Physical Environment Changes in the Keum River Estuary by the Dyke Gate Operation: I. Mean Sea Level and Tide

Abstract

Analyzing the tide data taken at Kunsan inner and Outer ports, non-tidal and mean sea level and harmonic constants of major constituents are investigated to examine the effects of the dyke gate operation on the sea level change in Keum River estuary. Non-tidal and annual mean sea levels decrease at Kunsan Inner and Outer ports after the dyke gate operation, especially showing an abrupt drop of non-tidal sea level at Kunsan Inner port. This non-tidal sea level drop results in the mean sea level gradient change between the inner and outer port, which can be mainly explained in terms of the decrease of river discharge from the dyke. Amplitudes of the and tides at the Inner port increase after the dyke gate operation, showing an abrupt jump, and phases of both tides slightly decrease. Amplitude and phase of the and tides show slight changes after the dyke gate operation. This significant change of semi diurnal tide amplitude is believed as a result of superposition of incident tidal wave and reflected tidal wave from the dyke.