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A Coupled Hydrodynamic and Water Quality Modeling for a Microcystis Bloom Event in a Stratified Reservoir

Author(s): S. W. Chung; H. S. Lee

Linked Author(s): Han Soo Lee

Keywords: Lgal bloom; Cyanobacteria; Microcystis; Daecheong Reservoir; ELCOM-CAEDYM

Abstract: The buildup of buoyant planktonic cyanobacteria at the water surface of lakes and reservoirs is a worldwide concern because of its influence on public and ecological health. Ecological modeling can provide a valuable tool for the understanding of underlying processes and key control variables. The objectives of this study were to construct a three-dimensional (3D) coupled hydrodynamic and ecological model, ELCOM-CAEDYM, for the simulations of cyanobacterium Microcystis aeruginosa (hereafter M. aeruginosa) bloom in the stratified Daecheong Reservoir (Korea), and examine the principal processes that determine the temporal and spatial variability of algal biomass during an abnormal mono-specific bloom event. The model was validated against observed water balance, water temperature, and water quality variables in 2006, and applied to simulate the complex interactions between the physical and biochemical processes during the bloom event. The results indicated that the location of M. aeruginosa bloom is highly influenced by the physical mixing processes of nutrient-rich inflow driven by several flood events. The horizontal and vertical mixing of inflow determined the spatial heterogeneity of limiting nutrient (phosphorus), and subsequently resulted in the rapid accumulation of M. aeruginosa in the specific area (R3). In addition, stable thermal stratification and weak wind speed (<4.0 m/s) provided competitive advantage to M. aeruginosa given its buoyancy control capability. The establishment of near-surface buildups of M. aeruginosa was dependent on the extent of wind-driven turbulence.


Year: 2012

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