Preliminary study on evolutions of Yangtze River and Dongting Lake water and sediment fluxes exchanges based on MLP method

This study establishes the regression relationship among key nodes of water and sediment exchange in the Yangtze River and Dongting Lake on the basis of MLP (Multi-layers Perceptrons) method and calculates and analyzes the linkage changes of nodes between the Yangtze River and Dongting Lake. This study draws the following conclusions: (1) Analysis of changes of water and sediment flux in the three outlets and the main stream after Jingjiang artificial cut off shows that the riverbed erosion and water regime change in the Chenghan River section is one of the most important links in the water and sediment flux evolution of the Yangtze River and Dongting Lake. The serious sedimentation of the Chenghan River section leads to the discharge of water and sediment in Jingjiang blocked. (2) After the application of the TGP (Three Gorges Project), the flow and sediment relations between the upper and lower reaches, the mainstream and tributaries of the Jingjiang are weakened in a relatively prominent degree. (3) When the water level of Hankou is higher than 26 m, the flow increase of Luoshan is basically stable when the water level of Hankou has a rise of 1 m. The stable value is 4,400 m³/s, 4,300 m³/s, 4,500~4,700 m³/s and 4,000 m³/s respectively before and after the sluice construction of Tiaoxian outlet, after the Jingjiang cut off, after the interception of Gezhouba and the operation of the TGP. (4) The response of water and sediment discharge capacities of the three outlets of Jingjiang to Yichang's inflow is weakened gradually. During time intervals before the application of TGP, the response of water and sediment discharge capacities of the three outlets to Yichang's inflow is the strongest when the water discharge of Yichang is 35,000 m³/s in the flood season. After TGP is applied, the response is the strongest when the water discharge of Yichang is 25,000 m³/s before and after the flood season.