Why is the Yarkant River braided in the Pamir mountains? The formation section in the braided river Wikipedia says that very erodible soil causes braided rivers. Intuitively, a rising mountain range like the Pamirs would not be easily erodible. 

The Yarkant changes so abruptly, I'm curious what special geological feature is at these straight/meandering-to-braided junctions.


  The critical factor that determines whether a stream will meander or braid is bank erodibility. A stream with cohesive banks that are resistant to erosion will form narrow, deep, meandering channels, whereas a stream with highly erodible banks will form wide, shallow channels, inhibiting helical flow and resulting in the formation of braided channels.


Braid 1

Here's near the edge of the Pamir range.



Braid 2

Here's another braided section in the Pamirs, far upstream.



A source

There appears to be a glacier at a source of the Yarkant in Central Karakoram Park. If glaciers present/past explain braiding, why is it intermittent?



Minimal braiding in the Rockies

Mountainous braided rivers seem rare/mild elsewhere, like here in the Rockies in Missoula.
Braiding will occur in any river where two conditions are met: 1) a very high sediment load must be available, as is usually the case in a peri-glacial or post-glacial environment, and 2) there is an abrupt change from high energy rivers (steep hydraulic gradient) to low energy deposition with flat space on either side of the river. Go for a hike in any glacial or post-glacial mountains and you will see that rock hardness has little to do with sediment availability - there is always more sediment than the river can mobilize at any one time, even in extreme floods. The classic example is the Canterbury Plains on the east side of South Island New Zealand. Braiding is an inherently unstable and transient river configuration.
Meandering is the river's minimum energy configuration. It is another chaotic process, achieved through helicoidal flow and superelevation on the convex side of a bend. It will occur anywhere the river is laterally unconstrained, and where the rotational kinetic energy, perpendicular to the direction of flow, is a significant fraction of the forward kinetic energy.