Research and Application of Key Technologies for Dynamic Control of Reservoir Water Level in Flood Season

In today’s reservoir operation study, it is urgent to solve the issues on improving flood resource utilization, maximizing reservoir impoundment, and guaranteeing water supply through real-time regulation optimization under the premise of ensuring flood control safety and taking risks properly. Based on previous studies, the key real-time operation technologies for dynamic control of reservoir water levels in flood season are summarized. The Danjiangkou Reservoir was taken as an example, the division of flood stages, reservoir water level requirements for improving water supply guarantee, dynamic control indexes of reservoir water level for beneficial use in stages during the flood season, and flood control dispatching indexes are proposed. Moreover, a practicable real-time flood forecast operation scheme for Danjiangkou Reservoir was compiled. Its application in 2017 indicated that the established scheme can provide strong technical support to ensure the overall benefits of Danjiangkou Reservoir, including flood control, water supply, and power generation.

The Migration and Transformation of Nitrogen in the Danjiangkou Reservoir and Upper Stream: A Review

The Danjiangkou Reservoir in China is characterized by significantly high concentrations of total nitrogen (TN), and the sources are not clear. Recently, research on this reservoir has focused on the N cycle, the spatial and temporal distribution characteristics of N, and the factors influencing N concentration. Significant temporal and spatial differences in TN concentrations exist, both in the reservoir area and the tributaries. N concentration in the area is affected by numerous factors, including N transported by tributaries, nonpoint source pollution around the reservoir, internal N release, and atmospheric N deposition. Moreover, a dam heightening project led to a larger water-fluctuation zone and more bays in the reservoir, directly affecting its N cycle. However, further research is required to explore the N cycle on a large watershed scale in the Danjiangkou Reservoir and upper stream areas, determine N pollution sources using satellite remote sensing, and conduct simulations of a water body N cycle model based on data fusion. Although the issue of excessive TN has been alleviated to some extent by the South-North Water Diversion Project, the excessively high TN concentrations require more research to aid the implementation of N-reducing strategies.

A Comprehensive Method for Water Environment Assessment considering Trends of Water Quality

Water quality is a significant issue, and its assessment plays an important role in environmental management and pollution control. In this paper, we proposed a comprehensive water quality assessment method which takes into account both absolute and temporal trends in water quality. As the first step, we derived and applied a comprehensive pollution index (CPI) to characterize water pollution in 16 major tributaries to the Danjiangkou Reservoir, located in the upper reaches of the Hanjiang River in China. Next, we used Spearman’s rank correlation analysis to quantify temporal CPI trends in each tributary. As the final step, we conducted principal component analysis (PCA) using data on 8 water quality parameters and the temporal CPI trend from each of the 16 tributaries. The resultant comprehensive water quality assessment method identified tributaries, which stand to improve and threaten water quality in the Danjiangkou Reservoir from both immediate and future perspectives.

A Comprehensive Study of the Impact of Large-Scale Landscape Pattern Changes on the Watershed Ecosystem

The South-to-North Water Diversion Project (SNWD) is the world’s largest inter-basin water diversion project, and the Danjiangkou Reservoir is a water source of the middle route project of the SNWD. Dynamic monitoring of ecological environment changes in Danjiangkou Water source area can provide theoretical support for reservoir water storage security and ecosystem protection. In this study, the water storage of Danjiangkou reservoir was estimated and its dynamic change was analyzed. On this basis, the changes of landscape pattern and ecosystem services value caused by the SNWD project were analyzed. The results show that the reservoir storage presented an obvious growth trend from 2000 to 2019, especially after the middle route of the SNWD was opened in 2014. After the implementation of the SNWD project, the vegetation degradation in Danjiangkou reservoir area was obvious, which is mainly related to the expansion of construction land. The ecosystem service value of the Danjiangkou Reservoir was mainly determined by the water conservation supply value and climate regulation value. After the implementation of the SNWD project, the values of water conservation and supply, climate regulation, and hydropower generation showed an increasing trend, while the values of fixing carbon and releasing oxygen, and organic matter production showed a decreasing trend.