以跳台形式的溢流堰或急流陡槽,把水流挑射至下游水面,其挑射距离L′一般按公式 (1)计算(文献1,2)。式中:T_0=T+V_0~2/2g; T——上下游水面高差; Z——鼻坎顶端挑流水面至下游水面的高差; V_0——上游进水口行近流速; θ——鼻坎挑射角; h——鼻坎顶端水深; g——自由落体加速度。流速系数如下式φ=1/(1+∑ζ)~(1/2),(2) To jump the form of overflow weir or jet stream steep, the water jet to the downstream surface, the pick-up distance L ’is generally calculated according to equation (1) (References 1, 2). Where: T_0 = T + V_0 ~ 2 / 2g; T-- upper and lower reaches of the water surface elevation; Z - nose ridge top pick the surface to the downstream surface of the water level difference; V_0-- upstream inlet line near the flow rate; - nose ridge pick angle; h - nasal tip water depth; g - free-fall acceleration. The flow coefficient is as follows: φ = 1 / (1 + Σζ) ~ (1/2), (2)