The Bahamas could face a tripling of hurricane-related damage if surrounding ecosystems such as coral reefs and mangroves are lost or degraded, a new Stanford University-led study found.
The study, “Advancing Coastal Risk Reduction Science and Implementation by Accounting for Climate, Ecosystems, and People”, found that 15 percent of the country’s land mass is within a three meter sea level rise flood zone, giving The Bahamas the highest flood risk of any country in the Caribbean.
“Risk is compounded by the fact that the majority of the population lives in low elevation coastal zones less than 10 meters above sea level, within 5 km of the coastline,” read the report, which was published in Frontiers in Marine Science.
It read, “Modeled results show that the population most exposed to coastal hazards would more than double with future sea-level rise and more than triple if ecosystems were lost or degraded.
“We also found that ecosystem-based risk reduction differs across islands due to variation in a suite of ecological, physical and social variables.”
The study comes after Hurricane Dorian, a monster Category 5 storm, ravaged parts of Abaco, Grand Bahama and the surrounding cays. It left at least 67 dead, hundreds missing and thousands homeless. The majority of homes in Marsh Harbour, Abaco, were destroyed or severely damaged. Many reported that dangerous storm surges, as high as 20 feet, swept into their homes and in some cases dragged loved ones out.
The report found that the most susceptible coastlines in the country are those on the side of islands that “sit on extensive shallow banks, where the potential for significant storm surge is high”.
Grand Bahama is the most at risk island in the country, followed by Abaco, Acklins, Crooked Island, Andros and New Providence.
For Grand Bahama, the northern coast is the most exposed, and on Abaco, Acklins, Andros and Crooked Island the west coasts are the most exposed.
According to the study, nearly 10 percent of New Providence’s coastline is currently highly exposed.
“The most exposed areas on New Providence are primarily along the southern coast of the island where it is positioned on a shallow tongue of the Great Bahama Bank,” the report said.
The report found that coastal and nearshore ecosystems provide significant protection for the country from the impact of coastal hazards.
The ecosystems include coral reefs, sea grass and mangroves. The report found that loss of such ecosystems would very significantly increase the country’s susceptibility to those hazards.
“Our results suggest that if these habitats are lost, even under current sea-levels, the length of shoreline highly exposed to hazard throughout the country would quadruple,” it read.
On Abaco, about 25 percent of the population currently lives in highest risk areas, but the loss of ecosystems would result in nearly the entire island being at highest risk.
On New Providence, about three percent of the population is currently living in highest risk areas, but an additional nearly 10 percent, or 18,000 people, would be at highest risk with the loss of ecosystems.
On Grand Bahama, the report found that currently four percent of the population is living in highest risk areas, but a loss of habitat would result in nearly 25 percent of the population being at highest risk. On Exuma, only two percent of the population is currently living in high risk areas, but a loss of habitat would put over one third of the population at highest risk.
“We found that ecosystems provide coastal protection for islands where exposure is inherently high due to other factors (elevation, storm surge potential, etc.), and are equally important for maintaining low exposure of other island,” the report read.
“For example, Grand Bahama Island has the greatest extent of highly exposed shoreline of any island in The Bahamas (almost half of the island is at highest risk). However, Grand Bahama also benefits from coastal protection along over 300 kilometers of the island’s coastline by extensive seagrass beds, coral reef, mangrove, and coastal coppice forests.
“Our results suggest that if these habitats are lost, almost the entirety of Grand Bahama would be highly exposed relative to the rest of the country.
“In contrast, the shorelines of Great Inagua Island are less exposed to coastal hazard, due in part to higher elevations and lower storm surge potential relative to the rest of the country. But ecosystems, including a fringing reef encircling the island and mangrove forests, are also critical in protecting the island. We found that, like Grand Bahama, the loss of habitats would result in a 50 percent increase in exposure for Great Inagua Island.”
The protection of these natural habitats will become increasingly vital in the face of climate change and sea level rise. In response to the devastation associated with recent hurricanes, “the need to build coastal resilience is increasingly being recognized as a national priority for the security of Bahamian communities”, the report read.
However, it said that reliance on seawalls and other types of hardened shorelines is unsustainable due to the costs to build and maintain them.
“This is especially true for communities that depend on coastal and marine ecosystems for livelihoods and sustenance,” it read.
“Protecting and restoring coral reefs and coastal forests can be lower cost, sustainable alternatives for shoreline protection. However, decision-makers often lack basic information about where and under what conditions ecosystems reduce risk to coastal hazards and who would benefit.”