农业工程学报Issue(11)：110-117,8.DOI:10.3969/j.issn.1002-6819.2014.11.014
黄土坡面细沟形态变化及其与流速之间的关系
Morphological changes of rill on loess slope and its relationship with flow velocity
摘要
Abstract
Rill erosion is usually identified as a series of little rills up to 30 cm deep that can be obliterated by cultivation. Rills are small channels which function as both sediment sources and sediment transport vehicles on hill slopes. It is a quantum leap during the process of soil erosion on slopes, and is also the beginning of qualitative changes in the process of soil erosion. As an intermediate stage between overland and gully erosion, theories for soil detachments by rill erosion are different with that by inter-rill erosion. The loss of the topsoil and nutrients caused by rill erosion can reduce soil productivity, and the deposition of off-site sediments can bring sedimentation and water-quality deterioration in streams and reservoirs. Rill erosion is the main way of slope farmland erosion and plays an important role in soil erosion process on the Loess Plateau. On the Loess Plateau of China, the contribution of rill erosion can be up to more than 70% of slope erosion and about 50% of the total erosion. Studies on rill erosion can help control soil erosion on sloping land, and facilitate the development of agricultural production, and are a main content of studies on the development process of soil erosion. Rill morphology over the soil surface plays a significant role in determining the runoff and soil loss from sloping farmland. However, few attempts have been done on accurate measurement of the rill throughout the study area for that eroding rill evolves morphologically in time and space. The objectives of this study were to quantitatively measure the detailed rill morphology under controlled laboratory conditions and to provide more insight and detail for later experiments. The soil used in this study was the loess soil from Yangling, Shaanxi province in China. In this paper, in conducting indoor simulation rainfall experiments using deionized water at different slopes (10°, 15°, 20°, and 25°) and different rainfall intensities (90 mm/h and 120 mm/h), morphological changes of rill development on loess slope and its relationship with flow velocity were discussed. The results showed that: 1) Slope erosion had periodic development, and the changes of morphology of rill erosion process and changes in runoff sediment concentration was consistent; 2) the critical velocity when backward-step occurred under the experiment conditions was 0.19-0.21 m/s, and the backward-step could occur only when the flow velocity was greater than the critical values; 3) In the early stage of rill erosion development, the distance among rills affected its distribution, and backward-step did not occur among the earliest developed rills. The distance here was 12.5-17.5 cm. The rill erosion process was mainly dominated by cutting and headward erosion, and little by bank landslip; and 4) the changes of rill flow velocity with time substantially increased and then decreased, the flow velocity increased with decreased rill width, and this trend was particularly obvious on the 4 m slope where the flow velocity and width of rill were significantly (P<0.05) negatively correlated.关键词
土壤/侵蚀/流速/黄土坡面/细沟形态/坡面流速/细沟流速Key words
soils/erosion/flow velocity/loess slope/rill morphology/overland flow velocity/rill flow velocity分类
农业科技引用本文复制引用
王龙生,蔡强国,蔡崇法,孙莉英..黄土坡面细沟形态变化及其与流速之间的关系[J].农业工程学报,2014,(11):110-117,8.基金项目
国家自然科学基金面上基金项目（41271304）；黄土高原土壤侵蚀与旱地农业国家重点实验室开放基金项目 （）
