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
Why is this the answer?
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.
Related Irrigation Engineering MCQs
More solved Irrigation Engineering questions for AE/JE Civil Engineering exams.
- In irrigation, if the duty D (hectares per cumec) and delta delta (m) over the base...
- A silty soil of high compressibility is represented by
- Freeboard in a dam is the vertical distance between:
- The field irrigation requirement (FIR) for a crop is related to consumptive use (CU),...
- In canals likely to be water-logged, the preferable type of irrigation is
- A protection work at the downstream end of a weir in form of blocks of concrete or...
Practice more Civil Engineering questions
This MCQ belongs to JE Level Premium Test Series. Full tests include timed attempts, rank comparison and subject-wise analysis.