The harmonic analysis of tidal phenomena in lake and river

To investigate the characteristics of tide in the lake and river, we observed surface elevation at the Naju lake and the Youngsan river. First, we measured the water level of the Naju lake for one month(from 30, Dec., 1997 to 27, Jan., 1998). Next, we measured that along the Youngsan river’s tributary. Semidiurnal tide is dominated in the Naju lake. There have spring tide and neap tide also. The average period is 12.4 hours, and the tidal range is about 13.5㎜. Spectrum analysis show that high energy in the 27.4 hours and 12.8 hours. When there is a strong wind period, it makes the short periodic wave on the surface of the water. The amplitudes of M₂, S₂,O₁ and K₂ calculated by harmonic analysis are 0.558㎜, 0.393㎜, 0.477㎜ and 0.436㎜, respectively. The tidal range at the east and west is larger than that at the south and the north in the Chisuk river reservoir. When the water level of the east is low, that of the west is high.