the fitting quality of several water retention models in soil samples from lordegan, charmahal-va-bakhtiari

abstract water retention curve (wrc) is a fundamental property of soil. it is used to evaluate available water, permeability, drainage and movement of solutes. despite numerous studies on wrc of soils abroad, no local study has been carried out on charmahal-va-bakhtiari soils. the objective of this study was to compare the quality of fitting of several wrc models to lordegan soils and to select the appropriate models. the studied models were: brooks-corey, van genuchten, farrel-larson, libardi et al., simmons et al., bruce-luxmoore and campbell. fifty soil samples were collected from across lordegan plain and their texture were determined characterized for texture. water retention data were obtained using hanging water column and pressure plate apparatus. models were fitted using swrc 3.0 software. r-square ( ) and were used for evaluating fitting quality. all models did well with ranging from 0.90 to 1.00 and from 0.001 to 0.036. however, in all samples and all textural classes, van genuchten model fitted best. brooks-corey model was the weakest although its was always greater than 0.90 and its maximum was 0.036 . therefor, van genuchten model is recommended for soils of lordegan plain.