Thermal Stratification Modeling in the Inner Coastal Bays

Abstract

Hypoxia occurs repeatedly when water quality deterioration and damage to the aquaculture industry are reported in coastal inner bays. In general, hypoxia occurs when stratification develops, and the oxygen consumption rate of the water layers and sediment increases. Therefore, prediction of hypoxic water masses affecting the survival of marine benthos should be preceded by a stratification prediction. In this study, stratification at Dang-dong bay, the inner bay of Jinhae Bay located on the southern coast of Korea, was investigated using a vertical eddy diffusion model focused on the heat budget at the water surface. Air temperature, wind speed, vapor pressure, and duration of sunshine were used for this numerical model calculation. Simulation results show that the model simulates annual temperature changes and stratification well, and the root mean squared (RMS) error is calculated as 1.31 degrees C. The annual changes in water temperature were influenced by solar radiation, evaporation heat, long wave radiation energy, and the contribution of sensible heat was relatively small. It was confirmed that the water temperature in the inner bays, such as Dang-dong bay, is dominated by the heat flux at the water surface rather than the tidal flow. The model proposed in this study can be used for predicting the occurrence of hypoxia by simulating the thermal stratification in coastal areas using only weather input data.