Modeling the impacts of Poyang Lake Water Control Project on hydrodynamics and water quality

Poyang Lake Water Control Project planned on the flow channel that connects the lake to the Yangzi River will alter the hydrodynamics and consequently change the water quality.A 2D depth-averaged numerical model with wet and dry front treatment has been applied to improve the understanding of water environment of the Poyang Lake and investigate the effects of the hydraulic construction.The model results were validated against several series of measurements with satisfactory agreements on both hydrodynamics and water quality.According to the computational results,three different operation schemes of the water control project have significant impacts on hydrodynamics in the Poyang Lake especially in low flow period,as a result of the slow lake flow instead of rapid river stream in low flow season.Further analysis of the effects on water quality was carried out.Currently,water quality of the Poyang Lake in low flow season is worse than that in high flow season under present pollution loads.After the water control project is constructed,water quality in most part of the lake is improved in low flow season,while at the inlets of main inflow rivers it becomes worse.When the water control gate is entirely open annually in spring,the water quality get worse than that at present.In the rest time of a year there is no obvious difference among those cases.The results indicate that the risk of lake eutrophication increases at certain place in the Poyang Lake due to the water control project building.