Small mountain glaciers play a big role in recharging vital aquifers and in keeping rivers flowing during the winter, according to a new study published in Geophysical Research Letters, a journal of the American Geophysical Union.The study also suggests that the accelerated melting of mountain glaciers in recent decades may explain a phenomenon that has long puzzled scientists — why Arctic and sub-Arctic rivers have increased their water flow during the winter even without a correlative increase in rain or snowfall.