Question

what engineering structure is used in canals and waterways to raise and lower vessels between stretches of water at different levels? dam weir lock levee

Explanation:

A lock is a chamber in a canal or waterway that can be filled or emptied to raise or lower vessels between stretches of water at different levels. A dam is a barrier that stops or restricts the flow of water. A weir is a small overflow dam. A levee is a natural or artificial embankment that prevents flooding.

Answer:

Lock