Ch. 4— Technologies for Exploring the Exclusive Economic Zone • 131 



less accurately." If airborne bathymetric survey 

 techniques for shallow water can be further refined, 

 they would have the distinct advantage over ship- 

 based systems of being able to cover much more 

 territory in much less time and at reduced cost. 

 Technology for airborne surveys in deep water has 

 not yet been developed. 



Systematic Bathymetric Mapping of the EEZ 



NOAA has recently begun a long-range project 

 to survey and produce maps of the entire U.S. 

 EEZ. The NOAA ship Surveyor is equipped with 

 Sea Beam and has been mapping the EEZ since 

 May 1984. Initial Sea Beam surveys were made 

 of the Outer Continental Shelf, slope, and upper 

 rise off the coasts of California and Oregon.^* A 

 second Sea Beam was installed aboard Discoverer 

 in 1986. The Davidson has been equipped with BS' 

 since 1978. NOAA plans to acquire two additional 

 swath mapping systems with 1987 and 1988 fiscal 

 year funds. 



NOAA is currently able to map between 1,500 

 and 2,500 square nautical miles per month (with 

 two ships, Surveyor and Davidson, working on the 

 west coast continental slope). This is significantly 

 below the expected coverage rate for the Sea Beam. 

 Transit time, weather, crosslines, equipment fail- 

 ure, and decreased efficiency in shallower water are 

 factors that have limited production to about 50 

 square nautical miles per ship per day. Moreover, 

 NOAA has not yet surveyed any areas beyond 120 

 miles from the coast. With the GPS available only 

 part-time, too much time would be wasted in main- 

 taining accurate navigation control on the outer half 

 of the EEZ. Delays in launching satellites, the 

 Challenger accident, and several recent failures of 

 GPS satellites already in orbit are further eroding 

 the near- term usefulness of GPS and, therefore, 

 limiting the efficiency of NOAA surveys. 



The agency would like to map all 2.3 million 

 square nautical miles of the U.S. EEZ. With cur- 

 rent technology, funding, and manpower, this 

 project could take more than 100 years. In order 

 to ensure that the most important areas are sur- 

 veyed first, NOAA consults with USGS and uses 

 USGS's GLORIA side-looking sonar imagery to 

 select survey targets. USGS has provided funds to 

 NOAA for data processing; in return, NOAA ac- 

 cepts the survey priorities set by USGS. 



By mid- 1986, less than 1 percent of the U.S. EEZ 

 had been systematically surveyed with NOAA's Sea 

 Beam and BS^ systems. To date, few of the charts 

 or raw data have been publicly released because 

 the U.S. Navy has determined that public dissem- 

 ination of high-resolution bathymetric data could 

 endanger national security. NOAA and the Navy 

 are currently exploring ways to reduce the secu- 

 rity risks while producing bathymetric charts use- 

 ful for marine geologists, potential seabed miners, 

 fishermen, and other legitimate users (see ch. 7). 



NOAA's Survey Program is the only systematic 

 effort to obtain bathymetry for the entire EEZ; how- 

 ever, several academic institutions have mapped 

 small portions of the EEZ. For instance. Woods 

 Hole Oceanographic Institution, Lamont-Doherty 

 Geological Observatory, and Scripps Institution of 

 Oceanography have their own Sea Beam systems. 

 Much of the mapping these institutions have done 

 has been outside the U.S. EEZ. Moreover, addi- 

 tional bathymetric data (how much of it useful is 

 unknown) are gathered by the offshore petroleum 

 industry during seismic surveys. As much as 10 mil- 

 lion miles of seismic profiles (or about 15 percent 

 of the EEZ) have been shot by commercial geo- 

 physical service companies in the last decade, and 

 almost all of these surveys are believed to contain 

 echo soundings in some form (probably mostly 3 . 5 

 kilohertz data).^^ Some of these data are on file at 

 the National Geophysical Data Center (NGDC) in 

 Boulder, Colorado; however, most remain propri- 

 etary. Moreover, maps made from these data might 



^^W. Alpers and I. Hennings, "A Theory of the Imaging Mecha- 

 nism of Underwater Bottom Topography by Real and Synthetic Aper- 

 ture Kadar," Journal of Geophysical Research, vol. 89, No. C6, Nov. 

 20, 1984, pp. 10,529-10,546. 



"D.E. Pryor, "NOAA Exclusive Economic Zone Survey Pro- 

 gram, ' ' in PACON 86, proceedings of the Pacific Congress on Ma- 

 rine Technology, sponsored by Marine Technology Society, Hawaii 

 Section, Honolulu, HA, Mar. 24-28, 1986, pp. OST5/9,10. 



2*R.B. Perry, "Mapping the Exclusive Economic Zone," Ocean 

 Engineering and the Environment, Oceans 85 Conference Record, 

 Sponsored by Marine Technology Society and IEEE Ocean Engineer- 

 ing Society, Nov. 12-14, 1985, San Diego, CA, p. 1 193. The seismic 

 profiles themselves generally include ocean bottom reflections when 

 water depths are more than about 150 meters. These profiles are ac- 

 curate, continuous bathymetric records along the line of survey. 



