Question

why are the himalayan rivers are not drying up during summer ​

Answer 1

As in summer Himalaya has an average temperature of 30 degree the mountains of Himalayas are cold therefore the rivers of Himalayas not get dry

Answer 2

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The Himalayan rivers are perennial rivers as they originate in snow covered Himalayan mountains. During summers, the snow melts and the rivers get continuous supply of water. On the contrary, the peninsular rivers depend mostly on rainfall for its supply of water and thus becomes dry during the summer season