PAM对坡地降雨径流入渗和水力侵蚀的影响研究

The impacts of PAM on runoff/infiltration and water erosion from slope lands

通过野外沙壤土坡地人工降雨产流试验,研究了地表施用高分子聚合物PAM(Polyacrylamide)对降雨径流量、径流含沙量、一次降雨土壤侵蚀总量等的影响。通过对试验结果的分析,建立了表面施用PAM用量对径流、土壤侵蚀影响规律的数学模型。对于所试验的洪积沙质壤土,PAM用量0.5g.m-2时,可以提高土壤的入渗率,减少径流量;PAM用量3g.m-2时,可明显降低土壤入渗率,增加坡地径流量。用量在1g.m-2时,PAM对土壤入渗率影响的效果不稳定,该用量是PAM对土壤入渗率影响的一个拐点或非稳定点。利用PAM调节土壤入渗率存在一个最佳值(最大入渗速率),对应的PAM用量为提高土壤入渗率的最佳用量,对于所试验的洪积沙壤土来说为1.0 g.m-2左右。PAM的使用方法和用量对减小土壤入渗率也存在一个阈值,对于试验土壤此值在2.0g.m-2左右。不同用量PAM都能降低坡地径流的径流含沙率;当PAM用量较大时(2g.m-2),也能显著地降低一次降雨径流的挟沙总量。

Field rainfall simulation experiments were conducted to investigate the impacts of surfaceapplied PAM on runoff, infiltration, sediment yield. Mathematic model was formulated with the experimental data to quantify the relationship of PAM application amount with runoff and soil erosion. For the flood-depositional sandy loamy soil used in the experiments, surface application of PAM with amount of 0.5g·m^-2 can effectively increase infiltration rate, reduce runoff, while PAM of 3g·m^-2 dramatically reduces infiltration of rainwater and increases runoff. A PAM rate of about 1g·m^-2 is a unstable and critical amount, which also presents the transient point of the PAM-infiltration relationship, beyond which infiltration rate starts to decline. It indicates that there exists a PAM rate for maximizing infiltration rate, which is about 1.0g·m^-2 to the experimental soil. There also exists a PAM rate for reduction of infiltration rate. It is about 2.0g·m^-2. All PAM application rates effectively reduce the sand content of rainfall, when it reaches 2g·m^-2 the total sediment can be significantly reduced.