Ogee Spillway Designxls Install !!install!! Link

Always compute Vₐ and its head, then run a second iteration with the adjusted head. If the change in Hₑ exceeds 1%, include it permanently.

As noted in the USBR design procedure, the spreadsheet gives an initial weir size. That size should be input into a model of the watershed to simulate the reservoir routing. The HEC‑HMS simulation will determine whether the spillway can pass the Probable Maximum Flood (PMF) without overtopping the dam crest. ogee spillway designxls install