Questions? Call 888-624-8373

PAPERBACK
list:$17.00
Web:$15.30
add to cart

PDF BOOK
your price: $13.50
add to cart

Rights & Permissions

topleft topright

Our Seabed Frontier: Challenges and Choices (1989)
Commission on Engineering and Technical Systems (CETS)

Page
20
bottomleft bottomright
  E-mail
 Facebook
 Digg
 Stumble
 Twitter
More
Page
20

Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 20
3 PRESENT AND POTENTIAL USES OF THE SEABED The contribution of the ocean sector to the U.S. economy was about 2.6 percent of the total gross national product (GNP) in 1987 (Pontecorvo, 1989), an amount on the same scale as other components of GNP, such as mining, transportation, and communications. The role of the oceans as a resource base for future growth and development is likely to increase under the pressures of population growth and economic expansion (Corell, 1988~. This chapter identifies existing and potential uses of the seabed, assesses their current scope and future potential, estimates time frames required for development, and examines constraints to current and future development. Problems and issues associated with each resource or activity are analyzed, particularly existing or potential conflicts among different uses. Resources and uses examined include oil and gas exploration and development, mineral exploration and development, waste disposal, cables and military uses, biological resources, ocean energy resources, and cultural and recreational resources. The technology and information required to develop these resources or activities are examined in depth in Chapter 4. OIL AND GAS EXPLORATION AND DEVELOPMENT AND OFFSHORE STRUCTURES Background Since the first oil and gas wells were drilled from piers offshore of Summerland, California, in 1896, the U.S. petroleum industry has been shifting a greater percentage of its activities from onshore to offshore. Today, offshore oil and gas production is an important source of the nation's energy supplies. In 1985, 11 percent of total crude production (1.07 million barrels) and 25 percent of total gas production (1,335 billion m3) was produced offshore, and it is estimated that the percentage of U.S. oil and gas reserves from marine sources will continue to increase each year as land reserves decline (Bettenberg, 1987; OTA, 1985; Nehring, 1981; MMS, 1987~. The USGS estimated in 1981 that 26 to 41 percent of the oil and 25 to 30 percent of the natural gas that will be discovered and recovered in U.S. controlled territory in the future will be found offshore within the EEZ. Offshore oil and gas production also began to move toward the Arcti~specifically the Beaufort, Chukchi, and Bering seas when activities in the Beaufort Sea commenced in the mid 1970s. The technology and operational expertise associated with hydrocarbon exploration is well developed for activities conducted from mobile structures, such as jack-up rigs or submersibles; floating vessels, drill ships, or semisubmersibles (Figure 3-1~; and fixed structures for up to 300-m depths, such as template type platforms, tower platforms, or caisson platforms (over 4,100 of these platforms have been successfully installed offshore [Anon, 19~. In addition, design and 20

OCR for page 21
1 POSTED BARGE ~1 SUBMERSIBLE ~1 LILII~U1 21 JACK-UP RIG SEMI-SUBMERSIBLE DRILLSHIP 1 ~ _ ~ ~1,,. .,,, l 3 m 12 m FIGURE 3-1 Family of offshore exploration drilling rigs ~ 90 m ILl it, 900 m + - DEEP WATER \ construction capabilities for new types of production structures for water deeper than 300 m-guyed towers, tension leg platforms, compliant towers, and subsea production systems (Figure 3-2)-have improved greatly over the last decade (OTA, 1985~. Exxon installed the first guyed tower (Lena) in 300 m of water (LeBlanc, 1983) in 1983 and Conoco's installation of its tension-leg platform Joliet in 535 m of water was scheduled to be completed in August 1989 (Ocean Oil Weekly, 1989~. Three other production systems have also been installed in deep waters: Shell's Cognac (312 m) and Bullwinkle structures (412 m), and Placid's Penrod 72 (465 m) (Ocean Oil Weekly, 1987 and 1988~. Subsea production systems are an important alternative for deepwater field development. Although over 100 of these systems have been installed around the world in a variety of water depths, Placid Oil's subsea system installed in the Gulf of Mexico at a site in 680 m of water is the maximum depth for the U.S. EEZ (Wickizer, 1988~. This system is an attractive cost-saving option for well completions in water depths greater than 1,000 m, since the wells are drilled from a floating rig and completed on the seafloor. The majority of the subsea completions are a single well classified as a "wet" system that relies on a Bowline to transport the hydrocarbon to a nearby fixed or floating platform for processing before transporting the oil and gas to market. The ~dry" system places an atmospheric chamber around the wellhead on the seafloor, allowing Bowline connection and maintenance to be performed by workers inside the chamber. In the future, subsea production systems of the dry type will be used more widely in water depths from 1,000 to 2,000 m, especially for satellite reservoirs. Improvements in deepwater Bowline installation and artificial lift technology should allow the system to be economically attractive for water depths out to 3,000 m. To date, arctic activities have primarily involved exploration wells drilled from artificial islands, although a few wells have been drilled from mobile steel caissons like the one shown in Figure 3-3 (Yokel and Bea, 1986~. Improving the nation's capability to produce oil and gas from the EEZ will continue to depend on improving these technologies in order to move into the frontier areas like the Arctic and deep water (over 300 m).

OCR for page 22
WATER DEPTH FEET, _ _ 2000 1 500 1000 500 22 GRAVITY FIXED GUYED TENSION-LEG BUOYANT SUBSEA COMPLETION PLATFORM PLATFORM TOWER PLATFORM COMPLIANT TOWER 700 - 2000 FEET 1000 - 3000 FEET 1000 - 2500 FEET (200 - 600 METERS) (300 - 900 METERS) (300 - 750 METERS) 0 - 700 FEET 0 - 1000 FEET METERS (0 - 200 METERS) (0 - 300 METERS) 600 500 / ~ / ~ 400 -300 _~_ it, ~ 0110 ~ ~ L_ FIGURE 3-2 Range of water depths FIGURE 3-3 Mobile steel arctic caisson production platform. 3000- 10000 FEET (900 - 3000 METERS) FLOATING PLATFORM , .. l ll l l l 111 1~1 111 1 11 111 1 11 y ,. -. GUY-LINES \~ TETHERS SEABED ANCHOR r Pl.Es for various types of production platforms. s_ lo, - ~ ~, ;,; t; . . . Scope of Development Future offshore oil and gas activities will include development of presently unleased areas of the outer continental shelf (OCS) where mature technology offers assurance of operationally safe, environmentally sound, and economically secure development (NRC, 1979 and 1977~. Although oil and gas reserves in frontier areas of the EEZ cannot be forecast with absolute certainty, since 1975 the number and extent of exploration and recovery activities in water depths greater than 300 m has

OCR for page 23
23 increased dramatically. For example, the number of deepwater wells drilled in the Gulf of Mexico increased fourfold since 1975 (Figure 3-4), and in 1988 Shell Oil set a new world depth record when it spudded a well in 2,273 m of water in the Mississippi Canyon area. Most of the production of oil and gas has occurred to date in the shallow water of the Gulf of Mexico and offshore California. Some studies (OTA, 1985) suggest that most of the undiscovered oil and gas in the United States will exist offshore Alaska and California and in the deep water of the Gulf of Mexico. Trends suggest that actual production (including subsea completions) in water depths up to 2,000 m is likely by the end of this century. As EEZ oil and gas development expands farther in these deeper waters, construction and operating costs will increase due to the logistical requirements of operating farther from land. As a result, production configurations are likely to change to more-wells per platform, more processing facilities, and fewer but larger platforms. As the capital investment and population per platform increases, the knowledge requirements for platform design and the operational environment will become even more exacting. To ensure that sound engineering design principles and practices are followed, industry groups, such as the American Petroleum Institute, will need to update their guidelines of recommended practices (API, 1987~. Uncertainties are inherent in predicting overall potential value to the nation of EEZ oil and gas resources. Uncertainty exists concerning the possible size, quality, and production costs of reservoirs that may exist, especially in the Arctic and deepwater areas of the continental slope. Ongoing development of an expanded and improved capability for resource forecasting in the entire EEZ is extremely important (USGS, 1986~. The ramifications of this issue will require joint government and industry consideration of policies influencing developmental planning and economic strategy. In addition to the size and quality of oil and gas reserves that may be located in deepwater and arctic environments, economic factors and technical constraints will affect future development of EEZ reserves. Among the important economic factors are world oil prices, availability of oil from dependable sources, and production costs. The primary technical constraints facing designers will be depth limits of current platform and pipeline technology; lack of knowledge about new seafloor sediment types; and lack of understanding of geological, biological, and oceanographic processes that control seafloor conditions that impact platform and pipeline design and operation. Development Constraints Many technical and economic constraints face the offshore oil and gas industry as it moves farther onto the continental slope and into unexplored arctic regions. The environmental hazards of operating in deep and ice-infested waters are considerably greater, and overcoming them will be far YEAR ~ 975 1 976 1 977 1 978 1 979 1 980 1 981 1982 1983 1984 FIGURE 3-4 Number of ~ 985 deepwater exploration ,9~86 wells in the Gulf of 1988 Mexico in water deeper than 180 m. Z" A (SHELL'S COGNAC PLATFORM INSTALLED) , ~ (EXXON'S LENA PLATFORM INSTALLED) ~'''~,,,~ i ,,,,,,,,,,,, ,,~,,~,,,,~, .,~,'',,, ,~ 0 10 20 30 40 50 60 NUMBER OF EXPLORATION WELLS WATER DEPTH OF WELLS 180 TO300 m > 300 m

OCR for page 24
24 more costly than previously experienced and will require innovative approaches to the design of drilling operations and structures (Wickizer, 1988~. Despite these challenges, development of EEZ oil and gas resources is proceeding and can be enhanced by long-term planning and regulatory requirements that reflect sound understanding of the seabed environment. The sections that follow describe the information needed to improve the state of knowledge of this environment that will lead to such understanding. Seafloor Gradients Site-specific studies already completed for the oil and gas industry on the continental slope indicate that seafloor bathymetry, slopes, and local relief are considerably more complex than on the shelf. lithe severity and diversity of bottom relief may be important factors in development decisions, because areas with steep bottom slopes and rugged terrain may be too difficult to operate in and therefore uneconomical to develop. By comparison, bottom conditions on the shelf have never proven severe enough to be intractable to engineering solutions to detect and avoid problems. A related problem is that existing bathymetric maps for EEZ continental slopes are not accurate enough to develop site-specific oil production systems. Considerably more detailed information on water depths and gradients is needed for potential development sites. It should be noted that multibeam swath bathymetry does not address the accuracy levels necessary for site-specific development. Sea Beam, for example, covers a swath of 0.8 times the water depth with a resolution of 5 percent of water depth. In 4,000 m of water, a swath width of more than 3 km results in a spatial resolution of about 200 m (Tyce and P'yor, 1988~. Seafloor Geologic Processes Seafloor or near-seafloor processes-such as landslides, turbidity currents, erosion/scouring, faulting, creep diapirism, gas seeps, and sediment collapse-can impose considerable constraints on the development of engineered structures, depending on their magnitude and frequency. Many of these processes are present and active on the continental slope: for example, active faults, diapiric uplift, recent landslides, and subsidence all occur on the Gulf of Mexico slope (see Figure 2-4) (Campbell et al., 1986~. Arctic frontier regions pose many different geologic hazards to development, including ice scour, freezing and thawing cycles of ice-bonded sediments, and gas hydrate stability (NRC, 1986~. - An important constraint to EEZ development in deepwater and polar regions is the lack of knowledge and understanding of distribution and intensities of these processes. Moreover, they cannot be predicted from available regional geologic information. For example, a submarine landslide large enough to damage production facilities may be too small to show up in regional geologic data. Furthermore, even if a landslide is discerned, the data may not be sufficient to pinpoint its origin, so it wouldn't be useful in predicting future events. Thus, it is essential that regional data be interpreted in a wav that Drovides a useful context for Planning subsequent detailed. ~ ~ ~ ~ 1 ~ A .. · ~- . · . . . . . . _ _ _ . . _ _ slte-specl~lc geophysical surveys, which are always required to evaluate the area s potential for exploration and production. Because of the complexity of deepwater and arctic frontier regions and associated higher operation costs, it is especially prudent to evaluate potential production constraints before beginning exploratory drilling. Knowledge If data from site-specific geophysical studies are combined with geotechnical information, it is possible to quantitatively predict the possible effects of seabed processes on seafloor installations

OCR for page 25
25 over their lifetimes (Figure 3-5~. However, such an integrated approach goes beyond routine geological surveying and measurement of geotechnical properties (Campbell et al., 1988~. Engineering Properties of Sediments Knowledge of sediment properties, such as static and dynamic stress and strain behavior or compressibility and consolidation characteristics, is fundamental when evaluating geologic processes and designing piles, conductors, well heads, templates, anchors, and pipelines. A variety of techniques are used for offshore site investigations, such as laboratory testing of recovered samples combined with in situ measurements, which are now successfully used to depths of up to 1,000 m (McClelland and Ehlers, 1986~. (More detailed discussion of engineering properties and problems of acquiring reliable data are presented in Chapters 2 and 4.) Several important geotechnical problems arise when developing oil and gas production facilities for deep water and the Arctic. First, unique or exotic sediment types with fundamentally different properties and physical behavior are being encountered on the continental slope. For example, gas hydrates have been found in surface sediments in water as shallow as 450 m in the Gulf of Mexico and even in shallower water in the Arctic (Brooks et al., 1986~. They are interspersed within the sediment matrix as small, contained ice pockets, or may have the form of large, conical shaped, ice- infested mounds that extend laterally hundreds of meters. The hydrates may pose design problems for foundations if they are heated by adjacent production well conductors and thereby become mobilized (Hooper and Young, 1989~. Similarly, landslides and seafloor eruptions may be related to INTEGRATED STUDIES GEOLOGY ) Geophysics Field Data Interpretation and Maps Site Geology I - Lab Tests 1 ~ Interpretation Hazards and Risks ~ ~1 (~INEERIN: struct(lre an(' Site Location Concepts .. -'is Stress History / ~DeS\ Engineering Geology Model Borings Wild In Silu Tests Lab Tests Foun(~tio Allalysis - Follntlation Design Parameters FIGURE 3-5 Interactive evaluation process for integrating geological and geotechnical information. SOURCE: Campbell et al., 1988.

OCR for page 26
26 expansion, contraction, or degeneration of hydrate materials (McIver, 1982; Prior et al., 1989~. EEZ development will therefore require determining occurrence, stability, and likely future behavior of gas hydrates. Additional information, such as seafloor temperatures, will be required as a basic input for analysis of heat transfer from wells or pipelines in areas where gas hydrates occur. In addition to gas hydrates, sediments are encountered in deepwater areas that exhibit the relatively high sensitivities (i.e., significantly reduced strength when disturbed) normally associated with bioturbation and high organic content. Such physical behavior can constrain foundation design because of the potential for slope failure, or loss of shear strength affecting foundation installations (Hooper and Dunlap, 1989~. Improving knowledge about this type of sediment and determining related engineering constraints are important problems to resolve. Gases in deepwater sediments are a greater concern than shelf sediment gases because the hydrostatic pressure is greater and there is a greater likelihood that gas expansion due to heating from oil and gas production will affect foundation sediments. All the various gas phases~issolved, vapor, or solid-are detrimental and can adversely influence foundation conditions (Esrig and Kirby, 1977; Whelan et al., 1977~. A separate yet related set of geotechnical problems is the lack of technology available for sampling and testing deepwater areas (discussed in detail in Chapter 4~. Cost-effective systems for geotechnical sampling and testing are presently-not available for deployment from remotely operated vehicles (ROVs) or tethered-type seafloor platforms (Young et al., 1988~. Production Siting and Facilities Considerable progress has been made in using geological and geotechnical data to conduct integrated risk analysis for the design of platforms and pipelines on the continental shelf. For example, in the Mississippi delta mudslide area, wave and sea bottom interaction models have been used successfully to determine foundation loading due to mudflows (Kraft and Ploessel, 1986~. Deepwater areas of the EEZ will require correspondingly appropriate geological and geotechnical models for these and other complex processes. For example, diapiric or gas-induced slope failures are understood only qualitatively, and sediment and foundation interactions under earthquake loading-including stress propagation and modification of sediment properties-are poorly understood. Quantitative data for a wide range of deepwater sites that can be used to formulate analytical models and calibrate them to specific design conditions will be required for development of these areas to proceed (American Society of Civil Engineers, 1983~. There is considerable debate over the advantages and disadvantages of various deepwater structural systems, such as compliant towers, tension leg platforms, or subsea production systems (Figure 3-2~. Design and emplacement of these new types of structures require site-specific geotechnical data and engineering and verification criteria that are presently based on single prototype designs. Hence, new innovative structures will require environmental data obtained by monitoring full-scale installations to assess the performance of foundation elements, including piles, mats, and anchors. Seabed pipelines that transport oil and gas from offshore production platforms to refining or storage facilities are an important component of offshore development. At the end of 1985, there were 12,500 km of pipeline in the U.S. EEZ (NRC, 1985~. Oil spills resulting from ruptures of these pipelines are a major concern because they can cause extensive local environmental damage. But, historically, pipeline ruptures have released far less petroleum into the marine environment than other transport systems, such as coastal tankers and barges (NRC, 1985~. Any natural phenomenon that presents a potential hazard to a pipeline must be considered, however, and protective measures taken. Burial in the ocean bottom is the most effective way to protect them, but in some areas, such as potential sites of large mass wasting, the only solution may be to keep pipelines out of the region altogether. Deepwater and arctic areas pose new engineering challenges to pipeline routing, installation, monitoring, and repair similar to those associated with drilling and

OCR for page 27
27 production. Problems that are unique to pipelines include design for an ice-gouged seafloor, and leak detection and repair in ice-covered areas. Summary Over the last 40 years, offshore oil and gas technology has evolved that allowed the design and construction of facilities and equipment capable of extracting oil and gas from the continental shelf in a safe and pollution-free manner. If the industry is to move beyond its present capability to new areas of the EEZ, the difficulties of operating in more demanding and hostile environments must be solved. Developing equipment and platforms that can meet the challenge of these areas will be costlier, riskier, and more time consuming than previous offshore efforts, and will be affected not only by technical progress but also by nontechnical factors, such as fluctuating world oil prices, the impact of unstable political regimes in oil-producing countries, and a domestic regulatory climate subject to conflicting public pressures. Equally significant will be the extent to which government and industry cooperate to achieve a proper balance between meeting the nation's energy needs and environmental concerns and maintaining a competitive and technically innovative domestic oil and gas industry. MINERAL EXPLORATION AND DEVELOPMENT Background During the late 1960s to mid 1970s, interest in seabed minerals was stimulated by exploration of extensive deposits of manganese nodules on the deep Pacific seabed. Amid this enthusiasm, recovery and processing prototype systems were developed and claims were staked in the deep ocean. This success also resulted in exploration for other potentially valuable marine mineral deposits in shallow water. By the late 1970s, however, falling minerals prices, combined with U.S. disagreement with Law of the Sea provisions over ocean mineral rights, caused the fledgling marine mining industry to shelve deep ocean mining exploration and systems development at a point where proof of concept and site reconnaissance were accomplished. In 1983, interest in offshore minerals was again stimulated by the EEZ proclamation, combined with the Reagan administration's expressed concern over dependence on foreign sources for strategic minerals. The impact of the EEZ proclamation was to reaffirm and clarify the jurisdiction of the Outer Continental Shelf Lands Act (OCSLA) of 1953, which established regulations for developing mineral resources on the outer continental shelf, and expand it to include U.S. territories as well. EEZ marine minerals are conventionally classified into five groups-aggregate materials, placers, phosphorites, metalliferous oxides, and metalliferous sulfides. Occurrences of sulfur and miscellaneous mineral lodes, such as lead and zinc, are known to exist in the EEZ arid comprise a sixth category in this report. These marine minerals are widely varied both with regard to type and location. Occurrences of marine minerals are widespread throughout the EEZ, with aggregates and placers off both coasts of the United States in mostly shallow waters. Sulfur, also a shallow-water mineral, is found in the Gulf of Mexico. Further offshore and in generally deeper waters off the southeast coast, phosphorites and manganese nodules have been discovered. In the deeper oceans, manganese crustal deposits are located on the slopes of Pacific seamounts and islands, and polymetallic sulfides are located at Pacific Ocean thermal vents or spreading centers. Principal characteristics and geographic locations of known EEZ mineral deposits discussed below are summarized in Table 3-1; additional information regarding extent, content, and location is given in DO! (1987), OTA (1987), and Broadus (1987~. 1. Aggregates, siliceous sand and gravel and carbonate sands widely used for construction, beach replenishment, and concrete and ceramics manufacture, are widespread on the U.S.

OCR for page 28
- ~ ~ e 7- e e E ~E ~j E D ~: E o ~ E o _ _ ~C C o o ._ ._ ~C ~C _ ~_ C.} c ~eo L: C ~C C °uC 8 .E ~8 .E ~ ~,~ ~ . V: - ._ c) a o - ._ C) - Ct :t ._ ._ ~=C C.) ~ E ~ ._ _ ._ C , cr . fL) E ~ ·- C>. ~ c C) - e~ - c ~ o c E oo~ Co G ~S .C ~ C ~ .~= 3 -` .O a~ ~ o 8 ~ o_ - .- a ~ m C Y o 8 ~ E _ E o ~, o C _ ~D C o e ~_~ 't, oE_ E -2 _ y- o ~ ~U o E ._ ~. _ ~ ~C ~ D U. ~n O c E 8 ~ - o o C ~ ~ ~ ~ ~ ~ - ~q o - - c c ~ ~.D ~ ;= ~ ~ ~ ~ ~ ~ ~ ~ e o" ~ - ~ ~ tee .o c~,,, .c>- e 3 c~ ~e~ et ~ ~ ~ ~ < ~6~ t_ ~ _ _ ~e c ~O |_ O et ~ O c~ ~q Oe ~ s ~ ~ E ._ E . _ _ ~ .-c C C . C C ~ ~o ~e E o ~ ~ ~o ~, ~ ~ ~ .c .t c ~a: ~ c~ ._ e ~_ .Y ~E ~ y c ._ ~ .E o 5 Y 8 ~ ~ E'~ = E ~ E E ~ E e ~ u, ~ C ~ o 8.= i, c 8 ~o o ~ 5. E ~ ~ _ ~ ~ D e o o o e - o ._ 5 .~3 ~C 2 c.- _ ~ c ~ ~ ~ O ~ - ou f2 ~ ~0 °es c .- ~ CL.c _ E E o E E o8` 8 ~o ~o ~_ e c ~; :' c~ O 8 ._ ~ E o O O ~C1 ~ ~ O ~Z ~ 2 C ~ ~ _

OCR for page 29
29 continental margins. Mining of these deposits, while dependent on local transport economics and market conditions, is presently done in shallow, nearshore waters and provides an alternative to onshore reserves (Katz, 1987~. 2. Placers, heavy sands aggregated by oceanic hydraulic sorting, are the subject of accelerated mapping and exploration because they contain strategic and precious minerals and industrially useful refractor materials and abrasives, and because they are readily recoverable using available technology. Of special interest are the titanium group minerals on the Atlantic and Pacific shelves, chromite sands off Oregon, and gold and platinum on the Bering shelf. Gold placers have been mined nearshore and on beaches in Alaska, Oregon, and California since the early 1900s, and potentially valuable deposits exist farther offshore. 3. Phosphontes have been mapped from North Carolina to Florida out to the Blake Plateau. They contain trace quantities of platinum, uranium/thorium, and cadmium. Onshore phosphate deposits and low-cost overseas resources are adequate to meet near-term needs, but projected closings of Florida phosphate mines (due to soaring land values and environmental concerns) may eventually make EEZ phosphate mining economically viable. 4. Metalliferous oxides (ferromanganese deposits) consist of manganese nodules and crusts that contain strategic and industrially valuable metals, including copper, cobalt, nickel, manganese, and platinum group metals. The nodules occur mostly in the deep ocean outside the EEZ and to a lesser extent on the Blake Plateau. Manganese crust deposits are more abundant in the EEZ and are found on the flanks of Pacific seamounts and islands. 5. Metalliferous sulfides (also referred to as polymetallic sulfides) deposits contain zinc, copper, lead, gold, silver, trace amounts of barium and other metals, and large quantities of iron, which adds little to the deposits' economic value. Polymetallic sulfides are found along active spreading centers, such as the Gorda Ridge off Oregon. 6. Sulfur and miscellaneous minerals are found in shallow territorial waters along the continental shelf. Sulfur deposits are mined from nearshore caprock salt domes in the Gulf of Mexico, and a 1988 lease sale in the Gulf presages extension of sulfur mining into federal waters. In addition, barite was mined for ten years off southeast Alaska, and a lead-zinc-silver lode in the Gulf of Maine was mined in the early 1970s. Both operations successfully used conventional shallow-water dredging barges. Other shallow-water lodes with a greater diversity of metals are likely to be present in EEZ waters off Alaska and New England, and may eventually become commercially viable resources. Commercial offshore mining is not a new phenomenon. It has been conducted since the mid 1800s, but these operations have been nearshore and in relatively shallow waters. The standard marine mining system has been the dredge, which has proven adequate for unconsolidated or weakly consolidated ore bodies in water depths to 60 m and in relatively calm seas. Major advances in methods and mining systems will be required to recover much of the EEZ deepwater deposits previously described. The present state of commercial recovery technology and needed advancements are described in OTA (1987) and Cruickshank (1987~. Scope of Development Minerals markets are volatile, yielding to worldwide demand and socio-political forces. The U.S. minerals industry, squeezed by low international commodities prices and high domestic production costs, experienced a major recession from 1977 to 1987. Low demand and depressed prices continue to plague the industry, contributing to a worsening trade imbalance, poor international competitive position, and declining U.S. minerals production and industry employment (DOI, 1987~. Except for isolated exploitation of shallow-water minerals, nearshore sand and gravel, and placers, this economic climate discourages offshore exploration or mining activities. Although it is presently cheaper to import most hard minerals from abroad, U.S. market conditions are subject to fluctuations caused by such factors as unstable political regimes in Third

OCR for page 30
30 World countries, changing trade policies among U.S. economic allies, or increased labor and production costs in producing countries. The United States is nearing total dependence on foreign sources for some metals essential to national defense and industrial needs~.g., cobalt, chromium, manganese, and the platinum group metals (Table 3-2~. The need for secure supplies of these minerals, along with decreasing availability of economically mineable onshore deposits, provides an im fetus to identity and quantify domestic mineral resources within the EEZ. This will require improved seabed mapping and exploration technologies, better quantification of extent of deposits, , and continued advancements In offshore mineral recovery capabllltles. An assessment of EEZ mineral deposits that have potential for eventual economic recovery was made by a selected group of experts from government, academia, and industry at a workshop of this committee. Time frames estimated in Table 3-3 represent the group's collective opinion on probable time frames when normally evolving economic conditions may warrant initial commercial recovery. Each deposit was also evaluated for potential for accelerated development in the event that external influences create an improved economic climate or urgent national need. One factor in predicting long-term development time frames for EEZ mining is that the U.S. marine mining industry is not competitive with nations such as Japan, France, the United Kingdom, and West Germany. The United States lags behind these countries in the ability to mine and market presently recoverable marine reserves and resources because of their lower labor rates, fewer regulatory and environmental constraints, and access to government assistance (e.g., joint industry- government development and exploration programs) (DOI, 1987~. In fact, the lack of TABLE 3-2 U.S. Net Import Reliance On Selected Nonenergy Minerals MINERAL PERCENTAGE IMPORTED MAJOR SOURCES (1981-1984) COLUMBIUM MANGANESE MICA (SHEEN STRONTIUM BAUXITE & ALUMINA COBALT PLATINUM GROUP TANTALUM POTASH CHROMIUM no ASBESTOS BARITE ZINC NICKEL TUNGSTEN SILVER MERCURY CADMIUM SELENIUM GYPSUM GOLD COPPER SILICON IRON ORE IRON & STEEL ALUMINUM NITROGEN SULPHU R SOURCE: DOI, 1987. :::::~:: -::: :::::::::: ::: :::::::::: ::::::::::::::::::: ::: :::::: ::::: , , ,... . ,.,,,, ., . . .. .. . '. ... ..1 m. .. I:= .::: :::.: :,:.:::: :: ::::: :::::: :::::::::::::: :::: ::: ::::: ::::::: .1~: :: - G _ ILL ... : ......... . . 3 .,...:,,, ""':':'':,':'22: :2:::,:2:' ,:': ."":"' 2':2 '"2 ' 2:::':2 : 2: 1 ILL ,, ,.,.,-.- ... :: :::::::::::::::::::.:::::::.: :.:: .:.:...:.: :.: :::::::::::::::: ::: :::.:::::: .:.:::: _ - . . . .. .... : : :.:: :. =,:] . :.: :.::.:::.::::::::.::::::::::,:,:.::::.,: ..: : :::: .: :: : 7t 3 - :: :::: ::::: :: . . :: .::::::: 3 ....................................... 6 1 it= ................ ,,,, .! BRAZIL, CANADA, lldAILAND REPUBLIC OF SOUTH AFRICA, FRANCE, BRAZIL, GABON INDIA, BELGIUM, FRANCE, MADAGASCAR MEXICO, SPAIN AUSTRALIA, JAMAICA, GUINEA, SURINAME WRE, ZAMBIA, CANADA, NORWAY REPUBLIC OF SOUTH AFRICA, UK, U.S.S.R. THAILAND, BRAZIL, MALAYSIA, AUSTRALIA CANADA, ISRAEL REPUBLIC OF SO. AFRICA, ZIMBABWE, YUGO., TURKEY THAILAND, MALAYSIA, BOLIVIA, INDONESIA CANADA, REPUBLIC Of GUM AfRICA CHINA, MOROCCO, CHILE, PERU CANADA, PERU, MEXICO, AUSTRALIA CANADA, AUSTRALIA, BOTSWANA, NORWAY CANADA, CHINA, BOLIVIA, PORTUGAL CANADA, MEXICO, PERU, UK. SPAIN, ALGERIA, JAPAN, TURKEY CANADA, AUSTRALIA, PERU, MEXICO CANADA, UK., JAPAN, BELGIUM-LOX. CANADA, MEXICO, SPAIN CANADA, URUGUAY, SWITZERLAND CHILE, CANADA, PERU, MEXICO BRAZIL, CANADA, NORWAY, VENEZUELA CANADA, VENEZUELA, LIBERIA, BRAZIL EURO. ECON. COMM., JAPAN, CANADA CANADA, JAPAN, GHANA, VENEZUELA U.S.S.R., CANADA, TRINIDAD ~ TOBAGO, MEXICO CANADA, MEXICO

OCR for page 49
49 Constraints to Development Geophysical Constraints Geological processes and the composition of the substrate are the most dominant physical constraints on emplacement and maintenance of ocean cables and military uses. Some of these considerations are summarized below. · Seismic tectonic activity: Special design criteria and considerations are necessary where seismic activity causes ground motion that can damage cables or other bottom-mounted structures. · Seafloor instability: Routing of cables and placement of structures are affected by downslope mass wasting processes (debris flows, turbidity currents, and slumps and slides), which cause movement and eventual failure of cables and other structures on the seabed. Rerouting of cables and selective placement of structures to avoid these hazardous areas are often required. · Sediment transport dynamics: Where sediment transport and scour processes are active, cables may need to be buried or rerouted. Bedload movement and the development of bedforms can expose previously buried cables, resulting in strumming (vibrations set up by hydrodynamic forces), reduction in support, and ultimate failure. Additional research and field data are needed to more accurately model interactions between currents, the seabed, and the cable. · Ice gouging In high-latitude regions cables must be buried deep enough to protect them from gouging by sea-ice keels. · Subsea permafrost and gas hydrates: Not only is burial difficult in permafrost, it provides a thermally unstable environment that can result in differential collapse of the substrate and eventual failure of cables. · Bottom topography: Submarine cable routes are directly determined by ocean bottom topography. Extreme rates of change in depth may require detouring to avoid excessively long segments of suspended cable, where currents cause the cable to strum. For extreme lengths, suspended cables can break under their own weight. Seafloor structures and acoustical performance of sensor systems are all affected by bottom topography. Excessive variances can create azimuthal blockage of acoustical transmissions. · Acoustical properties of the ocean bottom: These are directly affected by substrate composition and are important in developing sensor systems. · Traf~cabili~ of the seabed: As ROVs and AUVs become more common for underwater tasks, trafficability of the sea bottom will become an important factor as "bottom crawlers," which depend on the seabed for support and traction as they maneuver, are introduced to military applications. Use Conflicts A major issue in the development of military uses of the seabed is the conflict between military applications and commercial, recreational, and environmental interests. The most intrusive situation by the military, as viewed by civilian interests, is the exclusion of civilian uses from military areas for safety, interference, and security reasons. Fishing activity, dumping, and historic sites also preclude certain activities. Figure 3-8 illustrates various uses of the sea and how they impact the installation of a cable. Avoiding existing hazards is the responsibility of the cable system developer. Managing relations with fishermen to avoid deploying systems in areas with significant fishing activity is a key factor. Since commercial fishing activity moves from one area to another over time, cable operators must also work with fishermen to reduce the probability of a trawl striking the cable. The bottom trawling fishing industry uses gear that are often incompatible with the protection of ocean cables and sensor/transducer systems. Although ocean cables can be buried, some sensor

OCR for page 50
so \ \ \ \ \ Sewe Outfal / /'] J / // / / I E3 Fish Trap Area ~ Chemical Dump FIGURE 3-8 Hypothetical use conflicts for underwater cables. Trawling Ground Radioactive Waste Incineration Site Construction Debris Explosives Dump and transducer systems cannot be buried, either because of their mechanical configuration or mission performance criteria. Fishing gear can also tangle with moored devices, resulting in damage to gear or mooring or both. Restricting areas around moored devices is a protective alternative. Areas designated for mineral extraction may exclude the routing of cables, or, conversely, mining may not be feasible in heavily impacted areas of cable installations. Oil exploration activities may directly conflict with the effective performance of some tactical sensor systems. For example, seismic profiling for resource exploration represents an extreme form of acoustic pollution to an acoustic surveillance system. Countering these noise sources requires equipment with greater dynamic ranges and a substantial data processing investment. This interference with sensor systems produced by oil exploration seismic profiling and any other noise generators will constrain further development of these sensor systems. The U.S. Navy has recently explored these issues with the Western Oil and Gas Association. Summary Future growth in the number and value of ocean cables is assured by the soaring demand for digital transmission using fiber optics, which have produced more reliable, economical, and secure telecommunications. There is also every reason to believe there will be an increased military presence in the EEZ because the nation's defense depends on military activities carried out in these waters. Continued advances in technology that enhance defense capabilities will find application in the EEZ. But submarine cable systems will continue to face serious risk of interruption presented by geophysical processes and conflicting uses or restricted access. Additional research and field data

OCR for page 51
51 are needed to more accurately model the interactions between currents, the seabed, and cables for more effective protection (burial), and to prevent strumming of exposed cables. Technology is needed for more effective geotechnical survey and data interpretation and more cost-effective and reliable burying systems during and after installation. BIOLOGICAL RESOURCES Background Living resources associated with the benthic boundary layer fall into one of two categories in this report: commercially important fishery resources and organisms of special scientific interest or of potential importance as biotechnological or genetic resources. A third category of organisms (discussed in Chapter 2) are those of little or no direct economic importance, but whose roles in seabed processes must be considered in the context of other existing or potential seabed uses. The United States is one of the world's largest consumers of seafood products: 1987 per capita consumption was 15.4 pounds (edible weight), a record high (O'Bannon, 1988~. Commercial imports reached a record $8.8 billion in 1987, a 16 percent increase over 1986, and exports were a record $1.7 billion, a 22 percent increase. A large portion of the $6.1 billion trade imbalance in fishery products is attributed to aquaculture products, which are being produced in greater numbers in foreign countries. Domestic aquaculture operations are generally restricted to coastal waters and significant expansion beyond three miles into the EEZ seabed is unlikely and is therefore not discussed in this report. U.S. EEZ commercial fish and shellfish catches from 1982-1987 are summarized in Table 3-10. Foreign vessel catches have declined dramatically: the 1987 total foreign catch was 150,000 metric tons, only 13 percent of the average for the preceding five years. Only 8,400 metric tons (6 percent) were seabed finfish and shellfish species. U.S. vessel landings increased gradually over this period, and joint-venture catches (U.S.-flag catches transferred to foreign vessels) increased sharply. The total EEZ catch has not changed markedly over this six-year period, mirroring the overall world catch (O'Bannon, 1988~. The 1987 catches of seabed-associated species (Table 3-11) are combined landings by U.S. vessels and joint venture catches. Excluding species that include aquaculture products (clams, oysters, scallops), the catches of bottom species (shrimp, crabs, lobsters, and flounders) rank second through fifth in value of all species caught in the U.S. EEZ in 1987, exceeded only by salmon. TABLE 3-10 Commercial Catches (Metric Tons) in the U.S. EEZ Foreign Landings by Joint venture Year vessels U.S. vessels catches Total 1982 1,410,000 820,000 230,000 2,460,000 1983 1,320,000 730,000 430,000 2,480,000 1984 1,340,000 680,000 680,000 2,700,000 1985 1,140,000 770,000 910,000 2,820,000 1986 590,000 1,140,000 1,320,000 3,050,000 1987 150,000 1,180,000 1,590,000 2,920,000 SOURCE: O'Bannon, 1988.

OCR for page 52
52 TABLE 3-11 Catches of Seabed-Associated Species by U.S. nag Vessels in 1987 0-3 mile offshore zone 3-200 mile offshore zone weight value weight value (metric tons) ($million) (metric tons) (million) Shrimp 79,500$ 264.9 85,300$ 313.2 Crabs 106,500123.3 68,700198.5 Lobsters 17,900112.9 5,30041.6 Flounders 27,60024.9 284,000148.0 Halibut 12,30030.7 22,20057.5 Clams, oysters, scallopsa 35,500197.2 62,000172.4 Total 279,300$ 753.9 572,500$ 931.2 aIncludes aquaculture SOURCE: O'Bannon, 1988 Within the last ten years, new species of marine organisms have been discovered in the EEZ seabed where geological and chemical processes result in zones in which chemically reduced compounds mix with oxygenated bottom waters. For example: · the subduction zone off Oregon, where pore waters enriched in natural gas (methane) and probably hydrogen sulfide are squeezed out of the accretiona~r wedge; O ~. ~ ~ ~ ~ ~ _ , · oil- and gas-producing regions on the Louisiana continental slope, where methane and hydrogen sulfide are released from the sediment; · the Florida Escarpment, where thermochemical reactions at depth appear to be responsible for producing hydrogen sulfide-rich hypersaline brines; and · the Gorda Ridge off northern California and Oregon, where active hydrothermal vents occur. In these locations, unique animals have been found living symbiotically with bacteria that utilize the chemical energy in hydrogen sulfide. These characteristics suggest that such organisms may have important potential applications for biotechnological or genetic engineering. Scope of Development Although most fisheries experts believe that traditional fisheries are at or near maturity, there are opportunities to develop nontraditional seabed resources. Some resources of the continental slope can be harvested by extending existing technology into deeper water. Deepwater crab and ocean perch fisheries, for example, will require only minor technological modifications. Bacteria capable of using chemical energy for growth have been known for many years (for example, bacteria that grow on simple, one-carbon compounds such as methane have been the

OCR for page 53
53 subject of research on the production of single-cell protein), but previous research has concentrated on terrestrial-based free-living bacteria. Only recently has the symbiotic association of such bacteria with higher organisms been elucidated (Cavanaugh, 1983~. The consequences of these discoveries for genetic engineering and biotechnology may be substantial, insofar as these animal-bacterial symbiotic pairs have solved the problem of passing bacterially produced carbon compounds directly to the cells of the host animal. These findings take on added importance in light of the toxicity of hydrogen sulfide and hydrocarbons to most organisms. Animals living in these locations have evolved biochemical mechanisms to avoid toxicity, thus their study is of considerable physiological significance and warrants investigation (Felbeck and Somero, 1982~. Additionally, many bacterial species found in chemically unusual marine environments are logical candidates to study for their ability to degrade toxic chemicals (Jannasch, 1989~. Discoveries of microorganisms with the ability to metabolize chemical compounds previously thought to be resistant to biodegradation have stimulated the search for additional microbes with such desirable abilities (Roberts, 1987~. The use of natural products as pharmaceutical agents in the treatment of cancer, AIDS, and other diseases is receiving renewed interest from the National Cancer Institute (Booth, 1987~. Many marine benthic invertebrates are potential sources of such drugs. Although it is impossible to predict which organisms are likely to produce substances of medical value, organisms that have adapted to unusual conditions, such as those discussed above, are worthwhile candidates. Given the rapid pace of advances in isolating and cloning genes, it is difficult to estimate time frames for biotechnical development of genetic resources. In the past, screening organisms for the presence of compounds of possible pharmaceutical or commercial activity was haphazard. However, the Natural Products Branch of the National Cancer Institute has initiated a five-year program to search more systematically for drug candidates derived from various organisms, including marine invertebrates and blue-green algae (Booth, 1987~. An example of a potentially valuable natural product is didemnin B. an extract from a benthic tunicate that is being tested in clinical trials against a variety of human cancers. Development Constraints Increased utilization of wild stocks from the new regions of the EEZ will require confronting the longstanding problem of assessing population sizes. The abundance of fishes and invertebrates in topographically complex regions, such as banks, escarpments, and seamounts, are difficult to assess because these environments inhibit conventional sampling techniques, preventing accurate estimates of population size. Newer techniques based on ROVs, better sensors, acoustics, and improved data interpretation may alleviate present assessment problems. High-frequengy acoustical profiling techniques, for example, have detected high abundances of krill (euphausiids) in the benthic boundary layers of submarine canyons off Georges Bank that may be important food sources for commercial fisheries (Greene et al., 1988~. Use conflicts between defense operations, cables, and fishing gear may also inhibit fishing development. One such conflict arises over the need to provide safe navigation lanes for submarines. These lanes are well established, but fishing vessels tend to ignore them and enforcement efforts have been ineffective. Another conflict exists between bottom trawl gear and Navy underwater surveillance installations. Although the Navy has buried cables in trawling areas in the past, planned expansion of undersea surveillance installations could exacerbate this use conflict, potentially leading to the prohibition of bottom trawling in certain areas. Commercial transoceanic telecommunications installations pose a similar conflict. A number of seabed trawlers have reported fouling of underwater cables and fishing gear resulting in damage or loss to both cables and trawls. Underwater cable routes are marked clearly on the navigation charts, but general compliance does not exist and enforcement has been ineffective. Other seabed uses-oil and gas development,

OCR for page 54
54 mineral extraction, and waste disposal-pose additional potential conflicts in the absence of established use priorities. Development of nonfishery living resources will require characterization of benthic communities throughout the EEZ before potentially invaluable species are lost due to habitat alteration by other uses. The National Cancer Institute's program for identifying and collecting organisms with promise for supplying pharmaceutically active compounds (Booth, 1987), is primarily focused on tropical plants and coral reef invertebrates because these environments are rapidly disappearing or being altered. Benthic organisms that occur in seafloor areas with commercial utility (i.e., hydrocarbon seeps on the Louisiana continental shelf) or with potential economic value (i.e., polymetallic sulfides on the Gorda Ridge) are not presently included in this screening. So far, only a few species have been screened, and increased extinction rates of many rare species caused by habitat disruption could deprive the medical and scientific community of valuable sources of natural products. Summary EEZ biological resources are extensive and represent important sources of food and potentially valuable medical products. Information on their diversity, abundance, and occurrence is limited, however. The yield from traditional fisheries, using present technology, is at or near its upper limit and improving fisheries yields will depend on improved forecasting and stock assessments in topographically complex and deepwater regions to assess the potential for expanded fisheries. The potential for establishing the value of exotic organisms will hinge on the pace and extent of inventorying these resources and maintaining biodiversity in the oceans. OCEAN ENERGY RESOURCES Background Ocean energy resources-thermal energy, waves, tides, currents, salinity gradients, biomass, winds, and seafloor geothermal-and related technologies are in very early stages of development, and the extent to which they will make significant demands on the EEZ seafloor is difficult to estimate. Nevertheless, it is possible to consider possible effects and tentative information needs associated with ocean energy development. Not all potential ocean energy resources exist at all locations around the U.S. shoreline. · Ocean Thermal Energy Conversion (OTEC) requires a substantial temperature difference between warm surface water and cold deeper water and a nearshore steeply sloping seafloor, conditions that are found off Puerto Rico, the Virgin Islands, and Pacific islands (Figure 3-9~. Waves exist in all coastal locations but appear most suitable along the eastern seaboard. The ocean current most accessible to the United States that appears to be the best candidate for power generation is the Florida current off Miami. · Tidal power is most efficiently produced where the tidal range exceeds 5 m, either off eastern Maine or in Cook Inlet, Alaska. · Salinity gradients exist principally at the mouths of large rivers. · Biomass production requires a good nutrient supply, cold water temperatures, and adequate sunlight-conditions met off the south and central California coast. · Ocean winds exist all along the U.S. coast but are most persistent off the northeast coast. With the exception of OTEC and possibly wave energy, it is unlikely that these technologies will have a significant impact on U.S. energy supplies or require placement in the EEZ. Tidal power installations, given their need for embayments, enclosures, or ponds, will not involve the EEZ or its

OCR for page 55
55 20 CD llJ - c, EC on 1 60W 140 120 100 80 60 40 20 0 20E 40N 20 CD IL - LL EO 20 40S 40E 60 80 100 120 140 160 180 160W LONGITUDE/DEG FIGURE 3-9 Worldwide distribution of the ocean thermal resource. Contours are for the annual averages of monthly temperature differences (in degrees Celsius) between the ocean surface and depths of 1,000 m: (top) the Western Hemisphere, (bottom) the Eastern Hemisphere. The black areas in coastal regions indicate water depths less than 1,000 m. SOURCE: Cohen, 1982 seabed. Salinity gradient power, and most other ocean energy sources generally will require relatively shallow coastal waters and, probably would be located within the territorial sea. Scope of Development OTEC involves harnessing the temperature differences between surface and deeper waters and converting them to energy. A closed system version vaporizes a working fluid using warm surface water, which expands under high pressure to run a turbine, and is then recondensed by deep cold water. The open-cycle system uses sea water as the working fluid and produces fresh water as a byproduct. OTEC requires a 20° C or greater temperature differential between surface and deep water. In a shore- or shelf-based system, the deep cold water must be relatively close to the beach. An OI~EC system with potential EEZ applications is an at-sea floating facility with a pipe suspended to the deep Goldwater supply. Because of engineering problems associated with the suspended

OCR for page 56
56 Goldwater pipe, electrical power riser cables, and deepwater mooring, attention has been focused on onshore or nearshore bottom-mounted facilities with a Goldwater intake pipe resting on the sloping ocean floor. Floating systems could still become feasible in the future (beyond 10 to 15 years), however. In 1979, a small-scale, barge-mounted OTEC plant model moored off Hawaii (mini- OTEC) produced a small amount of power for a few weeks, thus confirming the validity of the principle (Cohen, 1982~. U.S. OTEC interest has focused on Hawaii, Guam, the Virgin Islands, and Puerto Rico, with the work in Hawaii being the most advanced. The state of Hawaii, the U.S. Department of Energy, and the Pacific International Center for High Technology Research have combined resources to build a pilot OTEC plant at Hawaii's Natural Energy Laboratory (NELH) at Keahole Point. The system includes the production of nutrient-rich, pathogen-free cold water for aquaculture and an open-cycle OTEC system for generating electricity. The NELH project consists of five, 40-inch-diameter Goldwater pipes in a 1,800-m system that can pump fluid from a depth of 660 m at a rate of 13,000 gallons per minute. The Goldwater pipe represents a significant technical challenge. It must be sufficiently long for its intake to reach the cold depths of the ocean, and it must have a diameter large enough to accommodate the flow of massive quantities of water (Rogers et al., 1988~. Extracting energy from ocean waves has been discussed for years by the British, Japanese, and Norwegian governments, and many wave energy devices have been proposed (McCormick, 1981~. A consensus has developed around the oscillating water column approach, in which the motion of water within the wave energy conversion device acts as a piston, compressing the air and forcing it through an air-driven turbine connected to a generator. Such devices can also serve as breakwaters, reducing costs to a very competitive figure, as low as 4 cents per kilowatt hour. This concept is reportedly being tested in a five-megawatt prototype system under construction in the Scottish Hebrides Islands (Baggott and Morris, 1985~. Although more wave energy is available in the deeper offshore waters, the system is being built in only 21-m depth because its designers have not found a way to permanently anchor a structure big enough to provide commercially useful energy supplies, while at the same time it is able to withstand maximum interaction with incoming waves. In late 1988, agreement on a wave energy project was reported between the kingdom of Tonga and the Norwegian government, who agreed to build and install a three-megawatt wave-generating facility in Tonga. Based on such recent developments, it is reasonable to predict that a number of wave energy projects will be built within the next 10 to 20 years. However, it is impossible to predict if and when wave energy conversion systems will be operated in the deeper waters of the EEZ. Higher wave energies make offshore operations attractive, but the problems of mooring and energy transmission to the mainland will undoubtedly retard such developments. Development Constraints OTEC could place technically significant demands on the EEZ seafloor. A commercial-scale shore-based facility would require a very large pipe (or tunnel) to supply cold water that will need to follow a sloping seafloor down to a depth of as much as 1,000 m to find seawater 20° C colder than surface water. The fixing of such a pipe (which could be as large as 9 m in diameter and 5,000 m long for very large-scale applications) to a steeply sloping seafloor will be technically demanding, and will require a wide range of seafloor information (Rogers et al., 1988~. The most important information will pertain to properties of the upper continental slope: strength and stress-strain time parameters, compressibility and stress history, permeability, effects of slope deformation and failure, landslides, turbidity currents, debris flows, faulting, erosion, and scour. Site-specific information will be needed on nearshore properties to successfully "fastens large Goldwater pipes to a sharply sloping seafloor (Lockwood and McGregor, 1988~. Floating and moored OTEC facilities and wave energy facilities will require information on the seafloor properties needed to construct safe and reliable mooring or anchoring systems. In some

OCR for page 57
57 configurations, the electrical energy would have to be transmitted to shore by seafloor cable, creating a need for detailed seafloor information along the cable route. Summary lathe development of ocean energy systems in the U.S. EEZ during the next 10 to 20 years depends on the potential economic advantage in specific areas where it is feasible. The most promising technolog~OTEC-is limited to subtropical and tropical areas where there is an adequate temperature differential and accessible deep ocean water. Higher oil prices will be the crucial factor driving the development of these technologies. Although wave evergy systems are being developed in Norway, Japan, and the United Kingdom, there is little interest in these systems in the United States. It is likely that islands with appropriate wave climates and high existing energy costs (Pacific islands qualify on both counts) will be the first places considered for wave energy systems, if they become commercially viable. Of the two technologies, OTEC will have more demand for EEZ seafloor information since wave energy systems will almost certainly be located on or near the shore. CULTURAL AND RECREATIONAL RESOURCES Background Cultural and recreational resources of the EEZ include marine archaeology, treasure seeking, and commercial salvage; recreation; and marine sanctuaries. . Marine archaeology, treasure seeking) and commercial salvage: Marine archaeology is a very small and relatively stable activity (perhaps no more than 100 individuals in the United States), but treasure seeking and commercial salvage are substantially larger and more visible. Commercial salvers, excluding treasure seekers, seek to retrieve hulls or cargo of recently sunk vessels. Their activities are regulated under maritime law, which asserts that abandoned shipwrecks and other items on the seafloor become the property of the "finders. · Recreation: Seafloor habitats are becoming underwater attractions in some coastal locations with large tourist populations. This trend will probably accelerate as the popularity of coastal and ocean recreation grows. · Manne sanctuanes: Ocean areas of special interest, uniqueness, value, and importance are the wet counterparts of national parks and forests, wildlife preserves, and historical monuments. They are set aside to protect unique recreational amenities (coral reefs), cultural sites (historic shipwrecks), habitats or wildlife areas, or valuable research sites. Most of them remain to be discovered, so a probable growing activity in the EEZ will be identifying and designating such areas for long-term protection. The approach usually employed is designation as a marine santuary under the Marine Protection, Research, and Sanctuaries Act (MPRSA). Eight marine sanctuaries have been designated so far: the U.S.S. Monitor off North Carolina, Key Largo and Looe Key off Florida, the Channel Islands, the Farallon Islands and Cordell Bank off California, Gray's Reef off Georgia, and Fagatele Bay in American Samoa. Six are located in the territorial sea and two in the EEZ: the U.S.S. Monitor and Gray's Reef (Figure 3-10~. Scope of Development In light of recent advances in deep sea and exploration technologies, such as the ARGO/JASON program at Woods Hole Oceanographic Institution (Ryan, 1986), shipwrecks and historical objects

OCR for page 58
58 1 20°E ~' / / / I ~ ~ 60 ~° 50°W '`\\~S~ of r O ~ QO ~Baker Islands by ~ 10°S ~ o,S~' 6` \r \ \ W\ 1 20°E 1 50°E Midway Northern -~ / lowland Mariana Wake / Islands Island Johnston Island Palmyra Atoll/ Jarvis Island American Samoa \ ~ ~1 1 1 it\ :~0°N ~ A0° 1 ~1 0°S I I I I I \1 1 / 60° Puerto Rico/ \ 20° .Virgin Islands'\ 1 1 0 2000 Km `~ 1 , 1 \ 0 1000 N.M. 1 , 1 1 180° 1 50°W 120° 90° FIGURE 3-10 The seven U.S. National Marine Sanctuaries, and the U.S. EEZ. SOURCE: After Foster and Archer, 1988. will probably be discovered in increasing numbers. Some discoveries will be of considerable archaeological, cultural, and historical value. In the EEZ, establishment of marine sanctuaries has been used to designate and protect such sites (for example, the U.S.S. Monitor), but beyond national jurisdiction there is no legal framework for this purpose. In the case of H.M.S. Titanic, the Congress created a "memorial," but its restrictions are legally enforceable only against U.S. citizens. In the future, it is likely that professional and amateur treasure seekers will increase in numbers and interest in marine archaeology will also grow, but at a smaller rate. The availability of small submersibles in the coming decade or two will further stimulate treasure hunting. It is reasonable to predict that information demands will accompany the growth in these activities. With the continued popularity of snorkeling and scuba diving, more individuals will seek access to the seafloor in scenic underwater areas. The recent availability of relatively inexpensive submersibles for recreation could also create the need for more underwater destinations. Despite unrealized earlier predictions, underwater hotels are also likely to be constructed in a few especially interesting settings. Tourist submersibles are already operating; several vessels carrying over 40 passengers and crew are operating in U.S. nearshore waters (U.S. Virgin Islands, Guam, and Hawaii), but not yet in the U.S. EEZ. While these activities will create new demands for more detailed seafloor information in selected locations in the foreseeable future, these will fall within the territorial sea. With increased exploration of the EEZ, many new ocean areas deserving protection as marine sanctuaries will be identified. After formal national designation, management plans are formulated

OCR for page 59
so to protect the resource for which the sanctuary was created, yet allow other uses that do not impact the protected resource. Development Constraints Recreational and cultural ocean activities- especially treasure hunting, salvage, and marine archaeology_vill benefit from better information on the nature of the bottom load bearing characteristics and bottom topography; bottom stability, potential for sediment erosion, transport, and deposition; thickness of unconsolidated sediments; strength of bottom currents; and visibility. For marine sanctuaries, specific criteria need to be developed in advance that spell out the properties of various ocean areas deemed appropriate for sanctuary designation. Such early identification of candidate areas would ensure that legitimate sanctuaries are established before inconsistent competing activities are approved. The identification and designation process will require detailed site-specific information on physical and biological characteristics. Summary Increasing utilization of ocean-related cultural and recreational resources will stimulate demand for better and more detailed seafloor information. Because many marine areas contain rare and endangered species, uniquely valuable habitats, scenic coral resources, unusual geological formations, archaeological or cultural resources, or represent sites having exceptional research or recreational values, sanctuary designation is an important federal responsibility. Yet, to date, it has been a relatively low-level effort with only eight sanctuaries designated thus far. A waiting list for consideration now includes more than 30 candidate sites (Foster and Archer, 1988~.

Representative terms from entire chapter:

marine environment