The Water Cycle

1. The Water Cycle Cait Cohen and Chelsea Carleton

2. How Is Water Cycled in the Biosphere? • Hydrologic cycle/water cycle • Collects, purifies, distributes earth’s supply of water • Powered by the sun and gravity • Main processes • Evaporation • Transpiration • Condensation • Precipitation • Infiltration • Percolation • Runoff

3. Pathway of Movement • Evaporation • Converts water into water vapor • Ocean=main reservoir • Provides 85% of water vapor in atmosphere • Acts as a natural distillation process • Transpiration • Precipitated water taken up by plant roots • Transported to leaves • Evaporated into atmosphere

4. Pathways • Condensation • Water vapor converts to droplets of liquid water • Occurs in atmosphere • Water vapor condenses to form cloud droplets • Precipitation (rain, sleet, hail and snow) • Most becomes surface runoff into streams and lakes • Some soaks into soil, becoming groundwater

5. Pathways • Groundwater=water beneath the earth’s surface lies between rock and soil • Water Table=where the rock and soil begin to be filled or "saturated" with water, marks the very top of the ground water layer • Infiltration • Movement of water into soil • Becomes soil moisture/groundwater • Percolation • Flow of water through soil and permeable rockformations • Goes into aquifers (groundwater storage areas)

6. Pathways • Runoff • Down slope surface movement back to sea • Resume the cycle

7. How Humans Affect Water Cycle • Clearing vegetation • Increases runoff • Reduce infiltration • Increased flooding • Accelerates soil erosion and land slides • Withdrawing large amounts of fresh water • Changing water quality (adding nutrients/pollutants) • Changing processes from purifying water naturally