Spatial variability of one-parameter model of soil water characteristic curve at field scale in black soil region of northeast China

The soil water characteristic curve (SWCC) is an important parameter for simulating soil water movement and solute trans-port, and has obvious spatial variability. The models fitting the SWCC generally contain two or more parameters, which makes the spatial variability of the soil water characteristic curve difficult to express. This paper established a one-parameter model of the soil water characteristic curve based on the Gardner model and analyzed its spatial variability with multifractal and joint multifractal methods. Parameter B in the one-parameter model had moderate variation. The local information leading to spatial variability of parameter B in the top soil layer (0-15 cm) and deep soil layer (15-20 cm) was its low values and high values, respectively. At the single scale, spatial variability of parameter B was mainly caused by the bulk density and clay con-tent in the 0-5 cm soil layer, and by the bulk density and sand content in the 5-10, 10-15, and 15-20 cm soil layers. At the multiscale, the most obvious two factors that led to spatial variability of parameter B were the bulk density and silt content in the 0-5 cm soil layer, bulk density and sand content in the 5-10 cm soil layer, and bulk density and clay content in the 10-15 and 15-20 cm soil layers, respectively. The relationships between parameter B and soil properties had scale dependence.

Automated summary

The soil water characteristic curve (SWCC) is a key parameter for simulating soil water movement and solute transport, and it exhibits significant spatial variability. This study developed a one-parameter model based on the Gardner model to describe the SWCC and analyzed its spatial variability using multifractal and joint multifractal methods. The results showed that parameter B in the one-parameter model had moderate spatial variation and was influenced by different soil layers and scales.