See How the Moon Causes Huge Waves on this River
On October 6, more than a hundred thousand tourists gathered on the banks of China’s Qiantang river to witness an extraordinary sight: a wall of water several feet tall racing its way upriver.
While this phenomenon may look like a tsunami, it’s actually a tidal bore, a wave that flows upstream in some rivers as high tide approaches. More than 80 rivers around the world have tidal bores, according to one widely-cited 1988 catalog.
What creates a tidal bore?
"Two principal factors affect the size and strength of bores … the magnitude of the tidal range and the shape of the river at its estuary,” said Victor Miguel Ponce, a professor in the civil and environmental engineering department at California's San
