earth science 6.2
TRANSCRIPT
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6.2 The Work of Streams
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Bed Load
• Sediment that is carried by a stream along the bottom of its channel
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capacity
• The total amount of sediment a stream is able to transport
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alluvium
• Sorted material deposited by a stream
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Delta
• An accumulation of sediment formed where a stream enters a lake or an ocean
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Natural Levee
• An elevated landform that parallels a stream and acts to confine its waters, expect during floodstage
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floodplain
• The flat, low-lying portion of a stream valley subject to periodic flooding
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flood
• Occurs when the discharge of a stream becomes so great that it exceeds the carrying capacity of its channel and overflows its banks
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Drainage basin
• The land area that contributes water to a stream
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Divide
• An imaginary line that separates the drainage of two streams; often found along a ridge
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Key Concept
• Streams generally erode their channels lifting loose particles by abrasion, grinding, and by dissolving soluble materials.
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Key Concept
• Deposition occurs as streamflow drops below the critical settling velocity of a certain particle size. The sediment in that category begins to settle out.
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Key Concept
• A narrow V-shaped valley shows that the stream’s primary work has been down
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Key Concept
• Most floods are caused by rapid spring snow melt or storms that bring heavy rains over a large region.
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Key Concept
• Measures to control flooding include artificial levees, flood control dams, and placing limits on floodplain development.
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Key Concept
• A drainage basin is the land area that contributes water to a stream