Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, 38123 Trento, Italy; Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 310, 12587 Berlin, Germany.
Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, 38123 Trento, Italy.
Sci Total Environ. 2018 Jan 15;612:1266-1275. doi: 10.1016/j.scitotenv.2017.09.042. Epub 2017 Sep 8.
Within the past 30years there have been two major heatwave events (in 2003 and 2006) that broke 500-year-old temperature records in Europe. Owing to the growing concern of rising temperatures, we analyzed the potential response in a number of river sections that are subject to hydropeaking and thermopeaking through the intermittent release of water from hydropower stations. Thermopeaking in alpine streams is known to intermittently cool down the river water in summer and to warm it up in winter. We analyzed the response of river water temperature to air temperature during heatwaves at 19 gauging stations across Switzerland, using a 30-yr dataset at a 10-min resolution. Stations were either classified into "unpeaked" or "peaked" groups according to four statistical indicators related to hydropeaking and thermopeaking pressure. Peaked stations were exposed to reduced temporal variability in river water temperature, and it was determined that correlations between river water and air temperature were weaker for peaked stations compared with unpeaked stations. Similarly, peaked stations showed a much weaker response to heatwaves compared with unpeaked stations. It is important to note that this "cooling effect" created by hydro-thermopeaking was most pronounced during the two major heatwave events that took place in 2003 and 2006. Furthermore, results from thermal stress events on the growth of a typical cold eurythermic fish species (brown trout) increased continuously in rivers subject to peaked station water release during heatwaves. While hydropower operations that take place high up on mountains releasing hypolimnetic water may mitigate the adverse effects of heatwaves on downstream alpine river ecosystems locally, our results show the complexity of an artificial physical template associated with flow regime regulation in alpine streams.
在过去的 30 年中，欧洲发生了两次重大热浪事件（分别是 2003 年和 2006 年），打破了 500 年的温度记录。由于对气温上升的日益关注，我们通过间歇性地从水电站释放水，分析了许多受水力峰值和热力峰值影响的河段的潜在响应。众所周知，高山溪流中的热力峰值会间歇性地降低夏季河水温度，并在冬季升高河水温度。我们分析了瑞士 19 个测量站在热浪期间河水温度对空气温度的响应，使用了 30 年的数据集，分辨率为 10 分钟。根据与水力峰值和热力峰值压力相关的四个统计指标，将测量站分为“无峰值”或“有峰值”两类。有峰值的测量站河水温度的时间变异性降低，与无峰值的测量站相比，有峰值的测量站河水温度与空气温度之间的相关性较弱。同样，与无峰值的测量站相比，有峰值的测量站对热浪的响应较弱。需要注意的是，这种由水热峰值产生的“冷却效应”在 2003 年和 2006 年发生的两次重大热浪事件中最为显著。此外，在热浪期间，有峰值的测量站释放的河水会导致河流中典型的冷水温水鱼类（褐鳟）的热应激事件增加，而在高山释放底层水的水电站运营可能会减轻热浪对下游高山河流生态系统的不利影响，但我们的结果显示了与高山溪流中水流模式调节相关的人工物理模板的复杂性。
