450 / 2024-03-19 17:46:44

Effects of lakes and tributary inflows on phosphorus fluxes in the middle and lower reaches of the Yangtze River

lakes and tributary inflows,phosphorus fluxes,in the middle and lower reaches of the Yangtze River,contribution

Subtheme 3: Eco-hydraulics and Environment > Topic 2: Water Eco-environment Monitoring and Simulation

In the middle and lower reaches of the Yangtze River, the pattern and coupling relationship of rivers and lakes are extremely complex. There are Dongting Lake, Poyang Lake and Han River flowing into the Yangtze River, which have direct impacts on phosphorus fluxes in the main stream. Based on the analysis of flow and sediment transport in the Dongting Lake, Poyang Lake and Han River, the paper studied the inter-annual and intra-annual characteristics of phosphorus fluxes in the two lakes and one tributary, initially established the quantitative relationship between phosphorus fluxes and sediment transport, and clarified the contribution of lakes and tributary inputs on the main stream phosphorus pollution. The results showed that for the lake-type inflow, the intra-annual trend of phosphorus concentration in Dongting Lake and Poyang Lake are relatively similar, showing the highest in dry-water period and the lowest in flood period. However, the intra-annual distribution of phosphorus concentration in Han River is relatively uniform, and basically comparable in dry season, level-water and flood periods. The phosphorus fluxes in the middle and lower reaches of the Yangtze River mainly came from Yichang, followed by two major lakes accounting for about 30% in total, and the Han River inputs was relatively small, less than 5%. In comparison, the lake-type inflow is large and dominated by fine sand, which has a greater impact on the phosphorus flux in the main stream than the tributary-type inflow.