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FEMA Unveils Essex County Coastal Erosion Hazard Map

“The ultimate goal is to produce maps that can be used by communities as planning tools to help develop, maybe, adaptation strategies for sea level rise and ultimately, help the areas become more resilient.”

FEMA
(TNS) - The Federal Emergency Management Agency presented coastal erosion hazard projections for Essex County for 2030, 2050 and 2100, including Plum Island and Salisbury Beach .

In 2015, the federal agency's Technical Mapping Advisory Council recommended that FEMA look closer at coastal erosion and future conditions of sea level rise, Kerry Bogdan of FEMA's Region I explained during a virtual Essex County town hall Feb. 16 .

A year later, FEMA initiated a study that sought to map long-term erosion and future flood risks along New England coastlines.

Bogdan noted that the study is nonregulatory, so it will not be used to require certain homeowners to buy flood insurance.

"We did this as a risk hazard communication tool," she said, noting that it is aimed at informing homeowners and community officials of what areas may be at risk for coastal erosion over time.

"The ultimate goal is to produce maps that can be used by communities as planning tools to help develop, maybe, adaptation strategies for sea level rise and ultimately, help the areas become more resilient," said Amanda Oi , one of the coastal engineers that worked on this study.

Coastal erosion threatens not only properties, but sometimes, lives, she said.

"Long-term erosion is generally expected to accelerate due to future sea level rise, which is going to put even more areas at risk," Oi said.

The engineer noted that these maps can be used as planning tools, which would "help communities understand what their risks are and begin to develop adaptation strategies."

Oi pointed out a 2019 study by the First Street Foundation and Columbia University . The study found that coastal flooding and erosion caused property values along the coasts of Massachusetts , Maine , New Hampshire and Rhode Island to decrease by approximately $403.1 million between 2005 and 2017.

In addition to other studies by FEMA , a number of other agencies and organizations have conducted studies that have primarily looked at either "flooding and inundation due to future sea level or they've looked at the historical rates of erosion that have been observed in the past," the engineer said.

Oi said this study is "a little different in that we are taking sea level rise and we are calculating how much it's going to accelerate our observed erosion rates, and we're projecting those into the future hazard zones."

These rates are also projected over three timeframes — 2030, 2050 and 2100.

"It's important to note that these maps show areas that are at risk to future erosion," Oi said. "They do not predict exactly where the shoreline will be in the future."

FEMA started studying Essex County as part of this work in 2018 and looked at a mix of bluff-backed and sandy shorelines, as well as protected and exposed areas, the engineer said.

The federal agency performed a 1-D transect-based analysis, spacing areas of observation every 50 meters along the Essex County coast and resulting in nearly 2,800 transects.

FEMA relied on shoreline data from the 1800s to 2000s to calculate historical rates of shoreline change, Oi said.

For sea level rise scenarios, the agency utilized projections developed by the National Oceanic and Atmospheric Administration , which was recommended by the Technical Mapping Advisory Council .

For this study, FEMA looked at four levels of sea level rise projections, ranging from "low, which assumes the observed rate of sea level rise continues into the future, all the way to high, which assumes up to 2 meters of sea level rise by the year 2100," Oi said.

To access the map, go to https://fema.maps.arcgis.com/apps/webappviewer/index.html?id=a4aa86031a3a40be9d453d781ff210b3.

Once on the site, users can insert an address into the search bar and select specific layers to see various sea level rise scenarios.

Staff reporter Heather Alterisio can be reached via email at halterisio@newburyportnews.com or by phone at 978-961-3149. Follow her on Twitter @HeathAlt.

Staff reporter Heather Alterisio can be reached via email at halterisio@newburyportnews.com or by phone at 978-961-3149. Follow her on Twitter @HeathAlt.

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