Step 1: Understanding the Concept:
Weir flow equations are derived by integrating the theoretical velocity of water over the vertical cross-sectional area of flow above the crest.
Step 3: Detailed Explanation:
The general discharge equation for a rectangular weir is:
\[ Q = \frac{2}{3} C_d L \sqrt{2g} H^{3/2} \]
This standard equation can be simplified into the general empirical form:
\[ Q = C L H^m \]
where:
\(C\) = discharge coefficient
\(L\) = length of the weir crest
\(H\) = head of water above the crest
\(m\) = exponent, which is theoretically \(1.5\) (or \(3/2\)) for a rectangular weir.
Analyzing the statements:
- Statement (A) uses an incorrect exponent of \(2/3\).
- Statement (B) uses an incorrect exponent of \(7/2\).
- Statement (C) matches the correct generalized form of the weir discharge equation.
Therefore, only statement (C) is correct.
Step 4: Final Answer:
The correct option is 4, which corresponds to (C) only.