For three gauging stations' tide level data by the Yellow River harbor, the Shengli Oilfield 18th well and the open sea, the auther use the harmonic analysis method to calculate their tidal harmonic constants. According to the oscillation amplitude and the phase's change rule as well as amphidromic region's hydrology characteristic discusses the position of the amphidromic point nearby the Yellow River delta. The results indicate the M2 tidal constituent amphidromic point is still existed and its position is located at 38°06.039 'N,118°58.291 ÉE or its vicinity. But the amphidromic point S2 tidal constituent has moved to the shore.
Amphidromic points and tidal amphidromic system is one of the most important characteristics of tidal waves movement. For a large-scale tidal waves system, given the precise existence of its main tidal constituent's amphidromic points, location and rotary characteristics, we can clearly show the image of tidal waves movement. On the contrary, based on indefinite or error amphidromic points, the image would be inaccurate or completely wrong. Amphidromic points is an important feature, which control tidal waves rotating characteristic and range of tidal's distribution. Existence of amphidromic point of tidal constituent M2 is the most obvious feature at the Yellow River Estuary. The Yellow River Estuary tidal waves are subject to the Bohai Sea's tidal waves. Semi-diurnal tidal constituents from the Bohai Strait rotate left at the Bohai Bay and rotate right at Laizhou Bay. They superpose at the Yellow River Estuary and form amphidromic point of Semi-diurnal tide. This phenomenon has attracted much attention of home and abroad scholars. As early as 1936, based on measured data Ogura pointed out that the Yellow River Estuary exists amphidromic point of tidal constituent M2 for the first time.
