m = μ [1 + k {h/(p + h)}2 ].
(5)
Gaugings were made with weirs of 0.75, 0.50, 0.35, and 0.24 metres height above the canal bottom and the results compared with those of the standard weir taken at the same time. The discussion of the results leads to the following values of m in the general equation (1):—
m = μ (1 + 2.5u2/2gh)
= μ [1 + 0.55 {h/(p + h)}2 ].
Values of μ—
| Head h metres. | Head h feet. | μ |
| 0.05 | .164 | 0.4481 |
| 0.10 | .328 | 0.4322 |
| 0.20 | .656 | 0.4215 |
| 0.30 | .984 | 0.4174 |
| 0.40 | 1.312 | 0.4144 |
| 0.50 | 1.640 | 0.4118 |
| 0.60 | 1.968 | 0.4092 |
An approximate formula for μ is:
μ = 0.405 + 0.003/h (h in metres)
μ = 0.405 + 0.01/h (h in feet).