Sometime in the 1780S, John Tyler, a landowner on Smith Island in Maryland's Chesapeake Bay, dug a narrow boundary ditch in the soft ground to mark his property. After more than 220 years, wind and water in the bay have conspired to eat away at the land. Today the "ditch" is a waterway nearly a quarter-mile wide and an example of how nature is slowly consuming the island.
"Over the years it got wider and wider, but we still call it Tyler's Ditch," says local historian Jennings Evans.
Smith Island is actually a collection of small islands that together make up the last inhabited island in the Chesapeake Bay not connected by a bridge to the mainland.
Scientists calculate the water level in the bay is rising by a little more than an inch per decade: The sea is slowly taking over these specks of land, home to the hardy descendants of 17th-century English settlers.
"I know [an inch per decade] doesn't sound like much, but the reason for concern, especially in Maryland, is because the land is very low," says Michael Kearney, a University of Maryland geology professor who has studied the impact of sea-level rise on Chesapeake Bay.
Higher water levels mean stronger waves, increased erosion, rapid loss of marsh, and bigger storm surges. This could have a devastating effect in southern Maryland counties, where the average tide level extends more than a half-mile inland from the bay. That means waves from a big storm could penetrate far inland, Dr. Kearney adds.
Waverly Evans, a lifelong Smith islander, doesn't need a scientific study to tell him what's happening. He has been a witness as the creeping Chesapeake waters swallow what were once island homes.
As he guides his boat through Tyler's Ditch, Mr. Evans raises a weathered hand and points across the water to a marsh-and-grass-covered island.
It was on this now-abandoned parcel that Evans was born in 1926 and lived as a boy. People there tended gardens; their chickens and pigs roamed their yards. The 10 homes made up a small community. But the water's unrelenting attack on the little island forced the families to leave.
"Down through the years, the salt and the marsh ate in, and the erosion and everything, and people started to move to higher ground," Evans says.
'We were eroding something fierce'
In 2001, the Army Corps of Engineers completed a $2 million bulkhead project at the Smith Island town of Tylerton to protect the town and stop erosion. At high tide, water slaps at the metal barrier at a level clearly above the land on the other side.
"We were eroding something fierce, terrible. [The bulkhead] has really prolonged this little town, anyway," Evans says.
Tylerton, together with Ewell and Rhodes Point are the three hamlets where people live on Smith Island. The island has lost more than 3,200 of its 11,000 acres to the sea over the past 150 years. Of the remaining land, about 900 acres is habitable. The population has dwindled from a high of more than 800 in the early 1900s to about 250 today.
Evans may see the past as he cruises by the long-abandoned land of his boyhood home, but scientists who study sea-level rise are more likely to see the future of the Chesapeake Bay.
More than 1,000 square miles of shoreline are less than three feet above sea level, making the region one of the most vulnerable in the United States to future climate-change-induced sea-level rise and increased storm surges from weather events like hurricanes.
Erosion is eating away at the Chesapeake shoreline at the rate of 580 acres per year, and saltwater intrusion has wreaked havoc with wetlands and agricultural land. Bob Fitzgerald, soil conservation board chairman for Somerset County, which includes Smith Island, has seen land once under cultivation slowly convert to marsh and then open water.
"The acceleration over the past 10 to 15 years is unbelievable," Mr. Fitzgerald says. He figures that about 5 percent of the more than 140,000 acres of farmland in Somerset County has been lost to the bay in that time.
Holding back the bay everywhere is impossible. Bulkheads and revetments are a common sight. With miles of water to blow over, winds create powerful waves. In many places, these traditional approaches help to stop the onslaught.
The Maryland Eastern Shore Resource Conservation and Development Council (RC&D) is trying another approach. It's working with landowners to construct "living shorelines" to reverse the loss of land and re-create native habitat.
'Living shorelines' help stop erosion
"Living shorelines are all about creating marsh," says Bhaskaran Subramanian, natural sciences manager for RC&D. "If you create marsh, that is one of the most potent ways of stopping erosion."
Creating a living shoreline involves building a stone barrier, backfilling the area with sand, planting marsh grasses, and then letting nature take over.
Graham Donaldson, a Centreville, Md., resident, contacted RC&D after nearly 40 feet of his backyard washed away. He was beginning to wonder how long it would be until the remaining 60 feet behind his house slipped into the water.
His living shoreline project took nearly a year to complete, but Mr. Donaldson, a former agriculture official with the World Bank, is convinced that he made the right decision. The marsh has flourished. The one-third acre of new habitat has become home to crabs, fish, and birds.
"It's aesthetically pleasing; it's biologically very successful, which for a gardener is a reward; and it's environmentally very effective," Donaldson says.