Eating
icicles or
snow instead of drinking
water is usually not encouraged in
survival texts. It might quench your thirst, but the
energy and heat lost melting the ice will eventually exhaust you. And here you are in an environment that's probably pretty exhausting already.
If you can afford to trade
food and rest for water, and have no alternative, then eating ice might be ok. But it is almost always better to melt the ice somehow (
fire, stove,
sun, NOT by holding it in your hand) and then drink the resulting water.