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# NOLIFA

NOLIFA is a parameter in the fort.15 file controlling controlling the finite amplitude terms and wetting-drying in ADCIRC. The value of NOLIFA effects the meaning of the minimum water depth parameter (H0) and requires the specification of additional parameters together with H0. When the finite amplitude terms are turned on, the time derivative portion of the advective terms should also be turned on for proper mass conservation and consistency (i.e., when NOLIFA > 0, then NOLICA = 1).

## Parameter Summary

The following table is a summary of possible NOLIFA values, description, details, and other necessary or recommended input parameters.

NOLIFA Value Description Details Other Required Inputs
0 linear bottom friction law uses a spatially constant linear bottom friction, ${\displaystyle \tau _{b}}$ of dimensions [1/T] FFACTOR
1 quadratic bottom friction law can specify a spatially constant or spatially varying dimensionless coefficient, ${\displaystyle C_{f}}$; in which ${\displaystyle \tau _{b}=C_{f}|U|/H}$ FFACTOR
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) FFACTORMIN, HBREAK, FTHETA, FGAMMA

## 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.