This version of HEC-RAS allows the user to model inline structures, such as gated spillways, overflow weirs, drop structures, as well as lateral structures. HEC-RAS has the ability to model radial gates (often called tainter gates), vertical lift gates (sluice gates), or overflow gates. The spillway crest of the gates can be modeled as either an ogee shape, broad crested weir, or a sharp crested weir shape. In addition to the gate openings, the user can also define a separate uncontrolled overflow weir.

This chapter describes the general modeling guidelines for using the gated spillway and weir capability within HEC-RAS, as well as the hydraulic equations used. Information on modeling drop structures with HEC-RAS is also provided. For information on how to enter gated spillway and weir data, as well as viewing gated spillway and weir results, see "Modeling Culverts" and "Modeling Gated Spillways, Weirs and Drop Structures" of the HEC-RAS User's Manual, respectively.