The Yellow River, Yangtze River, and Pearl River are the three largest rivers in China, flowing adjacent from north to south. They belong to the world-class rivers in terms of the magnitude of their water and sediment discharge into the sea. Originating from the Qinghai-Tibet Plateau, the Yellow River and Yangtze River, and from the Yungui Plateau, the Pearl River, these rivers generally flow from the mountainous western regions of China towards the eastern plains, ultimately draining into the Bohai Sea, East China Sea, and South China Sea, respectively, before entering the western Pacific Ocean.
The Yellow River is characterized by "less water and more sediment, with water and sediment from different sources." Its water volume accounts for about 2% of the total river discharge in China, mainly originating from the upper reaches above the Lanzhou station, while sediment mainly comes from the middle reaches in the Loess Plateau region, constituting around 90% of the total sediment load. Due to the scarcity of water and abundance of sediment, coupled with concentrated runoff during the flood season, extensive sediment deposition has led to the formation of the "hanging river" in the lower reaches of the Yellow River and the accumulation of sediment at the river mouth, forming the Yellow River Delta. The Yangtze River, China's largest river, contributes approximately 36% of the total river discharge in China. With abundant water flow, the Yangtze River carries sediment that accumulates in the middle and lower reaches, forming the Yangtze River Plain, and develops into the Yangtze River Delta at its mouth. The Pearl River is a complex river system composed of three main tributaries: West River, North River, and East River. Among them, the West River, as the largest tributary, accounts for about 77% of the total water discharge and 89% of the sediment load of the Pearl River.
Studies by scholars indicate that these three major rivers collectively discharge approximately 1.20×1012m3 of freshwater and 1.36×109m3 of sediment into the western Pacific Ocean annually. The fluctuating annual water and sediment discharge volumes of these rivers influence the water and sediment dynamics in the western Pacific Ocean, thereby triggering environmental changes in its continental shelf.
The Three Gorges Dam on the Yangtze River.
Pearl River Guangzhou section.
The Yellow River Xiaolangdi Water-Sediment Regulation Scene. All photos by Zhang Xingyong.
Ph.D. student Zheng Huiling and Professor Wang Yonghong from the School of Marine Earth Sciences at Ocean University of China analyzed the trends and variations of water and sediment fluxes in the Yellow River (Lijin Station), Yangtze River (Datong Station), and Pearl River (Gaoyao Station, Shijiao Station, Boluo Station) from 1960 to 2020 using measured data. They applied mathematical statistics to study the trends and variations of water-sediment fluxes in the three rivers and discussed their periodic characteristics using wavelet transform.
Their research results show significant changes in water and sediment entering the sea from the three major rivers from 1960 to 2020. The water and sediment entering the sea from the Yellow River experienced a sudden decrease in 1986, with a second sudden decrease in sediment in 1997. The sediment entering the sea from the Yangtze River and Pearl River experienced sudden decreases in 1992 and 1999, respectively, while the river flow showed a fluctuating trend without significant variation. Additionally, the water and sediment entering the sea from the three major rivers exhibited significant interannual and interdecadal periodic characteristics. The interdecadal co-evolution periods were concentrated before 1980, before 1990, and before 2000. The interannual co-evolution period was 5 years, with frequent transitions between wet (sediment) periods and dry (sediment) periods. According to the results of cross-wavelet analysis, the water and sediment entering the sea from the Yellow River, Yangtze River, and Pearl River showed significant resonant periods of 1-3 years from 1965 to 1975, mainly in phase, indicating consistent evolution characteristics of water and sediment entering the sea.
The above research results were published in the 2024 issue 1 of the "Bulletin of Soil and Water Conservation."
Scholars in the field of soil and water conservation believe that the research results reflect significant trends, variations, and periodic characteristics in the water and sediment entering the sea from China's three major rivers. This can be used for basin rational development and effective management.
Article link: http://stbctb.alljournal.com.cn/stbctb/article/abstract/20240116
