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close this bookInland Aquaculture Engineering (1984)
close this folderDESIGN AND CONSTRUCTION OF FRESHWATER FISH FARMS
close this folderChapter 8. Hydraulic Formulas Used in Designing Fish Farms
close this folder3. DESIGN FORMULAS FOR HYDRAULIC STRUCTURES
close this folder3.2 Design Formulas for Inlets
View the document3.2.1 Free fall pipe inlet
View the document3.2.2 Submerged pipe inlet
View the document3.2.3 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