The 'Lacey''s regime theory' for design of stable alluvial canals gives:
Choose the correct answer
Only the canal slope for a given discharge
Complete stable channel dimensions (perimeter, hydraulic radius, slope, velocity) from discharge Q and silt factor f
Only the canal lining thickness
Only for lined canals
Correct Answer
B. Complete stable channel dimensions (perimeter, hydraulic radius, slope, velocity) from discharge Q and silt factor f
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Lacey''s regime equations (complete): (1) Perimeter P = 4.75√Q; (2) Hydraulic radius R = 0.47(Q/f)^(1/3); (3) Slope S = f^(5/3)/(1840R^(1/6)Q^(1/6)) × ... (simplified: S = f^(5/3)/(3340R^(1/3))); (4) Velocity V = 10.8R^(2/3)S^(1/2). Three equations + continuity (Q=AV) for four unknowns (B, y, V, S) given Q and f. Silt factor f = 1.76√m_r (m_r = mean particle size in mm). Completely replaces Kennedy''s single equation.
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