PLUM ISLAND — The beach erosion problem here is not yet as dire as in the Cape Cod community of Chatham, where a barrier beach was breached in April 2007, but the consequences could be even more severe, according to an observer who is familiar with both situations.

Science writer William Sargent, an Ipswich resident, has written a book about Chatham's beach erosion called "Storm Surge: A Coastal Village Battles the Rising Atlantic." The book tells the story of a fierce nor'easter in January 1987, which eroded the beach and caused a storm surge that breached the dunes, washing away houses and sending tons of sand and seawater into Chatham.

"Buildings that were lost in Chatham were camps, with no running water," he said. "Here, there are 750 winterized homes."

Though the erosion at Plum Island has slowed somewhat since spring, when the receding dunes threatened a number of homes, Sargent sees parallels between Chatham and Plum Island, and he believes the time to act is now.

Sargent, who gave a talk on the island last month sponsored by the Plum Island Beach Committee, visited the island center on a recent weekend to take a another look at the disappearing dunes.

An Army Corps of Engineers team that inspected Plum Island last month has recommended the installation of something called a geotube along about 600 linear feet of beach. Sargent endorsed that course of action as a temporary solution.

"They need to get some geotubes in here before winter," he said.

Geotubes are large fabric cylinders that are up to 9 feet tall when filled with sand. Additional sand is then heaped around the tubes.

Geotubes have been used in places like Texas and the Carolinas, the Army Corps team members said, to provide a soft barrier that slows down erosion.

Sargent also noted a stone groin at Plum Island Center appears to be blocking a south-to-north migration of sand. The stretch of beach north of the groin is showing the worst of the erosion. Removing the groin, Sargent said, might help the northerly part of the island — but only at the expense of the southerly beach.

The disrepair of the South Jetty at the northern tip of the island has been cited as a factor because it supposedly is channeling waves toward the center, where they scour away the sand.

"It's nice to think it's something humans did, because then we can fix it," Sargent said.

The ebb and flow of beaches "is a chronic problem" that shoreline communities can learn to anticipate, he said.

"Typically, every community is taken by surprise" when erosion becomes serious, he said.