| Summary: | 【Objective】 Soil water retention curve (SWRC) is an important parameter for studying subsurface hydrological processes and solute transport in soils, but its direct measurement is labor-intensive. For large scale applications, it is often estimated indirectly using some easy-to-measure soil properties. In this paper, we propose a pedo-transfer function to estimate hydraulic parameters of the soils in hilly regions in the upper reach of the Yangtze River. 【Method】 Soil samples were taken from three land usages in the Yanting Wan’as watershed: paddy field, upland and forest. We measured their SWRC and other chemical and physical properties; the measured SWRC was fitted to the van Genuchten formula, from which we derived a pedo-transfer function to estimate the van Genuchten parameters using multiple stepwise linear regression analysis. Accuracy of the function was evaluated using the Pearson correlation analysis. 【Result】 ①Land use affects the ability of the soil to hold water. The land usage that affected water-holding capacity of the soil more was ranked in the order of paddy field > upland > forest land. In contrast, no significance was found in soil water supply capacity between different land usages. ②The coefficient of determination between the measured and predicted SWRC using the pedo-transfer function was greater than 0.97, and the proposed model was most accurate for soils taken from the upland. ③The proposed pedo-transfer function was more accurate than those proposed by Vereecken et al (1989), Wosten et al (1999), Weynants et al (2009) and Schaap et al (2001). 【Conclusion】 The pedo-transfer function proposed in this paper for estimating water release curve using easy-to-measure soil properties is accurate and efficient. It can be used to estimate hydraulic parameters of the soils in the hilly regions in the upper reach of the Yangtze River.
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