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  • Title: [Erosion process of loess slope and influencing factors in the loess hilly-gully region, China].
    Author: Liu R, Yu XX, Cai QG, Sun LY, Fang HY, Jia GD, He JJ.
    Journal: Ying Yong Sheng Tai Xue Bao; 2021 Aug; 32(8):2886-2894. PubMed ID: 34664462.
    Abstract:
    Rainfall intensity, slope length, and slope gradient are the important factors affecting runoff and sediment yield. In order to quantitatively analyze the effects of rainfall intensity, slope length, and slope gradient on the erosion process of Ansai loess slope in loess hilly and gully region, we analyzed the variation of runoff and sediment yield on Ansai loess with two slope lengths (5, 10 m), three slopes (5°, 10°, 15°) and two rainfall intensities (60, 90 mm·h-1) in an indoor simulated rainfall experiment. The results showed that the initial runoff generation time decreased with the increases of slope length, though the overall change was not significant. The initial runoff generation time decreased with the increases of rainfall intensity. Compared with the intensity of 60 mm·h-1, the initial runoff generation time decreased by 5.7-18 min under the intensity of 90 mm·h-1. Among them, the runoff initiation time on the slope of 10° was the fastest. With the duration of rainfall, runoff yield rate increased rapidly at first, and then gradually fluctuated around a certain value. The sediment yield rate increased rapidly in a short period of time at the initial stage of runoff generation, and then decreased after reaching the maximum, and being gradua-lly stable. The rates of runoff and sediment yield increased with the increases of slope length and rainfall intensity, but the law of change with slope was not obvious. With the increases of rainfall intensity, slope length and gradient, the total sediment yield increased accordingly. Under the rainfall intensity of 90 mm·h-1, the slope surface with the length of 10 m and slope of 15° generated rill, leading to the highest total erosion amount (11885.66 g). Under the rainfall intensity of 60 mm·h-1, the erosion amount per unit area decreased with the increases of slope length, and there was a critical erosion slope length in 5-10 m slope section. Slope length, slope and rainfall intensity all played a promoting role in runoff process. Rainfall intensity, slope length, and their interaction contributed more to runoff yield rate and total erosion amount. Rainfall intensity contributed the most to runoff yield rate, with a contribution rate of 49.8%. The contribution rate of slope length to the total erosion was the largest, which reached 37.8%. 降雨强度、坡长、坡度是影响坡面产流产沙的重要因素。为定量分析降雨强度、坡长、坡度对黄土丘陵沟壑区安塞黄土坡面侵蚀过程的影响,本研究基于室内人工模拟降雨试验,分析2个坡长(5、10 m)、3个坡度(5°、10°、15°)、2个降雨强度(60、90 mm·h-1)下安塞黄土坡面产流产沙规律。结果表明: 初始产流时间随坡长增加呈减小趋势,但总体变化不大;初始产流时间随降雨强度增加而减小,与60 mm·h-1相比,90 mm·h-1下缩短5.7～18 min;10°坡度上的径流起始时间最快。随降雨历时延长,产流率先快速增加,最终逐渐稳定在某一产流率值上下波动;产沙率在产流初期短时间内突然升高,达到最大值后减小,再逐渐达到稳定。产流率和产沙率随坡长和降雨强度的增加而增加,但随坡度变化规律不明显。随着降雨强度、坡长和坡度的增加,总产沙量相应增加。在降雨强度90 mm·h-1时,坡长和坡度分别为10 m和15°的坡面产生了细沟,导致总侵蚀量最大(11885.66 g)。降雨强度为60 mm·h-1时,随着坡长增加单位面积侵蚀量减小,在5～10 m坡段存在临界侵蚀坡长。坡长、坡度和降雨强度对坡面径流过程均有促进作用,降雨强度、坡长和两者之间交互作用对产流率和总侵蚀量的贡献率较大,其中,对产流率贡献最大的影响因素是降雨强度,贡献率为49.8%;坡长对总侵蚀的贡献率最大,为37.8%。.
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