Weir Equation Comparison
400
Broad 1.7*L*H^1.5
350
Sharp 1.8*L*H^1.5
300
Francis 1.8*(L-H/5)*H^1.5
Right V notch
Flow (liter/sec)
250
CanyonHydro.com Tabulation
200
150
100
50
0
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35
Head over weir (m)
theta 45
Width of weir (m) 1
G (m/sec^2) 9.81
Sharp Francis 1.8*(L-H/5)*H^1.5
Head (m) Broad 1.7*L*H^1.51.8*L*H^1.5 Right V notch
0.010 1.70 1.79 1.80 0.01
0.015 3.13 3.29 3.30 0.04
0.020 4.82 5.06 5.07 0.08
0.025 6.74 7.08 7.08 0.13
0.030 8.86 9.30 9.30 0.21
0.035 11.16 11.72 11.70 0.31
0.040 13.64 14.32 14.28 0.44
0.045 16.27 17.09 17.03 0.59
0.050 19.06 20.01 19.92 0.76
0.055 21.99 23.09 22.96 0.97
0.060 25.06 26.31 26.14 1.20
0.065 28.25 29.67 29.44 1.47
0.070 31.58 33.15 32.87 1.77
0.075 35.02 36.77 36.42 2.10
0.080 38.58 40.51 40.08 2.47
0.085 42.25 44.36 43.85 2.87
0.090 46.03 48.33 47.73 3.31
0.095 49.92 52.42 51.70 3.79
0.100 53.91 56.61 55.78 4.31
0.105 58.01 60.91 59.96 4.87
0.110 62.20 65.31 64.22 5.47
0.115 66.49 69.81 68.58 6.12
0.120 70.87 74.41 73.03 6.80
0.125 75.35 79.11 77.56 7.53
0.130 79.91 83.91 82.18 8.31
0.135 84.57 88.79 86.87 9.13
0.140 89.31 93.77 91.65 10.00
0.145 94.13 98.84 96.50 10.92
0.150 99.05 104.00 101.43 11.89
0.155 104.04 109.24 106.44 12.90
0.160 109.11 114.57 111.51 13.97
0.165 114.27 119.98 116.66 15.08
0.170 119.50 125.48 121.88 16.25
0.175 124.81 131.05 127.16 17.47
0.180 130.20 136.71 132.51 18.75
0.185 135.66 142.44 137.93 20.08
0.190 141.20 148.26 143.41 21.46
0.195 146.81 154.15 148.95 22.90
0.200 152.49 160.11 154.56 24.40
0.205 158.24 166.16 160.22 25.95
0.210 164.07 172.27 165.95 27.56
0.215 169.96 178.46 171.73 29.23
0.220 175.93 184.72 177.57 30.96
0.225 181.96 191.06 183.46 32.75
0.230 188.06 197.46 189.41 34.60
0.235 194.22 203.93 195.42 36.51
0.240 200.45 210.48 201.48 38.49
0.245 206.75 217.09 207.59 40.52
0.250 213.11 223.77 213.75 42.62
0.255 219.54 230.51 219.96 44.79
0.260 226.03 237.33 226.23 47.01
0.265 232.58 244.21 232.54 49.31
0.270 239.19 251.15 238.90 51.67
0.275 245.86 258.16 245.30 54.09
0.280 252.60 265.23 251.76 56.58
0.285 259.40 272.37 258.26 59.14
0.290 266.25 279.57 264.80 61.77
0.295 273.17 286.83 271.39 64.47
0.300 280.14 294.15 278.02 67.23
0.305 287.18 301.53 284.70 70.07
0.310 294.27 308.98 291.42 72.98
0.315 301.41 316.48 298.18 75.96
0.320 308.62 324.05 304.98 79.01
0.325 315.88 331.67 311.82 82.13
0.330 323.20 339.36 318.71 85.32
Head Inches cfm/in CanyonHydro.com Tabulation
Head m
0.25 0.05 0.006 0.92903
0.50 0.14 0.013 2.601285
0.75 0.26 0.019 4.830958
1.00 0.40 0.025 7.432243
1.25 0.55 0.032 10.21933
1.50 0.73 0.038 13.56384
1.75 0.92 0.044 17.09416
2.00 1.13 0.051 20.99609
2.25 1.35 0.057 25.08382
2.50 1.58 0.064 29.35736
2.75 1.82 0.070 33.81671
3.00 2.07 0.076 38.46186
4.00 3.20 0.102 59.45795
5.00 4.47 0.127 83.05532
6.00 5.87 0.152 109.0682
7.00 7.40 0.178 137.4965
8.00 9.05 0.203 168.1545
9.00 10.80 0.229 200.6706
10.00 12.64 0.254 234.8589
11.00 14.59 0.279 271.0911
12.00 16.62 0.305 308.8097
13.00 18.74 0.330 348.2006