How does water fill an aquifer?
Aquifers get water from precipitation (rain and snow) that filters through the unsaturated zone. Aquifers can also receive water from surface waters like lakes and rivers. When the aquifer is full, and the water table meets the surface of the ground, water stored in the aquifer can appear at the land surface as a spring or seep. Recharge areas are where aquifers take in water; discharge areas are where groundwater flows to the land surface. Water moves from higher-elevation areas of recharge to lower-elevation areas of discharge through the saturated zone. How does water circulate? Surface water and groundwater are part of the hydrologic cycle, the constant movement of water above, on, and below the earth’s surface (Diagram 2). The cycle has no beginning and no end, but you can understand it best by tracing it from precipitation. Precipitation occurs in several forms, including rain, snow, and hail. Rain, for example, wets the ground surface. As more rain falls, water begins to filter
