Source:

04-22-2009 17:01

Some runoff water is trapped for periods, for example in lakes. At high altitude, during winter, and in the far north and south, snow collects in ice caps, snow pack and glaciers.

Water also infiltrates the ground and goes into aquifers. This groundwater later flows back to the surface in springs, or more spectacularly in hot springs and geysers. Groundwater is also extracted artificially in wells.

This water storage is important, since clean, fresh water is essential to human and other land-based life. In many parts of the world, it is in short supply.

 

Editor:Yang Jie