About the tide of Qiantang River?

Not in a straight line, but because the tide caused by the moon is not facing the moon, but slightly behind the moon, so it will appear two or three days after the first day or the fifteenth day.

Tide watching is all about looking at the lunar calendar, and you can know the positional relationship between the sun, the earth and the moon, but the new calendar has no moon factor.

Qiantang River is famous for its trumpet shape at the mouth of the sea. At high tide, the river surface changes from large to small. "Thousands of troops and horses cross the single-plank bridge", the range of high tide will be enlarged, which will make the original humble tide soar. It may not be so obvious on the vast coast, but it can also be seen from the change of coastline position.