Our Seabed Frontier Challenges and Choices (1989) / Chapter Skim
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5. The Challenges of Eez Use
5. The Challenges of Eez Use
Pages 98-106
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From page 98... ...
A FRAMEWORK FOR SITE EVALUATION A realistic assessment of the constraints to engineering development and the impacts of EEZ use at specific sites will require a systematic integrated approach. An organized framework of investigation involving oceanographic, geologic, geotechnical, and biological data is needed to recognize the interrelationship of each on overall site performance.
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From page 99... ...
, ,; FIGURE 5-1 Site performance model. For example, a prospective location for deepwater oil and gas development may be geologically active or benign, possess strong or weak sediments, experience imperceptible or energetic currents, and have simple, resilient, or complex and vulnerable biological communities.
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From page 100... ...
Geology Analysis of the geologic characteristics of engineering sites aims at comprehensive evaluation of present three-dimensional sediment and structural geometry, site history, and future geologic behavior. Geologic data allow identification of constraints to engineering provided by existing site conditions and forecasts of possible magnitudes and distributions of geologic processes during the engineering design lifetime.
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From page 101... ...
Geotechnical Properties Most activities planned for the EEZ will require some type of installation or facility that will depend on seabed foundation support or subsurface installation. There are a large number of different foundation types and installation procedures required to accommodate the wide range of sediment conditions encountered throughout the EEZ Present geotechnical engineering practice offers highly advanced field investigation methods and analytical procedures available for design that will help achieve risk-free installation and performance.
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From page 102... ...
Oceanography For a prospective EEZ seabed utilization site, the principal components of oceanographic information critical to recognition of the balance of conditions and to the resulting site-performance model are water depth, seawater motion, sediment chemistry, and variability at or near the site. Some of the information on the geology and biology of the site also has oceanographic relevance.
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From page 103... ...
A fuller understanding of biological effects on seafloor uses and, conversely, the possible impacts of a use on biological communities, requires knowledge of the temporal variability in communities, production rates of benthic organisms, and the structure of benthic food webs and bioturbation rates. The notion of community structure embodies a variety of concepts, most notably the number of species present and the relative abundance of individual species.
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From page 104... ...
. rapidly traversing bottom vehicles capable of acoustic/in situ property cross correlation; deep-tow systems with multifrequency, multisensor packages in autonomous vehicles or improved towing and cable technology; · multipurpose systems with vessels dedicated to routine multipurpose surveying with a wide range of tools aimed at extensive suites of seafloor data acquired in single traverses; · multipurpose sensors from which simultaneous bathymetry, seafloor imagery, and subbottom profiles can be obtained; · improvements in acoustic sources, arrays, variable and multifrequency profiling systems, together with real-time processing, to address difficult geologic terrain and the requirements for engineering data at greater depths below the seafloor; · common, mutually compatible formats for digital recording and processing to facilitate exchange of data; and
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From page 105... ...
instruments capable of providing data for analyzing long-term sediment stability; · improved sampling and in situ testing devices for determining sediment properties in more difficult offshore environments; improved experimental testing methods that will allow the properties and behavior of the seabed to be reliably observed and predicted in a more controlled environment; and · compact deployment systems that can operate in a rapid transit mode and that will automatically measure seafloor properties or sample the sediments. A further nontechnical issue for acquiring geoscience data is the need to develop a coordinated research and development plan involving different agencies and industry user groups and academia in a cooperative effort to develop improved systems for sampling and performing in situ and laboratory tests on seafloor sediments.
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From page 106... ...
Monitoring projects on the scale of years to decades will be necessary to acquire real data on seafloor process activity. Such data on seafloor behavior, processes, and causative factors is a key element in predictive site evaluations and will expand the-usefulness of mapped data.
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