INSIGHT UPSC QUIZ

ANS. (B) 
Erosive power of a stream is proportional to the square of the velocity. Thus, when discharge increases, the depth increases and the velocity increases, resulting in dramatic increase of erosive power. As the volume flowing in a stream increases, the stream’s erosive power also increases. At a bend in a stream the water’s momentum carries the mass of the water against the outer bank. The greater depth on the outer side of the bend also leads to higher velocity at the outer bank. The greater velocity combined with the greater inertial force on the outer bank erodes a deeper channel. The result of all these actions is a meander.