Lecture-13_rivers+river-deposits

Lecture-13_rivers+river-deposits - Lecture 13: Rivers and...

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1 Lecture 13: Rivers and River Deposits Class reading from Boggs, Principles of Sedimentology and Stratigraphy Chapter 8: p.245 - 258. Other words commonly used to describe rivers and their deposits: (1) fluvial (Latin word for "river") (2) alluvial deposits for river deposits (from Latin "to wash against“)
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2 Rivers are classified based on their map pattern (plan form) Single channel: straight, sinuous, meandering Multiple active channels: braided (channels separated by unvegetated, erodible bars) anastomosed ( channels separated by vegetated, stable islands)
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3 Toutle River, WA, gravelly braided river Individual channels within a braided river are very active, changing form via sediment erosion and deposition of loose sediment between the master, vegetated banks. 600 m Red River, TX – sandy braided river
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4 Safid River delta, Iran Yellow River delta, China Anastomosing rivers -> Multiple channels; each with relatively stable banks Cooper Creek, Australia Saskatchewan River, Canada Channel banks are typically stabilized by plants.
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5 Radar image of the Rio Solimoes floodplain (Amazon River basin, 1971). Flow is from left to right. Note the surface topography marking the former positions of the channel on the floodplain. Meandering Channels - sinuous channels exhibiting systematic lateral movement of channel bends through time 550 m Trinity River, TX
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F g = pressure force Helical Circulation Flow and sediment transport in a channel bend c c R u F 2 ρ = Centrifugal force, F c , associated with particle following a curved path Acceleration of the fluid toward the outside bend produces a ‘piling up’ of fluid. This produces a cross stream slope, giving rise to a force toward the inner bank. Setup of helical circulation . Pressure force associated with surface slope is constant, centrifugal force varies with depth. Traditional Explanation for Cross-
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Lecture-13_rivers+river-deposits - Lecture 13: Rivers and...

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