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    川北丘陵区降雨对黄壤裸地坡面产流产沙的影响

    Effects of rainfall on runoff and sediment yield on yellow soil bare slope in the hilly area of northern Sichuan province

    • 摘要: 基于长时间序列的实测数据,揭示自然降雨条件下裸地坡面的产流产沙机制对区域水土流失精准防治具有重要科学价值。本研究基于川北丘陵区黄壤裸露径流小区2014—2022年连续观测数据,采用逐步回归与通径分析相结合的方法,系统分析降雨特征对坡面产流产沙的影响作用。结果显示,观测期内共发生138场侵蚀性降雨,分布于4—10月;多年平均径流深与土壤流失量分别为197 mm和1057.63 t/km²;通过逐步回归筛选出影响径流深的核心降雨指标为降雨侵蚀力(R)、降雨量(P)、最大30 min降雨强度(I30)和降雨历时(D),土壤流失量的关键驱动因子为R、I30和D;通径分析揭示降雨侵蚀力对径流深具有最强直接正向效应(0.692),其通过与其他指标的协同作用使总效应提升至0.906;I30虽直接抑制径流形成,但通过与其他因子的强间接正效应(0.7216)的影响,综合表现为显著正向作用(0.501);土壤流失量主要受降雨侵蚀力的直接驱动(0.836),I30虽直接通径系数为负,但通过与降雨侵蚀力间接正效应的影响,综合表现为促进土壤流失。本研究量化了降雨多因子交互作用对水土流失的影响,为区域土壤侵蚀模型参数优化提供理论支撑,为川北丘陵区水土保持措施的时空配置提供科学依据。

       

      Abstract: BackgroundBased on the long time series of measured data, exploring the rule of runoff and sediment yield on bare slope under natural rainfall condition, it is important for soil erosion control. MethodsUsing observed data (2014-2022) of runoff and sediment yield on bare slope of yellow soil in hilly area of northern Sichuan,the study analyzed the influence of rainfall factors on runoff and sediment yield on slope by using the method of stepwise regression and path analysis. ResultsThe results showed that 138 erosive rainfall events occurred during the observation period, which distributed from April to October. Average annual soil loss was 1057.63t/km2, average annual runoff depth was 197 mm. Stepwise regression analysis showed that rainfall erosivity, rainfall, I30 and rainfall duration were the main indicators affecting runoff, rainfall erosivity, I30 and rainfall duration were the main indicators affecting soil loss. Path analysis revealed that rainfall erosivity had the strongest direct positive effect(0.692) on runoff depth, which increased the total effect to 0.906 through the synergistic effect with other factors. Although I30 directly inhibited runoff, it showed a significant positive effect (0.501) through strong indirect positive effect (0.7216) with other factors. Soil loss was mainly directly driven by rainfall erosivity ( 0.836 ). Although I30 had direct negative on soil loss, it promoted soil loss through the indirect positive effect with rainfall erosivity. ConclusionsThe study quantifies the influence of rainfall multi-factor interaction on soil erosion, provides theoretical support for the optimization of regional soil erosion model parameters, and provides scientific basis for soil and water conservation measures in the hilly area of northern Sichuan.

       

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