When water from rainfall and snowmelt enters and saturates the soil column, some of that water flows to streams, some evaporates and some is absorbed by plant roots. The rest drains downward to recharge underground aquifers, where it can remain for months, years or even millennia. If you dig deep enough, groundwater can be found almost anywhere, even beneath the Sahara Desert. Groundwater is vital to both people and ecosystems because of the ability of aquifers to store water during wet periods for use during dry periods. It supports domestic, municipal, industrial and especially agricultural usage in places where surface waters are not available, and it sustains streams and rivers, via contributions to baseflow, in between precipitation events
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