Strong anthropogenic activities and climate change have caused distinct hydrology and sediment dynamics in river systems worldwide. Yet, the integrated picture of sediment discharge changes and quantitative attribution of these changes from a basin-wide perspective were limitedly understood. In this study, we quantified the variations of sediment discharge and in-reach sediment budget in the Yellow River basin (YRB) during 1956–2019 and examined the underlying reasons. Both streamflow and sediment load in the YRB have substantially decreased during 1956–2000 except the headwater, and the reduction rate increased along the mainstem. However, the streamflow has significantly increased (p < 0.05) since 2000 due to increased precipitation, and the sediment load at most stations tended to stabilize. The contribution of soil conservation measures (SCMs, including check-dams, terraces, grass plantation, and afforestation) and reservoirs to sediment load reduction was more than 50% in the headwater and middle reaches and over 90% in the upper and lower reaches. The sediment yield coefficient decreased linearly with reservoir capacity and exponentially with the proportional area of SCMs (p < 0.01). With continuous dam construction, the channel erosion in the headwater decreased to nearly zero, and the sediment deposition in the upper and middle reaches increased linearly with storage capacity of reservoirs. In contrast, the sediment deposition in the lower reaches displayed a linear correlation with the concentration of sediment derived from the middle reaches (p < 0.05). This study provides quantitative results for sediment dynamics of entire river system, which facilitates development of sustainable watershed management strategies.

中文翻译：

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黄河从源头到三角洲的泥沙排放与达区泥沙收支时空变化

强烈的人为活动和气候变化已经在全球河流系统中造成了不同的水文和沉积物动态。然而，从流域范围的角度来看，对沉积物排放变化的综合图和这些变化的定量归因了解有限。在这项研究中，我们量化了 1956-2019 年黄河流域 (YRB) 的泥沙排放和到达泥沙收支的变化，并研究了根本原因。1956-2000 年期间，长江流域的水流和泥沙负荷除源头外均显着减少，并且沿干流减少率增加。然而，水流显着增加（p < 0.05) 自 2000 年以来，由于降水增加，大部分站点的泥沙负荷趋于稳定。水土保持措施（SCMs，包括堤坝、梯田、植草、植树造林）和水库对减少泥沙负荷的贡献在上游和中游达到50%以上，在上下游达到90%以上。产沙系数随水库容量线性下降，随SCMs的比例面积呈指数下降（p < 0.01)。随着大坝的不断建设，源头河道冲刷量下降到接近于零，上中游的泥沙沉积量随水库蓄水量呈线性增加。相比之下，下游沉积物沉积与中游沉积物浓度呈线性相关（p  < 0.05）。本研究为整个河流系统的沉积物动力学提供了定量结果，有助于制定可持续流域管理策略。