基于石漠化－允许流失量－洼地修正的喀斯特流域土壤侵蚀估算及其驱动力分析

Assessment and Driving Mechanisms of Soil Erosion in Southwestern Guangxi Based on Modified RUSLE Model for Karst Peak-Cluster Depression Basins

    摘要
  • 摘要:
    目的 桂西南喀斯特峰丛洼地流域作为我国五大生态脆弱区之一，其特殊的喀斯特峰丛洼地地貌使得对该地区土壤侵蚀评估难以使用传统模型计算，需要考虑石漠化因子及洼地对土壤侵蚀的影响，来正确评估该地区2000 ~ 2020年土壤侵蚀结果，并揭示其驱动机制。
    方法 通过石漠化因子、土壤允许流失量修正通用土壤流失方程（RUSLE, Revised Universal Soil Loss Equation），利用MK趋势分析探究其2000 ~ 2020年间土壤侵蚀模数时空变化趋势，并结合地理探测器揭示土壤侵蚀驱动机制。
    结果 通过石漠化因子、土壤允许流失量修正模型，并排除了洼地的影响，平均土壤侵蚀模数下降4.22 t hm−2 a−1，使模型计算结果更为准确；2000 ~ 2020年间，土壤侵蚀量呈现波动下降的趋势，每年减少约为0.07 t hm−2 ，侵蚀量总体下降了约8.2%；土地利用对土壤侵蚀的解释力最大，植被覆盖度、降雨量次之，各驱动因子对土壤侵蚀表现出明显的交互作用，其中土地利用与岩性的交互作用最强。
    结论 2000 ~ 2020年桂西南喀斯特地区的土壤侵蚀状况呈现出持续改善的趋势。利用石漠化因子、土壤允许流失量修正模型，并排除洼地影响，可以显著提升土壤侵蚀评估的准确性。使用地理探测器进一步揭示了修正模型后土地利用、植被覆盖度等因子驱动力的变化，这为制定科学、有效的水土保持措施提供了重要的参考依据。

     

    Abstract:
    Objective The karst peak-cluster depression basin in southwestern Guangxi, as one of the five major ecologically fragile areas in China, poses challenges for soil erosion assessment due to its unique topography. Traditional models are inadequate for this region, necessitating the consideration of rocky desertification factors and the impact of depressions on soil erosion. This study aims to accurately assess soil erosion in this area from 2000 - 2020 and to reveal its driving mechanisms.
    Method The RUSLE model was modified by incorporating rocky desertification factors and soil loss tolerance considerations. The Mann-Kendall (MK) trend analysis was used to explore spatio-temporal trends in soil erosion from 2000 - 2020. Furthermore, a geographical detector was employed to quantify the explanatory power of various factors on the spatial distribution of soil erosion.
    Result ① By utilizing the rocky desertification factor and revising the soil loss tolerance model, while excluding the influence of depressions, the average soil erosion modulus decreased by 4.22 t hm−2 a−1, resulting in an improvement in the accuracy of the model. ② From 2000 - 2020, soil erosion showed a fluctuating downward trend, with a reduction rate of approximately 0.07 t hm−2 a−1. The overall erosion amount decreased by approximately 8.2%. ③ Land use explained soil erosion the most, followed by vegetation coverage and rainfall. The driving factors exhibited significant interactions, with the strongest interaction observed between land use and lithology.
    Conclusion Soil erosion in the karst region of southwestern Guangxi continuously improved from 2000 - 2020. By incorporating rocky desertification factors and soil loss tolerance considerations into the refined model, there was a noticeable decrease in both soil erosion area and erosion modulus. The main driving factors also changed. In the future, soil erosion control efforts in southwestern Guangxi should be given to land use patterns and their interactions with lithology and soil types, to provide important reference for formulating scientific and effective soil and water conservation measures.

     

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