模拟降雨条件下砾石含量对塿土工程堆积体坡面产流产沙的影响

为探究砾石含量对塿土堆积体坡面产流产沙的影响,采用室内人工模拟降雨试验,以土质坡面为对照,研究5种砾石含量(10%、20%、30%、40%、50%)堆积体坡面在不同降雨强度(1.0、1.5、2.0、2.5 mm·min^-1)下的产流产沙特征。结果表明:不同试验条件下的平均径流率在2.18～13.07 L·min^-1,不同雨强条件下平均径流率均在砾石含量10%(或20%)和50%时分别达到最大值与最小值;平均流速在0.06～0.22 m·s^-1,流速变化复杂,砾石含量越小,流速变幅越大,变异系数也越大,砾石含量10%时平均流速最大。砾石的存在可有效抑制产沙,最大减沙效益可达84.2%,雨强相较于砾石含量对平均产沙率的影响更大。偏相关分析表明,平均径流率、流速、产沙率均与砾石含量呈极显著负相关;平均产沙率与平均径流率、平均流速以及二者交互项均呈极显著线性函数关系,其中,与平均径流率的相关性最强。本研究可为塿土区工程堆积体水土流失治理和侵蚀模型的建立提供参考。

Effects of gravel content on runoff and sediment yield on Lou soil engineering accumulation slopes under simulated rainfall conditions.

To investigate the effects of gravel content on runoff and sediment yield on Lou soil accumulation slopes, we conducted indoor simulation rainfall experiments and examined the characteristics of runoff and sediment yield on accumulation slopes with five gravel contents (10%, 20%, 30%, 40%, 50%) under four rainfall intensities (1.0, 1.5, 2.0, 2.5 mm·min^-1), with a no gravels slope as control. The average runoff rate under different test conditions ranged from 2.18 to 13.07 L·min^-1. The average runoff rate was the maximum under the gravel content of 10% (or 20%) and the minimum under the 50% gravel content. The average flow velocity ranged from 0.06 to 0.22 m·s^-1. The variation of flow velocity was complex. The smaller the gravel content, the larger the range of variation and the coefficient of variation. The average flow velocity reached the maximum when the gravel content was 10%. The presence of gravel effectively inhibited the sediment yield, and the sediment reduction benefit reached 84.2%. The rainfall intensity had more influence on the average sediment yield rate than gravel content. Results of partial correlation analysis showed that gravel content was significantly negatively correlated with the ave-rage runoff rate, the average flow velocity, and the average sediment yield rate. The relationships between the ave-rage sediment yield and the average runoff rate, the average flow velocity, and their interaction were all extremely significant linear functions, with the strongest relationship between the average sediment yield and the average runoff rate. This study could provide references for the control of soil erosion and the establishment of erosion models for engineering accumulations in Lou soil areas.