What does this word mean? SINUOSITY

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What does this word mean?SINUOSITY
B Is how straight a river has been or potentially
could be.
A Is the curving nature of a rivers course.
C Is the pattern of pools and riffles on the
river bed.
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MEANDERS Key Features Formation
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Pools and Riffles

• Pools are areas of deep water and greater
  erosion. (Energy build up due to less friction)
• Riffles are areas of shallow water caused by
  deposition of coarse sediment

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Sinuosity

• Is the curving nature of a rivers course.

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Thalweg

• The position of the rivers fastest flowing
  current.
• (Least friction, greater energy, greatest erosion)

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1. Origins of meanders in times of flood and
related to the occurrence of sand bars, pools and
riffles
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2. Usual spacing of pool to pool or riffle to
riffle is regular at 5 times the bed width.
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3. This is thought to be because of secondary
flows within the main flow. E.g. Helicoidal flow
corkscrew movement that erodes and deposits
material.
4. Secondary flows increase the sinuosity of the
meander.
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5. These produce a regular meander wave length of
10 times the bed width.
6. A river is said to be meandering in the
sinuosity index is above 1.5.
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7. Meanders have an asymmetrical cross section
with erosion greater on the outside bend where
discharge and velocity are greatest and friction
is at a minimum.
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8. Material is deposited on the inside of a
meander bend as a point bar.
9. At point bars particles are usually graded in
size (sorted) with the largest particles found on
the upstream side.
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10. As erosion occurs on the outside of the
meander bend, the whole meander migrates
downstream.
11. Material forming the point bar becomes a
contributory factor in floodplain formation.
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13. Temporary straightening of the channel means
the main flow is in mid channel, meaning
deposition now occurs at the river banks and the
old curve is therefore abandoned to leave an
ox-bow lake.
12. As sinuosity increases, during flood events
the flow may cut of the meander bend at the neck,
thus shortening its course.
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