WATER EXCHANGE BETWEEN LAKE AND OCEAN FROM NUMERICAL MODEL REPRODUCTIVITY OF SALT IN BRAKISH LAKE OBUCHI

Abstract

 Since the height of the bump, which is caused by oyster beds in the Obuchi river around the mouth of the Obuchi lake affects the tidal water transport, the circulation and mixing of materials in the lake, the relationship between the bump and the water level was investigated by the model reproducibility of the salinity in the brackish Obuchi lake. After conducting a sensitivity analysis with a change in the seafloor depth of the overall model topography (zo m), the maximum likelihood method was applied using observations from 2016 to 2020 to estimate a maximum likelihood value with an error deviation of zo (0.17 ± 0.085 m). The error deviation is comparable to the amplitude of the annual tidal constituent in this area, which indicates that the annual tidal constituent passively affects the salinity in the Obuchi lake. Moreover, using the model, the dilution process of the tracer (virtual dye) was investigated by filling the lake with a uniform concentration of 1 unit m⁻³. The tracer concentration decreased with a constant half-life. The maximum likelihood value of zo lead to the half-life of 13.4 (11.5 - 15.9) days.