In drainage systems, what is the term for the lowest point of the internal cross-section of a pipe or channel?

The term for the lowest point of the internal cross-section of a pipe or channel is referred to as the invert. In hydraulic engineering and drainage design, the invert represents the bottom of the flow conduit, which is critical for determining how gravity drives water flow through the system. The invert elevation is essential for calculating flow capacity and ensuring proper drainage performance, as it affects factors like hydraulic gradient and potential for sedimentation.

Understanding the invert level also helps engineers design systems that prevent backflow and maintain efficient drainage. It’s a key reference point for various analyses, such as determining how high water might rise in relation to surrounding features and ensuring that the system complies with local regulations regarding water management.

The other terms—profile, flowline, and datum—serve different roles in engineering contexts. The profile is typically used to describe the overall shape or elevation change of a drainage feature. Flowline may refer to the path that water takes within a channel or the theoretical line representing the flow of water within a system. Datum generally pertains to a reference point or level from which measurements are taken but does not specifically indicate the lowest point within a conduit.