砾石覆盖对海涂围垦区粉砂土坡面土壤可蚀性影响试验研究

Experiment on effect of rock fragment cover on slope erodibility of saline-sodic soil in costal reclamation area

通过人工模拟降雨试验,选取2种坡度(15°,30°),2种降雨强度(92,119 mm/h)和6种砾石覆盖度(0,10%,20%,40%,60%,80%),探究砾石覆盖对海涂围垦区粉砂土坡面侵蚀及土壤可蚀性的影响.结果表明:随累积降雨量增加,土壤可蚀性参数先增大后减小,并趋于稳定.坡度对土壤可蚀性影响显著,坡度越陡,坡面土壤可蚀性越大.砾石覆盖度与土壤可蚀性参数并非呈单调关系.坡度较陡且低覆盖度时,砾石覆盖增加坡面侵蚀;而当高覆盖度时,砾石覆盖可降低坡面径流速率,增加入渗率,减小土壤侵蚀率.适当盖度砾石覆盖能够改变边坡表面粗糙程度,降低坡面土壤可蚀性.砾石覆盖坡面径流雷诺数与土壤可蚀性参数呈显著线性负相关关系.通过径流雷诺数与土壤可蚀性参数线性关系定量分析能够较好反映坡面高钠盐土颗粒输移水动力学过程,对于构建盐碱土边坡泥沙输移预测模型具有重要意义.

The effects of rock fragments cover(RC) on the saline-sodic soil erosion and the interrill erodibility were investigated through simulated rainfall with two intensities (92 mm/h and 119 mm/h), two slope gradients (15% and 30%), and six rock fragments covers (0%, 10%, 20%, 40%, 60% and 80%). Results show that with the increase of cumulative rainfall, the soil erodibility increa-ses firstly, then decreases and tends to be stable. The soil erodibility is significantly increased with slope gradient increasing. The soil erodibility varies non-monotonically with RC. Under the condition of deeper slope and lower RC, soil erodibility increases with RC increasing. While infiltration rate increases, runoff rate and soil erodibility decreases with RC increasing when RC is higher. The appropriate RC can change the roughness of slope surface and reduce the soil erodibility. A significant negative li-near correlation exists between Reynolds number of runoff and soil erodibility on the slope with rock fragments cover. Quantitative analysis of linear relationship between Reynolds number and soil ero-dibility can reflect hydrodynamics process of saline-sodic soil on slope surface, which is of significance to building a prediction model of sediment transport in saline-sodic soil slope.