Why does the tide of Oujiang River in Wenzhou, Zhejiang rise and fall?

Tides are natural phenomena in coastal areas. In ancient times, the daytime was called "tide" and the evening was called "sunseeker", both of which were called "tide". Its occurrence is related to the sun and the moon, and also corresponds to the traditional lunar calendar in China. On the first day of the first lunar month, the sun and the moon are on one side of the earth, so they have the largest tidal force, which will cause a "spring tide". Near the 15th or 16th day of the first lunar month, the sun and the moon are on both sides of the earth, and the tidal force of the sun and the moon will also cause a "spring tide". When the phases of the month are the first quarter moon and the second quarter moon, that is, on the eighth and 23rd day of the lunar calendar, the tidal force of the sun and the tidal force of the moon cancel each other out, so a "small tide" occurs. Therefore, there is a saying in the agricultural proverb that "the spring tide rises on the fifteenth day of the first month, and the beaches are everywhere on the 23rd day of the eighth lunar month". In addition, there was a climax on the first day. Because the moon moves eastward more than 13 degrees on the celestial sphere every day, which is about 50 minutes in total, that is, the noon time of the moon (1 lunar day =24: 50) is delayed by about 50 minutes every day (there will be tides at the next noon, usually twice a day), so the time of high tide is also delayed by about 50 minutes every day.