Bathymetric chart
Also called: Nautical chart · Topic: Topographical Maps: Relief Representation and Interpretation · NCERT: Beyond NCERT
Meaning
A bathymetric chart is a map of the depth of water and the shape of the seabed or lakebed. It uses isobaths, which are lines joining points of equal depth below the water surface. It is like a contour map of the land, but turned upside down. These charts are vital for safe shipping, port building, fishing and laying undersea cables. In India, the National Hydrographic Office, Dehradun, prepares charts of Indian waters.
Example
Charts of the Palk Strait between Tamil Nadu and Sri Lanka show very shallow water. Because of this, large ships cannot pass through it and must sail around Sri Lanka.
Don't confuse with
- Contour line: this shows equal height above mean sea level on land. An isobath shows equal depth below the water surface.