Evaluating gully erosion using 137Cs and 210Pb/137Cs ratio in a reservoir catchment
Evaluating gully erosion using 137Cs and 210Pb/137Cs ratio in a reservoir catchment
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DOI：
10.1016/s0167-1987(02)00132-0
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发表时间：
2003-02
影响因子：
6.5
通讯作者：
Y. Li;J. Poesen;Jc Yang;B. Fu;Jh Zhang
中科院分区：
文献类型：
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作者：
Y. Li;J. Poesen;Jc Yang;B. Fu;Jh Zhang
西部丘陵区的水蚀是黄河、长江泥沙的主要来源。沟道侵蚀在总输沙量中的作用大多被忽略。以羊圈沟水库流域为研究对象，分析了流域尺度和坡面尺度的产沙和泥沙来源。利用放射性核素137 Cs示踪技术，研究了不同土地利用方式下坡面水蚀产沙的分布规律。利用水库的泥沙记录估算了流域的总产沙量。通过比较表层土壤和次表层土壤中137 Cs活度和210 Pb/137 Cs比值，以及水库泥沙沉积物在集水区出口处的含量，确定了沉积物来源和主要的水蚀过程。结果表明，景观位置对耕地坡面产沙的影响最大，其次是梯田坡面，最小的是植被坡面。坡面产沙量的增加顺序为：耕作坡地顶部>上部>下部>中部，梯田坡地顶部>下部>上部>中部。与耕作坡地相比，梯田坡地的平均产沙量减少了49%，植被坡地减少了80%。与耕作沟坡相比，植被沟坡的产沙量减少了38%。这些数据表明，梯田和多年生植被覆盖在控制沉积物输送在山坡规模的有效性。0-5cm土壤~（137）Cs平均活度和~（210）Pb/~（137）Cs比值（2.22-4.70Bqkg-1和20.70-22.07）和5- 30 cm的底土耕地丘陵和沟坡上的Bqkg-1和28.57接近于水库沉积物的Bqkg-1（分别为3.37Bqkg-1和29.08）。这些结果表明，在集水区的主要泥沙来源是从表层土壤和底土的耕作斜坡，沟蚀是主要的水蚀过程中贡献的泥沙在研究区。土地利用类型的变化可以极大地影响沟道侵蚀的产沙量。草地和林地增加了42%，农田相应减少了46%，流域的泥沙产量减少了31%。
Water erosion in the hilly areas of west China is the main process contributing to the overall sediment of the Yellow River and the Yangtze River. The impact of gully erosion in total sediment output has been mostly neglected. Our objective was to assess the sediment production and sediment sources at both the hillslope and catchment scales in the Yangjuangou reservoir catchment of the Chinese Loess Plateau, northwest China. Distribution patterns in sediment production caused by water erosion on hills and gully slopes under different land use types were assessed using the fallout137Cs technique. The total sediment production from the catchment was estimated by using the sediment record in a reservoir. Sediment sources and dominant water erosion processes were determined by comparing137Cs activities and210Pb /137Cs ratios in surface soils and sub-surface soils with those of sediment deposits from the reservoir at the outlet of the catchment. Results indicated that landscape location had the most significant impact on sediment production for cultivated hillslopes, followed by the terraced hillslope, and the least for the vegetated hillslope. Sediment production increased in the following order: top>upper>lower>middle for the cultivated hillslope, and top>lower>upper>middle for the terraced hillslope. The mean value of sediment production declined by 49% for the terraced hillslope and by 80% for the vegetated hillslope compared with the cultivated hillslope. Vegetated gully slope reduced the sediment production by 38% compared with the cultivated gully slope. These data demonstrate the effectiveness of terracing and perennial vegetation cover in controlling sediment delivery at a hillslope scale. Averaged137Cs activities and210Pb /137Cs ratios in the 0–5cm surface soil (2.22–4.70Bqkg−1and 20.70–22.07, respectively) and in the 5–30cm subsoil (2.60Bqkg−1and 28.57, respectively) on the cultivated hills and gully slopes were close to those of the deposited sediment in the reservoir (3.37Bqkg−1and 29.08, respectively). These results suggest that the main sediment sources in the catchment were from the surface soil and subsoil on the cultivated slopes, and that gully erosion is the dominant water erosion process contributing sediment in the study area. Changes in land use types can greatly affect sediment production from gully erosion. An increase in grassland and forestland by 42%, and a corresponding decrease in farmland by 46%, reduced sediment production by 31% in the catchment.