Hydraulics of Two-Stage Straight Drop Spillways

摘要

The report identifies the five flow regimes likely to occur during the passage of outflow hydrographs over two-stage straight drop spillways and presents a method for developing rating curves for such structures under any flow conditions. The advantages of the method are fully appreciated only in applications where at least one of the two stages is susceptible to submergence. The components of the compound section delineating the crest of the spillway may be rectangular or trapezoidal weirs. Satisfactory performance of the structure, in regard to energy dissipation, dictates symmetrical configuration of the compound section about the axis of the lower stage. Still, the method can be used in the development of rating curves for existing structures not meeting the aforesaid performance requirement.