What term describes an obstruction placed in flowing water to measure the rate of flow?

The term that describes an obstruction placed in flowing water to measure the rate of flow is known as a weir. A weir is a structure that can be constructed at various sizes and shapes, designed to measure the discharge of water in open channels. The water flowing over the weir creates a specific flow pattern, allowing for precise measurement of the water’s flow rate based on the height of the water above the weir crest.

Weirs are commonly used in hydrology and environmental studies to gather data on water flow in rivers, streams, and other bodies. They are valuable instruments because they can be effectively designed to account for variations in water levels, making them useful for monitoring and managing water resources.