Influence of Vegetation Restoration in Construction Access Roads on Soil and Water Loss in Southeastern Xizang Autonomous Region
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S157.1

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    Abstract:

    [Objective] We aimed to elucidate the process of runoff and sediment production on the upper and lower slopes of construction access roads under vegetation recovery conditions, reveal the impact of vegetation recovery on soil and water loss at the slope scale after the disturbance caused by the construction of access roads in an ecologically fragile subalpine forest and shrubland area of Southeastern Xizang Autonomous Region, in order to provide a theoretical basis for the prevention and control of soil and water loss and vegetation restoration after the disturbance caused by the construction road project. [Methods] Typical slopes under different vegetation recovery conditions after disturbances on the upper and lower slopes of construction access roads were selected for indoor simulated rainfall experiments. In this study, we investigated the processes of runoff and sediment production under four types of vegetation coverage (0%, 30%, 60%, and 90%), three slopes (15°, 30°, and 45°), and two rainfall intensities (30, 60 mm/h) after engineering disturbance to determine the impact of vegetation recovery in construction access roads on soil and water loss. [Results] ① After the engineering disturbance of the construction access roads, vegetation recovery on the bare upper and lower slopes effectively delayed the initial runoff time, and this effect became more pronounced with increasing vegetation coverage, especially on the upper slopes. ② When the vegetation coverage was within the range of 0 to 60%, the stable runoff rate on both the upper and lower slopes significantly decreased with increasing vegetation coverage, wherein the stable runoff rates under 60% and 90% vegetation coverage were similar. Compared with bare slopes, the benefits of runoff reduction under 60% and 90% vegetation coverage were 59%—75% and 58%—77% respectively, indicating that the critical vegetation coverage value for runoff reduction was 60%. ③ Sediment reduction benefits under 30% and 60% vegetation coverage reached 29%—82% and 86%—96% respectively. Below a vegetation coverage of 60%, the sediment reduction effect significantly increased with increasing coverage; beyond this critical threshold, even with increased coverage, the sediment reduction benefits showed slight change. ④ Under the same vegetation coverage, slope, and rainfall intensity conditions, the total runoff volume from the upper slopes formed by excavation was always higher than that from the lower slopes formed by filling, whereas the total sediment yield from the lower slopes was always higher than that from the upper slopes, indicating significant differences in soil erosion on the slope surface after the disturbance of the construction of access roads between the excavation and filling slopes. [Conclusion] For the prevention and control of soil and water loss in areas disturbed by the construction of access roads in Southeastern Xizang Autonomous Region, a vegetation recovery rate of 60% offers good control benefits and economic feasibility. When designing soil and water conservation measures, more emphasis should be placed on ‘controlling water’ for excavation slopes and ‘blocking sediment’ for filling slopes. Only by fully considering these differences can better soil and water conservation be achieved in disturbed areas on access roads.

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冉心昊,王冠,李亚桐,肖辉杰.藏东南施工便道植被恢复对坡面水土流失的影响[J].水土保持通报英文版,2024,44(4):20-32

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History
  • Received:December 04,2023
  • Revised:March 19,2024
  • Adopted:
  • Online: September 04,2024
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