Depths on a depth curve are measured from which reference?

Depths on a depth curve are measured from which reference?

• A. Normal surface elevation of the water body.
• B. Mean sea level.
• C. Bottom depth.
• D. Atmospheric pressure.

Answer: (A)

Depths on a depth curve are a measure of how far below the water’s surface the bottom lies. The reference used is the normal surface elevation of the water body—the standard height of the water surface, not the bottom or some external datum. In other words, depth equals bottom depth below that surface. Atmospheric pressure isn’t what sets this measurement, and while mean sea level is a common reference for global vertical datums, depth curves inside a lake or sea use the water surface as the reference point, which can vary with tides and conditions.

Depths on a depth curve are a measure of how far below the water’s surface the bottom lies. The reference used is the normal surface elevation of the water body—the standard height of the water surface, not the bottom or some external datum. In other words, depth equals bottom depth below that surface. Atmospheric pressure isn’t what sets this measurement, and while mean sea level is a common reference for global vertical datums, depth curves inside a lake or sea use the water surface as the reference point, which can vary with tides and conditions.