Performance Evaluation of Models That Describe the Soil Water Retention Curve between Saturation and Oven Dryness

their accuracy (RMSE), linearity (coeffi cient of determination, R 2 , and adjusted coeffi cient of determination, R 2 adj ), and prediction potential. Th e latter was evaluated by correlating the model parameters to basic soil properties. Retention data for 137 undisturbed soils from the Unsaturated Soil Hydraulic Database (UNSODA) were used for the model comparison. Th e samples showed considerable diff erences in texture, bulk density, and organic matter content. All functions were found to provide relatively realistic fi ts and anchored the curve at zero soil water content for the coarse-textured soils. Th e performance criteria were similar when averaged across all data sets. Th e criteria were found to be statistically diff erent between the eight models only for the sandy clay loam soil textural class. An analysis of the individual data sets separately showed that the performance criteria were statistically diff erent between the models for 17 data sets belonging to six diff erent textural classes. We found that the Khlosi model with four parameters was the most consistent among diff erent soils. Its prediction potential was also relatively good due to signifi cant correlation between its parameters and basic soil properties.