on improved means of navigation, transportation, safe
overseas anchorages, and later on conquest, commerce,
communications, and trade with many cultures in coral
reef environments. By the mid nineteenth century, emphasis shifted toward resource exploitation and colonization
of overseas continents and islands, including guano and
phosphate extraction at many coral islands and atolls,
and mining of valued ores and expansion of plantation
agriculture and ranching at many larger tropical islands
and sub-continents. By the mid twentieth century, engineering in coral reef environments focused on supporting
modern global warfare, nuclear weapons testing, and civil
works for emerging democratic states including construction of military bases, airfields and ports, urbanization,
and reconstruction.
The consequence of these shifts was massive pollution
and degradation of many coral reefs, especially during the
past century. Only during the past half century has there
been emphasis placed on minimizing the ecological
impacts of engineering, coastal construction and related
development. This chapter reviews past and present engineering on coral reefs and offers measures to reduce lingering effects and avoiding future environmental effects
on Pacific coral reefs attributed to engineering and related
construction.
Engineering and coastal construction
requirements on coral reefs
Generally, the four principal engineering categories on coral
reefs have been: (1) dredging and excavation for navigation
channels and turning basins for ships and boats; (2) discharge of fill to expand land, create airfields, harbors, and
connect islands via causeways on especially smaller islands
and atolls; (3) collecting or constructing armor rock for fortifying shorelines, harbor breakwaters, and onshore facilities; and (4) mining and quarrying reef blocks for concrete
production and construction of buildings. The last category
is covered in a companion section in the chapter on Infrastructure on Coral Reefs that includes additional case studies and expands the geographic scope of this review beyond
Pacific reefs. The discharge or dumping of toxic and hazardous waste (hazmat) is beyond the scope of this review
but which can result in adverse consequences to coral reefs.
Assessment and remediation of hazmat sites are potentially
dangerous and require specialists such as eco-toxicologists
and industrial/environmental engineers at great cost. Hazmat sites can be avoided by prior planning and design that
leads to proper construction, operations, and maintenance
of facilities.
Coastal engineering on small Pacific low reef islands
and atolls is especially needed because land areas and
water supplies are limited and vulnerable to adverse seas
and storm conditions. Coral rock is often very hard, especially on wave exposed reef crests which render it valuable
for protecting shorelines, but its extraction often requires
heavy equipment or use of explosives in zones of heavy
surf that drives up the cost of the shore protection.
A common alternative to moving and placing large stones
is using smaller, portable stones or rubble that can be carried by hand to fill up larger fish traps or wire-meshed
cubes (gabions) previously placed on the shoreline. The
rock-filled traps or gabions simulate the benefit of larger
individual stones that better withstand movement and the
erosive force of wave action and currents. Additional traps
or gabions are later placed atop one another to create
a seawall or sloping revetment along the shoreline. The
advantages of this approach are that heavy equipment,
blasting or quarrying of larger stone are not required.
One disadvantage is that the wire meshing is not permanent and eventually corrodes, abrades or fails, reducing
the structure to amorphous rock piles or ridges with
reduced capacity to protect shorelines unless the wire
mesh structures are routinely replaced. Furthermore, the
shorelines where smaller stones and rubble are collected
may be exposed to greater levels of erosion.
Improperly placed or designed shore protection structures of any kind eventually reverts back to shoreline erosion and the continuous need for more reef rock, rubble,
and other forms of general purpose fill for repairs and haphazard shore protection. Continued excavation of coral
sand and rock is also common at population and government centers in response to population immigration, especially from outer islands. As populations grow, additional
coral rock and fill are needed for living areas, shore protection, dwellings, and road causeways connecting neighboring settlement islands on atolls. However, insufficient
baseline studies and inadequate design have caused many
road causeways to fail (Figure 1) or degrade adjacent reef
areas (Figure 2) especially on atolls and barrier reefs.
WWII military bases on atolls also required road causeways to establish defensive perimeters, gun emplacements,
shore protection, airfields, seaplane landing areas, protected
harbors, and dredged navigation channels, if natural passes
were absent. Inadequate width of channels, turning areas for
ships, and aids to navigation at hastily constructed WWIIera harbors have also led to degraded reefs, many ship
groundings, loss of fuel and supplies, loss of life, and the
spread of alien and invasive marine and terrestrial species.
Inadequate culverts or bridge openings in fill causeways
connecting adjacent islands often led to shoreline erosion
and failure of causeways at both military and civilian atolls
and islands, disrupting land access and communications
between adjacent islands. Many of these effects can be mitigated through proper engineering and related oceanographic assessment of wave energy, currents, and tidal
fluctuations. Table 1 summarizes engineering activities,
equipment, and construction purposes at coral reefs.
Adverse ecological consequences of poorly
designed engineering activities and structures
Serious direct effects to reefs can result from dredging,
other forms of excavation, and discharge of fill on reefs
to create land. Filling reefs to create land represents
a permanent loss of the buried reefs as well as additional
392
ENGINEERING ON CORAL REEFS WITH EMPHASIS ON PACIFIC REEFS
overseas anchorages, and later on conquest, commerce,
communications, and trade with many cultures in coral
reef environments. By the mid nineteenth century, emphasis shifted toward resource exploitation and colonization
of overseas continents and islands, including guano and
phosphate extraction at many coral islands and atolls,
and mining of valued ores and expansion of plantation
agriculture and ranching at many larger tropical islands
and sub-continents. By the mid twentieth century, engineering in coral reef environments focused on supporting
modern global warfare, nuclear weapons testing, and civil
works for emerging democratic states including construction of military bases, airfields and ports, urbanization,
and reconstruction.
The consequence of these shifts was massive pollution
and degradation of many coral reefs, especially during the
past century. Only during the past half century has there
been emphasis placed on minimizing the ecological
impacts of engineering, coastal construction and related
development. This chapter reviews past and present engineering on coral reefs and offers measures to reduce lingering effects and avoiding future environmental effects
on Pacific coral reefs attributed to engineering and related
construction.
Engineering and coastal construction
requirements on coral reefs
Generally, the four principal engineering categories on coral
reefs have been: (1) dredging and excavation for navigation
channels and turning basins for ships and boats; (2) discharge of fill to expand land, create airfields, harbors, and
connect islands via causeways on especially smaller islands
and atolls; (3) collecting or constructing armor rock for fortifying shorelines, harbor breakwaters, and onshore facilities; and (4) mining and quarrying reef blocks for concrete
production and construction of buildings. The last category
is covered in a companion section in the chapter on Infrastructure on Coral Reefs that includes additional case studies and expands the geographic scope of this review beyond
Pacific reefs. The discharge or dumping of toxic and hazardous waste (hazmat) is beyond the scope of this review
but which can result in adverse consequences to coral reefs.
Assessment and remediation of hazmat sites are potentially
dangerous and require specialists such as eco-toxicologists
and industrial/environmental engineers at great cost. Hazmat sites can be avoided by prior planning and design that
leads to proper construction, operations, and maintenance
of facilities.
Coastal engineering on small Pacific low reef islands
and atolls is especially needed because land areas and
water supplies are limited and vulnerable to adverse seas
and storm conditions. Coral rock is often very hard, especially on wave exposed reef crests which render it valuable
for protecting shorelines, but its extraction often requires
heavy equipment or use of explosives in zones of heavy
surf that drives up the cost of the shore protection.
A common alternative to moving and placing large stones
is using smaller, portable stones or rubble that can be carried by hand to fill up larger fish traps or wire-meshed
cubes (gabions) previously placed on the shoreline. The
rock-filled traps or gabions simulate the benefit of larger
individual stones that better withstand movement and the
erosive force of wave action and currents. Additional traps
or gabions are later placed atop one another to create
a seawall or sloping revetment along the shoreline. The
advantages of this approach are that heavy equipment,
blasting or quarrying of larger stone are not required.
One disadvantage is that the wire meshing is not permanent and eventually corrodes, abrades or fails, reducing
the structure to amorphous rock piles or ridges with
reduced capacity to protect shorelines unless the wire
mesh structures are routinely replaced. Furthermore, the
shorelines where smaller stones and rubble are collected
may be exposed to greater levels of erosion.
Improperly placed or designed shore protection structures of any kind eventually reverts back to shoreline erosion and the continuous need for more reef rock, rubble,
and other forms of general purpose fill for repairs and haphazard shore protection. Continued excavation of coral
sand and rock is also common at population and government centers in response to population immigration, especially from outer islands. As populations grow, additional
coral rock and fill are needed for living areas, shore protection, dwellings, and road causeways connecting neighboring settlement islands on atolls. However, insufficient
baseline studies and inadequate design have caused many
road causeways to fail (Figure 1) or degrade adjacent reef
areas (Figure 2) especially on atolls and barrier reefs.
WWII military bases on atolls also required road causeways to establish defensive perimeters, gun emplacements,
shore protection, airfields, seaplane landing areas, protected
harbors, and dredged navigation channels, if natural passes
were absent. Inadequate width of channels, turning areas for
ships, and aids to navigation at hastily constructed WWIIera harbors have also led to degraded reefs, many ship
groundings, loss of fuel and supplies, loss of life, and the
spread of alien and invasive marine and terrestrial species.
Inadequate culverts or bridge openings in fill causeways
connecting adjacent islands often led to shoreline erosion
and failure of causeways at both military and civilian atolls
and islands, disrupting land access and communications
between adjacent islands. Many of these effects can be mitigated through proper engineering and related oceanographic assessment of wave energy, currents, and tidal
fluctuations. Table 1 summarizes engineering activities,
equipment, and construction purposes at coral reefs.
Adverse ecological consequences of poorly
designed engineering activities and structures
Serious direct effects to reefs can result from dredging,
other forms of excavation, and discharge of fill on reefs
to create land. Filling reefs to create land represents
a permanent loss of the buried reefs as well as additional
392
ENGINEERING ON CORAL REEFS WITH EMPHASIS ON PACIFIC REEFS