A BED-POROSITY VARIATION MODEL AND ITS APPLICATION

Abstract

This study aims at developing a bed-porosity variation model available for the analysis of the change in porosity of bed material as well as the bed variation. The porosity was assumed to be a function of characteristic parameters of grain size distribution. The functions were obtained for typical distribution type such as log-normal and Talbot distributions by means of a particle packing model and a measurement method. An exchange model of bed material and transport sediment was introduced to obtain the time and space variations of porosity and grain size distribution of bed material. The model was applied to the bed variation for the sediment mixtures with two-grain sizes and continuous grain size distribution to examine the performance of the model. It was found that the model could provide the reasonable results on the porosity change as well as the bed variation.