Question

Why do some rivers change their course?

Answer 1

on the faster side of river less sediment is deposit and because the water flowing is faster more erosion takes place and small curve are formed . At the slower side of river more sediment from erosion of the outer curve is deposit . This is the time when river changes it's course

Answer 2

ANSWER:

Rivers change their course over a particular period of time due to the rock that the shores are made up of.

EXPLANATION:    

Due to constant deposition of river sediments on the slower side and the vast amount of erosion that takes place on the faster side. This process keeps on continuing till the curves get sharpened, so that river cuts through the curve and forms another path and thus river changes its course.