黄土陡坡裸露坡耕地浅沟发育过程研究

根据黄土陡坡地浅沟地形特征参数,在室内人工建筑浅沟发育初期的雏形模型,研究浅沟发育不同阶段沟头溯源侵蚀、沟壁扩张和沟槽下切变化规律,分析浅沟侵蚀对坡面侵蚀产沙的贡献。结果表明,浅沟发育不同阶段对应于不同的浅沟侵蚀过程。浅沟发育初期,沟头溯源侵蚀、沟壁扩展和沟床下切均相对活跃,且溯源侵蚀速率大于沟壁扩张速率和沟床下切速率;浅沟发育中期,以沟槽下切和沟壁扩张为主;浅沟发育后期,以沟壁扩张为主,但沟壁扩张速率明显小于浅沟发育的初期和中期阶段。浅沟发育初期和中期阶段,浅沟侵蚀量占总坡面侵蚀产沙的58%;浅沟发育后期,浅沟侵蚀量占总坡面侵蚀产沙的26%~59%。

Ephemeral Gully Development Process at Loess Steep Hillslope

According to the topographic characteristic parameters of ephemeral gully at loess steep hillslopes,the mold of ephemeral gully shape at initial stage was made to quantify the change processes of ephemeral gully headcut advance,gully-wall collapse and channel deep-cutting in three stages(the beginning,middle and late stages) of ephemeral gully development.The results showed that different stages of ephemeral gully development corresponded to different ephemeral gully erosion process.In the beginning stage of ephemeral gully development,ephemeral gully headcut,gully-wall collapse and channel deep-cutting were very active,the speed of ephemeral headcut advance was much higher than the speeds of gully-wall expansion and channel deep-cutting.In the middle stage, gully-wall collapse and channel deep-cutting were dominant.In the late stage,gully-wall collapse was dominant,but the speed of gully-wall expansion was lower than that in middle stage.In the beginning and middle stages of ephemeral gully development,ephemeral gully erosion accounted for 58.4% of the total sediment yield in ephemeral gully catchment;in the late stage,ephemeral gully erosion took up 26%-594% of the total sediment yield.