花岗岩红壤坡面沟头高度对沟床跌穴发育过程的影响  

nfluence of Headcut Height on the Developmental Processes of Gully Bed Plunge Pool on a Granite Red Soil Slope

作　　者：王建羽 林哲 廖达兰 段晓倩 邓羽松 WANG Jianyu;LIN Zhe;LIAO Dalan;DUAN Xiaoqian;DENG Yusong(Forestry College of Guangxi University,Nanning 530004,China;Agricultural College of Guangxi University,Nanning 530004,China)

机构地区：[1]广西大学林学院,南宁530004 [2]广西大学农学院,南宁530004

出　　处：《水土保持学报》2024年第3期1-11,共11页Journal of Soil and Water Conservation

基　　金：国家自然科学基金项目(42107350);中央引导地方科技发展资金项目(桂科ZY21195022)。

摘　　要：[目的]为明确花岗岩红壤坡面沟头溯源侵蚀的关键过程及形成机制。[方法]通过设定5个沟头高度(25,50,75,100,125 cm)研究花岗岩红壤坡面沟床跌穴发育过程。[结果](1)随沟头高度增加,沟床径流雷诺数、径流剪切力、径流功率和射流参数(触底流速、射流剪切应力、瞬时动能、跌穴径流能耗)均表现为增加趋势。(2)红土层沟床形成“V”形跌穴,随流量增加跌穴形态变化增大,但只形成面积较小的跌穴。而砂土层在冲刷过程中,沟床跌穴发育较为明显,当流量增大到120 L/min后,沟床破碎化程度增加,跌穴轮廓逐渐清晰,横截面积增大。(3)通过随机森林算法和沙普利值构建并表征模型各参数的关系,红土层沟床径流的弗罗德数、径流功率、水平出射动能、雷诺数与横截面积呈负相关;砂土层沟床径流的弗罗德数和跌穴径流能耗与横截面积呈负相关。沟床跌穴侵蚀程度可用随机森林算法构建模型预测(LCCC=1.02,R_(adjusted)^(2)=0.876和0.868)。[结论]研究结果可为揭示沟头溯源侵蚀机理和沟蚀防治提供理论依据。[Objective]Headcut bed plunge pool point development is a key process in headcut erosion on granitic red soil slopes,but the mechanism of its formation is not clear.[Methods]We investigated the process of gully bed plunge pool development on granite red soil slopes by setting five headcut heights(25,50,75,100 and 125 cm).[Results](1)As the height of the headcut increased,the Re,τ,ωand the jet parameters(Vbottom,τmax,EKbottom,andΔEH)showed an increasing trend.(2)After the laterite soil layer scouring to form a"V"type of small plunge pool,with the increase in the flow of the form of plunge pool gradually increased,but it is difficult to form a large area of the plunge pool,and the laterite soil layer is more stable than the sandy soil layer.During the scouring process of the sandy soil layer,the development of headcut bed drop points was more obvious,and when the flow rate increased to 120 L/min,the degree of gully bed fragmentation was gradually drastic,and the outline of the drop points was gradually clearer,and the cross-sectional area increased.(3)The random forest algorithm and Shapley values were used to construct the model and characterize the relationship between the parameters.The results showed that in the laterite layer,Fr,ω,EKbrink,and Re were negatively correlated with the cross-sectional area;and in the sandy soil layer,Fr andΔEH were negatively correlated with the cross-sectional area.Higher accuracy of predictive models constructed by the random forest algorithm(LCCC=1.02,R^(2)_(adjusted)=0.876 and 0.868).[Conclusion]The results of the study can provide a theoretical basis for revealing the mechanisms of headcut erosion and gully erosion control.

关 键 词：花岗岩红壤 沟床跌穴 水力参数 形态演变 

分 类 号：S157.1[农业科学—土壤学]