Catch basins and other structures, including valves, elbows, reducers, etc. have their own equations for losses based on the type of structure, these are minor losses separate from the pipe friction loss that must be added to determine the total loss for a system. There are many software programs you can find that compute the HGL and EGL, depending on the type of system being anaylyzed. The USEPA and USAACE both have some freeware that is pretty good for some analysis. USEPA develops SWMM and USAACE develops the HEC models. There are also programs like SewerCAD, StormCAD, and WaterCAD, which are better for design, but not free. These things are commonly available and discussed online, a little search with Google would have told you most of the answers in about 5 minutes. Generally, this is not something you should mess with if you are not an engineer, because you need to make sioome assumptions and be able to recognize issues that may have been lost in the modeling. If you are an engineer, you should sue your college program for a failure to meet the ABET educational standards required for Civil Engineering degrees.