Fig. 6

Semivariograms and fitted variogram models of granulometric parameters. Variogram models were fitted by the least-squares method, and the model that produces the fewest residual errors was chosen from among the Gaussian, spherical, and exponential models. The spherical model was used for mean and median grain-size, sorting, and gravel fractions, the exponential model was used for the CV value, and the Gaussian model was used for skewness, kurtosis, and mud fractions