Rahn, J.L.

Surveying subaqueous beach profiles and features beyond wading depths can be a costly process, requiring use of expensive equipment and boats. This paper describes the materials and methods of a simple, low-cost technique for underwater bathymetric surveying, herein named the diver depth-gauge profiling (DDGP) method. Although accuracy of depth data depends on the quality of the depth gauges used, it is commonly within 0.3 m. Data collection reliability was evaluated by repeated underwater beach profile surveys, and an example of its use in the Caribbean is provided.

Saba and St. Eustatius/Sint Eustatius (Statia) represent geologically young (less than a million years) Pleistocene island arc volcanoes that rise at the northernmost part of the Lesser Antilles. Both are small islands less than 21 km2 in size with populations around 2000, and both have stratovolcanic features and many Pelean domes with adjacent pyroclastic flows. As a single volcano, Saba’s steep slopes drop off precipitously into the sea, while St. Eustatius lies at the northern end of a shallow submarine bank that links to St. Kitts and Nevis to the southeast. Similar in geologic history and perhaps co-eruptive (though Statia is slightly older and has more erosional features and some uplift), the islands also have similar climates, winds, waves, and ocean current regimes, but lack often-found-in-the-Caribbean geomorphic features such as dunes, perennial streams, wetlands, karst, aquifers, and inland water bodies. Saba and Statia both have heritage sites, including a few (small) Amerindian archaeological sites, but most historical research centers on post-European history including maritime figures, agriculture, and slavery. Owing to their small sizes, neither has been developed very heavily, though Saba is famous for its scuba diving and Statia is known for its oil terminal. Both islands face similar environmental hazards that include hurricanes, earthquakes and volcanism, and drought.

Abstract
Surveying subaqueous beach profiles and features beyond wading depths can be a costly process, requiring use of expensive equipment and boats. This paper describes the materials and methods of a simple, low-cost technique for underwater bathymetric surveying, herein named the diver depth-gauge profiling (DDGP) method. Although accuracy of depth data depends on the quality of the depth gauges used, it is commonly within 0.3 m. Data collection reliability was evaluated by repeated underwater beach profile surveys, and an example of its use in the Caribbean is provided.