What Is a Sudden Rise in a Tidal River Called? The Tidal Bore Phenomenon

A tidal bore is a fast-moving, turbulent wave front that travels upstream in a river mouth as the tide rises.

It occurs where tidal range is large, river channel is shallow/funnel-shaped, and incoming tide overtakes river outflow. Famous examples: Qiantang River (China), Severn (UK), Amazon (pororoca).