Stepwise design of head regulator

The design of a canal head regulator proceeds in these steps.

1. Collect data: canal discharge $Q$, river HFL, pond level, canal FSL and bed level, silt factor $f$, safe exit gradient.
2. Crest level: fix the crest 0.6 to 1.2 m above the river bed or under-sluice crest, so that bed load is excluded.
3. Waterway: head over the crest $H =$ pond level $-$ crest; $L = \dfrac{Q}{C\,H^{3/2}}$ with $C = 1.7$ (broad crest). Provide bays and piers.
4. Height of gates: pond level $+$ free-board; top of piers above HFL.
5. Scour depth and cut-offs: $R = 1.35(q^2/f)^{1/3}$; d/s cut-off to $1.5R$ below the d/s water level, u/s cut-off to $1.0R$ or less.
6. Impervious floor length: from Khosla's exit gradient, $G_E = \dfrac{H_s}{d}\dfrac{1}{\pi\sqrt{\lambda}}$, with $H_s$ the maximum static head; $\alpha = b/d$ from $\lambda$; $b = \alpha d$.
7. Floor thickness: from the uplift pressure at key points by Khosla's method, $t = \dfrac{h}{G-1}$.
8. Protection works: d/s inverted filter and launching apron, u/s block protection, wing walls.
9. Check the stability of piers and the exit gradient; prepare drawings.