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Vulnerability of Central American coasts to storm hazards assessed

A profile of the relative vulnerability of Central America's Caribbean and Pacific coasts to the hazards of storm-induced coastal erosion and storm surge is now available, courtesy of a study recently conducted by the Water Center for the Humid Tropics of Latin America and the Caribbean (CATHALAC, in English).

The analysis included the seven Central American countries (i.e. Belize, Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica, and Panama) and was done to provide a reference level for decision-making regarding coastal planning.

Methodology

Utilizing powerful computer models embedded in geographic information systems (GIS) to examine such vulnerability along the region's approximately 15,000 km of coastline, the study addressed two main questions:

  • Which parts of Central America's coasts are most vulnerable to storm-induced coastal erosion and storm surge?
  • How do coastal / marine ecosystems such as mangrove forests and coral reefs affect coastal vulnerability?

The study was done by applying a novel modeling toolset developed by Stanford University in the context of their ongoing Natural Capital project which seeks to quantify the ecosystem services provided by different natural habitats. That toolset, the Integrated Valuation of Environmental Services and Tradeoffs (InVEST), includes a Coastal Vulnerability model which allows for qualitatively assessing exposure to storm-induced coastal erosion and storm surge by taking into consideration a range of criteria, including geomorphology, topographic relief, natural habitats, projected sea level rise, wave and wind exposure, and surge potential.

Current vulnerability profile

Based on modeling using 2010 data, and at a spatial resolution of 1km, the study indicates that the most vulnerable coastal areas in Central America include much of Nicaragua's Caribbean coast, much of Guatemala's western Pacific coast, and the [Pacific] coast of El Salvador. By contrast, Panama's coral reef-shielded Caribbean coast, and the Bay of Panama on the Pacific are among the least vulnerable, including parts of the Gulf of Fonseca, and the eastern portion of the Bay of Amatique. Some 41.2% of the region's coasts were estimated to have very low or low vulnerability to storm-induced coastal erosion and storm surge, while 19.9% was assessed to have moderate vulnerability, and 39% of the coast was estimated to have high or very high vulnerability.

Furthermore, in terms of vulnerability to storm-induced coastal erosion, the modeling indicates that some 43.1% of Central America's coasts possess very low to low vulnerability to that hazard, while 22.2% of the coast exhibited moderate vulnerability, and 34.8% of the coast exhibited high to very high vulnerability. In terms of vulnerability to storm surge, some 40.5% of the Caribbean and Pacific coasts were estimated to have very low to low vulnerability to that hazard, while 20.8% of the coast exhibited moderate vulnerability, and 38.7% of the coast exhibited high to very high vulnerability.

Alternative vulnerability scenario

Comparative modeling was also done to examine the protection that mangrove forests and coral reefs provide to Central America's coasts. A scenario was modeled 'removing' the region's mangrove forests and coral reefs, and under such a setting, the region's coastal vulnerability to storm-induced coastal erosion and storm surge increases substantially. Without the protection of mangrove or coral reef, 49% of the region's coasts would be categorized as highly to very highly vulnerable, while only 31.7% of the coastline would exhibit very low to low vulnerability to storm-induced coastal erosion and storm surge. Examining specific sites where intact coastal ecosystems currently provide protective influence, without the presence of such ecosystems, areas where vulnerability would increase include much of Panama's Caribbean coast, as well as various sections of coast in Belize and northern Honduras (including the Bay Islands). In the latter cases, many of the areas near the Mesoamerican Reef currently exhibit very low or low coastal vulnerability relative to other areas, but such would not be the case in absence of the Reef.

Additionally, under the scenario without the protective influence of mangrove forest and coral reef, [high to very high] vulnerability to coastal erosion increased to 59.7%, while some 50.1% of coastline exhibited high to very high vulnerability to storm surge. While the modeling merely provides a profile of the Central American coasts' relative overall vulnerability to storm-induced coastal erosion and storm surge, the key role of coral reefs and other intact natural ecosystems (i.e. natural capital) in terms of disaster prevention / risk reduction can nevertheless still be appreciated.

Synergies

The coastal vulnerability assessment follows on previous work by CATHALAC in the areas of earth observations and disaster management. In addition to implementing the Regional Visualization & Monitoring System (SERVIR) in Mesoamerica and the Dominican Republic since 2005, since 2010 CATHALAC has served as a Regional Support Office of the United Nations Platform for Space-based Information for Disaster and Emergency Response (UN-SPIDER). Under the mandate of the 2009 Presidential Summit of the Tuxla Mechanism, the Center has also been implementing the Mesoamerican Territorial Information System (SMIT) platform for disaster risk reduction, in the context of the Proyecto Mesoamerica initiative. Additionally, since 2007, CATHALAC has served as a participating organization in the inter-governmental Group on Earth Observations (GEO) which is laying the groundwork for the eventual implementation of the Global Earth Observation System of Systems (GEOSS).

Visualizing the results

The Central America coastal vulnerability analysis data are presented in CATHALAC's Regional GeoViewer at: http://portalgis.cathalac.org/cathalac/maps/, and a technical summary of the study will be published in SERVIR (www.servir.net). For more information about CATHALAC's ongoing research and capacity-building programs, please visit: www.cathalac.org.

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