Key Laboratory of Surficial Geochemistry, Ministry of Education, Department of Hydrosciences, School of Earth Sciences and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Nanjing, PR China.
Key Laboratory of Surficial Geochemistry, Ministry of Education, Department of Hydrosciences, School of Earth Sciences and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Nanjing, PR China.
Environ Res. 2020 Apr;183:109221. doi: 10.1016/j.envres.2020.109221. Epub 2020 Feb 7.
Hydrological and thermal river regimes have changed greatly due to the construction of reservoirs and dams. Water temperature changes have important significance for aquatic habitats and freshwater ecosystems. To investigate the impact of large reservoirs on the water temperature regime along the middle reach of the Yangtze River, we present a probabilistic modeling framework to ascertain the joint dependence structures of air-water temperature and discharge-water temperature between pre-reservoir and post-reservoir periods based on the copula theory. The results show that the principle of maximum entropy (POME) method can better estimate the marginal distributions of temperature regimes. Reservoir operation disturbed the dependence structures of air-water temperature, especially after the Three Gorges Reservoir (TGR) was put into operation. Different shifts in the occurrence probabilities of high or low water temperatures at the downstream and upstream stations under extreme air temperature and discharge are observed, indicating the great effects of reservoirs on the dependence structures of the downstream river flow and thermal regime. Relying on the developed model, we propose the appropriate ranges of air temperature and discharge to maintain a suitable water temperature for Chinese sturgeon (Acipenser sinensis) spawning activity. The results of this study demonstrate the influence of dams on the thermal regime and can be helpful for optimizing reservoir operations to enhance biological conservation in the Yangtze River.
由于水库和大坝的建设，水文和热河状况发生了巨大变化。水温变化对水生栖息地和淡水生态系统具有重要意义。为了研究大型水库对长江中游水温状况的影响，我们提出了一个概率建模框架，基于 copula 理论确定水库前后时期空气-水温和流量-水之间的联合依赖结构。结果表明，最大熵原理（POME）方法可以更好地估计温度状况的边缘分布。水库运行扰乱了空气-水温的依赖结构，特别是三峡水库（TGR）投入运行后。在极端气温和流量下，下游和上游站高或低水温发生概率的不同变化表明，水库对下游河流流量和热状况的依赖结构有很大影响。利用所建立的模型，我们提出了适宜的空气温度和流量范围，以维持中华鲟（Acipenser sinensis）产卵活动的适宜水温。本研究的结果表明了水坝对热状况的影响，并有助于优化水库运行，以加强长江的生物保护。
