down”.

All rivers flow downhill overall.

Why isn’t there a deepening canyon? In some cases there is, but rivers are just water flowing downhill on the surface of the land. Rivers generally go the way they go in the first place because that’s the way the land is already sloped, even if it’s so gradual that you wouldn’t think the land wasn’t completely flat. Land is almost never completely flat. Water goes whichever way is down, and where that way is clear enough and there is enough water built up, a stream or river is the result.

Rivers carve out a bit when they are fast enough, but they also carry soil and deposit it, leaving buildups of soil, which can change which way “down” is, resulting in wandering rivers that sometimes change course, leave oxbow lakes, etc.

There are some spots on some rivers where the water goes up very briefly due to momentum having been built up horizontally and then having the lowest way forward be shallower than before, but that will erode away, and is hardly worth mentioning.

Florida’s St. Johns River flows north unlike most rivers.

@marinelife Ah – but does that necessarily mean uphill?

@marinelife @janbb No, any compass direction can be downhill.

Since water is heavier than air, it seems that unless propelled by a greater force, gravity dictates that water will flow downhill.

The world’s longest river flows generally north, and downhill.

@CyanoticWasp , Are you saying that along the course of the Mississippi there is a general drop in elevation, a kind of tilt toward sea level?

@LostInParadise not exactly (on the Mississippi, at least), because there are dams on it, but wherever it is free-flowing (including between the dams) then yes, the surface of the river actually has a slope.

@Brian1946 I thought that the Amazon was the longest river.

@Nullo

I’ve read that too.

According to the Wiki section on the Nile, it’s ”...generally regarded as the longest river in the world.”.

However, in the Wiki ‘List of rivers by length’ section, it shows:

“River….....Length (miles)

Nile…....... 4,132
................(4,258)

Amazon…3,976
...............(4,345)”

I don’t remember what the differences are in the parameters that they use to determine the different lengths of each river.

@CyanoticWasp You wrote: ”... along the course of the Mississippi there is a general drop in elevation, a kind of tilt toward sea level?”
Along every river, “there is a general drop in elevation”.

A tidal river can reverse the flow.

There is a river in Virginia called the New River(Kanawha_River) which flows north against the general lie of the land. I think this is because, despite its name, it is a very old river which existed before the landscape tilted upwards following glaciation. The river itself does not flow uphill as this is impossible but has carved a channel through the hills.

Yes, @Zaku, I could have been more precise even more precise than I normally attempt to be by saying that in any body of water where there is a ‘flow’, the surface of the water has a change in elevation, and that elevation change is what leads to the flow. No change in elevation = no flow: a puddle, pond or lake. Change in elevation = a flowing rill, brook, stream, or river.

PS: I didn’t write exactly what you attributed to me; the question was someone else’s. Just to be precise.

@yarnlady describes a siphon which carries water up over a mountain and down the other side.

The end must be lower than the beginning, and it has to be an enclosed tube.

http://www.shammysolutions.com/members/1618064/uploaded/Syphon_Siphon_Hose_Instructions.jpg

@CyanoticWasp Oh I see, I was quoting part of your quote of someone else.