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    黄土坡面植被恢复对沟壑形态的影响研究

    The impacts of vegetation restoration on loess gully morphology

    • 摘要: 植被恢复通过改变土壤属性和水沙过程影响沟壑形态。本研究聚焦无定河流域典型黄土坡面沟壑,通过农田坡面与退耕恢复植被坡面沟壑形态的对比,揭示植被恢复对沟壑形态的影响。基于高精度的DEM、RGB影像和点云数据,进行沟道系统分区和沟道网络分级,提取沟头、支沟及主沟的点云数据分析沟道剖面形态,基于DEM量化沟床粗糙度。结果表明,植被恢复坡面与农田坡面的沟壑形态的明显差异:植被恢复坡面沟头剖面较农田坡面更为陡峭;随着沟道网络级别的升高,植被恢复坡面与农田坡面的横剖面形态差异逐渐缩小;植被恢复坡面的沟床地表粗糙度高于农田坡面,支沟的地表粗糙度普遍高于主沟。本研究揭示了生态治理通过抑制土壤侵蚀对沟壑形态的影响。

       

      Abstract: Background Ecological restoration featured with revegetation plays effective role on mitigating soil erosion in this area. It significantly reduced the surface runoff and sediment generation, enhanced the soil resistance to shear forces and eventually reshaped the morphology of gullies. This study focused on the morphological traits of gullies in the loess hillslope, aimed to reveal the impact of vegetation restoration on soil conservation and reflects the effectiveness of ecological restoration. Methods A agricultural hillslope and a revegetated hillslope with gully system occurred were selected to conduct the comparative analysis. High-precision 3D models, RGB images, and point cloud data were obtained using drone-based LiDAR scanning and photogrammetry. The zonation of gully systems was implemented based on slope gradient variation. The Shreve stream ordering method was applied to classify the gully channel network. Subsequently, cross-sectional of the point cloud data at gully heads, tributaries, and main gullies were extracted for gully morphology analysis. and the roughness of gully bed was quantified based on the high-resolution digital elevation model. Results The results indicate that ecological restoration resulted in noticeable difference in gully morphology between agricultural hillslope and revegetated hillslope. In the revegetated hillslope, gully heads were steeper compared to those on the agricultural hillslope. The higher the gully network order, the more diminished the morphological difference in cross-sectional profiles between the gullies on the two hillslopes. The roughness of gully bed was higher on the revegetated hillslope than on the agricultural hillslope, with bed of tributary gullies exhibiting greater roughness than that of main gullies. Conclusion Through the comparative analysis of gully morphology and gully bed roughness, this study highlighted the critical role of vegetation restoration played in soil and water conservation and demonstrated the effectiveness of ecological restoration in mediating gully morphological traits. The findings provide scientific evidence for assessing the effectiveness of ecological restoration on the Loess Plateau.

       

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