Why did Zhejiang Tide happen?
The mouth of Hangzhou Bay is large and small, which intensifies the tide.
At that time, the summer monsoon prevailed.
Zhejiang Tide is qiantang bore.
Qiantang river tidal bore
Qiantang bore-the most spectacular tide.
In the history of our country, there are three famous tidal bore: Qingzhou tidal bore, Guanglingtao tidal bore and qiantang bore tidal bore.
Clear fees (1664-? "Argument on Guangling Pottery" says: "The tide surged in Shandong in the Spring and Autumn Period, and Guangling flourished in the Han and Six Dynasties. After the Tang and Song Dynasties, the tides in Zhejiang rose and fell, covering the north and south of the earth, and there were people who really knew it. "
Qiantang hole appeared later than Guangling pottery and was formed at the latest in the Eastern Han Dynasty. Wang Chong's Lun Heng Xu Shu mentioned that "Zhejiang, Henan and Shangyu rivers all have their own paths". He also said that Qiantang Zhejiang "all set up Zixu Temple to comfort their grievances and stop their violent waves". However, Wang Chong only said that "there are pottery in Qujiang, Guangling, and literati endowed it", but did not say that Qiantang River was endowed with tide. It can be seen that in the Eastern Han Dynasty, the fame of Qiantang Hole was far less than that of Guanglingtao. It is estimated that the custom of watching tides in Qiantang was also formed at that time.
Causes of tidal bore in Qianjiang River
The spectacular Qian Jiangchao is not only influenced by the gravity of the moon and the sun, but also related to the trumpet-shaped mouth of Qiantang River. Nearly 500,000 mu of reclaimed land east of Zheshan in Jiang Nanan, Qiantang blocked the estuary like a peninsula, making the section from Zheshan to Qiantang River 12 like a small belly bottle, and the tide is easy to enter but difficult to retreat. The outer mouth of Hangzhou Bay is 100 km wide, and it is only a few kilometers wide outside 12. The riverbed in the eastern part of the estuary suddenly rises and the beach is shallow. When a large number of tides flood in from the mouth of Qiantang River, the river surface shrinks rapidly, and secondly, it is related to excessive sediment deposition under Qiantang River, which blocks and rubs the tidal current and makes the front slope of the tidal current steep and gentle, thus forming a wave after catching up with the front wave, wave after wave, wave after wave.
The mystery of the rise and fall of autumn tide in Qiantang
"August 18th tide, spectacular world." This is an eternal famous sentence of Su Dongpo, a great poet in the Northern Song Dynasty, praising the autumn tide in Qiantang. For thousands of years, Qiantang River has attracted many tourists with its unique and extraordinary trend.
Every year around August 18th of the lunar calendar is the best time to watch the tide. During this period, the autumn is sunny and the golden wind is pleasant. On the seawall at the mouth of Qiantang River, tourists gathered together to watch this spectacle with great interest. There are three best places to enjoy the autumn tide in Qiantang. A seawall in the southeast of Yan Guan Town, Haining County is the first good place to go. The tide here is the most abundant, characterized by the first line, so it is called "the first line tide of Haining Pagoda". At the beginning of the tide, a white river flashed across the horizon, accompanied by a rumbling sound, like a dull thunder rolling on the horizon. The tide is coming from all directions. Like a flock of white swans in a row, flapping their wings and flying. The tide rises and falls, and the singing skills are getting stronger and stronger. In an instant, the white training peak came into my eyes. A water wall three or four meters high stood upright on the river, pouring waves and splashing pearls and jade. This is Malik Pentium. The tide rushed to the seawall and set off a 9-meter-high tidal peak. Sure enough, "the sky is full of turbid waves, crossing the river and destroying the mountains!" This radiant spray swallows the sound, and the scenery is spectacular and powerful. It is said that one year, a one-ton "Zhenhai Xiongshi" was rushed out 100 meters away. When the tide caused great repercussions, it flew away peacefully. Someone wrote: "The tide comes to splash the snow and the sky floats, and the tide goes to Lei Wusheng", which accurately describes the spectacular scene of the tide.
At Babao, the second scenic spot 8 kilometers east of Yan Guan Town, you can see the spectacle of tidal head collision. After the tide rises into the estuary, due to the different topography of the north and south banks, the tide speed is faster in the south and slower in the north, and the tide head is gradually divided into two sections. The fast-moving part of the south is called the south tide; The delayed northern tidal head comes from the east in the view of tidal watchers on the north shore, so it is called the East Tide. The southern tide rushed to the south bank and was thrown back, turning around and rushing north, just hitting the late East tide. At the moment, there was a loud noise, like a landslide, and thousands of snow peaks rose on the other side of the river. It was really shocking!
In the third scenic spot, Laoyancang, which is located at 12km west of Yan Guan Town, you can enjoy the tide of repeat customers. There is a "T-shaped dam" with a height of 9 meters and a length of 650 meters, which goes straight into the middle of the river like a giant arm to turn the tide. At this point, the momentum of the tide has been slightly reduced, but when rushing to the T-shaped dam head, it is still like a lion leaping, screaming and choppy. Then the tide turned around and fled back to the shore of xiang tang, and people came up to watch the tide on the top of xiang tang. The sudden attack of low tide often makes the tide watchers unprepared, terrified and lose their manners.
In addition, there is tide watching day and night in Haining. Watching the tide during the day is very interesting, with a wide field of vision and a panoramic view of the surging tide. It is also wonderful to watch the night tide in the bright moon.
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, August 18 of the lunar calendar is the birthday of the tide god, so the tide peak is the highest. The court of the Southern Song Dynasty stipulated that this day would be a day to inspect the navy on the Qiantang River, and later it became a tide festival. Pan Lang, a poet in the Northern Song Dynasty, wrote in a poem:
Long memories of watching the tide, full of people vying to see 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 see the dream a few times, but I am still chilling.
This poem is a true portrayal of the activities of "making waves" and "watching the tide" in those years.
Why is the autumn tide in Qiantang so spectacular and punctual? This is a question that many people naturally think of. In this regard, a legend goes like this: During the Spring and Autumn Period and the Warring States Period, there was a State of Wu in Anhui, Jiangsu Province today, and Fu Cha, the king of Wu, defeated the State of Yue in Zhejiang Province today. On the surface, Gou Jian, the king of Yue, surrendered to the State of Wu, but secretly he was ready to restore it. Wu Zixu, the minister of the State of Wu, knew about it and persuaded the king of Wu to kill Gou Jian many times. Because some treacherous court officials have slandered Wu Zixu many times in front of the prince of Wu. Regardless of treachery and loyalty, the prince of Wu gave Wu Zixu a sword to commit suicide, boiled his body, put it in a leather bag and threw it into the Qiantang River. Nine years after Wu Zixu's death, Gou Jian, the King of Yue, really destroyed the State of Wu under the planning of the doctor Wen Zi. However, the King of Yue also believed the rumor and forced Wen Zi to commit suicide. Although Wu Zixu and Wen Zhong, the heroes of the two enemy countries, are separated by the Qiantang River, each protecting his master, but the ending is the same, attached to hatred. Their resentment turned into huge waves and set off an angry tide in Qiantang.
Of course, legends are just legends. The reason why the autumn tide in Qiantang is so prosperous is mainly the unique geographical conditions.
Hangzhou Bay outside Qiantang River is a typical trumpet-shaped bay with wide outside and narrow inside, deep outside and shallow inside. The estuary is 100 km wide, reaching Ganpu in the west, and the river suddenly shrinks to 20 km. When we arrived in Yan Guan Town, Haining, the river was only 3 kilometers wide. At high tide, the wide and deep bay mouth swallowed a lot of seawater at once. With the rapid contraction of the river, it becomes narrower and shallower, and the rushing tide on the road can't rise evenly, so the waves behind push the waves in front, and each wave is higher than the other. Near Dajiashan, there is a huge underwater sandbar, and the tide swarms in, setting off a towering and amazing wave, forming a steep water wall and forming the initial tidal peak.
Do all trumpet-shaped bays produce tidal bore? The answer is no, there are other reasons for the spring tide in Haining. On the coast of Zhejiang, at the turn of summer and autumn, the southeast wind prevailed, and the wind direction was roughly the same as that of tidal waves, which helped the tide and added fuel to the fire; Tidal waves spread fast in deep water and slow in shallow water, and Qiantang River is very prominent from deep to shallow. This special condition can make the back wave catch up with the front wave quickly, and the layers of huge waves overlap to form a tidal head. In addition, tidal bore is also related to the gravity of the moon and the sun. Wang Chong, a thinker in the Eastern Han Dynasty, said in Lun Heng: "Tao rises and falls with the moon, and it is full of loss." Because the sun, the moon and the earth are lined up in a line around the first and fifteenth day of each month in the lunar calendar, the tides on the first and fifteenth day of each month are particularly large, while around the eighteenth day of the lunar calendar, the earth is closest to the sun, with the greatest gravity in a year, and the tidal bore at this time is naturally the most violent.
Someone asked, will the autumn tide in Qiantang change? In fact, the autumn tide in Qiantang has been changing. Due to the change of the peak position of tidal current, people's tidal observation points have also changed. The tidal observation point in the Song Dynasty is the right-angled river section over Hangzhou. After the Ming Dynasty, Yan Guan Town in Haining became a tidal scenic spot nearby. With the changes of modern rivers and seas, the highest tide level once moved to Toupeng in the west, and in recent years it moved to Babao in the east. The most interesting thing is the decline of 1985 Qiantang autumn tide.
1985 The eighth day of the eighth lunar month is an auspicious day for tide watching. On this day, a dozen tourists went to Yan Guan Town to watch the tide. However, when the tide came, I saw a very thin money line approaching slowly, and the silver line appeared and disappeared. The closer we get, the more we can't get in touch, only the waves stop. The height of the tidal bore is only 50 to 60 cm, which makes the tidal watchers disappointed. Some people worry that the autumn tide in Qiantang will disappear.
In fact, the autumn tide in Qiantang River has not disappeared, but what is worrying is that the autumn tide has indeed gradually weakened in the past decade. And 1985 is particularly prominent. According to the analysis of relevant people, the main reason is that 800,000 mu of land was reclaimed from the sea to the west of Ganpu, which narrowed the river channel above Babao, resulting in the decrease of tidal inflow and the elevation of river bed. In addition, in the rainy season of 1985, the discharge of Qiantang River decreased by 1/3 compared with the average of previous years, and the scouring force on sediment was greatly weakened. A large amount of sediment brought by the tide is deposited on the river surface in the same area, which makes the deposition in this area thicker and forces the main river line to move southward. In this way, when the tide rushes to Qiantang River, it only turns south and goes upstream. Because the flow path is lengthened, the energy consumption of tides is too large. When the tide reached Yan Guan Town, it was "exhausted" and became a "spent force".
According to this conclusion, the Qiantang River tide will not disappear, because the shape of the bell mouth of the whole Hangzhou Bay has not changed. However, as the river channel narrows year by year, the qiantang bore Interchange will gradually move eastward. In the future, the best place to watch the tide is from Ding Qiao to Shibao in the east of Yan Guan. Nan 'an reclaimed seventeen sections in Xiaoshan County, Hangzhou.