Qiantang river tide, also known as haining tide, is a tidal bore at the mouth of Qiantang river in Hangzhou Bay, Zhejiang Province. One of the world-famous tidal bore is also one of the largest astronomical tides in the world. International geographers call Qiantang River, Amazon River in South America and Ganges River in South Asia "the world's three strong tidal rivers". ?
Qianjiang Guanchao is located in Yan Guan Town, Haining, 45km northeast of Hangzhou. It is caused by the gravity of celestial bodies and the centrifugal effect of the earth's rotation, as well as the special terrain of the bell mouth of Hangzhou Bay. Every year on the 15th day of the eighth lunar month, the tidal bore in Qianjiang River is the largest, and the tidal head can reach several meters. When the tide came, the sound was like thunder, and the avalanche was spectacular. Tide-watching began in the Han and Wei Dynasties (1 6th century) and flourished in the Tang and Song Dynasties (7th century to13rd century). After more than two thousand years, it has become a local custom. ?
History?
Watching autumn tide in Qiantang has become a custom as early as the Han, Wei and Six Dynasties, especially in the Tang and Song Dynasties. According to legend, the eighth day of the eighth lunar month is the birthday of the tide god, so the tide peak is the highest. In the Southern Song Dynasty, the imperial court stipulated that the navy division should be inspected on the Qiantang River on this day. Later, they became accustomed to each other, and August 18 gradually became a tide-watching festival. In addition to the three-day tide-watching festival around August 18 of the lunar calendar, there are considerable tides at the beginning and middle of each month in the lunar calendar, which can be used as a "tide-chasing tour". Yan Guan Town, Haining, 50 kilometers away from Hangzhou, is the best place to watch the tide. ?
In ancient Hangzhou, the Phoenix Mountain and Jianggan area were the best places to watch the tide. Due to the change of geographical location, Yan Guan in Haining has been the first scenic spot to watch the tide since the Ming Dynasty, so it is also called "Watching the Tide in Haining". On the day of tide-watching, especially in the days around August 18 of the lunar calendar, there were cars and people on the road. Overlooking the bell mouth of Qiantang River at sea, the tide forms turbulent waves, just as Malik is rushing. When the sandbar of the riverbed near Ganpu is blocked, the tidal wave rises by three to five meters, and the tidal range is nine to ten meters. ?
Pan Lang, a poet in the Northern Song Dynasty, wrote in his "Jiuquanzi": "Looking back on the tide for a long time, Manzhouli people fought for the river. I suspect that the sea is empty and drums are beating all around. Xiang Tao, the frolic in the frolic, stands upright and keeps the red flag wet. I don't look at my dreams more, but I am still chilling. " This poem is a true portrayal of the activities of "frolicking" and "watching" the spring tide in Qiantang River. ?
cause
in time
From August 16 to August 18 of the lunar calendar, the sun, the moon and the earth are almost in a straight line, so the tidal gravity (the difference between the gravity of the moon, the sun or other celestial bodies on the earth and the gravity of the earth per unit mass, or the resultant force of the inertial centrifugal force generated by the movement of the earth around the center of mass and the gravity of the moon (the sun)) is the largest.
The right place?
It is related to the trumpet-shaped estuary of Qiantang River. Nearly 500,000 mu of land was reclaimed to the east of Zheshan Mountain on the south bank of Qiantang River, which blocked the estuary like a peninsula, making the section from Zheshan Mountain to Qiantang River 12 like a small belly bottle, which is easy to retreat when the tide rises. The width of the outer mouth of Hangzhou Bay is 100 km, which is only a few kilometers away from the outer 12 section. The riverbed in the eastern part of the estuary suddenly rises and the beach is shallow. When there is a large number of tidal bore in the mouth of Qiantang River, it is difficult to ebb because of the rapid contraction of the river surface. Secondly, it is related to the sediment deposition under the Qiantang River, which blocks and rubs the tidal current, making the front slope of the tidal current steep and gentle, thus forming a wave after catching up with the front wave, and one wave overlaps with another.
Wind?
Southeast winds are often blown along the coast, and the wind direction is roughly the same as the tide, which is helpful to the tide.
tide
The tidal water in Qiantang River is related to the peak discharge and total flood volume in the first three or four months of tide. According to the values of peak discharge and total flood volume, the tide can be estimated. Han Zengcui, a professor-level senior engineer and consultant of the Institute of Water Conservancy and Estuary, said, "The tide at 20 12 may be slightly smaller than that at 20 1 1, but it is definitely larger than that in 2004, 2007 and 2008." ?
Zhou, director of Hangzhou Water Conservancy Facilities Supervision Center, said that many people don't know the power of the tide, and they think they can run back to the levee before the tide comes. Zhou said that this idea is seriously wrong. He took out a set of data: the average person runs only 6-8 meters per second, but in the spring tide, the tide speed can reach 12 meters per second, and only Liu Xiang, an Asian flier, can go with the flow.
enjoy
Best viewing period
The middle of August in the lunar calendar is the best time to watch the tide. It has the reputation of "August 18th Tide, without it in the spectacular world". In fact, the tidal bore of Qiantang River changes regularly, and the tide is restricted by many factors, such as astronomy, geography, river bed elevation, runoff, the direction of the main channel (channel), climate and so on. ?
Except for the first half and the second half of the lunar calendar, August and a half are not necessarily chosen. But the autumn tide is bigger than the spring tide, because the rainfall in Qiantang River basin is mainly concentrated in the rainy season and typhoon season from mid-March to mid-September; The rainfall from June 65438 to February of the following year is relatively small. In different places, you can enjoy different tidal scenes, such as "first-line tide" in the tower, "confluence tide" in the babao and "ebb tide" in the old salt warehouse. ?
The most dangerous viewing spot?
Zhou, director of Hangzhou Water Conservancy Facilities Supervision Center, believes that the north and south banks of Qiantang River have different degrees of danger according to different topography, and the downstream is generally more dangerous than the upstream. There are eight specific danger points, which should be paid special attention to when watching the tide: Haining Daxia, Haining Laoyancang, Qibao, Xiaoshan No.9 Dam, Xiasha No.7 Grid, Xiaoshan Meiren Dam, Sanbao and Jiuxi. ?
Zhou particularly stressed that you must not enter the dangerous area in the early hours of the morning, flood season and other dangerous periods, otherwise you will lose the opportunity to escape because you can't see clearly or handle it calmly. According to the characteristics of tidal bore in Qiantang River, the spectacular tidal scene is often the most dangerous place, so tourists should never go down to the beach and groin to watch the tide. ?
Swallow people?
On August 2, 2007, the tide of Qiantang River in Hangzhou instantly submerged dozens of people swimming in the river. At 20 10, 10, 10, 10,65438, 10, 6 people fell into the water, 2 people were rescued and 4 people were missing. ?
20 12 On July 23rd, three migrant workers were involved in the tidal water of Qiantang River.