梁越, 秦伟, 张勤, 丁琳, 许海超, 石晨雨, 安乐平. 多时间尺度小流域侵蚀产沙对土地利用/覆被格局的变化响应[J]. 农业工程学报, 2023, 39(8): 155-166. DOI: 10.11975/j.issn.1002-6819.202301056
    引用本文: 梁越, 秦伟, 张勤, 丁琳, 许海超, 石晨雨, 安乐平. 多时间尺度小流域侵蚀产沙对土地利用/覆被格局的变化响应[J]. 农业工程学报, 2023, 39(8): 155-166. DOI: 10.11975/j.issn.1002-6819.202301056
    LIANG Yue, QIN Wei, ZHANG Qin, DING Lin, XU Haichao, SHI Chenyu, AN Leping. Response of sediment yield under different temporal scales to land use/cover pattern changes in typical watershed of Loess Plateau[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2023, 39(8): 155-166. DOI: 10.11975/j.issn.1002-6819.202301056
    Citation: LIANG Yue, QIN Wei, ZHANG Qin, DING Lin, XU Haichao, SHI Chenyu, AN Leping. Response of sediment yield under different temporal scales to land use/cover pattern changes in typical watershed of Loess Plateau[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2023, 39(8): 155-166. DOI: 10.11975/j.issn.1002-6819.202301056

    多时间尺度小流域侵蚀产沙对土地利用/覆被格局的变化响应

    Response of sediment yield under different temporal scales to land use/cover pattern changes in typical watershed of Loess Plateau

    • 摘要: 为阐明多时间尺度小流域侵蚀产沙对土地利用/覆被格局的变化响应机制,该研究基于吕二沟流域1982-2020年逐日降雨、水沙实测资料和土地利用/覆被数据,综合运用 K-均值聚类法、多元回归分析等方法,从年际和年内月际2个时间尺度对比分析了不同土地利用/覆被格局下的流域侵蚀产沙变化及其与泥沙连通性指数的关系。结果表明:1)1982-2020年间,吕二沟流域由耕地为主体向农林草复合结构转变、泥沙连通性指数显著下降,可将整个研究期划分为1982-1985年、1986-1990年、1991-2000年和2001-2020年共4个阶段,分别对应土地利用/覆被格局Ⅰ、Ⅱ、Ⅲ和Ⅳ。2)随着以林草地增加为主的土地利用/覆被变化,流域产流、产沙能力减弱。相较土地利用/覆被格局Ⅰ,土地利用/覆被格局Ⅳ的年均径流深显著降低;后期土地利用/覆被格局(Ⅲ和Ⅳ)下的汛期月产流产沙能力显著小于前期(土地利用/覆被格局Ⅰ)。3)基于月降雨量、月最大日降雨量和月侵蚀性降雨日数3个降雨指标,可将研究期内的汛期月降雨划分为4种类型:小雨量、弱侵蚀性的A型,中雨量、弱侵蚀性的B型,大雨量、中侵蚀性的C型,大雨量、强侵蚀性的D型;在大雨量中侵蚀性的C型降雨下,不同土地利用/覆被格局间的月际径流深和产沙模数均不存在显著差异(P>0.05)。年际和月际尺度下,小流域产沙模数均与泥沙连通性指数呈指数递增关系,但C雨型下的关系减弱。研究为干旱半干旱区流域土地利用/覆被格局优化配置和功能提升提供科学依据。

       

      Abstract: Abstract: The influence of land use/cover patterns on soil erosion and sediment transport can be one of the most important indicators to optimize the soil and water conservation measures in a watershed. However, it is still lacking in the quantitative evaluation of the land use/cover pattern and their impacts on soil erosion and sediment yield at the watershed scale. This study aims to explore the long-term changes in the sediment yield on the interannual and intermonthly temporal scales from 1982 to 2020, together with their responses to the land and use/cover pattern. A typical watershed was selected in the Loess Plateau, and the Lyuergou watershed. The M-K trend analysis was employed to elucidate the long-term temporal trends of annual rainfall, runoff, and sediment yield in the study area. An investigation was explored on the changes in the runoff and sediment under different vegetation patterns using the land use/cover pattern. The index of connectivity was chosen to characterize the impacts of the land use/cover pattern on soil erosion and sediment yield. Accordingly, quantitative relationships were also established between the index of connectivity and sediment yield. In addition, the monthly rainfall amount, the maximum daily rainfall amount, and erosive rainfall days were selected as the indices to classify the rainfall types. The results indicated that the Lyuergou watershed experienced cropland abandonment and vegetation restoration, where the index of connectivity decreased significantly during 1982-2020. Consequently, the whole study period was divided into four stages: 1982-1985, 1986-1990, 1991-2000, and 2001-2020, corresponding to the land use/cover pattern Ⅰ, Ⅱ, Ⅲ, and Ⅳ, respectively. The average annual sediment yield varied consistently, as the land use/cover pattern changed. Significantly downward trends were found in the average annual sediment yield and runoff depth, whereas, the annual rainfall amount showed no significant changing trend. Specifically, the annual runoff depth and sediment yield of land use/cover pattern Ⅳ decreased by 74.5% and 68.1%, respectively, compared with the land use/cover pattern Ⅰ, respectively. The average monthly runoff depth and sediment yield in the flood season were 11.7, 5.9, 1.8, 4.0 mm and 713.4, 377.4, 112.0, 317.9 t/km2 in the land use/cover pattern Ⅰ, Ⅱ, Ⅲ, and Ⅳ, respectively. The runoff depth and sediment yield under the later land use/cover pattern (Ⅲ and Ⅳ) were significantly lower as opposed to those in the early land use/cover pattern Ⅰ. The erosive rainfall in the flood season was classified into four types: type A (minor rainfall amount, and weaker rainfall erosivity), type B (medium rainfall amount, and weaker rainfall erosivity), type C (great rainfall amount, and medium rainfall erosivity), and type D (great rainfall amount, and larger rainfall erosivity). Type A, B and C contributed to the most sediment yield on the small watershed. However, there was no significant difference in the monthly runoff depth and sediment yield among different land use/cover patterns under type C. The sediment yield on both interannual and intermonthly scales increased exponentially with index of connectivity, whereas the relationships were weaker under type C. The finding can provide a strong reference to the optimal allocation of land use/cover patterns and soil and water conservation measures in arid and semi-arid areas.

       

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