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Truncated triangular weir formula

TT1 caracterized by:

  • \(C_d\): discharge coefficient
  • \(Z_d\): triangle's lower overflow elevation
  • \(Z_t\): triangle's higher overflow elevation
  • \(B/2\): half-opening of the triangle

Formula

for \(Z_{am} \leq Z_t\)

\[Q = C_d \frac{B}{2 (Z_t - Z_d)} \left ( Z_{am} - Z_d \right )^{2.5}\]

for \(Z_{am} > Z_t\)

\[Q = C_d \frac{B}{2 (Z_t - Z_d)} \left ( \left ( Z_{am} - Z_d \right )^{2.5} - \left ( Z_{am} - Z_t \right )^{2.5} \right )\]

Thin wall weir: \(C_d\) = 1.37

Thick weir without contraction (rounded \(r > 0.1 * h1\)): \(C_d\) = 1.27

Triangular profile weir: (1/2 upstream, 1/2 or 1/5 downstream): \(C_d\) = 1.68 and 1.56