Ocean forces continue to shape Katama cut
The Katama cut continues to provide an evolving example of the powerful natural forces that are at work shaping the Vineyard shoreline. It has also left Edgartown more vulnerable to flooding from storm generated tidal surges.
In April 2007, the one-two punch of storm-driven ocean waves and powerful spring tides knocked open a cut in Norton Point Beach, the two-mile long barrier beach that had linked Katama to Chappaquiddick, and left two long narrow spits of sand.
This spring a second narrow breach occurred in the Chappaquiddick section of Norton Point Beach, which grew into a separate opening. The result is a small sand bar island in the middle of the cut. How long that will last depends on the winds and tides.
A photo taken from a plane several weeks ago shows a wide opening, a sand bar in the middle and rows of breaking waves. Summer weather patterns are certain to further affect the shape of the beach.
Jo-Ann Taylor is a coastal planner with the Martha's Vineyard Commission. In a recent interview with The Times about the changes occurring at Norton Point, Ms. Taylor, whose background includes oceanographic research, said what is happening is nothing new.
She said eventually the opening will move east until the inlet turns itself into the Swan Pond, a small body of water located at behind the barrier beach at Wasque Point.
"It always strikes me, looking at the Swan Pond," she said, "how peaceful and bucolic it looks and its history is so turbulent. And that has happened over and over again."
With the caveat that the unexpected can happen, Ms. Taylor said that using history as a guide Vineyarders can expect the Chappy side to be very short on sand, and the cut will need ten to 15 years to seal off completely.
She said people are incredulous when they hear how long she expects the process to take but it is really just a drop in the bucket when viewed against the backdrop of geological time. "It is just important for us to enjoy the spectacle," she said.
Photo by Matthew Fuller
Beyond providing a convenient alternate off road vehicle route to Chappaquiddick and a place for recreational pursuits, the barrier beach also provided protection from the Atlantic Ocean. The loss of that important barrier means Katama Bay is exposed to the full brunt of any storms that sweep up from the south, especially a hurricane.
"What the barrier beach does is protect the harbor and the village from major storms, particularly storm surge," said Ms. Taylor.
According to the National Hurricane Center (www.nhc.noaa.gov), the greatest potential for loss of life due to a hurricane comes from storm surge, water that is pushed toward the shore by the force of the winds swirling around the storm. This advancing surge combines with the normal tides to create the hurricane storm tide, which can increase the mean water level 15 feet or more.
Ms. Taylor said the funnel shape of Katama bay would tend to accentuate a surge of water pushed up by any strong storm. Downtown Edgartown could be especially hard hit since many of it wharves are already underwater during astronomically high tides.
Ms. Taylor said there is no question that should the right weather conditions develop, Edgartown would face significant public and property safety issues associated with hurricane storm surge.
"And that exposure is going to be there until the breach closes," she said.