The Water Cycle

W ATER C YCLE ( AKA H YDROLOGIC C YCLE ) Continuous movement of water from the atmosphere to the earth’s surface and back to the atmosphere again.

3 MAIN PROCESSES INVOLVED IN THE WATER CYCLE : Evapotranspiration: the process of evaporation (liquid water changing into water vapor) and transpiration (plants giving off water vapor into the atmosphere).

Condensation: water vapor (gas) changes into liquid water. Precipitation: water falls from clouds to the ground.

G ROUNDWATER The underground water that fills almost all the pores in rock and sediment. Makes up 90% of the earth’s unfrozen freshwater supply.

Aquifer: a body of rock in which large amounts of water can flow and be stored. Aquitard: a body of rock in which water cannot flow or be stored.

R OCK PROPERTIES THAT AFFECT GROUNDWATER Porosity: percentage of open spaces in rock. Determined by : Sorting: well-sorted- equal sized = more porous Poorly sorted-unequal sized = less porous

Permeability: how easily water flows through open spaces. For a rock to be permeable, open spaces must be connected. Think about the school… All the doors open = Permeable All the doors closed = Impermeable

Z ONES OF G ROUNDWATER Zone of Saturation: the layer of ground where all the pores are filled with water. The upper surface of the zone of saturation is called the water table. Zone of Aeration: the area between the water table and the earth’s surface. Capillary fringe: the area just above the water table where water is drawn up into this area by “capillary action”