降雨和汇流条件下浅沟侵蚀过程试验研究

目的]探究含沙水流汇入对含有浅沟微地形的裸土和草地坡面的侵蚀产沙过程的影响,为该地区浅沟侵蚀治理提供理论依据,并为坡沟系统的土壤侵蚀模型建立奠定基础。方法]通过降雨和放水相结合的野外模拟试验和人工建筑的浅沟模型开展研究。结果]含沙水流汇入裸土浅沟坡面的侵蚀量增加了15%～58%,而对草地浅沟坡面的侵蚀影响不显著,说明草地恢复对于减少由汇流作用的侵蚀具有显著效益。试验条件下裸坡和草地坡面泥沙浓度都在产流开始时达到最大然后逐渐降低,最后达到稳定,然而含沙水流汇入使得泥沙浓度达到稳定所需的时间延长。含沙水流汇入能够显著增加浅沟发育速度,特别是浅沟沟宽和下切深度增加明显,草地恢复可以显著减缓浅沟的下切侵蚀,进而减缓浅沟的发育速度。对于裸土和草地浅沟坡面,含沙水流汇入显著增加了浅沟部位流速,尤其是草地浅沟部位各坡段流速平均增幅达到了55%。结论]增加含沙水流汇入会显著增加裸坡坡面上的浅沟侵蚀量和浅沟的发育速度,而对草地坡面上浅沟的侵蚀和发育影响不显著。

Experimental Study on Ephemeral Gully Erosion Processes Under Simulated Rainfall and Silt-laden Inflows

Objective] The influences of silt-laden inflow on ephemeral gully erosion process of bare slope and grassland slope were studied in order to provide theoretical basis for soil erosion control of ephemeral gully and lay a foundation for establishing a soil erosion model for loess areas.Methods] A series of field rainfall simulation experiments were conducted on an artificial ephemeral gully(EG) to investigate the impacts of upslope inflowon runoff and erosion processes within the EG.Results] The silt-laden inflow significantly increased the erosion of the bare slope with ephemeral gully by 15%~58%, and had no significant effect on the erosion of the grassland with ephemeral gully, indicating that grassland had significant benefits for reducing the erosion caused by the convergence. Under the experimental conditions, the sediment concentration of the bare slope and the grassland slope reached the maximum at the beginning of the runoff and then gradually decreased, and finally kept stable. However, the time required for the sediment concentration to stabilize under the silt-laden inflow increased. The silt-laden inflow accelerated the development of ephemeral gully, especially on the width and the depth of the ephemeral gully. While the grassland significantly slowed down the erosion of the ephemeral gully, especially the development of ephemeral gully under cut retarded. For the bare slope and grassland with ephemeral gully, the silt-laden inflow increased the flow velocity of the ephemeral gully, especially the average velocity of the grassland with ephemeral gully increased by 55%.Conclusion] The amount of ephemeral gully erosion and the speed of ephemeral gully development on bare slope increased with increasing silt-laden inflow, while the impact on the erosion and development of the ephemeral gully on grassland slope was not significant.