I’m usually the one who poses that logical question :-)
In the long run, rivers can only be fed by seasonal snowfall and meltoff, just like in our Rocky Mountain west. The presence or absence of a semi-permanent glacier is irrelevant except that the current alleged melting is a temporary river water bonus. If the glaciers were static or growing, there would be less water today and the current growing season at certain altitudes would be shorter or non-existent. (This being the tropics to the south, the seasons are monsoonal rather than temperature-driven below the temperate altitude zone.)
A common error - but minor in the scheme of the great CAHW hype.
Much of India is near the equator, but its mountain border with Tibet to the north is in the northern hemisphere. Glaciers have been retreating worldwide since about 1800. Well before any man-made CO2 increase had any effect. Cornelius Vanderbilt, for example, made his first money in transportation moving people across the frozen Hudson River south of NYC by being one of the few willing to chip ice off of his frozen boats in Staten Island and Long Island each winter.