EVALUATION OF ADVECTION DIFFUSION PROSESS OF TURBIDITY DUE TO WIND EFFECT OCCURRED IN LAKE INAWASHIRO

Abstract

Lake Inawashiro located in the center of Fukushima Prefecture is an acid lake which had sufficient self-purification mechanism and the water quality was extremely good. In recent years, however, water quality became worse due to pollution from the surrounding area. Previous studies of the authors reported a density current from field observation and also numerical simulation to reproduce the current in the lake. In this study, the numerical model has been improved by introducing the effect of wind to turbidity in order to achieve a higher accuracy. Furthermore, several hypothetical wind conditions are imposed to have a better understanding of this effect. It is found that the density current is highly influenced by the wind velocity. Simulation using relatively weak wind speed shows that the density current occurs at the center of the northern shallow area, whereas by increasing the wind velocity, the density current occurs in the east side of the shallow area.