Machine-translated by Google. Questions are authored in English.
Top

Discussion

According to Lacey's theory, the bed slope is given by :

  • A.\(\frac{F^{1/3}}{3340\ Q^{1/6}}\)
  • B.\(\frac{F^{4/3}}{3340\ Q^{1/2}}\)
  • C.\(\frac{F^{2/3}}{3340\ Q^{1/4}}\)
  • D.\(\frac{F^{5/3}}{3340\ Q^{1/6}}\)

Answer: D

Lacey's bed slope is \(\frac{F^{5/3}}{3340\ Q^{1/6}}\).

Lacey's regime theory for alluvial channels gives the slope in terms of the silt factor \(f\) and the discharge \(Q\) in cumecs:

\[ S = \frac{f^{5/3}}{3340\,Q^{1/6}} \]

A coarser silt (larger \(f\)) needs a steeper slope to keep it moving, and a larger channel can carry it at a flatter slope, which is why \(f\) is in the numerator and \(Q\) in the denominator. The exponents 1/3, 4/3 and 2/3 on \(f\), and 1/2 and 1/4 on \(Q\), do not belong to the regime equations.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.