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 $Z_{am}\le Z_t$

$$Q=C_d\frac{B}{2(Z_t-Z_d)}{(Z_{am}-Z_d)}^{2.5}$$

for $Z_{am}>Z_t$

$$Q=C_d\frac{B}{2(Z_t-Z_d)}({(Z_{am}-Z_d)}^{2.5}-{(Z_{am}-Z_t)}^{2.5})$$

Thin wall weir: $C_d$ = 1.37

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

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