Prediction of the Asymptotic Water Depth in Rough Compound Channels

Abstract

We report on a curious result related to the computation of the asymptotic depth in rough compound channels by one-dimensional approaches. Such approaches, which are widely used in practice, utilize one of a number of well-established methods for estimating the equivalent composite/compound roughness. It was found that many of these methods yield predictions of the asymptotic water depth which erroneously depend on the initial, control, depth. Only one of the methods examined was found not to exhibit this unsatisfactory behavior. We explain the results by analysis of the governing equations.