Ranojit Kumar Dutta^{1, 2,}, Jun Ma^{1, 3}, Baishakhi Das⁴, Defu Liu^{1, 3}

Algal blooms occur frequently in Xiangxi Bay (XXB), which is one of the largest tributaries of the Three Gorges Reservoir (TGR). Floating curtain weirs (FCWs) are hydraulic structures that act as a barrier to divert density currents and diffuse heat across the width of the water body. Numerical modeling of FCWs is become a widely accepted method for controlling algal blooms. A laterally averaged two-dimensional hydrodynamic and water quality model (CE-QUAL-W2) was used to simulate the effects of FCWs, including those on water temperature, hydrodynamics and chlorophyll-a concentrations, for XXB. The developed model was calibrated using data collected in XXB from January to December 2010. The results indicated that the maximum chlorophyll-a concentrations observed were 74-154 mg/m³ at the XX09, XX06 and XX01 sampling sites. The performance of the FCWs suggests that the overall chlorophyll-a concentrations are markedly reduced by more than 85% as a function of the FCW heights and locations. Seasonally, an algal bloom reduction rate of more than 62% was observed in the summer. FCWs with heights of 3, 5, and 7 m reduced algal blooms by up to 99% at XX09 during March 26-28, April 24-27, July 18-26, August 5-20, and 23-28, and September 3-8 and 12-16, respectively. Therefore, the proposed FCWs can reduce algal blooms and improve water quality to save domestic water and aquatic ecosystems in XXB.

Modeling effects, Floating curtain weirs (FCWs), Xiangxi Bay (XXB), Algal blooms, CE-QUAL-W2 model, Three Gorges Reservoir (TGR)