黄土坡面水沙过程及水流阻力变化试验研究

为明确复杂地表产流产沙规律及其与水流阻力的关系,采用间歇性人工模拟降雨实验,开展了黄土高原的裸坡、人工掏挖、鱼鳞坑、等高沟垄四种典型坡面在五场降雨条件下的水沙演化过程、阻力来源及阻力规律研究。结果表明:鱼鳞坑、人工掏挖两种措施均以降雨时间到达55 min为临界点,继续降雨则其蓄水拦沙的作用失效。各地表水流阻力均来源于降雨阻力、颗粒阻力、形态阻力的叠加。地表输沙率与水流阻力之间均表现出负相关,输沙率随水流阻力的增大而下降。鱼鳞坑、等高沟垄措施在一定的降雨历时范围内均具有显著的减流减沙效应,而较之鱼鳞坑,等高沟垄在延缓径流,控制侵蚀方面具有更好的效用。

Study on runoff and sediment processes and flow resistances on loess slopes

Four typical microtopography slopes in the Loess Plateau were selected as bare slope,artificial digging,fish scale pits,contour plowing.With intermittent artificial rainfall experiment,runoff and sediment processes are studied on four typical slopes in five rainfall sessions.Sources and laws of resistance on special topography are analyzed.Results are shown as follows:Fish scale pits and artificial digging played a significant role in water storage and silt detention.Flow resistances of all treatments come from superposition of rain resistance,grain resistance,and form resistance.Resistance source of bare slope is mainly grain resistance,while the other three treatments were dominated by form resistance.Sediment discharge showed a negative correlation with flow resistances of four slopes.Sediment discharge decreased with increasing of flow resistances.Contour plowing and fish scale pits had significant effect on runoff and sediment reduction within certain rainfall duration.