Hydrologic Cycle The continuous hydrologic cycle. The hydrologic cycle is the continuous circulation of water from land and sea to the atmosphere and back again : water evaporates from oceans, lakes, and rivers into the atmosphere. This water later precipitates as rain or snow onto the land where it evaporates or runs off into streams and rivers ; or it infiltrates (seeps) into the soil and rock from which some is transpired back into the atmosphere by plants. The remainder becomes ground water, which eventually seeps into streams or lakes from which it evaporates or flows to the oceans. Source: U.S. Geological Survey