William,

My tidal fluctuations are set up like this for a 10-yr event; and I'm using a time step of 1 second. A time step of 15 minutes should be fine if your system can remain stable.

I1 'Chisman' 1
* NTIDE
J1 5
* KO NI NCHTID DELTA
J3 0 8 0 0.005
* Time Elev Time Elev Time Elev Time Elev Time Elev
J4 0.0 4.0 6.3 1.0 12.6 4.0 18.9 1.0 23.2
4.0
J4 29.5 1.0 35.8 4.0 42.1 1.0


Andrew B. Scott, P.E.
ascott@RKKENGINEERS.COM