Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China.
Environ Sci Pollut Res Int. 2018 Dec;25(35):35084-35098. doi: 10.1007/s11356-018-3387-y. Epub 2018 Oct 16.
Floodplain lakes are valuable to humans because of their various functions and are characterized by dramatic hydrological condition variations. In this study, a two-dimensional coupled hydrodynamic and water quality model was applied in a large floodplain lake (i.e., Poyang Lake), to investigate spatial and temporal water quality variations. The model was established based on detailed data such as lake terrain, hydrological, and water quality. Observed lake water level and discharge and water quality parameters (TN, TP, COD, and NH-N) were used to assess model performance. The hydrodynamic model results showed satisfactory results with R and MRE values ranging between 0.96 and 0.99 and between 2.45 and 6.14%, respectively, for lake water level simulations. The water quality model basically captured the temporal variations in water quality parameters with R of TN, TP, COD, and NH-N simulation ranges of 0.56-0.91, 0.44-0.66, 0.64-0.67, and 0.44-0.57, respectively, with TP of Xingzi Station and COD of Duchang Station excluded, which may be further optimized with supplementation of sewage and industrial discharge data. The modeled average TN, TP, COD, and NH-N concentrations across the lake were 1.36, 0.05, 1.99, and 0.48 mg/L, respectively. The modeled spatial variations of the lake showed that the main channel of the lake acted as a main pollutant passageway, and the east part of the lake suffered high level of pollution. In addition, consistent with previous water quality evaluations based on field investigations, water quality was the highest (average TN = 1.35 mg/L) during high water level periods and the poorest (average TN = 1.96 mg/L) during low water level periods. Scenario analysis showed that by decreasing discharge of upstream flow by 20% could result in the increase of TN and TP concentrations by 25.6% and 23.2% respectively. In summary, the model successfully reproduced the complex water and pollutant exchange processes in the systems involving upstream rivers, the Poyang Lake, and the Yangtze River. The model is beneficial for future modeling of the impact of different load reduction and other hydrological regime changes on water quality variation and provides a relevant example for floodplain lake management.
由于具有多种功能，泛滥平原湖泊对人类具有重要价值，其水文条件变化显著。本研究应用二维水动力和水质耦合模型对大型泛滥平原湖泊（即鄱阳湖）进行了时空水质变化研究。该模型基于湖泊地形、水文和水质等详细数据建立。利用实测湖泊水位和流量以及水质参数（TN、TP、COD 和 NH-N）来评估模型性能。水动力模型结果表明，湖泊水位模拟的 R 和 MRE 值分别在 0.96 到 0.99 之间以及 2.45 到 6.14%之间，具有较好的效果。水质模型基本能够捕捉水质参数的时间变化，TN、TP、COD 和 NH-N 的 R 值模拟范围分别为 0.56-0.91、0.44-0.66、0.64-0.67 和 0.44-0.57，除了星子站的 TP 和都昌站的 COD 之外，这些参数可能需要进一步优化，并补充污水和工业排放数据。模型计算得到的鄱阳湖平均 TN、TP、COD 和 NH-N 浓度分别为 1.36、0.05、1.99 和 0.48mg/L。模型模拟得到的湖泊空间变化表明，湖泊的主河道是主要的污染物通道，湖泊的东部受到较高水平的污染。此外，与基于野外调查的先前水质评价结果一致，高水位期水质最好（平均 TN=1.35mg/L），低水位期水质最差（平均 TN=1.96mg/L）。情景分析表明，上游流量减少 20%，TN 和 TP 浓度将分别增加 25.6%和 23.2%。总的来说，该模型成功地再现了涉及上游河流、鄱阳湖和长江的复杂水和污染物交换过程。该模型有利于未来模拟不同的负荷减少和其他水文条件变化对水质变化的影响，并为泛滥平原湖泊管理提供了一个相关的范例。
