ABSTRACT
In the pursuit of methods to estimate hydraulic conductivity – the key parameter in the description and prediction of flow in porous media – grain-size based methods have the appeal of simplicity, but their reliability is questionable. A number of empirical methods were surveyed and summarized. Their validity was assessed by comparing the predictions to actual measurements on several representative samples (taken from previous studies). Although the limited number of the samples precludes any sweeping statistical conclusions and does not necessarily describe all modelling situations, the results nevertheless show that grain-size based methods, particularly those that take into account grain-size dispersion and properly account for the controlling influence of the smaller fractions, can be an acceptable substitute for more expensive laboratory measurements and field tests when accuracy is not of the essence and small-volume support is desired. Among the methods described, Beyer’s and the US soil classification formula are favoured.
