Test Review 3

Test Review 3 - -Chapter 15-Streams Streams are major...

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Unformatted text preview: --------------------------------------Chapter 15----------------------------------------------------------------------------------------------Streams- Streams are major component of the hydrologic cycle powered by the sun and gravity. Transports sediment. Running water is the most effective sculptor of the landscape. channeled flow of water of any size (river, brook, creek are loosely defined by size)Channel: conduit for carrying waterFloodplain: flat low-lying area surrounding the channel that is normally dry but may become submerged during high stream flows.Stream forming: 1.Sheetwash: overlapping films or sheets of water that move downslope (think of water flowing down a driveway). Faster-moving sheetwash scours a channel. 2.Channel lengthens upslope by eroding at start of channel (headwarderosion); secondary streams (tributaries) join. the main stream to form a drainage basinDendritic Drainage basin- Flat-lying strata of uniform lithology, ex tree root Radial Drainage basin- Isolated high, volcanoRectangular drainage basin- 2 sets of fractures, ex waveTrellis drainage basin - Valley & Ridge, resistant ridge, ex squaresDrainage divide: ridge that separates one drainage basin from anotherContinental divide: drainage divide that separates streams that drain into the Atlantic Ocean and the Pacific OceanLaminar flow: channelized flow paths are all parallel to one anotherTurbulent flow: irregular flow paths, produced in irregular channels or at high velocitiesDissolved load: high in humid climates (higher chemical weatheringSuspended load: finer-grained material that does not generally touch the bottomBed load: coarser-grained material that slides or saltates(bounces) along the bottomStream erosion- Energy derived from gravity, Erosion maximized during floods: large water volume, high velocity, abundant sediment. Types:1. Scouring: running water picks up sediment and moves it. 2.Breaking & lifting: force of moving water can break chunks of rock and lift them from the bottom of channel. 3.Abrasion: sediment in suspended load “sandblasts” other rocks. Potholesare bowl-shaped depressions produced by gravel swirled by turbulent flow. 4.Dissolution: minerals dissolve in waterDischarge = Volume of water passing by a given point in a given period of time: Q=AV, where Q=discharge, A=cross-sectional area, & V=average velocity. Narrower & deeper=faster. velocity is highest at Center & top. Discharge Increases downstream. Cross-section geometry: V-trapezoid-shaped. Channel depth/width increases with increasing discharge.Headwater flow– Gradient is steep, discharge is low, sediment is coarse, channels are straight and rockyToward the mouth water flow– gradient flattens, discharge is high, sediment is fine, channels are highly curved on broad floodplainsCross section evolution- 1. Mostly hard rock: stream erosion dominates; forms slot canyon with subvertical walls in u shape. 2....
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Test Review 3 - -Chapter 15-Streams Streams are major...

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