Question

Consider the following measuring structures:
1. Submerged broad-crested weir
2. Free broad-crested weir
3. Free sharp-crested weir
4. Free ogee spillway
The correct sequence of the increasing order of the discharge coefficient of these structures is

• A. 1, 2, 4, 3
• B. 2, 1, 3, 4
• C. 2, 1, 4, 3
• D. 1, 2, 3, 4

Answer 1

The correct option is D 1, 2, 3, 4

$Forogeespillway{C}_{d1}=1.19C_{ds}$
$C_{ds}$ is the discharge coefficient for sharp-crested weir. So 4 will come after 3.
The classification of weir is:

$H_1/B_w\le 0.1Longcrestedweir$

$01<H_1/B_w<0.35Broad-crestedweir$

$0.35\le H_1/B_w<1.5Narrow-crestedweir$

$H_1/B_w\ge 1.5$ Sharp-crested weir
Further submerged weirs have lesser coefficient of discharge compared to free weirs. So 2 will come after 1.