Question 1985Navigation General

The correct answer is C) bore. A bore is a tidal phenomenon that occurs in some river mouths and estuaries, where the incoming high-tide wave crest overtakes the preceding low-tide trough, resulting in a wall of water proceeding upstream. This happens when the tidal range is large and the seafloor gradient is relatively shallow, allowing the fast-moving high tide to catch up with the receding low tide. The other options are incorrect because: A) A boundary wave is not the term used to describe this specific tidal phenomenon. B) A seiche is a standing wave in an enclosed or partially enclosed body of water, which is different from a bore. D) A surge is a sudden and unexpected rise in water level, not specifically related to the tidal crest overtaking the trough.