Developing Pedotransfer Functions for Predicting FC and PWP |
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| Authors: | Afshin Honarbakhsh Mohammad Tahmoures Yaser Ostovari Somaye Noroozi |
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| Institution: | 1. Associate Professor in Watershed Engineering, Department of Rangeland and Watershed Engineering, Faculty of Natural Resources and Earth Sciences, Shahrekord University, Shahrekord, Iran;2. Faculty of Natural Resources, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran;3. Young Researchers and Elite Club, Marvdasht Branch, Islamic Azad University, Marvdasht, Iran;4. M.Sc. Student in Water Sciences Engineering, Irrigation and Drainage, Department of Water Engineering, College of Agricultural, Shiraz University, Shiraz, Iran |
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| Abstract: | Using pedotransfer functions (PTF) is a useful way for field capacity (FC) and permanent wilting point (PWP) prediction. The aim of this study was to model PTF to estimate FC and PWP using regression tree (RT) and stepwise multiple linear regressions (SMLR). For this purpose, 165 and 45 soil samples from UNSODA and HYPRES datasets were used for development and validation of new PTFs, respectively. %Clay, geometric mean diameter (dg), and bulk density (BD) were selected as predictor variables due to the highest correlation and lowest multicollinearity. The results showed that clay percentage with W* = 0.89 and dg with W* = ?0.57 were the most effective variables to predict PWP and FC, respectively. The RT method had a better performance (R2 = 0.80, ME = ?0.002 cm3cm?3, RMSE = 0.05 cm3cm?3 for FC and R2 = 0.85, ME = 0.003 cm3cm?3, RMSE = 0.03 cm3 cm?3 for PWP) than SMLR in estimation of FC and PWP. |
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| Keywords: | HYPRES regression tree stepwise multiple linear regression UNSODA |
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