Question

do you think without the support of glaciers himalayas would have not been perennial river​

Answer 1

yes this is true because glaciers are one who melt down slowly to form these large perineal streams such as ganga

the water is again deposited on these glaciers in the form of snow and hence this cycle keeps on going

hope it helps

u ............

Answer 2

Though there are rivers before the formation of himalayas known as antecedent rivers they are rainfed in nature

After the formation of himalayas and due to high altitudinal condition ice caps are formed and resulting the antecedent river making it perennial.

Maybe that's one of the reason to making a note that himalayas are third pole