Application Study of MIKE11 in Meiliang Lake Water Transfer Experiment

Abstract

In order to strengthen the scientific and technological research work of cyanobacteria control in Taihu Lake, the "Taihu (Meiliang Lake) water transfer on the control of cyanobacteria, improve lake water quality" project declared by Wuxi Hydraulic Society was approved by the municipal Association for Science and Technology. By further studying the effect of pumping station water transfer on controlling cyanobacteria and improving the water quality of Meiliang Lake, it is of great practical significance to implement the comprehensive water environment management of Taihu Lake basin and give full play to the ecological and social benefits of Taihu Lake. This project mainly through the pump station water transfer test work, synchronously monitoring wind direction, water level, flow, water quality (dissolved oxygen, total phosphorus, total nitrogen, permanganate index, algae density, etc.) data, combined with the waterway section data measured in advance to prepare a river network file, reasonably determine the simulation calculation range, determine the boundary conditions and calculation period. MIKE11 hydrodynamic model and water quality convection and diffusion model were adopted for simulation calculation and analysis, and model verification was carried out, achieving ideal simulation results. The analysis showed that the water transfer test had little effect on pollutant concentration, and the comprehensive evaluation category of Meiliang Lake water quality did not change, still classified as V ~ poor V, and the main items exceeding the standard were total phosphorus and total nitrogen. During the experiment period of 8 days, the water transfer reduced the permanganate index by 147 tons, the total phosphorus by 5 tons, the total nitrogen by 42 tons, and the algal density by 2.45 million cells /L. If the water transfer rate of Meiliang Lake pumping station is 60 m³/s and that of Dashihe Pump station is 30 m³/s, the permanganate index of Meiliang Lake can be reduced by 440 tons, total phosphorus by 16 tons and total nitrogen by 119 tons, and the algae density can be reduced by 4.28 million cells /L. The water transfer increased the water flow speed of Meilang Lake, increased the self-purification capacity of the lake body, greatly reduced the water pollutants in Wuxi Taihu Lake key water source protection area and sightseeing area, and reduced the density of algae.