Fig. 4. Plot of the relationship between , the pore size distribution index in Eq. [9], and , the coefficient of variation characterizing the WRC (Eq. [4]). The "+" symbols represent the calibration data (Assouline, 2005). The dashed lines indicate the 95% confidence limits of the fitted curve (Eq. [16]) (solid line) to these data. The solid and open circles represent the calibration and the validation data in this study, respectively.