Showing 2 results for Van Genuchten Model
H. R. Fooladmand, S. Hadipour,
Volume 15, Issue 58 (3-2012)
Abstract
Soil water characteristic curve shows the relationship between soil water content and matric suction, which has an important role in water movement in the soil. The measurement of this curve is expensive and time-consuming in laboratory therefore, many methods have been proposed for its estimation including pedotransfer functions. By using the pedotransfer functions, soil water characteristic curve can be estimated based on other easily measured soil physicochemical properties. Parametric pedotransfer functions have been offered for parameters of the existing soil water characteristic curve models. In this study, 12 internal and external parametric pedotransfer functions of Brooks and Corey, Campbell and van Genuchten models were used and evaluated for 30 top soil samples in Fars province. To this end, the soil water characteristic curve and other necessary soil properties were measured, and then all soils according to the texture were divided into three groups of fine, medium and course textures. The results showed that the parametric pedotransfer functions of van Genuchten model were better than the other models, beacause of the better fit of this model to the measured data. Also, the results demonstrated that the parametric pedotransfer functions of Wosten et al. were the most appropriate method for estimating the soil water characteristic curve for the selected soils in Fars province, and that internal pedotransfer functions were not appropriate
H. Aryanpour, M. Shorafa,
Volume 18, Issue 67 (6-2014)
Abstract
Soil tillage changes chemical and physical properties which can change the soil available water capacity. For understanding the effect of soil disturbance in cultivated soil on available water, parameter pedotransfer functions of these soils created and their results were compared with measured available water by moisture release curves. For this purpose 54 soil samples were taken from cultivated and non cultivated soils of Abyek-Qazvin area northwesthern Iran. Selected properties of these soils such as particle size distribution, bulk density, organic carbon, calcium carbonate, cation exchange capacity and pH were determined. Soil moisture curve of samples were obtained by pressure plates. Parameter pedotransfer functions were created by Mualem-van Genucten model for non cultivated soil and their available water were predicted. The predicted available water was compared with measured available water. The results illustrated that the predicted results had higher correlation coefficient for moisture of permanent wilting point compared to of field capacity moisture, As the correlation coefficient was inccreased from 0.67 to 0.83 and also the root mean square error (RMSE) reduced from 2.59 to 1.06. So the predicted available water was overestimated.
