Closure to “Mechanics of Dispersion in Natural Streams”

Abstract

The Mechanics of Dispersion in Natural Streams. A method is given for predicting longitudinal dispersion coefficients in natural streams. The analysis is based on recognition that transverse velocity gradients (rather than the previously considered vertical velocity gradients) are the primary dispersive mechanism. The method consists of measuring the average shear and cross-sectional velocity distribution of the particular stream in the field. An integral formula can then be applied to predict the dispersion coefficient. Laboratory experiments are described which verify the theoretical results in flows whose velocity distributions are similar to those found in natural streams. Experiments in real streams will be described in future papers.