Inland Aquaculture Engineering (1984)
 DESIGN AND CONSTRUCTION OF FRESHWATER FISH FARMS
 Chapter 8. Hydraulic Formulas Used in Designing Fish Farms
 3. DESIGN FORMULAS FOR HYDRAULIC STRUCTURES
 3.2 Design Formulas for Inlets
 3.2.1 Free fall pipe inlet 3.2.2 Submerged pipe inlet 3.2.3 Open flume inlet

### 3.2.3 Open flume inlet

Figure 8. Open flume inlet l/sec

where

Q = design discharge of the inlet, l/sec
B = width of the throat, cm
H = height of the designed full supply level in the feeder channel above the sill level of the inlet
C = discharge coefficient

Table 10 Values of Discharge Coefficient C for open Flume Inlet

 B in cm C 6 to 10 0.0160 10 to 15 0.0164 over 15 0.0166

Figure 9. Relationships of discharge to B and H

 Length of the cistern: lc = 0.82 H2, m Depth of the cistern: dc = 0.1 H2, m where H2 = water depth in the pond, m Depth of the glacis dg = 0.5 H, m where H = maximum water depth above the sill level of the inlet, m

Example 3

Design an open flume inlet for a discharge of 150 l/sec if the water depth in the feeder canal is 45 cm and 1.50 m in the pond.

Solution

The corresponding width of the throat to the water depth of 150 l/sec is defined from Figure 9.

then

B = 30 cm
dg = 0.5×H = 0.5×0.45 = 0.23 m
lc = 0.8×H2 = 0.8×1.50 = 1.20 m
dc = 0.1×H2 = 0.1×1.50 = 0.15 m