Washover Could Lead To New Break

By: Tim Wood

Topics: Erosion

Washovers on South Beach could create another break, officials say. Low spots that were washed over during recent storms are evident in this photo taken last week. SPENCER KENNARD PHOTO

CHATHAM – Recent winter storms have sent waves crashing over low sections of South Beach, and in one particular location created a washover that officials say could lead to a new break in the barrier beach.

Much of South Beach south of Lighthouse Beach is little more than strips of sand barely above high water. One spot about a half mile down the beach where the higher dunes give way to low, flat sand, just past the ramshackle collection of driftwood and found objects known as the Outermost Shack, is particularly susceptible to frequent washovers, especially in recent weeks.

A new cut in that area could cause sand to fill in Outermost Harbor and the former Southway areas located behind South Beach, and may also lead to further deterioration of the entrance channel to Chatham Harbor.

“I think a lot is going to happen in the next year or so,” said Dr. Graham Giese, director of the Land and Sea Interaction Program at the Center for Coastal Studies in Provincetown, who has studied the outer Cape's barrier beach system extensively.

A fourth break in this spot would have significant short-term effect, but would be just another step in the 150-year Nauset Beach cycle of breaching and regrowth which was initiated by the breach opposite Lighthouse Beach 30 years ago. A few years later South Beach attached to the mainland just south of Lighthouse Beach. Ultimately, the sand that now makes up South Beach will move west and south, said Giese.

“We know that it's headed toward a continuous barrier beach extending from Morris Island to Monomoy Point someday, as it has in the past,” he said.

South Beach has been washing over at low spots for years, said Coastal Resources Director Ted Keon. A more recent change, however, is that the deep navigation channel from the ocean into Chatham Harbor is working against the outer edge of South Beach, narrowing it further.

Unlike the original break and one that occurred opposite Minister's Point in 2007, a break at this location is not likely to become a channel with water flowing continuously at all tides. It is likely to be more like the 2013 break in South Beach further south, where most of the flow was in a westerly direction on the incoming tide from the Atlantic side of the beach. Giese likened it to a one-way street, with the incoming tide carrying sediment that would otherwise have ended up along the outer edge of the beach.

That may ultimately wash away all of the sand in front of the Beach and Tennis Club and properties to the south, which could eventually see erosion as they did in the early days of the original break, Giese said.

“All the problems they had before they'll have again,” he said. But that could be many years away – there's no way to tell just how long the process will take.

Eventually there could be a number of breaks along the length of South Beach. “These are just different ways of getting the sand east to west and north to south,” Giese said.

A break along South Beach could also result in less water flowing through the main inlet, Keon said, which could increase shoaling. That area, including the infamous Chatham Bar, has deteriorating in recent months – not uncommon in the winter – making the process of entering and leaving Chatham Harbor difficult even for experienced fishermen.

“It will not make it better,” Giese said of the effect another break could have on the inlet.

Ultimately, the movement of South Beach to the west and south could plug up Outermost Harbor and even close the channel between Morris Island and Monomoy, creating one continuous landform. It was like that in the past, when folks drove dune buggies all the way down to the tip of Monomoy.

Elevations on North Beach Island are also low and the spit experienced overwashing during the recent storms, Keon said. Storms have also cut into the outer dunes along North and Nauset Beach, he added.

The town's north and east facing town landings fared fairly well during the storms, he said, and remain in “good shape.”

There's a lot of interest in the South Beach situation among local folks. Resident Randy Saul created a Facebook page called Chatham's Three Breaks featuring photos and videos of the beach now and in the past. The visuals provide a glimpse into how often the beach terrain changes, despite the fact that the overall process evolves over decades. What's happening now, however, bears watching, Giese said.

“I think we should keep our eyes on things,” Giese said. “I'm in awe of the way nature's able to achieve its work.”