, ▁which ▁is ▁given ▁by ▁the ▁flow ▁equation ▁for ▁a ▁we ir : ▁ ▁Q ▁= ▁ 3 . 1 W [ H ▁+ ▁va 2 / 2 g ] 3 / 2 ▁= ▁ 3 . 1 He 3 / 2 ▁ ▁Where : ▁ ▁Q ▁= ▁dis charge ▁of ▁in let ▁( ft 3 / s ) ▁ ▁W ▁= ▁width ▁of ▁the ▁ch ute ▁or ▁in let ▁( ft ) ▁ ▁H ▁= ▁depth ▁of ▁flow ▁over ▁the ▁cr est ▁( or ▁floor ) ▁of ▁the ▁in let ▁( ft ) ▁ ▁He ▁= ▁specific ▁energy ▁head ▁in ▁reference ▁to ▁the ▁cr est ▁of ▁the ▁in let , ▁or ▁the ▁head ▁over ▁the ▁cr est ▁of ▁the ▁in let ▁( ft ) ▁ ▁va ▁= ▁mean ▁velocity ▁of ▁approach ▁at ▁which ▁the ▁depth ▁H ▁is ▁measured ▁( ft / s ) ▁ ▁g ▁= ▁ 3 2 . 1 6   ft / s 2 ▁ ▁Stra ight ▁In let ▁▁ ▁If ▁the ▁flow ▁rate ▁per ▁unit ▁width ▁is ▁defined ▁as ▁q ▁= ▁Q / W , ▁then ▁the ▁equation ▁can ▁be ▁written ▁as : ▁ ▁q ▁= ▁Q / W ▁= ▁ 3 . 1 [ H ▁+ ▁va 2 / 2 g ] 3 / 2 ▁= ▁ 3 . 1 He 3 / 2 ▁ ▁The ▁coefficient , ▁ 3 . 1 ▁var ies ▁for ▁different ▁entrance ▁conditions . ▁The ▁value ▁of ▁the ▁coefficient ▁is ▁slightly ▁higher ▁if ▁the ▁convey ance ▁channel ▁has ▁a ▁greater ▁width ▁than