A Puerto Rican flag flies on an empty beach at Ocean Park, in San Juan, Puerto Rico. (AP Photo/Carlos Giusti, File)

PR - Hurricane María Significantly Changed Puerto Rico Coasts, Says Report

SAN JUAN — Hurricane María tore through Puerto Rico more than five years ago, leaving damage that will mark the Caribbean archipelago for decades to come.

The energy grid has still not recovered and a deep collective trauma remains within many Puerto Ricans, but perhaps the most noticeable scar left by the hurricane physically is the changes it brought to the coastline.

María, a Category 4 storm that swept through Puerto Rico in September 2017, left the island with a “new coast,” according to a new study by the Institute of Investigation and Coastal Planification of Puerto Rico (CoRePI-PR).

The hurricane caused about 61 miles of coastline to migrate inland, particularly in Vieques, Arecibo, Loíza, Isabela, Culebra, Luquillo, Ponce, Hatillo, Manatí, and Cabo Rojo. The small island municipality of Vieques saw its coastline move 12 miles, according to the study “State of Puerto Rico’s Beaches Post-Hurricane Maria,” the results of which were presented on Wednesday at the University of Puerto Rico-Rio Piedras.

Unlike past studies, CoRePI-PR sought to investigate the state of beaches in all 44 coastal municipalities. About 67 percent of the Puerto Rican population, 2.4 million people, live in coastal municipalities. Within that percentage, 22 percent (728,000) live in a location at high risk for flooding.

“For years, the people of Puerto Rico have had their backs turned to coastal erosion,” principal investigator Dr. Maritza Barreto Orta said. She underscored the importance of having up-to-date data instead of having to rely on decades-old information that no longer applied in a post-María Puerto Rico.

Changes to the coastline between September 2017 and July 2018 have left more communities vulnerable to extreme weather events such as hurricanes or other tropical storms. Separate studies have found that the effects of climate change will cause hurricanes like María five years ago or the recent Fiona —which brought unprecedented flooding— to become more common.

“The implication when a water line moves inland over time is that in a future winter storm or hurricane storm event, then the extent of flooding will be greater than before,” Dr. Barreto Orta said. “Places where there is inland water line migration are examples of areas where we have to raise the planning flag because they are much more exposed areas than others.”

Changing Coastlines Lead to Gains and Losses

Hurricane María made landfall along Puerto Rico’s southern coast on September 20, 2017, causing a great amount of erosion and accretion in the island’s 1,285 beaches. In its wake, 42 percent of beaches showed some signs of erosion, while more than 58 percent showed signs of accretion.

Ten months later, in July 2018, 40 percent of beaches showed signs of erosion while 60 percent showed signs of accretion.

Researchers found new erosion zones on the southeast of the island, particularly in Patillas, Santa Isabel, Guayama, Juana Díaz, and Ponce. Although they had not yet identified the possible causes, they hypothesized that it could be due to the loss of natural erosion barriers, such as coral reefs, mangrove deforestation, and the effects of climate change or human impact in the area.

Researchers also identified 36 miles of dry beach that migrated to the inland water line. “The migration of beach planes inland could be an important indicator of sedimentary systems that are trying to reach their geomorphic equilibrium in the face of new scenarios in the area,” the study said.

“Having 58 km (36 miles) of coastline where the beaches are migrating inland is good news because it tells us that the beaches are finding their equilibrium” in the face of rising sea levels, said Barreto Orta, who’s also an oceanographer and a coast erosion specialist. “The bad news is that migration of beaches does not occur where there are structures, and the problem is that if the water continues to enter and the ‘backbeach’ does not move, it will cause a loss of beaches.”

“Backbeach” is the piece of land that lies behind the beach, stretching inward from the point of the high watermark. The study found the municipalities with the most migration were Vieques, Humacao, Hatillo, Mayagüez, Aguada, Arecibo, Camuy, Isabela, Vega Baja, and Rincón.

Even though Vieques experienced the most extensive loss in its coastline, Barreto Orta signaled that Aguada was the municipality most affected by coastal erosion

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