In the previous chapter, we derived relations between the hydraulic parameters of estuary flow and the topography. In this chapter, we shall derive analytical equations for tidal damping/amplification (on the basis of the conservation of momentum equation) and wave celerity (using the combined mass and momentum equations). These equations are derived through the method of characteristics and Lagrangean analysis. This approach uses analytical derivation and not scaling. The latter, called perturbation analysis, is useful for identifying the main mechanisms at play and for assessing orders of magnitude, but, used as a tool for derivation, does not always result in correct equations, as will be demonstrated. The analytical equations derived in this chapter are more general versions or refinements of well-known (classical) equations, such as Green's law and other rules of thumb. Most of these classical equations are only correct for frictionless channels with a constant topography, or apply to either progressive or standing waves. The general equations derived in this book apply to the full range of tidal waves (with a phase lag varying between 0 and ?/2) and the natural topographies of alluvial estuaries.