Comment: 08:30 - 09:10 (00:40)
Source: Annenberg/CPB Resources - Earth Revealed - 21. Groundwater
Keywords: "Earth's surface", valley, "saturated zone", groundwater, river, lake, season, rainfall, effluence
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Our transcription: In valleys, the zone of saturation may rise to meet the Earth's surface at river and lake beds.
When the rivers and lakes are full, a continuous supply of new groundwater recharges the zone of saturation, and water flows from the surface into the ground.
However, during the dry summer months when surface water levels are low, groundwater may flow in the opposite direction, providing the rivers and lakes with their only supply of water in the absence of rain.
This phenomenon is called "effluence."
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Geology School Keywords
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