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20 Cards in this Set
- Front
- Back
Hydrological cycle
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97% of earth's water is stored in ocean, evaorated then precipated on land - some soaks in (infiltration) some flows over land as streams (runoff), some evaorpates back into the atmosphere and is transpired by plants, some stored in glaciers, but most return to ocean by streams
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streamflow
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stream erodes, transports according to its velocity and channel shape
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gradient
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slope of stream chanel over its length; cross-sectional shape determines how much of the channel contacts water, slowing it down, rougher more friction
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discharge
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volume of water flowing thorugh the stream's cross section per second; if discharge increases, stream usually gets wider, deeper and faster downstream
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erosion
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by abrasion using partilces in transport as cutting tools to scour channel walls and in circular eddies to cut potholes into the channel floor
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transport
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4 types of sidements
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dissolved
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ions in solution from cheical weathering and ground water
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suspended
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sediment that remains above the bed
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bed load
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particles sliding and rolling along the channel floor
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saltation
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jumping and skipping of particles that alternate between bed and suspended loads
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deposition
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occurs when stream can no logner carry its load and particles fall to the bed; can form a channel deposit of sand and gravel bars or floodplain deposit of mud beyond the channel
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stream valleys
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a stream cuts vertically but its banks cave in by mass wasting to develop narrow V-shaped valleys with waterfalls and rapids in rough channels
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wide valleys
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form on gentle gradients and cut sideways forming floodplains as the stream shifts back and forth across the valley leaving a thick fill of sediments
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meanders
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bends on floodplains where a stream erodes the outsides of bends at cut banks deposits on the insides at point bars
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drainage patterns
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determined by the network of tributaries ffeeding the stream; pattern of a basin depends on rock types and structures
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dendritic
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uniform bedrock where channels follow local slopes
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radial
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fro volcano or rock dome
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rectangular
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streams flows over joints or a fault system with right angle bends
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artificial levees
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built along stream banks to increase the volume that stream can hold
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flood control dams
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built to store water than let it out slowly, flood valleys, displace wildlife, drown forests
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