Determination of the Coastline

Due to the tide and wave, there are (at least) 4 kinds of coastlines:

• Mean Sea Level - MSL, used in topo-map.

• Lowest Astronomical Tide – LAT, used in navigational chart.

• Highest Astronomical Tide – HAT, used to define an island. This is also a “security line” to protect the coastal area against tidal-flood.

• Actual Apparent Coastline - AAC, this is the visible coastline on aeral photographs / satellite images, which separated land from water. This line is between LAT and HAT.