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Background <p>The Three Gorges Reservoir Area (TGRA) represents a typical ecologically fragile region and a critical zone for soil and water conservation in China. Soil erosion within the water-level fluctuation zone (WLFZ) has emerged as a key threat to the ecological security of the entire reservoir system.</p> Objective <p>This study investigated soil particle-size distribution (PSD) characteristics and multifractal parameters across different elevations and soil depths within the WLFZ using multifractal analysis. We further examined relationships between multifractal dimensions and key soil physicochemical properties, and explored the mechanism by which Cynodon dactylon (L.) Pers. mitigates soil erosion in this region.</p> Methods <p>Four elevation zones were established: a control site at 180&#xa0;m (CK), a high-elevation zone (HE: 165–175&#xa0;m), a mid-elevation zone (ME: 155–165&#xa0;m), and a low-elevation zone (LE: 145–155&#xa0;m). Within each elevation, soil samples were collected from four depth intervals (0–10, 10–20, 20–30, and 30–40&#xa0;cm) for laboratory analysis. Cynodon dactylon (L.) Pers. was selected for vegetation restoration, and a suite of soil erosion resistance indices was quantified.</p> Results <p>Relative to the control elevation (180&#xa0;m), the HE–LE zones exhibited significant reductions in soil organic matter content, macroaggregate proportion, MWD, and GWD by 8.86%–44.00%, 13.37%–43.92%, 9.93%–37.75%, and 14.13%–52.84%, respectively. Conversely, soil bulk density increased by 6.55%–39.87%. These parameters also generally deteriorated with increasing soil depth. The correlation analysis further revealed that the multifractal dimensions D₀, D₁, and D₂ were positively correlated with soil organic matter, aggregate stability, MWD, and GWD, but negatively correlated with bulk density. Planting <i>Cynodon dactylon</i> (L.) Pers. significantly enhanced soil organic matter, erosion resistance indices, cohesion, and internal friction angle, while reducing the soil erodibility K, thereby effectively improving soil anti-erodibility in the WLFZ.</p> Conclusion <p>Our findings demonstrate that alternating erosion and deposition processes serve as the primary drivers of soil structural evolution in the WLFZ, resulting in progressive soil particle coarsening and overall degradation of soil structure. As a highly effective restoration species, <i>Cynodon dactylon</i> (L.) Pers. can substantially alleviate soil erosion and improve soil stability in the WLFZ of the TGRA.</p>

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Multifractal analysis reveals the characterics of soil PSD in the water-level fluctuation zone of the Three Gorges Reservoir, China

  • 期刊论文

  • 发表日期：

    2026年6月25日

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  • Bijie Hu,
  • Zhen Ju,
  • Yuqi Wang,
  • Ping Zhou,
  • Yi Long,
  • Zhonglin Shi

摘要

Background

The Three Gorges Reservoir Area (TGRA) represents a typical ecologically fragile region and a critical zone for soil and water conservation in China. Soil erosion within the water-level fluctuation zone (WLFZ) has emerged as a key threat to the ecological security of the entire reservoir system.

Objective

This study investigated soil particle-size distribution (PSD) characteristics and multifractal parameters across different elevations and soil depths within the WLFZ using multifractal analysis. We further examined relationships between multifractal dimensions and key soil physicochemical properties, and explored the mechanism by which Cynodon dactylon (L.) Pers. mitigates soil erosion in this region.

Methods

Four elevation zones were established: a control site at 180 m (CK), a high-elevation zone (HE: 165–175 m), a mid-elevation zone (ME: 155–165 m), and a low-elevation zone (LE: 145–155 m). Within each elevation, soil samples were collected from four depth intervals (0–10, 10–20, 20–30, and 30–40 cm) for laboratory analysis. Cynodon dactylon (L.) Pers. was selected for vegetation restoration, and a suite of soil erosion resistance indices was quantified.

Results

Relative to the control elevation (180 m), the HE–LE zones exhibited significant reductions in soil organic matter content, macroaggregate proportion, MWD, and GWD by 8.86%–44.00%, 13.37%–43.92%, 9.93%–37.75%, and 14.13%–52.84%, respectively. Conversely, soil bulk density increased by 6.55%–39.87%. These parameters also generally deteriorated with increasing soil depth. The correlation analysis further revealed that the multifractal dimensions D₀, D₁, and D₂ were positively correlated with soil organic matter, aggregate stability, MWD, and GWD, but negatively correlated with bulk density. Planting Cynodon dactylon (L.) Pers. significantly enhanced soil organic matter, erosion resistance indices, cohesion, and internal friction angle, while reducing the soil erodibility K, thereby effectively improving soil anti-erodibility in the WLFZ.

Conclusion

Our findings demonstrate that alternating erosion and deposition processes serve as the primary drivers of soil structural evolution in the WLFZ, resulting in progressive soil particle coarsening and overall degradation of soil structure. As a highly effective restoration species, Cynodon dactylon (L.) Pers. can substantially alleviate soil erosion and improve soil stability in the WLFZ of the TGRA.