Tidal Bore Formation

Tidal bore formation occurs where a large tidal range forces an incoming tide up a shallow, narrowing river mouth or estuary fast enough that the leading edge of the tide steepens into a single wave or a train of waves that travels upstream against the river own current. It requires a specific combination of a very large tidal range, a funnel-shaped estuary that concentrates the incoming water, and a shallow riverbed, conditions met at only a few dozen rivers worldwide, the Qiantang River bore in China and the Severn bore in England among the most powerful. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/