南方典型土壤坡面产流产沙过程对PAM的响应

Response of Runoff and Sediment to PAM in Typical Soil Slopes of South China

采用室外人工模拟降雨试验方式,系统对比研究了2种聚丙烯酰胺(Polyacrylamide,PAM)配比方案(2 g/m^2和10 g/m^2,分别用PAM1200-2和PAM1200-10表示)在140 mm/h短时强降雨条件下对坡度为10°的南方红壤区4种不同典型岩性发育土壤坡面的产流、产沙过程的影响机制。结果表明:各坡面总产流量、单位采样时段径流系数、累积单位采样时段径流系数均有显著提升(p<0.01),径流提升率由大到小依次为:第四纪红壤坡面、红砂岩红壤坡面、紫色土坡面、花岗岩红壤坡面;除花岗岩红壤坡面外,PAM1200-10的径流提升率均大于PAM1200-2,坡面产生稳流的时间由短到长依次为:第四纪红壤坡面(12 min)、红砂岩红壤坡面(15 min)、花岗岩红壤坡面(24 min)和紫色土坡面(24 min),2种PAM配比在提升坡面产流方面,无显著性差异;各坡面的总产沙量、单位采样时段泥沙质量浓度、单位采样时段泥沙量均显著降低(p<0.01),2种PAM配比方式均以第四纪红壤坡面减沙率最为显著,其余不同配比的坡面减沙率略有不同,除紫色土坡面,PAM1200-10的减沙率均大于PAM1200-2;其中PAM1200-2的减沙率波动性较大,除紫色土坡面外,PAM1200-10配比的减沙率均较为平稳,在花岗岩红壤坡面,PAM1200-10与PAM1200-2相比,减沙成效显著(p<0.01)。

The artificial simulation rain experiment in field was designed to study the influence mechanism of polyacrylamide（ PAM） on the process of runoff and sediment in four typical red soil slopes derived from different soil parent materials of South China under the condition of 140 mm/h short-duration heavy rainfall. The experimental treatments included two kinds of PAM application rate of 2 g/m^2 and 10 g/m^2,which were expressed as PAM1200-2 and PAM1200-10,respectively. The results showed that the total runoff,unit sampling time runoff coefficient,cumulative sampling time runoff coefficient in each slope were increased significantly（ P〈0. 01）,and the runoff with elevation order was quaternary red soil slope,red sandstone red soil slope,purple soil slope and granite red soil slope. The increase efficiency of runoff in the treatment of PAM1200-10 was more than that in PAM1200-2 treatment in different soil slopes except granite red soil slope. The increasing order of steady flow time was quaternary red soil slope（ 12 min）,red sandstone red soil slope（ 15 min）,granite red soil slope（ 24 min） and purple soil slope（ 24 min）. There was no significant difference between the two kinds of PAM application rate（ PAM1200-2 and PAM1200-10） in raising runoff yield. There was a significant decrease（ P〈0. 01） in the total sediment,unit sampling time sediment concentration and unit sampling time sediment of each slope,the sedimentreduction rate was the most remarkable in quaternary red soil slope with both of the two kinds of PAM application rate,there was slight difference in sediment reduction in red soil slopes derived from other three types of parent materials. The sediment reduction rate of PAM1200-10 was greater than that of PAM1200-2 in different soil slopes,except purple soil slope. Among them,the sediment reduction rate of PAM1200-2 was more volatile than that of PAM1200-10. The sediment reduction rate of PAM1200-10 was relatively stable except the purple soil slope. In granite red soil slope,the effect of the sediment reduction of PAM1200-10 was significantly improved than that of PAM1200-2（ P〈0. 01）.