So? It splits and if the land features were any different between the split and the confluence, it could go separate ways. That was just the first example I found. I'm sure there are others.
The thing is that water always runs the easiest way. If there are two ways that are quite easy to go ... than one has to be exactly as easy as the other one for the water to split
Because of how gravity works on rivers and the fact that two riverbeds being made of the exact same material and having the same inclination is astronomically rare, rivers don't fork downstream without soon rejoining (except in the short term before erosion and grade difference takes its toll).
Originally Posted by NymTevlyn
Let's say you have a river that hits a point that splits off into two low points and decides to take both ways. At first you have a river forking off in two far separate directions and perhaps never rejoining. However the differences in slope and erosion on each branch means that eventually one out-erodes the other and, as water follows gravity, steals all of the others water. The result is usually one river and one dry riverbed.
Your picture is a perfect example of this. If you look close you can see the empty carved areas where it breached through but the flow lost out to another flow direction and dried up.
also you can see this tiny little river-thingy between the two river splits ... this whole thing looks more like a formerly huge river that goes through a dry period
Originally Posted by Nomadic
Periodic flooding can put the drying river into two different streams
Periodic flooding can also put the flooded river into two different streams
The point about not forking downstream is that it's not stable.
A stable river won't fork downstream.
That picture does indeed show a river forking but it is an exact text book example of the exception to this rule and this is because that river is heavily sedimented and is constantly changing its course. In a few years the river will not look like it does now and as has been stated all the little curves around the main flow show how it is drying up, switching into a new path and forming whats called 'OxBow' lakes as the curves get cut off. This isnt a stable river and its called 'braiding' - heres another wiki pic
The thing is that these braids in the path are really all part of one river. You will not find that these braids stay separated and one will go to one coast and another to a different coast. They always are very transitory and always join back up and usually in a very small about of distance. If they dont join back up then one of the two main links to the sea will dry up.
Braiding always happens when there is a lot of sediment as when the river drops it then it switches direction. So you cant have braiding on any steep bit of river or where it might have just dumped off a load of sediment - like just after exiting a lake.
Most of the maps here are of country / continental sized areas where you just wont see this kind of thing.
For reference, here is a smaller scale version of a braided river I photographed in Alaska.