Dujuan – a big bore
The tidal bore in the Qiantang is lifted even higher by rain from Dujuan
Typhoon Dujuan has flooded cities, caused landslides and required evacuations since its landfall in east China on Tuesday morning. Coincidentally, it has also enhanced an already wondrous sight in Haining City.
The world’s largest tidal bore surges up the Qiantang River, enanced by the moon, which is at its closest point to us in its elliptical orbit. A tidal bore is a wave, fronting an incoming tide, and occurs in many rivers arond the world. Tide size varies throughout the year and now is the time of maximum height.
The effect of Dujuan’s rain coming down the river and a high tide coming up, caused the water level to rise sharply, forming the biggest bore in five years, reaching as high as 9 metres. The Qiantang bore can reach speeds of 40km/h.
These tidal bores are a well-known natural wonder caused by the gravitational pull of the moon, and the funnel shape of the Hangzhou Bay.
Dujuan, no longer a typhoon, is still a tropical depression and as such has brought a typical rainfall of 200 millimeters to Zhejiang province. The highest reported total was 329 millimeters, caught in the Zhenhai District of Ningbo City.
The heavy rainfall caused flooding and landslides in Ningbo City, disrupting traffic and damaging roads. The iron gate at a scenic spot in Longguan Town of Yinzhou District was swept away by flood.
The remnants of Typhoon Dujuan will bring significant rain in the coming few days to Fujian and Zhejiang Provinces, the Yangtse River and Shanghai.