Soil and water conservation are important measures in regulating runoff and sediment load on the Loess Plateau. Information on how land use and land cover changes, especially the implementation of the soil and water loss control project, can affect the sediment load dynamics and hydrological variables is important since large-scale eco-environmental governance programs are being implemented. In this study, an improved double mass curve and the decomposition method were used to assess the effects of different soil and water control measures on runoff and sediment load in the Lvergou, which is a small basin on the Loess Plateau in China, based on 60 years of data. We conclude that the total precipitation (P) was not statistically significantly different (p > 0.05), whereas heavy rain increased significantly (p < 0.01). Annual runoff (R) and sediment load (S) decreased significantly from 1954 to 2010, with abrupt changes in 1990 and 1986. Sensitivity analysis indicates that P is more influential than temperature (T) in affecting R and S. This study indicates that soil and water conservation are the strongest contributors to reducing annual runoff and sediment load, with their contributions reaching 84.2% and 91.1%, respectively, while the remaining percentage was caused by climate variations. Among all soil and water conservation measures, the runoff and sediment load in the basin were most sensitive to the terrace. There were obvious changes in the rainfall-flood and rainfall-sediment relationships due to extreme rainfall conditions. Compared with historical extreme rainfall events, the decreases in flooding and sediment load in the river basin after 2000 under similar rainfall and intensity conditions were obvious. This result further indicates that the implementation of soil and water conservation measures plays an important role in reducing flooding and sediment load in this region by changing the water-sediment relationship during extreme rainfall. These results can provide important an reference for understanding the causes of sharp decrease of water and sediment in the Loess Plateau basin.

中文翻译：

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黄土丘陵沟壑区水土保持措施对减少产沙量的影响

水土保持是黄土高原调节径流泥沙负荷的重要措施。由于正在实施大规模的生态环境治理计划，因此有关土地利用和土地覆盖变化的信息，特别是水土流失控制项目的实施，如何影响泥沙负荷动态和水文变量是很重要的。本研究采用改进的双质量曲线和分解方法，基于 60年的数据。我们得出结论，总降水量 (P) 在统计上没有显着差异 (p > 0.05)，而大雨显着增加 (p < 0.01)。1954—2010年年径流（R）和泥沙负荷（S）显着下降，1990年和1986年发生突变。敏感性分析表明，P对R和S的影响大于温度（T）。本研究表明土壤节水和节水是减少年径流和泥沙负荷的最强贡献者，贡献率分别达到84.2%和91.1%，其余百分比是由气候变化引起的。在所有水土保持措施中，流域的径流和泥沙负荷对阶地最为敏感。由于极端降雨条件，降雨-洪水和降雨-沉积物关系发生明显变化。与历史极端降雨事件相比，2000年以后，在相似降雨强度条件下，流域洪水和泥沙负荷下降明显。这一结果进一步表明，水土保持措施的实施，通过改变极端降雨期间的水沙关系，对减轻该地区的洪水和泥沙负荷具有重要作用。这些结果可为了解黄土高原盆地水沙急剧减少的原因提供重要参考。