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NOLIBF is a parameter in the fort.15 file controlling the type of bottom stress parameterization used in a 2DDI ADCIRC run. This parameter must be specified but is ignored in a 3D run.

= 0 linear bottom friction law. The friction coefficient (FFACTOR) is specified below.

= 1 quadratic bottom friction law. The friction coefficient (FFACTOR) is specified below.

= 2 hybrid nonlinear bottom friction law. In deep water, the friction coefficient is constant and a quadratic bottom friction law results. In shallow water the friction coefficient increases as the depth decreases (e.g. as in a Manning-type friction law). The friction coefficient is determined as: FFACTOR=FFACTORMIN*[1+(HBREAK/H)**FTHETA]**(FGAMMA/FTHETA). The required parameters (FFACTORMIN, HBREAK, FTHETA, FGAMMA) are specified below.

Parameter Summary

The following table is a summary of possible NTIP values, description, details, and other necessary input parameters and files.

NTIP Value Description Details Other Required Inputs
0 No Astronomical Forcing - NTIF = 0
1 Astronomical Tidal Potential Reconstructs the tidal elevation using the analytical formulation for the equilibrium tidal potential[1] NTIF > 0
2 Astronomical Tidal Potential plus Self-attraction and Loading (SAL) Tide[2] Reconstructs the tidal elevation by summing the contribution from the analytical formulation for the equilibrium tidal potential[1] with the contribution from the prescribed SAL constituent values found in the fort.24 file. NTIF > 0, fort.24 file

Usage Notes

In the NWP section, if the user selects quadratic_friction_coefficient_at_sea_floor, mannings_n_at_sea_floor, or chezy_friction_coefficient_at_sea_floor, then NOLIBF must be 1 (nonlinear friction formulation) since all those formulations are nonlinear. If the NOLIBF were anything other than 1, it is an error that will cause ADCIRC to stop.

For 3D ADCIRC runs, spatially varying bottom friction should be specified using the bottom_roughness_length fort.13 file nodal attribute.


  1. 1.0 1.1 Eq. (27), page 17 in Luettich, R.A., Westerink, J.J., 1992. ADCIRC: an advanced three-dimensional circulation model for shelves coasts and estuaries, report 1: theory and methodology of ADCIRC-2DDI and ADCIRC-3DL, Dredging Research Program. Vicksburg, MS.
  2. Ray, R.D., 1998. Ocean self-attraction and loading in numerical tidal models. Mar. Geod. 21, 181–192. doi:10.1080/01490419809388134