【摘要】 雨型对细沟侵蚀过程起关键作用,而横垄坡面具有独特的细沟侵蚀特征。为定量研究雨型对横垄坡面细沟侵蚀过程的影响,以褐土横垄坡面为研究对象,设计了降雨动能、降雨量和平均雨强相同的4种雨型,采用可同时调节垄向和坡面坡度的土槽进行模拟降雨,分析了各雨型下细沟发育形态、产流产沙特征和细沟水流的水动力特性等。结果表明:雨型间细沟沟头溯源、沟壁崩塌和沟底下切侵蚀速率的不同导致细沟形态具有明显差异,增加-减弱型、减弱-增加型和减弱型的沟宽和沟深较增加型分别增加158.8%和38.9%,115.7%和-27.8%,21.6%和-33.3%,相应宽深比的增加率分别为14.9%,60.4%,82.6%。雨型间的细沟径流量和侵蚀量均差异显著,径流量为增加-减弱型>减弱-增加型>减弱型>增加型,而侵蚀量为增加-减弱型>减弱型>减弱-增加型>增加型。4种雨型下产沙率与径流率之间均符合幂函数关系,但增加-减弱型、减弱型和减弱-增加型方程中的指数较增加型(0.54)分别增加2.52,2.46,1.46倍。雨型间差异最大的水力学参数为雷诺数,侵蚀动力参数则为水流功率;增加-减弱型、减弱-增加型和减弱型的雷诺数和水流功率较增加型分别显著增加107.0%和106.8%,42.2%和41.9%,16.6%和16.7%。研究结果有助于深入理解横坡垄作对坡面细沟侵蚀过程的作用机制,并为横坡垄作措施的合理利用提供依据。更多还原

【Abstract】 Storm pattern plays a key role on rill erosion processes,and contour ridging has the unique characteristic of rill erosion.In this study,simulated rainfall experiment was conducted to determine the characteristics of rill morphology,runoff and sediment yielding,flow hydraulic characteristics and dynamic mechanisms of rill erosion.Using the runoff box for simultaneously changing the row grade and field slope,four storm patterns(the rising,falling,rising-falling,and falling-rising patterns)were set on cinnamon soil in a contour ridge system.All patterns included three rainfall intensities:30,60,and 90mm/h,and comprised the same kinetic energy,total rainfall amount,and average rainfall intensity.Results showed that the differences in rates of headward erosion,bank landslip,and the downcutting of rill bottom among storm patterns greatly changed rill morphology.Compared with the rising pattern,rill width and depth from the risingfalling,falling-rising,and falling patterns increased by158.8%and 38.9%,115.7%and-27.8%,21.6%and-33.3%respectively,while the correspondingly increased ratios of width to depth were 14.9%,60.4%,and82.6%,respectively.Rill runoff and sediment yield showed significant differences among storm patterns.Runoff ranked in the following order:the rising-falling >falling-rising >falling > rising pattern,and sediment yield was in order of the rising-falling>falling>falling-rising>rising pattern.Regardless of storm pattern,power function relationship was found between runoff rate and sediment yield rate,while the exponent in the rising-falling,falling,and falling-rising patterns increased by 2.52,2.46,and 1.46 timesrespectively,compared with the rising pattern.As for rill flow hydraulic characteristics,the largest difference occurred in Reynolds number,and stream power was in dynamic mechanisms parameter.Reynolds number and stream power from the rising-falling,falling-rising,and falling patterns significantly increased by107.0%and 106.8%,42.2%and 41.9%,16.6% and 16.7%,respectively,compared with the rising pattern.These findings would help understand the mechanism of contour ridge influence on rill erosion process,and was of great importance to apply the contour ridge tillage for soil erosion control.更多还原