Water temperature's cumulative effect induced by the construction of cascade reservoirs in the lower reaches of Jinsha River
Cascade reservoirs in the lower reaches of Jinsha River play a crucial role in watershed temperature regulation.However,there is still a lack of knowledge on how cascade reservoirs affect downstream temperature.This study quantitatively analysed the cumulative effect of four cascade reservoirs(Wudongde,Baihetan,Xiluodu and Xiangjiaba)in the lower reaches of Jinsha River on downstream temperatures.It examined overall temperature deviation,phase deviation,and extreme amplitude using long-term temperature data from Longjie(Three),Wudongde,Baihetan,Xiluodu,and Xiangjiaba stations.The results indicated that:(1)after the completion of the lower reaches of the Jinsha River cascade reservoirs,the"heat source effect"was significant.The aver-age annual discharge water temperature of Wudongde,Baihetan,Xiluodu and Xiangjiaba increased year by year.The annual water temperature variation decreased by 4.1,2.4,1.6 and 3.2℃ compared with that of the natural water temperature.The increased rate of the temperature along the reservoir decreased from 0.348℃/100 km in the natural state to 0.256℃/100 km at the present stage.(2)As the operational period of the cascade reservoirs along the Jinsha River increased,the cumulative effect on water tem-perature in the downstream reservoirs gradually intensified,with a slowing rate of change.By the year 2022,following the full com-missioning of the four hydropower stations,Wudongde,Baihetan,Xiluodu,and Xiangjiaba exhibited temperature lag times of 19,58,49 and 65 days,respectively.(3)Among these four reservoirs,Baihetan exerted the greatest effect on temperature.Different types of reservoirs exhibited diverse patterns in temperature transmission and accumulation.A hybrid reservoir showed positive effect when acting as a"head"reservoir.Stable stratification reservoirs showed positive effect.Unstable stratification and transitional res-ervoirs showed positive or negative effect at different stages.This study provided valuable guidance for optimizing water resource management and enhancing hydropower efficiency,while offering a scientific foundation for maintaining the health of downstream e-cosy stems.
Lower reaches of the Jinsha Rivercascade reservoirswater temperaturecumulative effects
万方数据
维普
