黄土高原南部地区人工模拟暴雨条件下不同坡度谷子坡耕地产流产沙过程

以谷子坡耕地为研究对象,通过人工模拟降雨试验,探究不同生育期谷子在不同坡度下对坡耕地坡面侵蚀过程的影响,揭示黄土高原地区坡耕地侵蚀过程特征和机理。根据试验区现行退耕还林(草)政策、降雨特点及谷子生长特性,在80 mm/h降雨强度和4个坡度(3°,5°,10°,15°)条件下分别对4个生育期(幼苗期、拔节期、抽穗期、灌浆期)的谷子种植坡面进行人工模拟降雨。结果表明:种植谷子对坡耕地坡面侵蚀过程有明显影响,随着谷子的生长,坡面初始产流时间不断延长,坡面产流曲线更快趋于平稳,坡面平均产流产沙强度逐渐降低,谷子的减流效应和减沙效益逐渐提高。3°与15°坡面初始产流时间由裸地5.25,1.40 min分别延长至灌浆期12.70,7.63 min; 3°与15°坡面平均产流强度在灌浆期分别降低至0.52,0.78 L/(m~2·min),平均产沙强度在灌浆期分别降低至0.83,2.07 g/(m~2·min);与裸地相比,谷子由幼苗期生长至灌浆期,坡面径流量减少12.27%～48.24%,产沙量减少19.90%～84.00%。研究结果为揭示黄土高原谷子坡耕地侵蚀机理提供参考,并为区域高质量发展供科学依据。

Runoff and Sediment Yield Processes in Millet Cultivated Land with Different Slopes Under Artificial Simulated Rainstorm in the Southern Loess Plateau

Taking millet sloping farmland in the Loess Plateau as the research object, through artificial simulated rainfall test, the influence of millet at different growth stages on the erosion process of sloping farmland with different slope gradients was explored, and the characteristics and mechanism of the erosion process of sloping farmland in the Loess Plateau were revealed. According to the current policy of returning cultivated land to forest (grass), rainfall characteristics and millet growth characteristics in the experimental area, artificial rainfall simulation was conducted on millet planting slopes at four growth stages (seedling stage, jointing stage, heading stage and grout stage) under the conditions of 80 mm/h rainfall intensity and four slopes (3°, 5°, 10° and 15°). The results showed that millet had a significant impact on the erosion process of sloping farmland. With the growth of millet, the initial runoff yield time increased, the runoff yield curve tended to be stable in shorter time, and the average runoff and sediment yield intensity decreased, and the runoff and sediment reduction benefit of millet increased gradually. On the 3° and 15° slopes, the initial runoff yield time increased from 5.25 and 1.40 min on bare ground to 12.70 and 7.63 min at the grouting stage, respectively. On the 3° and 15° slopes, the average runoff yield strength decreased to 0.52 and 0.78 L/(m²·min) during the grouting period, and the average sediment yield strength decreased to 0.83 and 2.07 g/(m²·min) during the grouting period. Compared with bare field, runoff and sediment yield decreased by 12.27%~48.24% and 19.90%~84.00%, respectively, from seedling stage to grouting stage. The results could provide a reference for revealing the erosion mechanism of millet sloping farmland in the Loess Plateau and provide a scientific basis for regional high-quality development.