I have a requirement for spillway design that requires passing 50%PMP in a 6-hour storm event. In Indiana, what would be the equivalent storm event in Hydrocad?
There are a number of 6-hour distributions in HydroCAD that might be of interest, but I suspect you're looking for the "Type B" referenced as follows: SCS Type B aka ESH from TR-20 Table 6, TR-60 Fig 2-6, NEH-4 Fig 21.2