As people in China celebrate the National Day and the Mid-Autumn Festival this week, they’re also expecting a spectacle that would sweep them off their feet – literally.
Qiantang River tidal bore, thought to be the largest tidal bore in the world, has awed residents and visitors in eastern China for hundreds of years.
Gigantic waves up to 10 metres (33 feet) travel down the trumpet-shaped Hangzhou Estuary at high speeds before crashing into the embankment with great momentum.
Spectacular: Due to the trumpet shape of the Hangzhou Estuary in China, multiple bores meet each other and become one
Rare: From there, the super tidal bore would continue travel up river until it reaches the shore of Haining in Zhejiang Province
Thrilling: Spectators gather to watch the annual Qiantang River tidal bore by the embankment – metres away from the waves
The tidal waves, caused by the gravitational pulls of the sun and the moon, occur every month. But the bore is the strongest and most impressive on the 18th day of the eighth month on the lunar calendar – due to the lining up of the moon, sun and the earth.
This year, the impressive tidal phenomenon will appear on October 7 on the Gregorian calendar.
As the day falls three days after China’s Mid-Autumn Festival, observing the Qiantang River tidal bore has been the traditional entertainment for many families.
Up the hill: Onlookers run away as waves from a tidal bore surge past a bank barrier of Qiantang River, China, on September 8
Waiting for the moment: Visitors and local residents watch the tidal bore of the Qiantang River in Hangzhou on September 8
Dangerous: Every year, thousands of people gather in Haining, the best observing spot, to enjoy the Qiantang tidal bore
Chinese residents would travel across the country to Haining, the best observing spot, to enjoy the thrill of the dramatic rise and fall of the tidal currents.
It could be a terrifying experience though.
A video showing last year’s Qiantang River bore, shared by People’s Daily Online on YouTube, shows a torrent of water gushing several feet over the bank barriers and onto the viewing platforms last year.
As the waves gather their momentum on Qiantang River, they could reach 43 kilometres or 25 miles per hour. That’s around 12 metres (39.3 feet) per second.
Gigantic waves: Slow runners are drenched and washed over as the incredibly powerful bore in Hangzhou on September 8
Powerful: Qiantang River bore could reach up to 10 metres (33 feet) and can travel as fast as 12 metres (39.3 feet) per second
The sizable tides can be as high as 10 metres (33 feet), which is nearly the height of three London double-decker buses stacked up.
Spectators appeared to like the adrenaline rush as they enjoyed running away from the embankment at the last minute when the waves crashed onto the shore.
Every year there are reports of casualties among spectators, but they haven’t stopped daredevil Chinese tourists from flocking to the shore to watch the annual spectacle.
WHAT IS A TIDAL BORE
Tidal bore is a rare tidal phenomenon, which sees a surge of waves forming on the ocean and washing inland up a river.
It’s rare because the river must be relatively shallow and it must have a narrow outlet to the sea for the tidal currents to gather momentum.
In the case of Qiantang River, its tidal bores are famous because of the unique shape of the Hangzhou Estuary which leads the river to the East China Sea.
The width of the trumpet-shaped estuary reduces from 100 kilometres (62 miles) near the sea to three kilometres (1.8 miles) near Haining. This means multiple tidal bores have to combine into one super bore to travel up river.
In general, tides are caused by the pull of the sun and the moon in relation to forces created by the spin of the earth. Highest tides occur when the pull of the sun and the moon are in line.
Around the time of a full moon, the tides can be exceptionally strong and robust tidal bores are created.
Source: National Geographic, Phys.org, Newxue.com