An elevation measured upward from chart datum for rocks, banks and flats that dry at low water and cover at high water. Charts print drying heights as underlined figures so they cannot be mistaken for depths. Survey data over intertidal ground give negative depths relative to chart datum, which become drying heights on the chart; lidar and high-water launch work are the usual ways to fill these areas.
Lidar has the bank top at 1.2 above datum, so it goes on as an underlined drying height, not a sounding.
Also heard as
- drying heights
- dries
Related terms
Chart datum
The low-water level from which charted depths are measured, set so actual depth is seldom much less than shown.
Rock awash
A rock whose top lies at about the level of chart datum, breaking the surface or just under it at low water.
Nautical chart
A map of waters and coasts made for mariners, showing depths, hazards, aids to navigation and landmarks.
ALB
Airborne lidar bathymetry: depth measured from an aircraft with green laser pulses that pass through the water.