不同降雨强度和下垫面条件对黑土区坡面产流产沙的影响

为了优选合适的东北黑土区堤防坡面侵蚀防控技术,基于人工模拟降雨的方法研究了不同降雨强度和下垫面条件下坡面的产流产沙特征,利用三维激光扫描仪对降雨后的坡面侵蚀形态进行监测,分析坡面土壤的侵蚀情况。结果表明,降雨强度增大,坡面的初始产流时间提前,产流率随降雨历时波动更加显著。在不同降雨强度下,植被措施使平均产流率降低7.4%～20.4%,在裸地上施加PAM(聚丙烯酰胺)使平均产流率增大6.8%～25.9%。随降雨强度增大,下垫面L1(裸地)和下垫面L2(均匀撒施5 g/m~2 PAM的裸地)的产沙率随降雨历时波动更加显著,其产沙率变化规律可以用幂函数进行描述。下垫面L1的总产沙量相比下垫面L2增幅明显,在裸坡上施加PAM能够减少总产沙量,起到固土效果。草地坡面在降雨过程中未出现产沙情况,裸地坡面的侵蚀形态主要表现为溅蚀和片蚀特征,施加PAM使得侵蚀严重区域的面积相较裸地减小了21.5%,能够起到一定侵蚀控制的效果。总体来看,草地坡面的保水固土效果要优于裸地坡面。在坡面上施加PAM使得土壤入渗能力减弱,但能减少侵蚀产沙,在实际工程中有应用价值。

Effects of different rainfall intensity and underlying surface conditions on runoff-sediment yield of slope surface within black soil region

In order to optimize suitable erosion control technology for the slop surface of the levee within the black soil region of Northeast China，the characteristics of the runoff-sediment yields of different rainfall intensities and underlying surface conditions are studied herein through artificial rainfall simulation method，while the slope erosion pattern after rainfall is monitored with 3-D lasers canner for analyzing the slope soil erosion status． The result shows that the rainfall intensity is increased and the initial runoff-yielding time is advanced，while the runoff-yielding rate is more significantly fluctuated with the rainfall duration． Under different rainfall intensities，the mean runoff-yielding rate is reduced by 7. 4% ～ 20. 4% by the relevant vegetation measures and the mean runoff-yielding rate is increased by 6. 8% ～ 25. 9% through applying PAM ( polyacrylamide) to the bare slope． With the increase of rainfall intensity，the sediment-yielding rates of L1 ( bare slope) and L2 ( bare slope averagely applied with PAM of 5 g /m2 ) of the underlying surface are fluctuated more significantly with the rainfall duration，for which the law of the sedimentyielding rate can be described by power function． The increasing amplitude of the total sediment yield of the underlying surface of L1 is significant if compared with that of the L2，thus the total sediment yield can be decreased by applying PAM to the bare slope，which can play a role of soil consolidation． During rainfall，no sediment-yielding phenomenon is there on grass-slope and the erosion pattern of the bare slope mainly exhibits the characteristics of splash erosion and sheet erosion，while applying PAM makes the area of the seriously eroded zone be decreased by 21. 5% and then can play a certain role to control the erosion． Generally，the water conservation and soil consolidation effect of grass slope is better than that of the bare slope． Though applying PAM on slope surface can reduce the infiltration capacity of soil，it can decrease the erosion sediment yield，thus has an application value in the actual engineering project．