Understanding the spatial and temporal distribution and driving factors of the nutritional status in the backwater area of typical tributaries in the Three Gorges Reservoir Region (TGRR) is important for the prevention and control measures. In this study, the Environmental Fluid Dynamics Code (EFDC) was used to extend in situ monitoring data, followed by the application of hydrogen and oxygen isotope data and scoring methods to predict the nutritional status in the backwater area of the Daning River. The results indicated that the nutritional status-sensitive period mainly ranged from May-October and was distributed at the end of the backwater area and tributary bay. The water temperature and intermediate density flow were identified as the key factors inducing deterioration in the nutritional status at the end of the backwater area and tributary bay, respectively. Nutrient reduction in the mainstream and tributary areas significantly affected the nutritional status in the backwater area. Notably, hydrodynamic adjustment under reservoir objectives is indispensable for improving the water environment in tributary bay after reaching the water quality standard. Our findings highlight the necessity of focusing on the upper reaches of the tributaries and reservoir for nutrient control and emphasize the importance of combining reservoir operation strategies to mitigate the deterioration in the nutritional status.

中文翻译：

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水库支流回水区营养状况及其对养分控制的意义


了解三峡库区典型支流回水区营养状况的时空分布及其驱动因素，对于防治措施具有重要意义。本研究采用环境流体动力学代码 （EFDC） 扩展原位监测数据，随后应用氢氧同位素数据和评分方法预测大宁河回水区营养状况。结果表明：营养状况敏感期主要在5—10月，分布在回水区和支流湾末端。水温和中等密度流量分别是导致回水区和支流湾末端营养状况恶化的关键因素。干流和支流地区养分减少显著影响了回水地区的营养状况。值得注意的是，在达到水质标准后，水库目标下的水动力调整对于改善支流湾水环境是必不可少的。我们的研究结果强调了关注支流和水库上游进行营养控制的必要性，并强调了结合水库运行策略以减轻营养状况恶化的重要性。