Identifying the soil structure of the piedmont-plains by the fractal dimension of particle size

Abstract

Soil structure fundamentally determines the hydrodynamic characteristics of the saturated–unsaturated zone, solute transport characteristics, and thermodynamic properties of the soil. Additionally, it regulates the process of transfer and conversion of matter and energy in the saturated–unsaturated zone. However, the quantification of soil structure is difficult because it depends on a combination of factors including soil particle sizes and types and spatial distribution of pores. In this study, the structural characteristics of the vadose zone are examined based on self-similarity in the soil and the fractal theory of non-linear science. This approach describes the soil particle sizes and spatial distribution of pores in the interior layers of the soil. The study area stretches across 165 km of the piedmont–plains of the Taihang Mountains. The particle sizes and volume percentages of particle sizes in 57 soil samples were measured using the Mastersizer 2000 laser diffraction particle size analyser (Malvern Instruments, U.K.). This information is then combined with the volume-based fractal dimension (D), calculated using the fractal theory, of the various samples. The results obtained indicate that: (i) the fractal theory can be used to effectively identify the characteristics of three-dimensional structural changes within the soil profiles. The average soil particle size decreases from the piedmont of the Taihang Mountains towards the plains. Similarly, the volume percentage of particle size and the maximum volume percentage of a single particle size decreases. Moreover, the D values show an overall declining trend; (ii) the D values of the soils of the piedmont–plains of the Taihang Mountains show significant spatial variations in the range of 1.037–1.925. Although there is no correlation between the D value and soil particle size, the D value is very sensitive to the soil structure uniformity. The higher the uniformity, the greater is the D value; and (iii) D values cannot be used as the sole basis for determining the soil hydraulic properties. The D values and soil hydraulic properties are correlated only for a particular range of soil particle sizes.

Effects of Different Vegetation Restoration Types on the Fractal Characteristics of Soil Particles in Earthy-Rocky Mountain Area of Northern China

“…This is well confirmed in this study as well. The fractal dimension decreases with the increase in soil depth, which may be related to the high content of litter in surface soil and the spatial distribution of organic matter [42]. This study shows that the multifractal dimension of the mixed forest is greater than that of the monospecies forest, and that of the broad-leaved forest is greater than that of the coniferous forest.…”

“…However, some scholars have studied relationship between the soil fractal dimension and physicochemical properties in the Loess Plateau. They found that the fractal dimension was negatively correlated with porosity and positively correlated with bulk density [42]. This may be related to the different environmental factors such as climate and soil in the study area, or it may be caused by different vegetation restoration types in the study area.…”

“…However, some studies have also shown that soil fractal dimension is negatively correlated with nutrient indicators. For example, Ma et al [45], He and Wang [42] and others have found that the fractal dimension is negatively correlated with the content of soil C, N, P, etc. Different scholars have different research results on the correlation between fractal dimension and soil nutrient index.…”

Grain size characteristics of surface sediment in the Jilantai Salt Lake Protection System after long‐term wind‐sand activities

“…The soil particle size distribution (PSD) reflects the process of soil weathering and formation, which is closely related to the soil structure and fertility, and this quantity also interacts with soil erosion and land deterioration (He & Wang, 2019; Lin et al, 2020). Artificial vegetation establishment could affect the soil PSD by (1) ameliorating the stability of the soil structure through roots and (2) effectively increasing soil nutrients and soil coverage via vegetation litter (Li et al, 2020).…”

Control and Interception Characteristics of the Debris-Flow Flexible Net Barrier Based on Orthogonal Design

“…However, open-type check dams compensate for the shortcomings of closedtype dams due to their unique characteristics, i.e., the trapping of coarse particles and discharge of fine sand and water [5][6][7]. As a novel debris-flow mitigation countermeasure, flexible net barriers, which may be quickly installed with helicopters and dissipate debrisflow energy through elastic and plastic deformation, have been increasingly applied in debris-flow mitigation, especially in the United States and Switzerland [8][9][10][11][12]. However, the impact behavior of debris flows on flexible net barriers is quite different from that on concrete dams because of the nonlinear geometrical characteristics and complicated deformation patterns of flexible net barriers [13][14][15] Many researchers have carried out physical experiments and numerical simulations on debris-flow flexible net barriers.…”