Coral Reef Project: Kwajalein Island Active
The USGS is working to provide a better understanding of how spatially-varying atoll morphology and coral cover interact with changes in water level to affect the propagation of waves of different heights and wavelengths across atoll reefs.
Overview
Kwajalein Island is the southernmost and largest island on Kwajalein Atoll, the largest coral atoll in the world, in the Republic of the Marshall Islands, which is a self-governed and freely associated republic with the United States. The atoll lies near the equator about 3,900 km (2,100 mi) southwest of Hawaiʻi, and is comprised of 97 islands and islets. Known locally as “Kwaj,” the island encompasses a total area of about 3.1 sq km (about 1.2 sq mi). Kwajalein, and several other islands on the atoll (including Roi-Namur), is leased by the United States as part of the U.S. Army Kwajalein Atoll, which is, in turn, part of the Ronald Reagan Ballistic Missile Defense Test Site, formerly known as the Kwajalein Missile Range.
Motivation
Observations show that sea level is rising globally at a rate almost double the Intergovernmental Panel for Climate Change’s 2007 report, and up to half an order of magnitude greater in the central and western Pacific Ocean. Recent estimates suggest sea level will exceed 1.0 m, and may reach 2.0 m, above 2000 levels by the end of the 21st century. Sea-level rise is particularly critical for unconsolidated low-lying coral atoll islands, many of which have maximum elevations of less than 4.0 m above present sea level, such as Kwajalein. These islands support 2000+ year-old cultures, yet the amount of land and water available for human habitation, water and food sources, and ecosystems is limited and extremely vulnerable to marine inundation from sea-level rise. Vertical coral reef flat accretion rates for coral reefs exposed to open-ocean storm waves (1 to 4 mm/yr) are up to an order of magnitude smaller than the rates of sea-level rise projected for the years 2000–2100 (8 to 16 mm/yr), therefore projected sea-level rise will outstrip potential new reef flat accretion, resulting in a net increase in water depth over exposed coral reef flats on the order of 0.4 to 1.5 m during the 21st century. The extreme vulnerability of these communities to changing oceanic and atmospheric conditions represents a serious threat through impacts on food and water security, public safety, and environmental health.
The USGS is working with Deltares, NOAA, and the U.S. Department of Defense to provide a better understanding of how spatially-varying atoll morphology and coral cover interact with changes in water level to affect the propagation of waves of different heights and wavelengths across atoll reefs. Such information is necessary to model how predicted sea-level rise and climate change may alter wave-driven inundation, and thus impacts to infrastructure, agriculture, and natural habitats, on low-lying atoll islands.
For additional information, visit the site, "The Impact of Sea-Level Rise and Climate Change on Pacific Ocean Atolls."
Learn more about coral reef and atoll studies at the USGS.
Below are data or web applications associated with this project.
Below are publications associated with this project.
Challenges of forecasting flooding on coral reef–lined coasts
A Bayesian-based system to assess wave-driven flooding hazards on coral reef-lined coasts
Atoll groundwater movement and its response to climatic and sea-level fluctuations
Wave dynamics and flooding on low-lying tropical reef-lined coasts
Doubling of coastal flooding frequency within decades due to sea-level rise
Land-use change and managed aquifer recharge effects on the hydrogeochemistry of two contrasting atoll island aquifers, Roi-Namur Island, Republic of the Marshall Islands
Identification and classification of very low frequency waves on a coral reef flat
Changes to extreme wave climates of islands within the Western Tropical Pacific throughout the 21st century under RCP 4.5 and RCP 8.5, with implications for island vulnerability and sustainability
Observations of wave transformation over a fringing coral reef and the importance of low-frequency waves and offshore water levels to runup, overwash, and coastal flooding
Many atolls may be uninhabitable within decades due to climate change
The influence of coral reefs and climate change on wave-driven flooding of tropical coastlines
Modeled changes in extreme wave climates of the tropical Pacific over the 21st century: Implications for U.S. and U.S.-Affiliated atoll islands
Below are news stories associated with this project.
Below are partners associated with this project.
- Overview
The USGS is working to provide a better understanding of how spatially-varying atoll morphology and coral cover interact with changes in water level to affect the propagation of waves of different heights and wavelengths across atoll reefs.
Overview
Kwajalein Island is the southernmost and largest island on Kwajalein Atoll, the largest coral atoll in the world, in the Republic of the Marshall Islands, which is a self-governed and freely associated republic with the United States. The atoll lies near the equator about 3,900 km (2,100 mi) southwest of Hawaiʻi, and is comprised of 97 islands and islets. Known locally as “Kwaj,” the island encompasses a total area of about 3.1 sq km (about 1.2 sq mi). Kwajalein, and several other islands on the atoll (including Roi-Namur), is leased by the United States as part of the U.S. Army Kwajalein Atoll, which is, in turn, part of the Ronald Reagan Ballistic Missile Defense Test Site, formerly known as the Kwajalein Missile Range.
Motivation
Observations show that sea level is rising globally at a rate almost double the Intergovernmental Panel for Climate Change’s 2007 report, and up to half an order of magnitude greater in the central and western Pacific Ocean. Recent estimates suggest sea level will exceed 1.0 m, and may reach 2.0 m, above 2000 levels by the end of the 21st century. Sea-level rise is particularly critical for unconsolidated low-lying coral atoll islands, many of which have maximum elevations of less than 4.0 m above present sea level, such as Kwajalein. These islands support 2000+ year-old cultures, yet the amount of land and water available for human habitation, water and food sources, and ecosystems is limited and extremely vulnerable to marine inundation from sea-level rise. Vertical coral reef flat accretion rates for coral reefs exposed to open-ocean storm waves (1 to 4 mm/yr) are up to an order of magnitude smaller than the rates of sea-level rise projected for the years 2000–2100 (8 to 16 mm/yr), therefore projected sea-level rise will outstrip potential new reef flat accretion, resulting in a net increase in water depth over exposed coral reef flats on the order of 0.4 to 1.5 m during the 21st century. The extreme vulnerability of these communities to changing oceanic and atmospheric conditions represents a serious threat through impacts on food and water security, public safety, and environmental health.
The USGS is working with Deltares, NOAA, and the U.S. Department of Defense to provide a better understanding of how spatially-varying atoll morphology and coral cover interact with changes in water level to affect the propagation of waves of different heights and wavelengths across atoll reefs. Such information is necessary to model how predicted sea-level rise and climate change may alter wave-driven inundation, and thus impacts to infrastructure, agriculture, and natural habitats, on low-lying atoll islands.
For additional information, visit the site, "The Impact of Sea-Level Rise and Climate Change on Pacific Ocean Atolls."
- Science
Learn more about coral reef and atoll studies at the USGS.
- Data
Below are data or web applications associated with this project.
- Publications
Below are publications associated with this project.
Filter Total Items: 30Challenges of forecasting flooding on coral reef–lined coasts
Understanding wave-driven coastal flooding is a challenging scientific problem; the need for forecasts is becoming more urgent because of sea level rise, climate change, and ever-growing coastal populations. The tools developed for sandy shorelines are generally not applicable to coral reef–lined coasts with their complex bathymetry, hydrodynamically rough reef platforms, steep and poorly sorted bAuthorsCurt D. StorlazziA Bayesian-based system to assess wave-driven flooding hazards on coral reef-lined coasts
Many low-elevation, coral reef-lined, tropical coasts are vulnerable to the effects of climate change, sea level rise, and wave-induced flooding. The considerable morphological diversity of these coasts and the variability of the hydrodynamic forcing that they are exposed to make predicting wave-induced flooding a challenge. A process-based wave-resolving hydrodynamic model (XBeach Non-HydrostaticAuthorsS. G. Pearson, Curt D. Storlazzi, A. R. van Dongeren, M. F. S. Tissier, A. J. H. M. ReniersAtoll groundwater movement and its response to climatic and sea-level fluctuations
Groundwater resources of low-lying atoll islands are threatened due to short-term and long-term changes in rainfall, wave climate, and sea level. A better understanding of how these forcings affect the limited groundwater resources was explored on Roi-Namur in the Republic of the Marshall Islands. As part of a 16-month study, a rarely recorded island-overwash event occurred and the island’s aquifeAuthorsFerdinand K. J. Oberle, Peter W. Swarzenski, Curt D. StorlazziWave dynamics and flooding on low-lying tropical reef-lined coasts
Many tropical islands and coasts are lined with coral reefs. These reefs are host to valuable ecosystems that support abundant marine species and provide resources for fisheries and recreation. As a flood defense, reefs protect coastlines from coastal storm damage and flooding by reducing the majority of incident wave energy. However, during storm and large swell conditions, coastal wave-driven flAuthorsAp van Dongeran, Curt D. Storlazzi, Ellen Quataert, Stuart PearsonDoubling of coastal flooding frequency within decades due to sea-level rise
Global climate change drives sea-level rise, increasing the frequency of coastal flooding. In most coastal regions, the amount of sea-level rise occurring over years to decades is significantly smaller than normal ocean-level fluctuations caused by tides, waves, and storm surge. However, even gradual sea-level rise can rapidly increase the frequency and severity of coastal flooding. So far, globalAuthorsSean Vitousek, Patrick L. Barnard, Charles H. Fletcher, Neil Frazer, Li H. Erikson, Curt D. StorlazziLand-use change and managed aquifer recharge effects on the hydrogeochemistry of two contrasting atoll island aquifers, Roi-Namur Island, Republic of the Marshall Islands
Freshwater resources on low-lying atoll islands are highly vulnerable to climate change and sea-level rise. In addition to rainwater catchment, groundwater in the freshwater lens is a critically important water resource on many atoll islands, especially during drought. Although many atolls have high annual rainfall rates, dense natural vegetation and high evapotranspiration rates can limit recharAuthorsMehrdad Hejazian, Jason J. Gurdak, Peter W. Swarzenski, Kingsley Odigie, Curt D. StorlazziIdentification and classification of very low frequency waves on a coral reef flat
Very low frequency (VLF, 0.001–0.005 Hz) waves are important drivers of flooding of low-lying coral reef-islands. In particular, VLF wave resonance is known to drive large wave runup and subsequent overwash. Using a 5 month data set of water levels and waves collected along a cross-reef transect on Roi-Namur Island in the Republic of the Marshall Islands, the observed VLF motions were categorizedAuthorsMatthijs Gawehn, Ap van Dongeran, Arnold van Rooijen, Curt D. Storlazzi, Olivia Cheriton, Ad ReniersChanges to extreme wave climates of islands within the Western Tropical Pacific throughout the 21st century under RCP 4.5 and RCP 8.5, with implications for island vulnerability and sustainability
Waves are the dominant influence on coastal morphology and ecosystem structure of tropical Pacific islands. Wave heights, periods, and directions for the 21st century were projected using near-surface wind fields from four atmosphere-ocean coupled global climate models (GCM) under representative concentration pathways (RCP) 4.5 and 8.5. GCM-derived wind fields forced the global WAVEWATCH-III waveAuthorsJames B. Shope, Curt D. Storlazzi, Li H. Erikson, Christie HegermillerObservations of wave transformation over a fringing coral reef and the importance of low-frequency waves and offshore water levels to runup, overwash, and coastal flooding
Many low-lying tropical islands are susceptible to sea level rise and often subjected to overwash and flooding during large wave events. To quantify wave dynamics and wave-driven water levels on fringing coral reefs, a 5 month deployment of wave gauges and a current meter was conducted across two shore-normal transects on Roi-Namur Island in the Republic of the Marshall Islands. These observationsAuthorsOlivia Cheriton, Curt D. Storlazzi, Kurt J. RosenbergerMany atolls may be uninhabitable within decades due to climate change
Observations show global sea level is rising due to climate change, with the highest rates in the tropical Pacific Ocean where many of the world’s low-lying atolls are located. Sea-level rise is particularly critical for low-lying carbonate reef-lined atoll islands; these islands have limited land and water available for human habitation, water and food sources, and ecosystems that are vulnerableAuthorsCurt D. Storlazzi, Edwin P.L. Elias, Paul BerkowitzThe influence of coral reefs and climate change on wave-driven flooding of tropical coastlines
A numerical model, XBeach, calibrated and validated on field data collected at Roi-Namur Island on Kwajalein Atoll in the Republic of Marshall Islands, was used to examine the effects of different coral reef characteristics on potential coastal hazards caused by wave-driven flooding and how these effects may be altered by projected climate change. The results presented herein suggest that coasts fAuthorsEllen Quataert, Curt D. Storlazzi, Arnold van Rooijen, Ap van Dongeren, Olivia CheritonModeled changes in extreme wave climates of the tropical Pacific over the 21st century: Implications for U.S. and U.S.-Affiliated atoll islands
Wave heights, periods, and directions were forecast for 2081–2100 using output from four coupled atmosphere–ocean global climate models for representative concentration pathway scenarios RCP4.5 and RCP8.5. Global climate model wind fields were used to drive the global WAVEWATCH-III wave model to generate hourly time-series of bulk wave parameters for 25 islands in the mid to western tropical PacifAuthorsJ.B. Shope, Curt D. Storlazzi, Li H. Erikson, C.A. Hegermiller - News
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- Partners
Below are partners associated with this project.