I'm not sure that you can model a drainage network. A drainage network meaning a system controlled by open channel flow (e.g. sewers, storm sewers).
Per EPANET site, and my experiance "EPANET is software that models water distribution piping systems. EPANET is public domain software that may be freely copied and distributed. It is a Windows 95/98/NT/XP program. EPANET performs extended period simulation of the water movement and quality behavior within pressurized pipe networks."
Thank you very much Jeff for your reply. The problem that I have to solve is about a drainage system under pressure. So it can be modeled through EPANET. What do you think about putting negative base demand to the junctions..?
Surely your school has something you can use. Ask your professor what program he wants the assignment completed in. Hopefully he or fellow students can assist in using said software.