降雨和径流综合作用下的细沟断面形态分异特征

Differentiation of Cross Section Morphology in Gully Influenced by Combined Action of Rainfall and Runoff

为探究特定细沟自身的空间形态差异及其形成机制,采用室内模拟试验,研究了沿程冲刷与溯源侵蚀共同作用条件下细沟断面形态的分异特征。结果表明,沟宽与宽深比沿坡长方向呈先减小后增大的非线性规律,沟深则呈沿程减小的线性规律;沟宽与流量、坡度指数关系中的流量指数、坡度指数沿坡长方向分别由0.95、0.79降至0.47、0.31,沟深关系中流量与坡度指数也呈类似的沿程递减规律,宽深比指数关系中的两个指数在坡面下方均接近于0;沿程冲刷对细沟断面的塑造作用体现为沟宽与沟深的同时增加,作用强度沿坡长方向降低;溯源侵蚀的塑造作用体现为沟宽增大速率大于沟深,断面向宽浅方向发展,作用强度逆坡长方向降低;沿程冲刷与溯源侵蚀在空间上的叠加效应导致了细沟断面形态的分异特征。因此,在沟蚀防治过程中,可在一定汇流范围内布置截排水设施,以避免形成较大股流导致沿程冲刷与溯源侵蚀。

To explore the differentiation of cross section morphology in a specific gully.Combined effects of streamwise erosion and headward erosion on the morphology of cross section were researched based on a rainfall-runoff simulation experiment.Conclusions are as follows:Width and ratio of width to depth increased initially and then decreased along the slope,while the depth has a decreased linear trend.Along the slope,the exponents of discharge and slope gradient in the relation between width,discharge and slope gradients reduced from 0.95 and 0.79 to 0.47 and 0.31,respectively.A similar decreased trend existed in the exponents in depth equation,and the two indexes reduced to zero in width/depth equation.The effects of discharge and slope gradient on gully morphology decreased along the slope.The bed-forming function of streamwise erosion shown that the width and depth increase simultaneously,the functional intensity decreased along the slope.The function of headward erosion reflected that the increased rate of width was greater than that of depth,and the functional intensity increased along the slope.Differentiation of cross section morphology in the gully was resulted in the combined effects of the streamwise erosion and headward erosion.To prevent the gully erosion,drainage facility is necessary to avoid the streamwise erosion and headward erosion of concentrated flow.Our results are of practical significance for the water and soil erosion management in gully.