Evaluation of Soil-Water Characteristic Curves for Different Textural Soils Using Fractal Analysis

Abstract

The soil-water characteristic curve (SWCC) is an essential tool to determine hydraulic and mechanical properties of unsaturated soils. As an inherent influencing factor, soil texture controls the characteristics of SWCCs. Fractal theory can quantitatively describe the physical characteristics of soil. This study used particle size distribution data and water content data contained in the UNSODA2.0 database to explore the fractal characteristics of 12 soil types with different textures under different matrix suctions. The SWCC fractal model was adopted to characterize the hydraulic properties of soil with various soil textures. The findings revealed that the mass fractal dimensions of particles from these 12 different soil types significantly differed and were closely related to the clay content. Fractal dimension increased with increasing clay content. The fractal dimension established a good relationship between soil structure and hydraulic properties. Fractal analysis can be used to determine the connection between physical properties and soil hydraulic parameters. The estimated results of the SWCC fractal model indicated that it had a good performance regarding the description of SWCCs for the 12 soil textures. The soil structure could be described through fractal dimensions, which can effectively indicate soil hydraulic characteristics. The estimated fractal dimension of this model could be obtained by particle size distribution. Furthermore, using the SWCC fractal model, we found that the SWCC of coarse textured soil changed sharply in the low suction stage and its residual water content was small, and the SWCC of fine textured soil changed gently with a large residual water content. The water retention capacity followed the order clay > silty clay > sandy clay > clay loam > silty clay loam > sandy clay loam > loam > silt loam > sandy loam > silt > loamy sand > sand.

Estimation of Soil Moisture Thresholds for Aggravation of Global Terrestrial Carbon Uptake Losses

“…SMT have a strong positive link with clay content while a negative correlation with sand content. Soil moisture increases gradually as clay content increases and sand content decreases under the same matrix suction (C. Yang et al., 2023). The regions where have higher clay content typically have wetter soil.…”

“…The regions where have higher clay content typically have wetter soil. These humid regions are theoretically more sensitive to drought (C. Yang et al., 2023), leading to higher SMT are detected. There is no discernible relationship between SMT and silt content.…”

Influence of Moisture Content and Dry Density on the Compressibility of Disturbed Loess: A Case Study in Yan’an City, China

“…The compression deformation coefficient (δ p ) and soil pore ratio (e i ) were used to investigate the relationship between soil compression deformation and soil moisture content and dry density under different loads. The percentage between the shape variable of the sample and the height of the sample before compression and the soil pore ratio during the compression process can be expressed by Equations (7) and (8). The compressibility and its variation rule under different conditions can be easily and intuitively judged by the compression deformation coefficient.…”

“…The compaction of disturbed loess can cause engineering problems such as ground cracking and slope instability [5]. These engineering disasters and geological problems are closely related to moisture in loess [6,7].…”

Soil Attributes and Their Interrelationships with Resistance to Root Penetration and Water Infiltration in Areas with Different Land Uses in the Apodi Plateau, Semiarid Region of Brazil

“…Freddi et al [54], in their study with a latosol (oxisol), found that soil density had a positive influence on the soil water content due to reduced macroporosity and the redistribution of pore sizes, corroborating the results achieved for the same soil class in this study (Figure 3a). The hydraulic functionality differs for soils with different textures, with microporosity playing an important role in this parameter due to the presence of materials with fine textures, e.g., clay and SOM, showing higher retention capacity when the soil is moistened [55,56].…”