Relative Sensitivity Analysis of the Soil Water Characteristics Curve

Abstract

This study was conducted to develop the SWCC estimation equation using scaling technique, and to investigate relative sensitivity of the SWCC according to the soil water tension, for the four kinds of soil texture such as Sand [S], Sandy Loam [SL], Loam [L] and Clay Loam [CL]. The SWCC estimation equation of scale factor [Θsc] (Eq. 1) was developed based on the log function (Eq. 2) and exponential function (Eq. 3). Θsc = [(Θ-Θr) / (Θs-Θr)] (Eq. 1) Θsc = -0.196 ln(H) + 0.4888 (Eq. 2) Θsc = 0.3804 (H) (-0.448) (Eq. 3) where, Θ: water content (g/g %), Θs: water content at 0.1bar, Θr: water content at 15bar, H: soil water tension (matric potential) (bar) Relative sensitivity of soil water content was decreased as increase soil water tension, those according to soil water tension were 0.952~0.620 compared to 0.1bar case. Relative sensitivity of scale factor was also decreased as increase soil water tension, those according to soil water tension were 0.890~0.577 compared to 0.2bar case.