The Purapel watershed in central Chile has experienced drastic land‐use changes since the 1950s, beginning with the conversion of native forests to forest plantations. Controversy exists on the effects of reforestation on sediment production in watersheds. The temporal evolution of stage–discharge curves and sediment production was evaluated and correlated with historic sediment deposition at the Purapel watershed's main gauging station. Annual stage–discharge curves and the evolution of the stage–discharge relationship over time were developed. Trends were generated using the Mann‐Kendall statistical test, comparing results with the evolution of sediment downstream. Obtained results denote a positive and significant trend at flows greater than 90 m³ s⁻¹ (Z = 2.77). This can be explained by major flows that deepen the bed, which is consistent with a significant and sustained decrease in channel width (Z = −2.51) and the production of sediments (Z = −2.49). Similarly, the average annual number of curves decreased from 1.7 to 1.4. This analysis supports the conclusion that sediment production from the Purapel watershed drastically decreased after the majority of forest plantations were established around 1990, with important implications on how to retain sediments on degraded slopes through large‐scale afforestation projects, as well as the necessary politics to make it happen.

中文翻译：

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建立人工林后阶段-流量曲线的稳定：对沉积物生产的影响

自1950年代以来，智利中部的普拉普拉（Purapel）流域经历了急剧的土地利用变化，始于将原始森林转变为人工林。关于重新造林对流域沉积物生产的影响存在争议。评估了水位流量曲线和泥沙产生的时间演变，并将其与Purapel流域主要测量站的历史泥沙沉积相关联。制定了年度排放量曲线和排放量关系随时间的演变。使用Mann-Kendall统计检验生成趋势，将结果与下游沉积物的演化进行比较。获得的结果表明流量大于90 m ³ s ^-1时有明显的积极趋势（Z = 2.77）。这可以用加深河床的主要水流来解释，这与河道宽度（Z = -2.51）和沉积物产生（Z = -2.49）的显着且持续的减少相一致。同样，年平均曲线数从1.7减少到1.4。该分析支持以下结论：在1990年左右建立了大多数人工林后，Purapel流域的沉积物生产急剧减少，这对如何通过大规模的造林项目将沉积物保留在退化的斜坡上具有重要意义，并且具有必要的政治意义。实现它。