Reservoir effects on the variations of the water temperature in the upper Yellow River, China, using principal component analysis

• Published in: Journal of environmental management 2020-05, Vol.262, p.110339-110339, Article 110339
• Main Authors: Ren, Lei, Song, Ce, Wu, Wei, Guo, Mengjing, Zhou, Xiaode
• Format: Article
• Language: English
• Subjects: Animals; China; Environmental Monitoring; PCA; Principal Component Analysis; Rivers; Seasons; Stratified intake; Temperature; Upper yellow river; Variation; Water; Water temperature index system
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2020.110339

Water temperature is an important factor that affects the number and variety of river species. After a reservoir is built, a river's thermal regime changes significantly. Analyzing and evaluating river water temperature variation trends caused by damming can provide scientific support for developing effective water management strategies for reservoirs. This paper aimed to construct an index system of water temperatures in high and cold areas of the Upper Yellow River, and a method was proposed for identifying river water temperature variation based on principal component analysis (PCA). The variation degree in the river water temperature caused by large reservoirs was analyzed quantitatively. A three-dimensional water temperature model was developed to simulate the effect of a stratified intake on the alleviation of low-temperature water. The results indicated that (1) the water temperature decreased in summer and increased in winter, seasonal temperature changes decreased, there was a time delay in water temperature processes and a time fluctuation in the temperature threshold. (2) Certain indices were obtained that considered fish spawning and breeding, thermal condition changes and interactions between the organisms influenced by the reservoirs. (3) A stratified intake has a good effect on mitigating the impact of low water temperatures on fish spawning to some extent. The index system of the water temperature and its gradient changes effectively analyzed the influence of the reservoirs on river water temperature variations. •An index system of water temperature of Upper Yellow River was Constructed.•Propose a method of the identification of river water temperature variation based on the principal component analysis (PCA).•A three-dimensional water temperature model was created to simulate the.•Thermal structure in stratified reservoir and the effect of stratified intake.