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黄土高原丘陵沟壑区小流域广泛分布的淤地坝不仅是治理水土流失的重要工程措施,同时也成为记录小流域侵蚀产沙历史变化过程的重要载体。本研究以陕西省绥德县王茂沟流域一级支沟——淤积年限为34年(1957-1990),淤积深度为11.325m的闷葫芦坝为研究对象,根据坝地沉积剖面的物理特征,发现该沉积剖面共有75个泥沙沉积旋廻,其中深度为818.5～903.5cm的沉降旋廻(第67个)137Cs含量最高,达4.90Bq/kg。根据1957-1990年间的降雨量资料和137 Cs的时标特征,建立了淤地坝沉积序列的时间坐标。在此基础上依据泥沙沉积量的累积曲线,将淤地坝运行期间小流域侵蚀历史划分为3个时期:1957-1964年的侵蚀剧烈期,年均侵蚀模数为16578.5t/km2;1965-1983年侵蚀相对平缓期,年均侵蚀模数为6062.9t/km2;1984-1990年,侵蚀再次增大期,年均侵蚀模数为19127.5t/km2。
Widely distributed silt dam in the small watershed in the hilly and gully regions of the Loess Plateau is not only an important engineering measure to control soil and water loss, but also an important carrier to record the historical process of soil erosion and sediment change in the small watershed. In this study, the first branch of Wangmaogou watershed in Suide County, Shaanxi Province - sediment age of 34 years (1957-1990), siltation depth of 11.325m of the stuffed gourd dam as the research object, according to the physical characteristics of the sediment profile, A total of 75 sediments of sediment deposition were found in this sedimentary section. Among them, the sedimentation volume of 137 Cs with the depth of 818.5-903.5 cm was the highest (4.90Bq / kg). Based on the rainfall data from 1957 to 1990 and the time-scale characteristics of 137 Cs, the time coordinates of the sedimentary sequence of the silt dam were established. On this basis, based on the cumulative curve of sediment deposition, the erosion history of small watershed during the operation of the check dam is divided into three periods: severe period of erosion from 1957 to 1964, average annual erosion modulus of 16578.5t / km2; 1965 In 1983, the erosion period was relatively flat with an average annual erosion modulus of 6062.9 t / km2. From 1984 to 1990, erosion increased again with an average annual erosion modulus of 19127.5 t / km2.