Channel roughness in 1D steady uniform flow: Manning or Chézy?

In river flow applications, consensus on the most appropriate roughness descriptor has yet to be found. A disturbing observation is that the coefficients and formulae of Chézy, Darcy Weisbach, Manning, Strickler and White Colebrook are used rather arbitrarily, and that a widely accepted scientific justification is lacking. The presented paper compares the most commonly used roughness parameters, and reflects on some arguments that are often used in favour of, or against, any of these. Some recent advances on the theoretical basis of different methods are put forward, and implications for commonly used hydraulic modelling packages are discussed