What is headwater in relation to a culvert?

• A. The height of water during a flood event
• B. The depth at the beginning (upstream) of the culvert
• C. The total flow capacity of the culvert
• D. The volume of water managed by the culvert

Answer: (B)

The term "headwater" refers specifically to the depth of water at the upstream end of a culvert, indicating the elevation of water just before it enters the structure. This measurement is crucial for understanding how much water is backing up or pooling in front of the culvert during flow events. Headwater levels can provide insight into hydrologic conditions, assist in sizing culverts appropriately, and help ensure that they are capable of managing expected flow rates without causing flooding or excessive water buildup.

Understanding headwater is essential for engineers, as it impacts the design considerations for the culvert, including its dimensions and the potential need for other water management strategies downstream. This measurement helps in assessing the performance of the culvert and evaluating hydraulic conditions, making it a key factor in drainage design and flood management.