In SewerGEMS or CivilStorm, why do I not see the option to change the Gravity Friction Method? How can I change the friction method for conduits to something other than Mannings?
The Gravity Friction Method calculation option only applies to the GVF-Convex (SewerCAD) and GVF-Rational (StormCAD) numerical solvers. If you're using the Implicit or Explicit dynamic solvers, conduits will always be using the Mannings method for gravity friction.
If you'd like to use the GVF-Convex (available in SewerGEMS) or GVF-Rational solver (available in SewerGEMS and CivilStorm) and specify a friction method other than Mannings, select it from the "active numerical solver" dropdown in the Calculation Options assigned to the scenario of interest.