Prediction of Soil Hydraulic Conductivity at Saturation Using Air Permeability at Any Individual Soil Water Content

摘要

Several studies aimed at linking hydraulic conductivity at saturation (K_(w,s)) to air permeability (K_a(θ_w)) of soil at given water content (θ_w) since it can be measured more rapidly and nondestructively than K_(w,s) especially regarding some new in situ technologies for K(θ_w) measurement.Following this, the current research aimed to develop a semi-theoretical relation between K_(w,s) and K_a(θ_w) using measured data in 27 soil samples.The K_a(θ_w) was measured at 12 different θ_w contents between 1.5 to 1,500 kPa suctions.Applying these measured data, we proposed a semi-theoretical function to predict K_(w,s) using K_a(θ_w) as input variable.The results showed that the proposed function was able to predict K_(w,s) using K_a(θ_w) at any individual θ_w content with really high accuracy consisting of R~2 = 0.986 and evaluating error (ER) of the 2% between measured and predicted K_(w,s) However, the outcomes revealed that K_a(θ_w) measurement at lower θ_w contents resulted in greater accuracy for proposed model.The pertinent section of the article applied multivariate linear regression (MLR) to develop pedo-transfer functions (PTFs) to estimate the parameters of the proposed model.The results revealed that the developed PTFs had relatively greater accuracy and reliability showing average determination coefficient (R~2) of 0.807 and 0.729 for training and test datasets, respectively.However, more detailed investigation with wide range of soil parameters are needed for more general PTFs development.