Calibration and Validation of Water Quality Model for Phytoplankton Simulation

Studying water quality problems in natural aquatic environment with numerical models is a very effective approach. As a result, many numerical models have been developed and applied to simulate water quality constituents in rivers, lakes, and coastal waters. The observed water quality in an aquatic system is a result of many physical, chemical, and bio-chemical processes, parameters of a water quality model associated to these processes need to be calibrated. Phytoplankton is one of the most important components in the water quality simulation. Its growth rate is significantly affected by temperature, sun light, and nutrients; while the death rate is influenced by the temperature. More than ten parameters need to be calibrated for modeling phytoplankton kinetics. In this study, a water quality model CCHE_WQ, developed at the National Center for Computational Hydroscience and Engineering (NCCHE), was applied to simulate the phytoplankton (as chlorophyll a) in Pelahatchie Bay in Mississippi. The parameters such as saturation light intensity, light extinction coefficient, optimal temperature for the growth, half-saturation constants for nutrients, etc. were calibrated and statistical analysis was conducted to evaluate the performance of numerical model by using different parameters.