玉米季横垄坡面片蚀阶段产流及水动力学参数变化特征

Change Characteristics of Runoff and Hydrodynamic Parameters of Sheet Erosion Processes on Cross Ridge Sloping Farmland during Maize Growing Season

为弄清玉米各生育期片蚀阶段的径流特征,采用人工模拟降雨与微小区试验相结合的方法,研究不同坡度下紫色土横垄坡面片蚀阶段产流及水动力学参数变化特征。结果表明:(1)15°坡面,拔节期和抽雄期片蚀出现时间在8min后,且与苗期和成熟期间达显著差异;20°坡面,拔节期和抽雄期片蚀出现时间在6min后,且与苗期、成熟期片蚀出现时间达显著差异。(2)15°坡面,径流总量和产流率均表现为成熟期>苗期>抽雄期>拔节期,且成熟期径流总量和产流率分别为31.25L和1.04L/min;20°坡面,径流总量和产流率却表现为苗期>成熟期>抽雄期>拔节期,且成熟期径流总量和产流率分别为34.62L和1.44L/min;径流总量和产流率总体表现为20°坡面显著高于15°坡面。(3)15°坡面,水流剪切应力在各生育期无显著差异,其它水动力学参数均表现为抽雄期最小,成熟期和苗期较大。20°坡面,单位水流功率在各生育期无显著差异,其它水动力学参数表现为拔节期或抽雄期最小,成熟期或苗期最大。断面单位能量和水流功率是试验条件下与横垄坡面片蚀产流率关系最密切的水动力学参数,可较好地表征横垄坡面产流特征。研究结果可为紫色土丘陵区坡耕地片蚀的有效防控提供理论依据。

To clarify the runoff characteristics of sheet erosion during maize growing season,change characteristics of runoff and hydrodynamic parameters of sheet erosion processes were studied on cross ridge sloping farmland with different slope gradients during whole maize growing stage in purple soil area based on the combining method of micro-plot and artificial simulated rainfall.The results showed that（1）The time of sheet erosion occurrence was after 8minutes of the rainfall on slope gradient with 15°at the jointing stage and tasseling stage,and the time of sheet erosion occurrence had the significant difference between the jointing stage,tasseling stage and seedling stage,mature stage.The time of sheet erosion occurrence was after 6minutes of the rainfall on slope gradient with 20°at the jointing stage and tasseling stage,and the time of sheet erosion occurrence had the significant difference between the jointing stage,tasseling stage and seedling stage,mature stage.（2）On slope gradient with 15°,the runoff amount and runoff rate showed that mature stageseedling stagetasseling stagejointing stage,and the runoff amount and runoff rate was 31.25 L and 1.04L/min respectively at the mature stage.However,on slope gradient with 20°,the runoff amount and runoff rate showed that seedling stagemature stagetasseling stagejointing stage,and the runoff amount and runoff rate was 34.62 Land 1.44L/min respectively at the seedling stage.The runoff amount ascended with the increasing slope gradient during whole maize growing stage.（3）On slope gradient with 15°,runoff shear stress had no significant difference among the growing stages of maize,and the other hydrodynamic parameters showed the minimum at tasseling stage,and a large value appeared at mature stage and seeding stage.On slope gradient with 20°,unit stream power had no significant difference among the growing stages of maize,and the other hydrodynamic parameters showed the minimum at tasseling stage or joint-ing stage,and the maximum appeared at mature stage or seeding stage.Stream power and section flow energy were the best parameters closely related to the runoff rate of sheet erosion process on cross ridge sloping farmland.Runoff characteristics of the cross ridge sloping farmland could be well described by stream power and section flow energy on the condition of our experiment.This results would provide theory basis for the effective prevention and control of sheet erosion in purple soil area.