Modeling planktonic dynamics in a subalpine lake in Taiwan

The subalpine lakes in Taiwan possess vital freshwater ecosystems. These lakes play an important role in subalpine ecosystems and provide many ecosystem services for human society, including water supply; regulation of climate and carbon storage; habitat for wildlife; and the promotion of many values, such as aesthetics, culture, education, and so on. However, research on subalpine lakes in Taiwan mainly focuses on basic measurements to gather data. A limited number of numerical models have been developed to explore related research on the simulation of aquatic ecosystems in subalpine lakes. To better understand the interaction between the hydrodynamics and ecosystems of a subalpine lake, this study developed and built a three-dimensional model of hydrodynamics and water quality/ecology in the Yuan-Yang Lake (YYL). The collected data, such as water depth, water temperature, water quality, and plankton, were utilized to validate the model. The results indicated that the three-dimensional hydrodynamic and water quality-ecological model, namely SCHISM-PLANKTON, accurately reproduced the variations in water depth, water temperature, water quality, and planktonic biomass. Sensitivity analysis revealed that phytoplankton biomass was significantly affected by the basal metabolic rate of phytoplankton, while zooplankton biomass was most influenced by the basal metabolic rate of zooplankton. The planktonic biomass of YYL was greatly affected by changes in inflow discharge. © 2020, Taiwan Joint Irrigation Associations.