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2 eqn
hydraulic radius
mannings formula
hydraulic radius
Efficiency of river channel
measures friction
proportion of water in channel that is in contact with water beds/banks
euqaion of hydraulic radius
cross sectional area/wetter perimeter
mannings formula
water in channels has different energy and efficiency depending on how rough the channel is
friction caused by beds and banks slows velocity of water
roughness = measured with n
equation of mannings formula
velocity = hydraulic radius x gradient /roughness (n)
higher the n is rougher the bed
types of flow
laminar flow
turbulent flow
helocoidal flow
laminar flow
parallel to channel beds
requires smooth and staight river/ channels with low velocity
rare
turbulent flow
irregular patterns
occurs when river has complex channel morphology and high velocity
bed roughness creates turbolence
holicoidal flow
cork crew motion
due to alternating pools (deeper parts and shallow parts)
flow forms meanders
sinousity
how curve the river is
thalweg
line of maximum velocity
