Variation of Flow-sediment Transport and Total Phosphorus Flux in the Jialing River

Phosphorus is an important nutrient or pollutant, which is mainly carried by sediment in rivers. The Jialing River Basin, as a key sediment-producing area in the upper reaches of the Yangtze River, is one of the main sources of sediment to the Three Gorges Dam deposition. Based on the study of flow-sediment transport characteristics at the Beibei Station of, this article analyzes the inter-annual and intra-annual variation characteristics of phosphorus flux in the Jialing River, and preliminarily establishes the relationship between monthly phosphorus flux and sediment transport. The results show that since the Three Gorges Dam impoundment, the annual runoff of Beibei Station on the Jialing River has slightly increased, while the sediment transport fluctuates due to rainstorm floods. The flow-sediment transport in the Jialing River basin is mainly concentrated in the flood season. From the year 2006 to 2019, the phosphorus flux showed a trend of increasing and then decreasing over time, with an average of 6757 tons. The seasonal variation was obvious during the year, showing the highest during flood season, followed by the mean flow season, and the lowest during dry season. The peak phosphorus flux appeared in July. Besides, there is a good correlation between phosphorus flux and sediment transport at Beibei Station, with the correlation coefficient above 0.7. However, the high-intensity sediment transport during rainstorm floods in the year 2018 did not lead to a significant increase in phosphorus flux. The research results can provide reference for the study of water environment improvement in the Yangtze River Basin.