| mannings_to_darcy | Convert Manning's n to Darcy-Weisbach f |
| n_bathurst1985 | Compute grain roughness via Bathurst (1985) |
| n_brownlie1981 | Compute form roughness via Brownlie (1981) |
| n_cowan1956 | Compute hydraulic roughness following Cowan (1956) |
| n_direct | Compute total channel roughness via direct field measurement |
| n_engelund1967 | Compute form roughness following Engelund and Hansen (1967) |
| n_fischenich2000 | Compute hydraulic roughness due to vegetation following Fischenich (2000) |
| n_freeman2000 | Compute hydraulic roughness due to vegetation following Freeman, Rahymeyer, and Copeland (2000) |
| n_jarrett1984 | Compute grain roughness via Jarrett (1984) |
| n_limerinos1970 | Compute grain roughness following Limerinos (1970) |
| n_maynord1991 | Compute grain roughness following Maynord (1991) |
| n_strickler1923 | Compute grain roughness following Strickler (1923) |
| n_vanrijn1984 | Compute channel form roughness following Van Rijn (1984) |
| n_wong2006 | Compute grain roughness following Wong and Parker (2006) |