EJones

The short answer to your question is that a riser has a vertical hole on the side of the pipe, where the standpipe has a horizontal pipe . To be sure that I'm clear I'll give the long answer. There are four discharge structures in the Hydraulic Toolbox Detention Basin Calculator: Weir, Standpipe, Riser, and known discharge. The Weir determines the flow that is available by using only Weir Flow. The Standpipe uses weir flow along the circumference of the pipe, until orifice dominates. The Riser uses weir flow across the submerged section of the hole (depending on shape and size) until ori