The Water Cycle

The Water Cycle: Nature’s Recycling System The Sun’s energy warms the water, water becomes water vapor and enters the atmosphere where it forms clouds. The clouds, carried by winds, release condensed water back to the earth’s surface as precipitation, which accumulates on the surface and as snowpack in the mountains. Small amounts of water held by plants, animals, automobiles and buildings are evaporated back into the atmosphere. Most of the water that returns to the earth’s surface as precipitation will infiltrate the soil, percolating into underground aquifers, or running off the surface into bodies of water. Smaller amounts are drawn up by plants, transpired through leaves, and evaporate back into the atmosphere. We cannot control the hydrologic cycle. And the water supply is fixed. So water must be conserved and properly managed. When it rains, each drop of water hits the earth like a small bomb, loosening particles of soil which flow into waterways as sediment. Riparian buffers, living barriers of tree and brush, can prevent sediment and pollutants from entering waterways. Contour strip cropping, ribbons of vegetation between row crops, prevents water erosion from taking topsoil. Crop residue left on fields also helps prevent erosion. It lessens the impact of falling rain and holds topsoil on the land. Cities and built up areas, where the land is largely covered by pavement, prevent water from soaking into the soil. In these areas, water runs off in high velocity through storm drains and sewers, carrying pollutants into the water system. As the earth’s population grows, the demand for water will grow with it. Sound management of water will be key to maintaining a safe, abundant water supply. UDSA NRCS: Helping People Help the Land