黄丘区野外坡面产流产沙过程对不同植被覆盖结构的响应

植被覆盖结构是影响坡面侵蚀过程的重要因素,通过在黄丘区罗玉沟流域开展自然植被覆盖坡面野外模拟降雨试验,分析了90 mm/h雨强条件下地下根系、地下根系+地表结皮层和地下根系+地表结皮层+植被冠层3种不同覆盖结构对坡面产流产沙过程影响。结果表明:植被根系层次对增强土壤入渗起主导作用,使土壤入渗量增加67%,稳定入渗率增加39.7%;3种植被覆盖结构中,地表结皮层对产流和产沙具有最好的调控作用,减流贡献率和减沙贡献率分别为43%和67%;根系小区和裸地小区累积产流量与累积产沙量之间呈幂函数关系,随着植被覆盖结构的叠加,累积产流量与累积产沙量之间呈线性函数的关系;多层次植被覆盖结构能够延长坡面侵蚀过程的发育期,缩短活跃期。研究结果对定量评价植被措施的减水减沙作用具有重要意义。

Response of Slope Runoff and Sediment Yield to Different Vegetation Cover Structures in the Loess Hilly Region

Vegetation cover structure is a key factor affecting slope erosion process. Based on the simulated rainfall experiment carried out on a slope covered by natural vegetation in Luoyugou watershed of loess hilly region, the effects of three different cover structures on slope runoff and sediment yield were studied under the condition of 90 mm/h rainfall intensity. These three cover structures included the underground root system, the underground root system plus the surface crust, as well as the combination of underground root system, the surface crust and the vegetation canopy. The results were as follows:(1) The root system of the vegetation played a leading role in enhancing soil infiltration, the amount of soil infiltration and the steady infiltration rate on the vegetation root slope increased by 67% and 39.7%, respectively, compared with those on bare slope. (2) For the three vegetation cover structures, the surface crust had the best regulation effect on the runoff and sediment yield, and the contribution rate of runoff reduction and sand reduction was 43% and 67%, respectively. (3) There was a power function relationship between the accumulative runoff yield and accumulative sediment yield in the vegetation root plot and the bare plot, and the relationship turned out to be linear function with the superposition of vegetation cover structure. (4) The multi-level vegetation cover structure could prolong the development period and shorten the active period of the slope erosion process. The research results were important for quantitative evaluation of the effects of vegetation measures on water and sediment reduction.