Keyan, A channel can be provided different elevations or slope along the length through the use of transitions and/or cross sections . The linked to wiki article also explains the difference between the two elements and when it's best to use one over…

Hi Nigel, From element point of view, you have little more options to enter in a manhole Vs a transition. From the hydraulics point both will calculate the headloss. Now, cross-section is a different element generally it represents the geometry of a…