Minimum time-step in EXTRAN

It has been recommended that time-step must be >= 1sec in EXTRAN
(SWMM4.4h). Could anyone pls inform what are the negative things may
arise if i use time-step < 1 sec (say 0.2 sec).

Regards
Ashis Dey, PhD.
dey.ashis@tk.pacific.co.jp

Ashis, you can use a very small time step in Extran without many
negative consequences other than model slowness. All of your inflow
boundaries and outfall boundary conditions will be interpolated
correctly at small time steps and the continuity error checks will also
sum correctly. The only negative thing that may happen in some models
is that with a small time step you may oscillate more between the St.
Venant equation solution and the normal flow equation solution.

Regards, Bob Dickinson
DickinsonRE@CDM.COM

Bob

Thanks for your information. Your note will be very helpful.

Regards
Ashis Dey