College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China; State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China.
State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China.
Sci Total Environ. 2019 Mar 25;658:1085-1097. doi: 10.1016/j.scitotenv.2018.12.207. Epub 2018 Dec 17.
Thermal stratification is common in reservoirs and greatly influences the aquatic environment. Changes in the uniformity of intra-annual runoff have been detected in several basins, but few studies have focused on the impacts that these changes have on thermal regimes. Using runoff data for Sanbanxi Reservoir, China, during 1950-2015, the long-term trends of intra-annual runoff uniformity were statistically analyzed and extrapolated for the 2050s and 2090s, and the relationship between these trends and the thermal regime of the reservoir were investigated. Moreover, the thermal regime was evaluated for future climate scenarios accounting for global warming. This study shows the following: 1) for South China, the concentration degree (C) for the distribution of intra-annual runoff in natural basins such as Sanbanxi Reservoir tended to be higher, but for rivers significantly impacted by human activities, C tended to be lower. 2) a higher C was associated with an increased reservoir temperature and released water temperature, and decreased thermal stability. For Sanbanxi Reservoir, a 10% increase in C corresponded to a change in annual average temperature, thermal stability, and released water temperature of 0.036 °C, -48.4 J m, and 0.153 °C, respectively. These changes were larger in summer than in other seasons; 3) global warming is predicted to increase reservoir temperature, released water temperature, and thermal stability, having a more significant influence on these parameters than intra-annual runoff uniformity; 4) future changes in thermal regimes will intensify oxygen stratification and hypolimnetic anoxia, promoting algal blooms, and delaying fish spawning. Effects of two methods aimed at controlling the thermal regime were also analyzed, including changing the operation level and intake elevation of the reservoir. This study investigated the response of the thermal regime of Sanbanxi Reservoir to climate change, and provides theoretical support for the management of water temperature and the reservoir's aquatic environment.
热分层在水库中很常见，对水生态环境有重要影响。尽管已有研究检测到一些流域年内径流量均匀度的变化，但很少有研究关注这些变化对热分层的影响。本文利用中国三板溪水库 1950 年至 2015 年的径流数据，对年内径流均匀度的长期趋势进行了统计分析和外推预测，并探讨了这些趋势与水库热分层之间的关系。此外，还考虑全球变暖，评估了未来气候情景下的水库热分层。研究表明：1）在中国南方，自然流域（如三板溪水库）年内径流分布的集中程度（C）较高，而受人类活动显著影响的河流，C 较低。2）C 值较高与水库温度和放水温度升高、热稳定性降低有关。对于三板溪水库，C 值增加 10%，年均温、热稳定性和放水温度的变化分别为 0.036°C、-48.4 J·m 和 0.153°C。这些变化在夏季比其他季节更大。3）全球变暖预计会增加水库温度、放水温度和热稳定性，对这些参数的影响大于年内径流均匀度。4）未来热分层的变化将加剧水体分层和底层缺氧，促进藻类繁殖，延迟鱼类产卵。还分析了两种控制热分层的方法的效果，包括改变水库的运行水位和进水高程。本研究调查了三板溪水库热分层对气候变化的响应，为水温管理和水库水生态环境提供了理论支持。
