A Proposed International Long-term Project to Systematically Map the World’s Ocean Floors from Beach to Trench: GOMaP (Global Ocean Mapping Program)

The concept of a long-term (20-30 year) systematic, international effort to map the entire world seafloor from beach to trench (GOMaP = Global Ocean Mapping Program) has been developing at a series of informal and formal meetings over the last 2 years. The goal of GOMaP is to systematically map the ocean floors with at least 100 per cent coverage sidescan and swath bathymetry, and to perform whatever other data collection could be carried out simultaneously (e.g., subbot­tom profiling, magnetics, gravity, physical oceanography and meteorology). Minimum standards for data accuracy, pixel navigation, and resolution have been recommended. Spatial resolutions for GOMaP sidescan sonar imagery should be 100 m or better in the deep sea. This is comparable to what has been achieved by the Shuttle Imaging Radar over the terrestrial earth, the MAGELLAN radar mapping of Venus, the MARS GLOBAL SURVEYOR and other probes on Mars, and the GALILEO mis­sion to the moons of Jupiter. Although spatial resolution for swath bathymetry is slightly less than for sidescan, the resolution of both systems improves sharply with decreasing water depths, particularly for the 10 per cent of the world ocean less than 500 m deep. The decrease of swath width with water depth implies that over 600 ship years are required to map waters 25-500 m deep, compared to just approximately 200 ship years for the deep ocean (500 m and greater). Better pixel navigation accuracy suggests hull-mounted systems (9-16 kHz for deep water, and 30 kHz or higher for shelf waters) may be superior to towed systems, although improvements in towed system navigation instrumentation and techniques may mitigate this difference in the future. Seafloor mapping with air-deployed hyper- spectral and laser bathymetric scanning may be required to replace or supplement shipborne mapping in clear waters less than 50 m deep.