Author(s): Yu Li; Xue Wang; Xiulin Liu
Linked Author(s):
Keywords: Xiluodu reservoir; Xiangjiaba reservoir; Cascade reservoir; Layered water withdrawal; Water temperature
Abstract: The range and extent of the impact of reservoir construction on downstream water temperature, as well as the measures and effectiveness of ecological regulation implemented by reservoirs, have consistently been focal points of interest and discussion within the academic community. By systematically analyzing the water temperature data from 9 hydrological stations and 12 observation sections along the main channel of the Yangtze River, we conducted a comprehensive analysis on the impacts of experimental ecological regulation at Xiluodu and Xiangjiaba cascade reservoirs. Our findings revealed that: (1) The annual distribution of water temperature along the Panzhihua-Zhuzhou section shows consistent changes. The warming period is from January to June, and the cooling period is from August to December. Water temperature at various hydrological stations along the course shows a gradual upward trend, with the Panzhihua station being the most prominent, exhibiting a temperature range of 0.8°C and a relative range rate of 5% between 2011 and 2016. The impact of tributary inflows on the main stream water temperature in the Panzhihua-Yibin section is significant, depending on the water temperature and volume of the tributary inflows as well as the regulation effect of the reservoirs. (2) The impact of the cascade reservoirs on downstream water temperature is mainly reflected in the release of low-temperature water in spring (March to May) and high-temperature water in winter (December to February). At the Pingshan station, the spring water temperature decreases by 2.2°C, with a variation rate of -11.7%, while the winter water temperature increases by 2.3°C, with a variation rate of 18.2%. (3) Although stratified water intake from the Xiluodu Reservoir has no significant effect on raising the downstream water temperature of Xiangjiaba (the storage exchange coefficient is only 0.4%), the high temperature (on average 1.8°C higher than the main stream from March to May) and large volume (accounting for 45% of the main stream’s water volume) of Minjiang River inflows, along with the rising temperatures along the course (from 11°C to 25°C), are the main drivers of the increasing water temperature along the Xiangjiaba-Zhuta section within the protected area.
Year: 2024