Scaling of saturated hydraulic conductivity: A comparison of models

This study compares eight models for scaling soil-saturated hydraulic conductivity, K-s, using a database of 402 data sets collected from 25 sources in the literature. The database includes data regarding K-s, particle size distribution, soil bulk density, and soil particle density, with textures ranging from sand to heavy clay. The results showed that models based on the nonsimilar media concept and the Kozeny-Carman model performed best for estimating soil K-s using scaling. In contrast, Campbell and Poulsen-Saxton models were not suitable for scaling K-s. The group of models that gave the second best estimation of K-s included Saxton, Cosby, Vereecken, and the complex Brakensiek models. All eight of the models had smaller estimation deviations for sandy soils than for clayey soils. Moreover, the results showed that the sample that had an average of the characteristics of all the samples should be taken as a reference point when scaling K-s, whereas for soil samples with identical texture, it would be better to employ the sample with minimum bulk density as the reference point. The NSMC and Kozeny-Carman models are recommended for scaling K-s.