Tidal bore

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Tidal bore

A tidal bore is a phenomenon in which the leading edge of the incoming tide forms a wave (or waves) of water that travels up a river or narrow bay against the direction of the river or bay's current. This natural occurrence is most commonly observed in areas with a large tidal range, typically more than 6 meters (20 feet), and where the incoming tide is funneled into a shallow, narrowing river or bay.

Formation and Characteristics

Tidal bores are formed when the incoming tide is funneled into a river or bay, causing the water level to rise rapidly. The wave created by this rising tide travels upstream against the river's current. The height and speed of a tidal bore can vary significantly depending on the topography of the river or bay, the volume of incoming water, and the tidal range.

Tidal bores can range from a few centimeters to several meters in height and can travel at speeds of up to 25 kilometers per hour (15 miles per hour). The wave can be a single crest or a series of waves, and it often creates a turbulent and frothy appearance as it moves upstream.

Notable Tidal Bores

Some of the most famous tidal bores occur in the following locations:

• The Qiantang River in China, which has one of the largest and most powerful tidal bores in the world.
• The Severn River in England, known for the Severn Bore, which can reach heights of up to 2 meters (6.6 feet).
• The Petitcodiac River in Canada, where the tidal bore can reach heights of up to 1 meter (3.3 feet).

Ecological and Economic Impact

Tidal bores can have significant ecological impacts on the rivers and bays they affect. The sudden influx of saltwater can alter the salinity of the river, affecting the local ecosystem and the species that inhabit it. Additionally, the turbulence created by the bore can disrupt sediment and nutrient distribution.

Economically, tidal bores can be both beneficial and detrimental. They can attract tourists and surfers, providing a boost to local economies. However, they can also pose a hazard to navigation and infrastructure along the riverbanks.

Recreational Activities

Tidal bores are popular among surfers and kayakers who seek the thrill of riding the wave upstream. The phenomenon also attracts spectators who gather to witness the impressive natural event.

Related Pages

• Tide
• River
• Bay
• Ecosystem
• Severn River
• Qiantang River
• Petitcodiac River

See Also

• Tidal range
• Tidal power
• Estuary