A field study of longitudinal dispersion

Abstract

The results of a comprehensive longitudinal dispersion experiment in a stream with an irregular, sinuous pattern are presented. The time-spread of tracer clouds was found to increase at a rate between [Formula: see text] as found for uniform prismatic channels, and x as found for highly irregular mountain streams. This ‘intermediate’ dispersive state is thought to be related to the stream’s degree of nonuniformity. The accuracy of one-dimensional approaches is considered, as is the applicability of a similarity analysis. A new definition of a 'mixing' length, based upon the condition of identical but shifted concentration–time curves, is proposed.